Gait and motor functions in cerebral palsy after bi-anodal transcranial direct current stimulation combined with treadmill training: A feasibility clinical study

Hikmat Hadoush; Nedal AbuSalem; Nihad A. Almasri; Nasim Alnuman; Alham Al-Sharman

doi:10.12688/f1000research.170839.2

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Research Article

Revised

Gait and motor functions in cerebral palsy after bi-anodal transcranial direct current stimulation combined with treadmill training: A feasibility clinical study

[version 2; peer review: 1 approved with reservations]

Hikmat Hadoush ^1,2, Nedal AbuSalem¹, Nihad A. Almasri^3,4, Nasim Alnuman⁵, Alham Al-Sharman^1,2

Hikmat Hadoush ^1,2, Nedal AbuSalem¹, [...] Nihad A. Almasri^3,4, Nasim Alnuman⁵, Alham Al-Sharman^1,2

PUBLISHED 11 Jul 2026

Author details Author details

¹ Department of Physiotherapy, University of Sharjah, Sharjah, Sharjah, United Arab Emirates
² Department of Rehabilitation Sciences, Jordan University of Science and Technology, Irbid, Jordan
³ Department of Physiotherapy, Qatar University, Doha, Doha, Qatar
⁴ Department of Physiotherapy, University of Jordan, Amman, Jordan
⁵ Department Biomedical engineering, German Jordanian University, Amman, Jordan

Hikmat Hadoush
Roles: Conceptualization, Formal Analysis, Methodology, Project Administration, Supervision, Writing – Original Draft Preparation, Writing – Review & Editing

Nedal AbuSalem
Roles: Data Curation, Formal Analysis, Investigation, Validation, Visualization, Writing – Review & Editing

Nihad A. Almasri
Roles: Formal Analysis, Methodology, Validation, Visualization, Writing – Review & Editing

Nasim Alnuman
Roles: Formal Analysis, Software, Validation, Visualization, Writing – Review & Editing

Alham Al-Sharman
Roles: Validation, Writing – Review & Editing

OPEN PEER REVIEW

REVIEWER STATUS

Abstract

Background

Children with cerebral palsy (CP) exhibit widespread alterations in cortical excitability and present with bilateral alterations in the bi-hemispheric sensorimotor functions, even when the initial brain lesion is unilateral.

Objective

This study evaluated the feasibility, safety, and preliminary efficacy of combining bilateral anodal transcranial direct current stimulation (tDCS) over the sensorimotor cortices with treadmill training in children with CP.

Method

A within-subjects case series was conducted with five children with CP. Participants received ten sessions of treadmill training (at 50% of their maximum over-ground speed) concurrently with bilateral anodal tDCS. Outcomes, assessed pre- and post-intervention, included postural alignment (medio-lateral and anterior-posterior), ankle dorsiflexion range of motion, gait variability, walking tolerance (6-minute walk test), motor function (GMFM-66), and hip/knee range of motion. Statistical analysis was performed using paired t-tests and effect sizes (Hedges’ g).

Results

The intervention was feasible and well-tolerated without any reported side effects. In addition, moderate to large effect sizes were observed in medio-lateral postural alignment (Hedges’ = 0.65) and left ankle passive dorsiflexion (Hedges’ = 1.49). Right ankle dorsiflexion showed a moderate improvement (Hedges’ = 0.77). Anterior-posterior alignment, gait variability, walking tolerance, gross motor function, or other ranges of motion showed minimal improvement.

Conclusion

Bilateral anodal tDCS stimulation combined with treadmill training therapy is a feasible and safe intervention for children with CP. The preliminary evidence of potentially clinically meaningful treatment effect in specific postural and impairment measures, provide preliminary treatment effect estimates that support the feasibility of conducting future adequately powered randomized controlled trials.

Keywords

Cerebral palsy, transcranial direct current stimulation, treadmill gait training, accelerometer gait analysis, motor function, range of motion, walking tolerance

Corresponding author: Hikmat Hadoush

Competing interests: No competing interests were disclosed.

Grant information: This study is supported by the Jordan University of Science and Technology and the Erasmus+ program of the European Union project entitled (establishment of an interdisciplinary clinical rehabilitation sciences master program at Just-CRS) (project no: “573758-EPP-1-2016-1-JOEPPKA2-CBHE-JP”).
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Copyright: © 2026 Hadoush H et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to cite: Hadoush H, AbuSalem N, A. Almasri N et al. Gait and motor functions in cerebral palsy after bi-anodal transcranial direct current stimulation combined with treadmill training: A feasibility clinical study [version 2; peer review: 1 approved with reservations]. F1000Research 2026, 15:637 (https://doi.org/10.12688/f1000research.170839.2) First published: 29 Apr 2026, 15:637 (https://doi.org/10.12688/f1000research.170839.1) Latest published: 11 Jul 2026, 15:637 (https://doi.org/10.12688/f1000research.170839.2)

Revised Amendments from Version 1

This version has been substantially revised in response to peer-review comments. The manuscript has been updated to improve methodological transparency, reporting consistency, and technical reproducibility. The intervention protocol has been expanded to include detailed tDCS parameters, including electrode size, current density, stimulation duration, ramp-up/ramp-down procedures, impedance monitoring, and a dedicated table summarizing the stimulation protocol. The gait assessment figure has been replaced with an appropriate illustration of the tri-axial accelerometer system used in the study, and inconsistencies in outcome measure terminology and citations have been corrected.
The statistical analysis has been revised to better reflect the exploratory nature of this feasibility study. Formal hypothesis testing and associated p-values have been removed, and the findings are now presented using an estimation-based approach with Hedges' g effect size estimates. Correspondingly, the Abstract, Results, Discussion, and Conclusion have been revised to avoid inferential claims and to present the findings as preliminary treatment effect estimates. Mechanistic interpretations have been moderated and are now presented as hypothesis-generating. Finally, the manuscript has been carefully edited to correct citation inconsistencies, improve clarity, and enhance overall reproducibility while maintaining open access to the complete de-identified participant-level dataset through the Zenodo repository.

See the authors' detailed response to the review by Umair Ahmed and Romasa Sarwar

Introduction

Motor control and coordination in pediatric cerebral palsy patients have been improved through various methods. Treadmill training demonstrates efficacy in enhancing gait velocity, balance, and functional independence. Furthermore, transcranial direct current stimulation (tDCS) presents a non-invasive and safe alternative to surgical or pharmacological treatments. Collectively, these interventions have proven effective in advancing gait performance and functional capabilities in this population.^1–3

Figure 1. The tDCS protocols.

A) shows the conventional tDCS precool done in previous literature, where the anodal stimulation only targeted the lesion side. Whereas B) shows the proposed tDCS stimulation in this study used bilateral anodal tDCS stimulation based on brain mapping data of a bilateral neuromotor deficit associated with reduced activation in bilateral corticospinal and sensorimotor pathways, even in cases of unilateral brain lesions.

The optimal protocol for administering tDCS to pediatric cerebral palsy patients has yet to be established. Contrary to earlier studies that utilized unilateral anodal stimulation targeting the contralateral motor cortex,^4–6 a hypothesis suggests that bilateral stimulation of both hemispheres could yield superior outcomes. This premise is supported by Nevalainen et al. (2012),⁷ who identified through magnetoencephalography (MEG) a widespread disruption in neural excitability within both sensory-motor cortices of children with CP. This bilateral impairment occurs even in cases of unilateral lesions and contributes to reduced activation in corticospinal pathways. Accordingly, subsequent research applying unilateral anodal tDCS to the ipsilateral motor cortex (non-lesioned hemisphere) demonstrated enhancements in motor functions such as reaching skills and movement duration.^8,9

As a feasibility study, this pilot research assessed the practicality and initial effects of administering bilateral anodal tDCS concurrently with treadmill training to enhance gait parameters, range of motion, and reduce spasticity in pediatric patients with diplegic CP.

Methods

Study design & participants

The study protocol received ethical approval based on the Declaration of Helsinki (JUST-420-2019). Besides, this study protocol and procedures were registered retrospectively in the National Clinical Trial Registry (https://clinicaltrials.gov/study/NCT07342660, Registration No.: NCT07342660). This is because the study originally registered within the Erasmus+ program database and the Jordan University of Science and Technology Deanship of Research system. However, internal registration would not be enabling the open access to the study protocol, Hereby, we proceeded with retrospective registration in a public registry and we clearly stated that in the registration database.

This exploratory feasibility case series employed a convenience sample of five children (aged 4–12 years) with spastic diplegic cerebral palsy recruited from the pediatric rehabilitation clinic. Inclusion criteria stipulated a Gross Motor Function Classification System (GMFCS) level of I-III, the ability to walk independently for at least 10 meters, and an IQ greater than 70. Key exclusion criteria included a history of orthopaedic surgery, neurolytic blocks, or Botox injections in the past six months, as well as the presence of concurrent orthopedic impairments, epilepsy, intracranial metal implants, or hearing aids. In addition, voluntary written informed consent was obtained from all participant children by their legal guardians before participation in the study.

Treadmill training & tDCS intervention

While prior research utilizing unilateral anodal tDCS in children with CP positioned a single anode over the C3 or C4 motor cortex and a cathode on the supra-orbital area according to the 10–20 EEG system,^5,7,8–11 the present study employed a bilateral montage. Using the 10–10 EEG system for more precise placement, two 4 × 4 cm saline-soaked sponge electrodes (16 cm² contact area) serving as the anodes were positioned over the left FC1 and right FC2 regions (encompassing motor and frontal areas), while two corresponding cathodes of identical size were positioned over the bilateral supra-orbital areas ( Figure 1).¹² A current intensity of 1 mA was delivered, corresponding to a current density of 0.0625 mA/cm². Stimulation was applied using a 3-second ramp-up and 3-second ramp-down period. Before each session, electrode-skin impedance was checked and maintained below 5 kΩ throughout stimulation to ensure stable current delivery and participant safety, Table 2.

Table 2. Bilateral anodal tDCS parameters.

Parameter	Value
Device	Neuroelectric tDCS
Stimulation type	Bilateral anodal tDCS
Electrode material	Saline-soaked sponge
Electrode size	4 × 4 cm (16 cm²)
Current intensity	1 mA
Current density	0.0625 mA/cm²
Anode locations	FC1 and FC2
Cathode locations	Bilateral supraorbital
Duration	10 min
Ramp-up	3 s
Ramp-down	3 s
Impedance	< 5 kΩ
Concurrent treadmill	Yes (entire 10 min)
Sessions	10
Frequency	5 sessions/week for 2 weeks

The therapeutic protocol commenced with two treadmill familiarization sessions. This was followed by ten combined treatment sessions, each consisting of a 12-minute interval: a 1-minute warm-up, a 10-minute simultaneous treadmill training and tDCS therapy period, and a 1-minute cool-down. Treadmill speed was initiated at 50% of the child’s maximum ground speed from the 6-Minute Walk Test (6MWT) and was progressively increased based on individual tolerance. Tolerance was gauged by the absence of fatigue complaints, a heart rate not exceeding 70% of maximum, and the maintenance of proper gait without shuffling. Assistants were present to provide support and verbal feedback to promote correct movement patterns. All enrolled participants completed the full intervention protocol, including all ten treatment sessions, without missed sessions, or withdrawals. The bilateral anodal tDCS was delivered continuously throughout the entire 10-minute treadmill training period, and throughout all sessions, children were continuously monitored for discomfort or adverse events, and stimulation was immediately discontinued if any intolerance occurred.

Outcome measures

Pre- and post-intervention data were collected, including body function measures like joint range of motion, activity measures such as walking endurance (6MWT), and motor function evaluation (GMFM-IS). Gait parameters in children walking on a 10-meter track were assessed using a tri-axial accelerometer measuring accelerations in x, y, and z axes ( Figure 2). Gait variability was determined using autocorrelation coefficients for each axis, indicating abnormality or normality. This method proved effective for studying gait function maturation in children by analysing deviations in each gait cycle relative to the mean value.^13–15

Figure 2. Tri-axial accelerometer-based gait assessment and data processing.

(A) Placement of the wearable tri-axial accelerometer over the lumbar region near the body's center of mass using an adjustable belt. (B) Orientation of the three orthogonal measurement axes: mediolateral (ML), anteroposterior (AP), and vertical (VT). (C) Schematic representation of the data acquisition and processing workflow. Acceleration signals recorded during overground walking were processed to quantify gait alignment (mediolateral and anteroposterior stability) and gait variability using autocorrelation analysis.

Data analysis

Given the exploratory nature of this feasibility study and the extremely small sample size (n = 5), the primary emphasis was placed on descriptive statistics and estimation of treatment effects rather than formal hypothesis testing. Mean ± standard deviation (SD) was calculated for all outcome measures. The magnitude of the intervention effect was estimated using Hedges’ g, which is recommended for studies with small sample sizes,¹⁶ because it provides a less biased estimate of standardized effect size. Effect sizes were interpreted according to conventional thresholds as small (0.2), moderate (0.5), and large (0.8). This analytical approach is consistent with current recommendations for pilot and feasibility studies, where estimation of treatment effects and identification of potential clinical signals are considered more informative than significance testing for guiding the design of future definitive trials. Gait outcomes were derived from the average of two 10-m walking trials completed before and after the intervention. The complete dataset is publicly available.¹⁷

Results

All five participants completed the ten planned intervention sessions, resulting in 100% adherence and no withdrawals. No stimulation-related side effects or intolerance were reported by the children, parents, or caregivers. The study found that after 10 sessions of bilateral anodal tDCS and treadmill treatment, there was a remarkable improvement in medio-lateral alignment during gait, with a large clinical effect size. However, there were no remarkable changes in anterior-posterior alignment and gait variability. Additionally, walking tolerance or distance travelled, and motor function showed minimal improvement after the treatment sessions. The treatment did have a remarkable impact on left ankle dorsiflexion and right ankle dorsiflexion, with large clinical effect sizes. However, the treatment had minimal effects on the passive range of motion of the left and right hip and knee (See details in Table 1).

Table 1. Outcome measures.

Demographic data	Age (years)	Height weight	Walking ground speed (km/hr.)
Participants (n = 5)	6.40 (0.9)	114.0 (5.4) cm 21.8 (2.3) kg	1.80 (0.53)
Outcome measures		Mean (SD)	Effect size (Hedges’)
Distance traveled (6MWT)	Pre	182.3 (52.9)	0.22
Distance traveled (6MWT)	Post	195.3 (54.4)	0.22
Motor function (GMFM-IS)	Pre	66.4 (1.5)	0.23
Motor function (GMFM-IS)	Post	66.0 (1.5)	0.23
Gait Spatiotemporal
Medio-lateral alignment	Pre	56.02 (7.9)	0.65
Medio-lateral alignment	Post	63.9 (7.8)	0.65
Anterior-posterior alignment	Pre	34.59 (19.9)	0.06
Anterior-posterior alignment	Post	35.69 (14.0)	0.06
Gait variability	Pre	0.11 (0.1)	−0.19
Gait variability	Post	0.10 (0.1)	−0.19
Passive ROM
Right ankle DF (knee extended)	Pre	11.0 (4.0)	0.77
Right ankle DF (knee extended)	Post	15.5 (6.3)	0.77
Left ankle DF (knee extended)	Pre	13.8 (4.0)	1.49
Left ankle DF (knee extended)	Post	19.6 (3.2)	1.49
Right knee flexion	Pre	101.3 (39.7)	0.18
Right knee flexion	Post	86.3 (39.0)	0.18
Left knee flexion	Pre	99.2 (39.0)	0.05
Left knee flexion	Post	86.7 (40.2)	0.05
Right hip abduction (knee extended)	Pre	29.6 (6.6)	0.09
Right hip abduction (knee extended)	Post	27.8 (2.8)	0.09
Left hip abduction (knee extended)	Pre	30.2 (5.3)	0.13
Left hip abduction (knee extended)	Post	26.0 (8.9)	0.13
Right hip extension	Pre	18.4 (5.0)	0.40
Right hip extension	Post	12.2 (4.7)	0.40
Left hip extension	Pre	16.2 (6.8)	0.14
Left hip extension	Post	13.0 (5.8)	0.14

Discussion

Two studies investigated the efficacy of integrating unilateral anodal tDCS with treadmill training to improve gait alignment in pediatric populations with CP.^8,10 The first reported improvements in balance functions, and static anterior/posterior, medio/lateral swaying,⁸ and the second reported improvements in pelvic tilting and distance traveled (6MWT). However, this study applied bilateral anodal tDCS over prefrontal and motor areas influenced by previous brain imaging findings⁷ of global excitability alterations and reduction in children with CP. Hereby, this study’s approach is reported to be safe with no side effects, and we may assume that this approach would improve results by targeting both sides of the brain.

To start with, the spatiotemporal parameters of gait can be evaluated in three axes: anteroposterior, medio-lateral, and vertical. Tri-axial accelerometers are used to record these dimensions, providing a valid tool for analyzing gait parameters.¹⁸

The observed improvement in medio-lateral alignment may be related to mechanisms previously proposed in the literature,¹⁴ where they reported that the major advantage of treadmill training over conventional ground training was in the lateral mechanical force the treadmill produced. In other words, the treadmill training will introduce mechanical lateral force to the body, and it was assumed that such mechanical lateral force generated by the treadmill would be behind the improvement in medio-lateral alignment in this study and previous studies.

On the other hand, in terms of gait variability, the gait pattern of children and adolescents with CP is often characterized by increased gait variability^15,16 and asymmetry¹⁹ compared with their healthy-developed peers. This manifests as stride-to-stride fluctuations. Normally, the fluctuations are relatively small in terms of the coefficient of variation in the gait speed and stride time.^20,21 Hereby, measuring gait variability is considered important because it serves as a sensitive and clinically relevant parameter in the evaluation of gait, mobility, fall risk, and the responses to therapeutic interventions.²¹ However, due to a lack of studies examining the changes in gait variability after the tDCS and treadmill treatments, this study’s results would be the first in this field and would add preliminary data that there are no remarkable improvements in gait variability post-tDCS treatment. Nevertheless, there is a crucial need for further studies in this regard.

Rehabilitation specialists use GMFM to measure motor function in children with CP for intervention effectiveness.²² This study finding comes from Grecco et al. (2015),¹⁰ who examined the effect of tDCS and treadmill gait training on 24 children with CP and found no significant changes in gross motor functions. This is because previous studies showed that significant improvements in gross motor function may require more time and intensive treatment, with one study reporting such improvement after 6 weeks¹⁸ and 12 weeks of intervention.²³ This highlights the importance of further research to understand the time and intensity required for interventions to have a significant impact on gross motor function in children with CP.

No research has explored how combining tDCS with treadmill training impacts passive ROM in children with spastic CP. The observed large treatment effect for ankle dorsiflexion may reflect the combined influence of treadmill training and bilateral anodal tDCS. Previous study showed that treadmill training can reduce ankle joint stiffness and improve heel strike in children with CP.²⁴ Besides, Treadmill training has been linked to increased anterior tibialis muscle activity, leading to improved ankle dorsiflexion.²⁵ In addition, tDCS could temporarily reduce spasticity in children with CP.²⁶ Hereby, the combined effect of tDCS and treadmill training may lead to improved ankle dorsiflexion by reducing joint stiffness and muscle spasticity.

Conclusion

This pilot study successfully demonstrated that the application of bilateral anodal transcranial direct current stimulation (tDCS) concurrently with standard treadmill gait training is both a safe and feasible intervention for children diagnosed with diplegic CP. This study effectively fulfills the role of an essential pre-clinical or proof-of-concept study, as recommended by medical research councils before proceeding to a large-scale RCT, which is recommended and crucially needed. However, this study is still an exploratory single-group feasibility study, the observed treatment effects should be interpreted cautiously and cannot be attributed solely to bilateral anodal tDCS or treadmill training. Future randomized controlled trials are required to determine treatment efficacy and to elucidate the mechanisms underlying the observed improvements.

Data availability

TDCS and Treadmill in CP is marked under a Creative Commons Attribution 4.0 International license (CC BY 4.0). To view a copy of this mark, visit: https://zenodo.org/records/18330054.¹⁷

References

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Version 2

VERSION 2 PUBLISHED 29 Apr 2026

Author details Author details

Hikmat Hadoush
Roles: Conceptualization, Formal Analysis, Methodology, Project Administration, Supervision, Writing – Original Draft Preparation, Writing – Review & Editing

Nedal AbuSalem
Roles: Data Curation, Formal Analysis, Investigation, Validation, Visualization, Writing – Review & Editing

Nihad A. Almasri
Roles: Formal Analysis, Methodology, Validation, Visualization, Writing – Review & Editing

Nasim Alnuman
Roles: Formal Analysis, Software, Validation, Visualization, Writing – Review & Editing

Alham Al-Sharman
Roles: Validation, Writing – Review & Editing

Competing interests

No competing interests were disclosed.

Grant information

This study is supported by the Jordan University of Science and Technology and the Erasmus+ program of the European Union project entitled (establishment of an interdisciplinary clinical rehabilitation sciences master program at Just-CRS) (project no: “573758-EPP-1-2016-1-JOEPPKA2-CBHE-JP”).
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Published: 11 Jul 2026, 15:637

https://doi.org/10.12688/f1000research.170839.2

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© 2026 Hadoush H et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Hadoush H, AbuSalem N, A. Almasri N et al. Gait and motor functions in cerebral palsy after bi-anodal transcranial direct current stimulation combined with treadmill training: A feasibility clinical study [version 2; peer review: 1 approved with reservations]. F1000Research 2026, 15:637 (https://doi.org/10.12688/f1000research.170839.2)

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Open Peer Review

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Reviewer Report 04 Jun 2026

Umair Ahmed, University of Lahore, Lahore, Pakistan

Romasa Sarwar, Physiotherapy, Link Medical Interface, Lahore, Punjab, Pakistan

Approved with Reservations

https://doi.org/10.5256/f1000research.188347.r485903

1. Is the work clearly and accurately presented and does it cite the current literature?
Partly
The manuscript is generally understandable and addresses a clinically relevant topic. The rationale for bilateral anodal tDCS is clearly introduced and is linked to prior evidence suggesting bilateral sensorimotor involvement in children with cerebral palsy. The topic is relevant, and most of the cited literature is appropriate to the intervention and population.
However, several presentation and citation issues require correction. The abstract reports the effect size for left ankle dorsiflexion as g = 1.42, whereas Table 1 reports g = 1.49 for the same outcome. One of these values appears to be incorrect and should be reconciled. In addition, p-values are reported for some outcomes in the abstract but are not consistently presented in Table 1, making it difficult to cross-reference the significance claims against the tabulated results.
There is also an unresolved sentence fragment in the Discussion: “Hereby, there However, this study applied bilateral anodal tDCS...”, which requires editorial correction. Reference 9, concerning wet cupping therapy in adults with chronic medical conditions, has no clear relevance to tDCS, treadmill training, gait, or cerebral palsy and appears to be misplaced. The Introduction also refers to Nevalainen et al. as a 2015 study, whereas the reference list appears to cite Nevalainen et al. as 2012. This citation inconsistency should be checked and corrected.

2. Is the study design appropriate and is the work technically sound?
Partly
The single-group feasibility case series design is acceptable for an early-stage investigation of safety, feasibility, and preliminary signal detection. The bilateral tDCS montage is rationally justified by prior neurophysiological evidence suggesting bilateral sensorimotor disruption in cerebral palsy. This is a technically interesting and potentially novel aspect of the study.
However, the technical reporting is incomplete. The tDCS protocol states the current intensity and electrode locations, but electrode size in cm² is not provided; therefore, current density cannot be calculated. Impedance monitoring, impedance thresholds, and ramp-up/ramp-down procedures are also not reported. These details are important for safety interpretation and technical reproducibility.
There is also inconsistency between the reported gait assessment method and Figure 2. The Methods section describes tri-axial accelerometry, whereas Figure 2 depicts a Vicon/Nexus motion-capture setup. It is unclear whether Vicon data were collected, whether they contributed to the reported outcomes, or whether the figure is unrelated to the data presented. This should be clarified.
The GMFM version is also inconsistently identified. The abstract refers to GMFM-66, whereas the Methods section and Table 1 refer to GMFM-IS. These are not interchangeable labels and may involve different scoring approaches. The correct instrument and scoring method should be confirmed and reported consistently.

3. Are sufficient details of methods and analysis provided to allow replication by others?
Partly
The manuscript provides some useful intervention details, including the number of treatment sessions, treadmill familiarisation sessions, treadmill speed basis, current intensity, and approximate electrode locations. However, several key details needed for replication are missing.

The tDCS electrode size, current density, impedance values or thresholds, and ramp-up/ramp-down procedures are not reported. Without these details, another research group could not fully reproduce the stimulation protocol.

Protocol Reporting

Electrode size (cm²) is not reported
Impedance monitoring during sessions is not mentioned
Ramp-up and ramp-down durations are not stated
It is not explicitly confirmed whether tDCS stimulation ran concurrently for the full 10-minute treadmill period
Recommendation: A dedicated tDCS parameter table following Peterchev et al. (2012) reporting standards should be added.

The statistical methods also require clarification. It is not clearly stated which outcomes were subjected to paired t-tests and which outcomes were interpreted using effect sizes only. This distinction should be explicitly stated in the Methods section or in a detailed table footnote.

Individual participant data are not presented in the manuscript. Given the very small sample size of five children, group means and standard deviations alone are insufficient to understand response variability, outliers, or consistency of response across participants.
Standard feasibility metrics are also incompletely reported. The number of children screened, number eligible, number declining participation, per-participant attendance, completion of all sessions, and treadmill speed progression are not clearly described. These details are especially important because the study is framed as a feasibility study and would inform the planning of a future trial.

4. If applicable, is the statistical analysis and its interpretation appropriate?
Partly
The statistical reporting requires substantial clarification before the preliminary efficacy claims can be interpreted reliably.

The Table 1 footnote reports t(9) = 3.97, p = 0.003 for medio-lateral alignment. However, the study included five participants in a single-group pre–post design. For a subject-level paired t-test with n = 5, the degrees of freedom should be n − 1 = 4, not 9. The reported df = 9 is therefore inconsistent with the stated sample size and paired design.

If df = 9 resulted from treating repeated walking trials as independent observations, this would raise a concern of pseudoreplication because repeated trials from the same child are not statistically independent. If trial-level data were analysed, the authors should use a method that accounts for clustering within participants, such as an appropriate repeated-measures or mixed-effects model.

Multiple outcomes appear to have been assessed for statistical significance, including walking tolerance, motor function, postural alignment, gait variability, and several passive range-of-motion outcomes. No correction for multiple comparisons is reported, and no clear primary efficacy outcome is identified. This increases the risk of Type I error, particularly in a sample of only five participants.

There are also internal reporting inconsistencies. The left ankle dorsiflexion effect size is reported as g = 1.42 in the abstract but g = 1.49 in Table 1. The abstract describes right ankle dorsiflexion as a moderate, non-significant improvement, whereas the Results section states that the treatment had a significant impact on both left and right ankle dorsiflexion. These inconsistencies should be corrected.

5. Are all the source data underlying the results available to ensure full reproducibility?
Partly
The manuscript provides a data availability statement and refers to a repository under a Creative Commons Attribution 4.0 license. Data is available on ZENODO. This is a positive aspect of the paper and supports transparency.
However, full reproducibility depends not only on the availability of the dataset but also on clarity of the analysis procedures. Because the manuscript does not clearly state which outcomes were analysed using paired t-tests, how repeated gait trials were handled, or how effect sizes were calculated, source data availability alone is not sufficient to ensure full reproducibility.

6. Are the conclusions drawn adequately supported by the results?
Partly
The conclusion that the intervention appears safe is supported by the reported absence of side effects or stimulation intolerance. However, the conclusion regarding feasibility should be more cautious because standard feasibility indicators, such as screening numbers, eligibility, recruitment flow, adherence, attendance, and protocol progression, are incompletely reported.

The conclusion that the intervention produced significant improvements in medio-lateral alignment and ankle dorsiflexion should also be interpreted cautiously. The reported degrees-of-freedom error, unclear handling of repeated gait trials, absence of correction for multiple outcome testing, and p-value reporting weaken confidence in the statistical significance claims.

The Discussion also appears to attribute observed changes to specific mechanisms, such as tDCS-related reduction in spasticity or treadmill-related lateral force effects. Because this was a combined-intervention, single-group case series without a control group, the study cannot separate the effects of tDCS, treadmill training, maturation, practice effects, or measurement variability. These mechanistic explanations should therefore be framed as speculative and hypothesis-generating rather than demonstrated findings.

The recommendation for future larger randomized controlled trials is appropriate and well aligned with the feasibility nature of the study. However, the manuscript should avoid overstating preliminary efficacy until the statistical and reporting issues are corrected.

Is the work clearly and accurately presented and does it cite the current literature?

Partly
Is the study design appropriate and is the work technically sound?

Partly
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Yes

References

1. Peterchev A, Wagner T, Miranda P, Nitsche M, et al.: Fundamentals of transcranial electric and magnetic stimulation dose: Definition, selection, and reporting practices. Brain Stimulation. 2012; 5 (4): 435-453 Publisher Full Text

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Neurological physiotherapy and rehabilitation; stroke rehabilitation; gait, balance and fall prevention; pediatric and adult neurorehabilitation; digital health, AI-assisted rehabilitation, and predictive analytics in physiotherapy; clinical trials and evidence-based rehabilitation interventions.

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however we have significant reservations, as outlined above.

CITE

Report a concern

Author Response 11 Jul 2026

Hikmat Hadoush, Department of Physiotherapy, University of Sharjah, Sharjah, United Arab Emirates

11 Jul 2026

Author Response
On behalf of this study authors, we sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined ... Continue reading
On behalf of this study authors, we sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised in the 2nd revised draft (submitted), point to point response and changes are shown below.

1. Comment Is the work clearly and accurately presented and does it cite the current literature?

The manuscript is generally understandable and addresses a clinically relevant topic. The rationale for bilateral anodal tDCS is clearly introduced and is linked to prior evidence suggesting bilateral sensorimotor involvement in children with cerebral palsy. The topic is relevant, and most of the cited literature is appropriate to the intervention and population.
However, several presentation and citation issues require correction. The abstract reports the effect size for left ankle dorsiflexion as g = 1.42, whereas Table 1 reports g = 1.49 for the same outcome. One of these values appears to be incorrect and should be reconciled. In addition, p-values are reported for some outcomes in the abstract but are not consistently presented in Table 1, making it difficult to cross-reference the significance claims against the tabulated results.
There is also an unresolved sentence fragment in the Discussion: “Hereby, there However, this study applied bilateral anodal tDCS...”, which requires editorial correction. Reference 9, concerning wet cupping therapy in adults with chronic medical conditions, has no clear relevance to tDCS, treadmill training, gait, or cerebral palsy and appears to be misplaced. The Introduction also refers to Nevalainen et al. as a 2015 study, whereas the reference list appears to cite Nevalainen et al. as 2012. This citation inconsistency should be checked and corrected.

Response:
We sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised.

Effect size inconsistency (g = 1.42 vs. g = 1.49):

Thank you for identifying this discrepancy. The value reported in the abstract (1.42) resulted from an earlier draft and has now been corrected to match Table 1. The abstract, tables, and manuscript have all been thoroughly cross-checked to ensure consistency.

Consistency of p-values between the Abstract and Table 1:

Response
We thank the reviewer for highlighting this inconsistency. Upon careful reconsideration of the statistical analysis, we revised our reporting approach to better align with the exploration nature of this feasibility study. Given the very small sample size (n = 5), we removed formal hypothesis testing and the associated p-values from both the Abstract and Table 1. Instead, the results are now reported consistently using Hedges' g effect size estimates, which represent the primary measure of treatment effects in this pilot study. This estimation-based approach is consistent with current recommendations for pilot and feasibility studies, where emphasis is placed on estimating the magnitude of intervention effects and identifying potential clinical signals rather than on formal statistical significance testing. Consequently, the Abstract and Table 1 are now fully consistent in their presentation of the study findings.

Editorial sentence fragment in the Discussion:

Response
We appreciate the reviewer for identifying this typographical error. The fragmented sentence:
"Hereby, there However, this study applied bilateral anodal tDCS..."
has been corrected to:
The Discussion section has also been carefully proofread to eliminate similar editorial issues.

Irrelevant Reference 9:

This reference has been removed and replaced with the appropriate publication describing ipsilateral anodal tDCS in children with cerebral palsy. The number of all subsequent references has been updated accordingly.

Nevalainen et al. citation year (2015 vs. 2012):

Thank you for noting this inconsistency. The correct publication year is 2012. The Introduction has been revised accordingly, and all in-text citations have been checked against the reference list to ensure complete consistency throughout the manuscript.

2. Comment:

The single-group feasibility case series design is acceptable for an early-stage investigation of safety, feasibility, and preliminary signal detection. The bilateral tDCS montage is rationally justified by prior neurophysiological evidence suggesting bilateral sensorimotor disruption in cerebral palsy. This is a technically interesting and potentially novel aspect of the study.

However, the technical reporting is incomplete. The tDCS protocol states the current intensity and electrode locations, but electrode size in cm² is not provided; therefore, current density cannot be calculated. Impedance monitoring, impedance thresholds, and ramp-up/ramp-down procedures are also not reported. These details are important for safety interpretation and technical reproducibility.

Response
We agree that additional technical information is essential for reproducibility and safety interpretation. Accordingly, the Methods section has been expanded to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area) and the corresponding current density (0.0625 mA/cm²). We have also clarified that stimulation was delivered using a gradual 3-second ramp-up and 3-second ramp-down procedure.
In addition, we added that electrode-skin impedance was monitored continuously throughout each session and maintained below the manufacturer's recommended safety threshold before stimulation commenced. These additions improve the reproducibility of the intervention and align the protocol with current reporting recommendations for tDCS studies.

There is also inconsistency between the reported gait assessment method and Figure 2. The Methods section describes tri-axial accelerometry, whereas Figure 2 depicts a Vicon/Nexus motion-capture setup. It is unclear whether Vicon data were collected, whether they contributed to the reported outcomes, or whether the figure is unrelated to the data presented. This should be clarified.

Response
We appreciate the reviewer for identifying this source of confusion. The gait outcomes reported in the present study were obtained exclusively from the tri-axial accelerometer system, which was used to calculate gait alignment and gait variability variables. A new appropriate figure is replaced the previous one with the appropriate illustration of the accelerometer-based gait assessment system used in the current study, and the accompanying legend has been revised accordingly.

The GMFM version is also inconsistently identified. The abstract refers to GMFM-66, whereas the Methods section and Table 1 refer to GMFM-IS. These are not interchangeable labels and may involve different scoring approaches. The correct instrument and scoring method should be confirmed and reported consistently.

Response
The abstract, method section, and Table 1 are now matched as GMFM-IS was the scale has been used.

3. Comment:

The manuscript provides some useful intervention details, including the number of treatment sessions, treadmill familiarisation sessions, treadmill speed basis, current intensity, and approximate electrode locations. However, several key details needed for replication are missing.

The tDCS electrode size, current density, impedance values or thresholds, and ramp-up/ramp-down procedures are not reported. Without these details, another research group could not fully reproduce the stimulation protocol.
Protocol Reporting
- Electrode size (cm²) is not reported
- Impedance monitoring during sessions is not mentioned
- Ramp-up and ramp-down durations are not stated
- It is not explicitly confirmed whether tDCS stimulation ran concurrently for the full 10-minute treadmill period
Recommendation: A dedicated tDCS parameter table following Peterchev et al. (2012) reporting standards should be added.
Response
We have expanded the intervention description in the method section to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area), current density (0.0625 mA/cm²), stimulation ramp-up and ramp-down periods (3 seconds each), impedance monitoring procedures, and in treadmill section we confirmation that bilateral anodal tDCS was delivered continuously throughout the entire 10-minute treadmill training period. These additional details improve reproducibility of the stimulation protocol.
In addition, a new Table 2 was created as recommended by the reviewer.

The statistical methods also require clarification. It is not clearly stated which outcomes were subjected to paired t-tests and which outcomes were interpreted using effect sizes only. This distinction should be explicitly stated in the Methods section or in a detailed table footnote.

Response
We thank the reviewer for this helpful observation. We agree that the statistical approach required clearer description. The Statistical Analysis section has been revised to explicitly state that this study is an exploratory feasibility study with an extremely small sample size (n = 5), the primary interpretation of the findings was based on Hedges' g effect size estimates rather than statistical significance alone. This approach is consistent with recommendations for pilot and feasibility studies, where estimation of treatment effects and assessment of clinical signals are generally considered more informative than formal hypothesis testing. Besides, Table 1 has also been revised.

Individual participant data are not presented in the manuscript. Given the very small sample size of five children, group means and standard deviations alone are insufficient to understand response variability, outliers, or consistency of response across participants.

Response
We thank the reviewer for this valuable suggestion. In accordance with the journal's open data policy and the editorial recommendations for F1000Research, the complete de-identified participant-level dataset has already been made publicly available [17] through the study's data repository, as cited in the Data Availability section of the manuscript. This publicly accessible dataset includes the individual outcome measures for all participants, allowing readers to examine participant-level responses, variability, and potential outliers directly. We believe that providing unrestricted access to the complete dataset offers greater transparency and facilitates independent verification and secondary analyses while maintaining participant confidentiality.

Standard feasibility metrics are also incompletely reported. The number of children screened, number eligible, number declining participation, per-participant attendance, completion of all sessions, and treadmill speed progression are not clearly described. These details are especially important because the study is framed as a feasibility study and would inform the planning of a future trial.

Response
We appreciate the reviewer's suggestion regarding the reporting of feasibility outcomes. This is an exploratory feasibility case series employing a convenience sample meeting specific inclusion criterion, hereby formal recruitment metrics such as the numbers screened, eligible, or declining participation were not applicable, as the primary feasibility objectives focused on intervention delivery, participant adherence, safety, and treatment tolerance.
To improve clarity, we have expanded the Results section to report that all enrolled participants completed the full intervention protocol, attended all ten treatment sessions, and experienced no dropouts or stimulation-related adverse events. In addition, the intervention description has been revised to clarify that treadmill speed was individualized and progressively increased according to each participant's tolerance while maintaining the predefined safety criteria.

4. Comment

If applicable, is the statistical analysis and its interpretation appropriate? Partly The statistical reporting requires substantial clarification before the preliminary efficacy claims can be interpreted reliably. The Table 1 footnote reports t(9) = 3.97, p = 0.003 for medio-lateral alignment. However, the study included five participants in a single-group pre–post design. For a subject-level paired t-test with n = 5, the degrees of freedom should be n − 1 = 4, not 9. The reported df = 9 is therefore inconsistent with the stated sample size and paired design. If df = 9 resulted from treating repeated walking trials as independent observations, this would raise a concern of pseudoreplication because repeated trials from the same child are not statistically independent. If trial-level data were analysed, the authors should use a method that accounts for clustering within participants, such as an appropriate repeated-measures or mixed-effects model. Multiple outcomes appear to have been assessed for statistical significance, including walking tolerance, motor function, postural alignment, gait variability, and several passive range-of-motion outcomes. No correction for multiple comparisons is reported, and no clear primary efficacy outcome is identified. This increases the risk of Type I error, particularly in a sample of only five participants. There are also internal reporting inconsistencies. The left ankle dorsiflexion effect size is reported as g = 1.42 in the abstract but g = 1.49 in Table 1. The abstract describes right ankle dorsiflexion as a moderate, non-significant improvement, whereas the Results section states that the treatment had a significant impact on both left and right ankle dorsiflexion. These inconsistencies should be corrected.

Response
We sincerely thank the reviewer for this thoughtful and constructive assessment of the statistical analysis. We carefully reconsidered the statistical approach considering the reviewer's comments and have substantially revised the manuscript.
Because this investigation was designed as an exploratory feasibility study with an extremely small sample size (n = 5), the statistical analysis focuses exclusively on descriptive statistics and Hedges' g effect size estimates to quantify the magnitude of the observed treatment effects.
Consequently, concerns regarding degrees of freedom, pseudoreplication, multiple comparisons, and Type I error no longer apply to the revised statistical analysis. All formal hypothesis testing, including paired t-tests, degrees of freedom, and associated p-values were removed.
In addition, the abstract and revised table 1 is now completely matched.

5. Comment:
The manuscript provides a data availability statement and refers to a repository under a Creative Commons Attribution 4.0 license. Data is available on ZENODO. This is a positive aspect of the paper and supports transparency. However, full reproducibility depends not only on the availability of the dataset but also on clarity of the analysis procedures. Because the manuscript does not clearly state which outcomes were analysed using paired t-tests, how repeated gait trials were handled, or how effect sizes were calculated, source data availability alone is not sufficient to ensure full reproducibility.

Response:
We sincerely thank the reviewer for recognizing the value of our open data repository in supporting research transparency. We agree that complete reproducibility requires not only access to the raw data but also a clear description of the analytical procedures.
Accordingly, we have revised the Statistical Analysis section to explicitly describe our estimation-based analytical approach. Because this was an exploratory feasibility study with an extremely small sample size (n = 5), formal hypothesis testing was removed, and all outcome measures were evaluated using descriptive statistics and Hedges' g effect size estimates. We have also clarified that gait outcomes were obtained by averaging two 10-m walking trials performed before and after the intervention, with these averaged values subsequently used for the effect size calculations. Together with the publicly available de-identified participant-level dataset deposited in Zenodo, these revisions provide sufficient methodological detail to allow independent verification and reproduction of the reported analyses.

6. comment Are the conclusions drawn adequately supported by the results?
Partly

The conclusion that the intervention appears safe is supported by the reported absence of side effects or stimulation intolerance. However, the conclusion regarding feasibility should be more cautious because standard feasibility indicators, such as screening numbers, eligibility, recruitment flow, adherence, attendance, and protocol progression, are incompletely reported.

The conclusion that the intervention produced significant improvements in medio-lateral alignment and ankle dorsiflexion should also be interpreted cautiously. The reported degrees-of-freedom error, unclear handling of repeated gait trials, absence of correction for multiple outcome testing, and p-value reporting weaken confidence in the statistical significance claims.

The Discussion also appears to attribute observed changes to specific mechanisms, such as tDCS-related reduction in spasticity or treadmill-related lateral force effects. Because this was a combined-intervention, single-group case series without a control group, the study cannot separate the effects of tDCS, treadmill training, maturation, practice effects, or measurement variability. These mechanistic explanations should therefore be framed as speculative and hypothesis-generating rather than demonstrated findings.

The recommendation for future larger randomized controlled trials is appropriate and well aligned with the feasibility nature of the study. However, the manuscript should avoid overstating preliminary efficacy until the statistical and reporting issues are corrected.

Response:
We thank the reviewer for these valuable comments. We have revised the manuscript accordingly. To better reflect the exploratory nature of this feasibility study, we removed all statements implying statistical significance and now present the findings as treatment effect estimates based on Hedges' g. The Discussion and Conclusion have been revised to avoid overstating efficacy, and mechanistic explanations are now clearly presented as speculative and hypothesis-generating rather than causal. We have also clarified that this convenience-sample feasibility study primarily evaluated intervention feasibility, safety, adherence, and treatment tolerance. Finally, the recommendation for future adequately powered randomized controlled trials has been retained and further emphasized.
On behalf of this study authors, we sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised in the 2nd revised draft (submitted), point to point response and changes are shown below.

1. Comment Is the work clearly and accurately presented and does it cite the current literature?

The manuscript is generally understandable and addresses a clinically relevant topic. The rationale for bilateral anodal tDCS is clearly introduced and is linked to prior evidence suggesting bilateral sensorimotor involvement in children with cerebral palsy. The topic is relevant, and most of the cited literature is appropriate to the intervention and population.
However, several presentation and citation issues require correction. The abstract reports the effect size for left ankle dorsiflexion as g = 1.42, whereas Table 1 reports g = 1.49 for the same outcome. One of these values appears to be incorrect and should be reconciled. In addition, p-values are reported for some outcomes in the abstract but are not consistently presented in Table 1, making it difficult to cross-reference the significance claims against the tabulated results.
There is also an unresolved sentence fragment in the Discussion: “Hereby, there However, this study applied bilateral anodal tDCS...”, which requires editorial correction. Reference 9, concerning wet cupping therapy in adults with chronic medical conditions, has no clear relevance to tDCS, treadmill training, gait, or cerebral palsy and appears to be misplaced. The Introduction also refers to Nevalainen et al. as a 2015 study, whereas the reference list appears to cite Nevalainen et al. as 2012. This citation inconsistency should be checked and corrected.

Response:
We sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised.

Effect size inconsistency (g = 1.42 vs. g = 1.49):

Thank you for identifying this discrepancy. The value reported in the abstract (1.42) resulted from an earlier draft and has now been corrected to match Table 1. The abstract, tables, and manuscript have all been thoroughly cross-checked to ensure consistency.

Consistency of p-values between the Abstract and Table 1:

Response
We thank the reviewer for highlighting this inconsistency. Upon careful reconsideration of the statistical analysis, we revised our reporting approach to better align with the exploration nature of this feasibility study. Given the very small sample size (n = 5), we removed formal hypothesis testing and the associated p-values from both the Abstract and Table 1. Instead, the results are now reported consistently using Hedges' g effect size estimates, which represent the primary measure of treatment effects in this pilot study. This estimation-based approach is consistent with current recommendations for pilot and feasibility studies, where emphasis is placed on estimating the magnitude of intervention effects and identifying potential clinical signals rather than on formal statistical significance testing. Consequently, the Abstract and Table 1 are now fully consistent in their presentation of the study findings.

Editorial sentence fragment in the Discussion:

Response
We appreciate the reviewer for identifying this typographical error. The fragmented sentence:
"Hereby, there However, this study applied bilateral anodal tDCS..."
has been corrected to:
The Discussion section has also been carefully proofread to eliminate similar editorial issues.

Irrelevant Reference 9:

This reference has been removed and replaced with the appropriate publication describing ipsilateral anodal tDCS in children with cerebral palsy. The number of all subsequent references has been updated accordingly.

Nevalainen et al. citation year (2015 vs. 2012):

Thank you for noting this inconsistency. The correct publication year is 2012. The Introduction has been revised accordingly, and all in-text citations have been checked against the reference list to ensure complete consistency throughout the manuscript.

2. Comment:

The single-group feasibility case series design is acceptable for an early-stage investigation of safety, feasibility, and preliminary signal detection. The bilateral tDCS montage is rationally justified by prior neurophysiological evidence suggesting bilateral sensorimotor disruption in cerebral palsy. This is a technically interesting and potentially novel aspect of the study.

However, the technical reporting is incomplete. The tDCS protocol states the current intensity and electrode locations, but electrode size in cm² is not provided; therefore, current density cannot be calculated. Impedance monitoring, impedance thresholds, and ramp-up/ramp-down procedures are also not reported. These details are important for safety interpretation and technical reproducibility.

Response
We agree that additional technical information is essential for reproducibility and safety interpretation. Accordingly, the Methods section has been expanded to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area) and the corresponding current density (0.0625 mA/cm²). We have also clarified that stimulation was delivered using a gradual 3-second ramp-up and 3-second ramp-down procedure.
In addition, we added that electrode-skin impedance was monitored continuously throughout each session and maintained below the manufacturer's recommended safety threshold before stimulation commenced. These additions improve the reproducibility of the intervention and align the protocol with current reporting recommendations for tDCS studies.

There is also inconsistency between the reported gait assessment method and Figure 2. The Methods section describes tri-axial accelerometry, whereas Figure 2 depicts a Vicon/Nexus motion-capture setup. It is unclear whether Vicon data were collected, whether they contributed to the reported outcomes, or whether the figure is unrelated to the data presented. This should be clarified.

Response
We appreciate the reviewer for identifying this source of confusion. The gait outcomes reported in the present study were obtained exclusively from the tri-axial accelerometer system, which was used to calculate gait alignment and gait variability variables. A new appropriate figure is replaced the previous one with the appropriate illustration of the accelerometer-based gait assessment system used in the current study, and the accompanying legend has been revised accordingly.

The GMFM version is also inconsistently identified. The abstract refers to GMFM-66, whereas the Methods section and Table 1 refer to GMFM-IS. These are not interchangeable labels and may involve different scoring approaches. The correct instrument and scoring method should be confirmed and reported consistently.

Response
The abstract, method section, and Table 1 are now matched as GMFM-IS was the scale has been used.

3. Comment:

The manuscript provides some useful intervention details, including the number of treatment sessions, treadmill familiarisation sessions, treadmill speed basis, current intensity, and approximate electrode locations. However, several key details needed for replication are missing.

The tDCS electrode size, current density, impedance values or thresholds, and ramp-up/ramp-down procedures are not reported. Without these details, another research group could not fully reproduce the stimulation protocol.
Protocol Reporting
- Electrode size (cm²) is not reported
- Impedance monitoring during sessions is not mentioned
- Ramp-up and ramp-down durations are not stated
- It is not explicitly confirmed whether tDCS stimulation ran concurrently for the full 10-minute treadmill period
Recommendation: A dedicated tDCS parameter table following Peterchev et al. (2012) reporting standards should be added.
Response
We have expanded the intervention description in the method section to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area), current density (0.0625 mA/cm²), stimulation ramp-up and ramp-down periods (3 seconds each), impedance monitoring procedures, and in treadmill section we confirmation that bilateral anodal tDCS was delivered continuously throughout the entire 10-minute treadmill training period. These additional details improve reproducibility of the stimulation protocol.
In addition, a new Table 2 was created as recommended by the reviewer.

The statistical methods also require clarification. It is not clearly stated which outcomes were subjected to paired t-tests and which outcomes were interpreted using effect sizes only. This distinction should be explicitly stated in the Methods section or in a detailed table footnote.

Response
We thank the reviewer for this helpful observation. We agree that the statistical approach required clearer description. The Statistical Analysis section has been revised to explicitly state that this study is an exploratory feasibility study with an extremely small sample size (n = 5), the primary interpretation of the findings was based on Hedges' g effect size estimates rather than statistical significance alone. This approach is consistent with recommendations for pilot and feasibility studies, where estimation of treatment effects and assessment of clinical signals are generally considered more informative than formal hypothesis testing. Besides, Table 1 has also been revised.

Individual participant data are not presented in the manuscript. Given the very small sample size of five children, group means and standard deviations alone are insufficient to understand response variability, outliers, or consistency of response across participants.

Response
We thank the reviewer for this valuable suggestion. In accordance with the journal's open data policy and the editorial recommendations for F1000Research, the complete de-identified participant-level dataset has already been made publicly available [17] through the study's data repository, as cited in the Data Availability section of the manuscript. This publicly accessible dataset includes the individual outcome measures for all participants, allowing readers to examine participant-level responses, variability, and potential outliers directly. We believe that providing unrestricted access to the complete dataset offers greater transparency and facilitates independent verification and secondary analyses while maintaining participant confidentiality.

Standard feasibility metrics are also incompletely reported. The number of children screened, number eligible, number declining participation, per-participant attendance, completion of all sessions, and treadmill speed progression are not clearly described. These details are especially important because the study is framed as a feasibility study and would inform the planning of a future trial.

Response
We appreciate the reviewer's suggestion regarding the reporting of feasibility outcomes. This is an exploratory feasibility case series employing a convenience sample meeting specific inclusion criterion, hereby formal recruitment metrics such as the numbers screened, eligible, or declining participation were not applicable, as the primary feasibility objectives focused on intervention delivery, participant adherence, safety, and treatment tolerance.
To improve clarity, we have expanded the Results section to report that all enrolled participants completed the full intervention protocol, attended all ten treatment sessions, and experienced no dropouts or stimulation-related adverse events. In addition, the intervention description has been revised to clarify that treadmill speed was individualized and progressively increased according to each participant's tolerance while maintaining the predefined safety criteria.

4. Comment

If applicable, is the statistical analysis and its interpretation appropriate? Partly The statistical reporting requires substantial clarification before the preliminary efficacy claims can be interpreted reliably. The Table 1 footnote reports t(9) = 3.97, p = 0.003 for medio-lateral alignment. However, the study included five participants in a single-group pre–post design. For a subject-level paired t-test with n = 5, the degrees of freedom should be n − 1 = 4, not 9. The reported df = 9 is therefore inconsistent with the stated sample size and paired design. If df = 9 resulted from treating repeated walking trials as independent observations, this would raise a concern of pseudoreplication because repeated trials from the same child are not statistically independent. If trial-level data were analysed, the authors should use a method that accounts for clustering within participants, such as an appropriate repeated-measures or mixed-effects model. Multiple outcomes appear to have been assessed for statistical significance, including walking tolerance, motor function, postural alignment, gait variability, and several passive range-of-motion outcomes. No correction for multiple comparisons is reported, and no clear primary efficacy outcome is identified. This increases the risk of Type I error, particularly in a sample of only five participants. There are also internal reporting inconsistencies. The left ankle dorsiflexion effect size is reported as g = 1.42 in the abstract but g = 1.49 in Table 1. The abstract describes right ankle dorsiflexion as a moderate, non-significant improvement, whereas the Results section states that the treatment had a significant impact on both left and right ankle dorsiflexion. These inconsistencies should be corrected.

Response
We sincerely thank the reviewer for this thoughtful and constructive assessment of the statistical analysis. We carefully reconsidered the statistical approach considering the reviewer's comments and have substantially revised the manuscript.
Because this investigation was designed as an exploratory feasibility study with an extremely small sample size (n = 5), the statistical analysis focuses exclusively on descriptive statistics and Hedges' g effect size estimates to quantify the magnitude of the observed treatment effects.
Consequently, concerns regarding degrees of freedom, pseudoreplication, multiple comparisons, and Type I error no longer apply to the revised statistical analysis. All formal hypothesis testing, including paired t-tests, degrees of freedom, and associated p-values were removed.
In addition, the abstract and revised table 1 is now completely matched.

5. Comment:
The manuscript provides a data availability statement and refers to a repository under a Creative Commons Attribution 4.0 license. Data is available on ZENODO. This is a positive aspect of the paper and supports transparency. However, full reproducibility depends not only on the availability of the dataset but also on clarity of the analysis procedures. Because the manuscript does not clearly state which outcomes were analysed using paired t-tests, how repeated gait trials were handled, or how effect sizes were calculated, source data availability alone is not sufficient to ensure full reproducibility.

Response:
We sincerely thank the reviewer for recognizing the value of our open data repository in supporting research transparency. We agree that complete reproducibility requires not only access to the raw data but also a clear description of the analytical procedures.
Accordingly, we have revised the Statistical Analysis section to explicitly describe our estimation-based analytical approach. Because this was an exploratory feasibility study with an extremely small sample size (n = 5), formal hypothesis testing was removed, and all outcome measures were evaluated using descriptive statistics and Hedges' g effect size estimates. We have also clarified that gait outcomes were obtained by averaging two 10-m walking trials performed before and after the intervention, with these averaged values subsequently used for the effect size calculations. Together with the publicly available de-identified participant-level dataset deposited in Zenodo, these revisions provide sufficient methodological detail to allow independent verification and reproduction of the reported analyses.

6. comment Are the conclusions drawn adequately supported by the results?
Partly

The conclusion that the intervention appears safe is supported by the reported absence of side effects or stimulation intolerance. However, the conclusion regarding feasibility should be more cautious because standard feasibility indicators, such as screening numbers, eligibility, recruitment flow, adherence, attendance, and protocol progression, are incompletely reported.

The conclusion that the intervention produced significant improvements in medio-lateral alignment and ankle dorsiflexion should also be interpreted cautiously. The reported degrees-of-freedom error, unclear handling of repeated gait trials, absence of correction for multiple outcome testing, and p-value reporting weaken confidence in the statistical significance claims.

The Discussion also appears to attribute observed changes to specific mechanisms, such as tDCS-related reduction in spasticity or treadmill-related lateral force effects. Because this was a combined-intervention, single-group case series without a control group, the study cannot separate the effects of tDCS, treadmill training, maturation, practice effects, or measurement variability. These mechanistic explanations should therefore be framed as speculative and hypothesis-generating rather than demonstrated findings.

The recommendation for future larger randomized controlled trials is appropriate and well aligned with the feasibility nature of the study. However, the manuscript should avoid overstating preliminary efficacy until the statistical and reporting issues are corrected.

Response:
We thank the reviewer for these valuable comments. We have revised the manuscript accordingly. To better reflect the exploratory nature of this feasibility study, we removed all statements implying statistical significance and now present the findings as treatment effect estimates based on Hedges' g. The Discussion and Conclusion have been revised to avoid overstating efficacy, and mechanistic explanations are now clearly presented as speculative and hypothesis-generating rather than causal. We have also clarified that this convenience-sample feasibility study primarily evaluated intervention feasibility, safety, adherence, and treatment tolerance. Finally, the recommendation for future adequately powered randomized controlled trials has been retained and further emphasized.
Competing Interests: No competing interests were disclosed. Close
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COMMENTS ON THIS REPORT

Author Response 11 Jul 2026

Hikmat Hadoush, Department of Physiotherapy, University of Sharjah, Sharjah, United Arab Emirates

11 Jul 2026

Author Response
On behalf of this study authors, we sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined ... Continue reading
On behalf of this study authors, we sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised in the 2nd revised draft (submitted), point to point response and changes are shown below.

1. Comment Is the work clearly and accurately presented and does it cite the current literature?

The manuscript is generally understandable and addresses a clinically relevant topic. The rationale for bilateral anodal tDCS is clearly introduced and is linked to prior evidence suggesting bilateral sensorimotor involvement in children with cerebral palsy. The topic is relevant, and most of the cited literature is appropriate to the intervention and population.
However, several presentation and citation issues require correction. The abstract reports the effect size for left ankle dorsiflexion as g = 1.42, whereas Table 1 reports g = 1.49 for the same outcome. One of these values appears to be incorrect and should be reconciled. In addition, p-values are reported for some outcomes in the abstract but are not consistently presented in Table 1, making it difficult to cross-reference the significance claims against the tabulated results.
There is also an unresolved sentence fragment in the Discussion: “Hereby, there However, this study applied bilateral anodal tDCS...”, which requires editorial correction. Reference 9, concerning wet cupping therapy in adults with chronic medical conditions, has no clear relevance to tDCS, treadmill training, gait, or cerebral palsy and appears to be misplaced. The Introduction also refers to Nevalainen et al. as a 2015 study, whereas the reference list appears to cite Nevalainen et al. as 2012. This citation inconsistency should be checked and corrected.

Response:
We sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised.

Effect size inconsistency (g = 1.42 vs. g = 1.49):

Thank you for identifying this discrepancy. The value reported in the abstract (1.42) resulted from an earlier draft and has now been corrected to match Table 1. The abstract, tables, and manuscript have all been thoroughly cross-checked to ensure consistency.

Consistency of p-values between the Abstract and Table 1:

Response
We thank the reviewer for highlighting this inconsistency. Upon careful reconsideration of the statistical analysis, we revised our reporting approach to better align with the exploration nature of this feasibility study. Given the very small sample size (n = 5), we removed formal hypothesis testing and the associated p-values from both the Abstract and Table 1. Instead, the results are now reported consistently using Hedges' g effect size estimates, which represent the primary measure of treatment effects in this pilot study. This estimation-based approach is consistent with current recommendations for pilot and feasibility studies, where emphasis is placed on estimating the magnitude of intervention effects and identifying potential clinical signals rather than on formal statistical significance testing. Consequently, the Abstract and Table 1 are now fully consistent in their presentation of the study findings.

Editorial sentence fragment in the Discussion:

Response
We appreciate the reviewer for identifying this typographical error. The fragmented sentence:
"Hereby, there However, this study applied bilateral anodal tDCS..."
has been corrected to:
The Discussion section has also been carefully proofread to eliminate similar editorial issues.

Irrelevant Reference 9:

This reference has been removed and replaced with the appropriate publication describing ipsilateral anodal tDCS in children with cerebral palsy. The number of all subsequent references has been updated accordingly.

Nevalainen et al. citation year (2015 vs. 2012):

Thank you for noting this inconsistency. The correct publication year is 2012. The Introduction has been revised accordingly, and all in-text citations have been checked against the reference list to ensure complete consistency throughout the manuscript.

2. Comment:

The single-group feasibility case series design is acceptable for an early-stage investigation of safety, feasibility, and preliminary signal detection. The bilateral tDCS montage is rationally justified by prior neurophysiological evidence suggesting bilateral sensorimotor disruption in cerebral palsy. This is a technically interesting and potentially novel aspect of the study.

However, the technical reporting is incomplete. The tDCS protocol states the current intensity and electrode locations, but electrode size in cm² is not provided; therefore, current density cannot be calculated. Impedance monitoring, impedance thresholds, and ramp-up/ramp-down procedures are also not reported. These details are important for safety interpretation and technical reproducibility.

Response
We agree that additional technical information is essential for reproducibility and safety interpretation. Accordingly, the Methods section has been expanded to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area) and the corresponding current density (0.0625 mA/cm²). We have also clarified that stimulation was delivered using a gradual 3-second ramp-up and 3-second ramp-down procedure.
In addition, we added that electrode-skin impedance was monitored continuously throughout each session and maintained below the manufacturer's recommended safety threshold before stimulation commenced. These additions improve the reproducibility of the intervention and align the protocol with current reporting recommendations for tDCS studies.

There is also inconsistency between the reported gait assessment method and Figure 2. The Methods section describes tri-axial accelerometry, whereas Figure 2 depicts a Vicon/Nexus motion-capture setup. It is unclear whether Vicon data were collected, whether they contributed to the reported outcomes, or whether the figure is unrelated to the data presented. This should be clarified.

Response
We appreciate the reviewer for identifying this source of confusion. The gait outcomes reported in the present study were obtained exclusively from the tri-axial accelerometer system, which was used to calculate gait alignment and gait variability variables. A new appropriate figure is replaced the previous one with the appropriate illustration of the accelerometer-based gait assessment system used in the current study, and the accompanying legend has been revised accordingly.

The GMFM version is also inconsistently identified. The abstract refers to GMFM-66, whereas the Methods section and Table 1 refer to GMFM-IS. These are not interchangeable labels and may involve different scoring approaches. The correct instrument and scoring method should be confirmed and reported consistently.

Response
The abstract, method section, and Table 1 are now matched as GMFM-IS was the scale has been used.

3. Comment:

The manuscript provides some useful intervention details, including the number of treatment sessions, treadmill familiarisation sessions, treadmill speed basis, current intensity, and approximate electrode locations. However, several key details needed for replication are missing.

The tDCS electrode size, current density, impedance values or thresholds, and ramp-up/ramp-down procedures are not reported. Without these details, another research group could not fully reproduce the stimulation protocol.
Protocol Reporting
- Electrode size (cm²) is not reported
- Impedance monitoring during sessions is not mentioned
- Ramp-up and ramp-down durations are not stated
- It is not explicitly confirmed whether tDCS stimulation ran concurrently for the full 10-minute treadmill period
Recommendation: A dedicated tDCS parameter table following Peterchev et al. (2012) reporting standards should be added.
Response
We have expanded the intervention description in the method section to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area), current density (0.0625 mA/cm²), stimulation ramp-up and ramp-down periods (3 seconds each), impedance monitoring procedures, and in treadmill section we confirmation that bilateral anodal tDCS was delivered continuously throughout the entire 10-minute treadmill training period. These additional details improve reproducibility of the stimulation protocol.
In addition, a new Table 2 was created as recommended by the reviewer.

The statistical methods also require clarification. It is not clearly stated which outcomes were subjected to paired t-tests and which outcomes were interpreted using effect sizes only. This distinction should be explicitly stated in the Methods section or in a detailed table footnote.

Response
We thank the reviewer for this helpful observation. We agree that the statistical approach required clearer description. The Statistical Analysis section has been revised to explicitly state that this study is an exploratory feasibility study with an extremely small sample size (n = 5), the primary interpretation of the findings was based on Hedges' g effect size estimates rather than statistical significance alone. This approach is consistent with recommendations for pilot and feasibility studies, where estimation of treatment effects and assessment of clinical signals are generally considered more informative than formal hypothesis testing. Besides, Table 1 has also been revised.

Individual participant data are not presented in the manuscript. Given the very small sample size of five children, group means and standard deviations alone are insufficient to understand response variability, outliers, or consistency of response across participants.

Response
We thank the reviewer for this valuable suggestion. In accordance with the journal's open data policy and the editorial recommendations for F1000Research, the complete de-identified participant-level dataset has already been made publicly available [17] through the study's data repository, as cited in the Data Availability section of the manuscript. This publicly accessible dataset includes the individual outcome measures for all participants, allowing readers to examine participant-level responses, variability, and potential outliers directly. We believe that providing unrestricted access to the complete dataset offers greater transparency and facilitates independent verification and secondary analyses while maintaining participant confidentiality.

Standard feasibility metrics are also incompletely reported. The number of children screened, number eligible, number declining participation, per-participant attendance, completion of all sessions, and treadmill speed progression are not clearly described. These details are especially important because the study is framed as a feasibility study and would inform the planning of a future trial.

Response
We appreciate the reviewer's suggestion regarding the reporting of feasibility outcomes. This is an exploratory feasibility case series employing a convenience sample meeting specific inclusion criterion, hereby formal recruitment metrics such as the numbers screened, eligible, or declining participation were not applicable, as the primary feasibility objectives focused on intervention delivery, participant adherence, safety, and treatment tolerance.
To improve clarity, we have expanded the Results section to report that all enrolled participants completed the full intervention protocol, attended all ten treatment sessions, and experienced no dropouts or stimulation-related adverse events. In addition, the intervention description has been revised to clarify that treadmill speed was individualized and progressively increased according to each participant's tolerance while maintaining the predefined safety criteria.

4. Comment

If applicable, is the statistical analysis and its interpretation appropriate? Partly The statistical reporting requires substantial clarification before the preliminary efficacy claims can be interpreted reliably. The Table 1 footnote reports t(9) = 3.97, p = 0.003 for medio-lateral alignment. However, the study included five participants in a single-group pre–post design. For a subject-level paired t-test with n = 5, the degrees of freedom should be n − 1 = 4, not 9. The reported df = 9 is therefore inconsistent with the stated sample size and paired design. If df = 9 resulted from treating repeated walking trials as independent observations, this would raise a concern of pseudoreplication because repeated trials from the same child are not statistically independent. If trial-level data were analysed, the authors should use a method that accounts for clustering within participants, such as an appropriate repeated-measures or mixed-effects model. Multiple outcomes appear to have been assessed for statistical significance, including walking tolerance, motor function, postural alignment, gait variability, and several passive range-of-motion outcomes. No correction for multiple comparisons is reported, and no clear primary efficacy outcome is identified. This increases the risk of Type I error, particularly in a sample of only five participants. There are also internal reporting inconsistencies. The left ankle dorsiflexion effect size is reported as g = 1.42 in the abstract but g = 1.49 in Table 1. The abstract describes right ankle dorsiflexion as a moderate, non-significant improvement, whereas the Results section states that the treatment had a significant impact on both left and right ankle dorsiflexion. These inconsistencies should be corrected.

Response
We sincerely thank the reviewer for this thoughtful and constructive assessment of the statistical analysis. We carefully reconsidered the statistical approach considering the reviewer's comments and have substantially revised the manuscript.
Because this investigation was designed as an exploratory feasibility study with an extremely small sample size (n = 5), the statistical analysis focuses exclusively on descriptive statistics and Hedges' g effect size estimates to quantify the magnitude of the observed treatment effects.
Consequently, concerns regarding degrees of freedom, pseudoreplication, multiple comparisons, and Type I error no longer apply to the revised statistical analysis. All formal hypothesis testing, including paired t-tests, degrees of freedom, and associated p-values were removed.
In addition, the abstract and revised table 1 is now completely matched.

5. Comment:
The manuscript provides a data availability statement and refers to a repository under a Creative Commons Attribution 4.0 license. Data is available on ZENODO. This is a positive aspect of the paper and supports transparency. However, full reproducibility depends not only on the availability of the dataset but also on clarity of the analysis procedures. Because the manuscript does not clearly state which outcomes were analysed using paired t-tests, how repeated gait trials were handled, or how effect sizes were calculated, source data availability alone is not sufficient to ensure full reproducibility.

Response:
We sincerely thank the reviewer for recognizing the value of our open data repository in supporting research transparency. We agree that complete reproducibility requires not only access to the raw data but also a clear description of the analytical procedures.
Accordingly, we have revised the Statistical Analysis section to explicitly describe our estimation-based analytical approach. Because this was an exploratory feasibility study with an extremely small sample size (n = 5), formal hypothesis testing was removed, and all outcome measures were evaluated using descriptive statistics and Hedges' g effect size estimates. We have also clarified that gait outcomes were obtained by averaging two 10-m walking trials performed before and after the intervention, with these averaged values subsequently used for the effect size calculations. Together with the publicly available de-identified participant-level dataset deposited in Zenodo, these revisions provide sufficient methodological detail to allow independent verification and reproduction of the reported analyses.

6. comment Are the conclusions drawn adequately supported by the results?
Partly

The conclusion that the intervention appears safe is supported by the reported absence of side effects or stimulation intolerance. However, the conclusion regarding feasibility should be more cautious because standard feasibility indicators, such as screening numbers, eligibility, recruitment flow, adherence, attendance, and protocol progression, are incompletely reported.

The conclusion that the intervention produced significant improvements in medio-lateral alignment and ankle dorsiflexion should also be interpreted cautiously. The reported degrees-of-freedom error, unclear handling of repeated gait trials, absence of correction for multiple outcome testing, and p-value reporting weaken confidence in the statistical significance claims.

The Discussion also appears to attribute observed changes to specific mechanisms, such as tDCS-related reduction in spasticity or treadmill-related lateral force effects. Because this was a combined-intervention, single-group case series without a control group, the study cannot separate the effects of tDCS, treadmill training, maturation, practice effects, or measurement variability. These mechanistic explanations should therefore be framed as speculative and hypothesis-generating rather than demonstrated findings.

The recommendation for future larger randomized controlled trials is appropriate and well aligned with the feasibility nature of the study. However, the manuscript should avoid overstating preliminary efficacy until the statistical and reporting issues are corrected.

Response:
We thank the reviewer for these valuable comments. We have revised the manuscript accordingly. To better reflect the exploratory nature of this feasibility study, we removed all statements implying statistical significance and now present the findings as treatment effect estimates based on Hedges' g. The Discussion and Conclusion have been revised to avoid overstating efficacy, and mechanistic explanations are now clearly presented as speculative and hypothesis-generating rather than causal. We have also clarified that this convenience-sample feasibility study primarily evaluated intervention feasibility, safety, adherence, and treatment tolerance. Finally, the recommendation for future adequately powered randomized controlled trials has been retained and further emphasized.
On behalf of this study authors, we sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised in the 2nd revised draft (submitted), point to point response and changes are shown below.

1. Comment Is the work clearly and accurately presented and does it cite the current literature?

The manuscript is generally understandable and addresses a clinically relevant topic. The rationale for bilateral anodal tDCS is clearly introduced and is linked to prior evidence suggesting bilateral sensorimotor involvement in children with cerebral palsy. The topic is relevant, and most of the cited literature is appropriate to the intervention and population.
However, several presentation and citation issues require correction. The abstract reports the effect size for left ankle dorsiflexion as g = 1.42, whereas Table 1 reports g = 1.49 for the same outcome. One of these values appears to be incorrect and should be reconciled. In addition, p-values are reported for some outcomes in the abstract but are not consistently presented in Table 1, making it difficult to cross-reference the significance claims against the tabulated results.
There is also an unresolved sentence fragment in the Discussion: “Hereby, there However, this study applied bilateral anodal tDCS...”, which requires editorial correction. Reference 9, concerning wet cupping therapy in adults with chronic medical conditions, has no clear relevance to tDCS, treadmill training, gait, or cerebral palsy and appears to be misplaced. The Introduction also refers to Nevalainen et al. as a 2015 study, whereas the reference list appears to cite Nevalainen et al. as 2012. This citation inconsistency should be checked and corrected.

Response:
We sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised.

Effect size inconsistency (g = 1.42 vs. g = 1.49):

Thank you for identifying this discrepancy. The value reported in the abstract (1.42) resulted from an earlier draft and has now been corrected to match Table 1. The abstract, tables, and manuscript have all been thoroughly cross-checked to ensure consistency.

Consistency of p-values between the Abstract and Table 1:

Response
We thank the reviewer for highlighting this inconsistency. Upon careful reconsideration of the statistical analysis, we revised our reporting approach to better align with the exploration nature of this feasibility study. Given the very small sample size (n = 5), we removed formal hypothesis testing and the associated p-values from both the Abstract and Table 1. Instead, the results are now reported consistently using Hedges' g effect size estimates, which represent the primary measure of treatment effects in this pilot study. This estimation-based approach is consistent with current recommendations for pilot and feasibility studies, where emphasis is placed on estimating the magnitude of intervention effects and identifying potential clinical signals rather than on formal statistical significance testing. Consequently, the Abstract and Table 1 are now fully consistent in their presentation of the study findings.

Editorial sentence fragment in the Discussion:

Response
We appreciate the reviewer for identifying this typographical error. The fragmented sentence:
"Hereby, there However, this study applied bilateral anodal tDCS..."
has been corrected to:
The Discussion section has also been carefully proofread to eliminate similar editorial issues.

Irrelevant Reference 9:

This reference has been removed and replaced with the appropriate publication describing ipsilateral anodal tDCS in children with cerebral palsy. The number of all subsequent references has been updated accordingly.

Nevalainen et al. citation year (2015 vs. 2012):

Thank you for noting this inconsistency. The correct publication year is 2012. The Introduction has been revised accordingly, and all in-text citations have been checked against the reference list to ensure complete consistency throughout the manuscript.

2. Comment:

The single-group feasibility case series design is acceptable for an early-stage investigation of safety, feasibility, and preliminary signal detection. The bilateral tDCS montage is rationally justified by prior neurophysiological evidence suggesting bilateral sensorimotor disruption in cerebral palsy. This is a technically interesting and potentially novel aspect of the study.

However, the technical reporting is incomplete. The tDCS protocol states the current intensity and electrode locations, but electrode size in cm² is not provided; therefore, current density cannot be calculated. Impedance monitoring, impedance thresholds, and ramp-up/ramp-down procedures are also not reported. These details are important for safety interpretation and technical reproducibility.

Response
We agree that additional technical information is essential for reproducibility and safety interpretation. Accordingly, the Methods section has been expanded to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area) and the corresponding current density (0.0625 mA/cm²). We have also clarified that stimulation was delivered using a gradual 3-second ramp-up and 3-second ramp-down procedure.
In addition, we added that electrode-skin impedance was monitored continuously throughout each session and maintained below the manufacturer's recommended safety threshold before stimulation commenced. These additions improve the reproducibility of the intervention and align the protocol with current reporting recommendations for tDCS studies.

There is also inconsistency between the reported gait assessment method and Figure 2. The Methods section describes tri-axial accelerometry, whereas Figure 2 depicts a Vicon/Nexus motion-capture setup. It is unclear whether Vicon data were collected, whether they contributed to the reported outcomes, or whether the figure is unrelated to the data presented. This should be clarified.

Response
We appreciate the reviewer for identifying this source of confusion. The gait outcomes reported in the present study were obtained exclusively from the tri-axial accelerometer system, which was used to calculate gait alignment and gait variability variables. A new appropriate figure is replaced the previous one with the appropriate illustration of the accelerometer-based gait assessment system used in the current study, and the accompanying legend has been revised accordingly.

The GMFM version is also inconsistently identified. The abstract refers to GMFM-66, whereas the Methods section and Table 1 refer to GMFM-IS. These are not interchangeable labels and may involve different scoring approaches. The correct instrument and scoring method should be confirmed and reported consistently.

Response
The abstract, method section, and Table 1 are now matched as GMFM-IS was the scale has been used.

3. Comment:

The manuscript provides some useful intervention details, including the number of treatment sessions, treadmill familiarisation sessions, treadmill speed basis, current intensity, and approximate electrode locations. However, several key details needed for replication are missing.

The tDCS electrode size, current density, impedance values or thresholds, and ramp-up/ramp-down procedures are not reported. Without these details, another research group could not fully reproduce the stimulation protocol.
Protocol Reporting
- Electrode size (cm²) is not reported
- Impedance monitoring during sessions is not mentioned
- Ramp-up and ramp-down durations are not stated
- It is not explicitly confirmed whether tDCS stimulation ran concurrently for the full 10-minute treadmill period
Recommendation: A dedicated tDCS parameter table following Peterchev et al. (2012) reporting standards should be added.
Response
We have expanded the intervention description in the method section to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area), current density (0.0625 mA/cm²), stimulation ramp-up and ramp-down periods (3 seconds each), impedance monitoring procedures, and in treadmill section we confirmation that bilateral anodal tDCS was delivered continuously throughout the entire 10-minute treadmill training period. These additional details improve reproducibility of the stimulation protocol.
In addition, a new Table 2 was created as recommended by the reviewer.

The statistical methods also require clarification. It is not clearly stated which outcomes were subjected to paired t-tests and which outcomes were interpreted using effect sizes only. This distinction should be explicitly stated in the Methods section or in a detailed table footnote.

Response
We thank the reviewer for this helpful observation. We agree that the statistical approach required clearer description. The Statistical Analysis section has been revised to explicitly state that this study is an exploratory feasibility study with an extremely small sample size (n = 5), the primary interpretation of the findings was based on Hedges' g effect size estimates rather than statistical significance alone. This approach is consistent with recommendations for pilot and feasibility studies, where estimation of treatment effects and assessment of clinical signals are generally considered more informative than formal hypothesis testing. Besides, Table 1 has also been revised.

Individual participant data are not presented in the manuscript. Given the very small sample size of five children, group means and standard deviations alone are insufficient to understand response variability, outliers, or consistency of response across participants.

Response
We thank the reviewer for this valuable suggestion. In accordance with the journal's open data policy and the editorial recommendations for F1000Research, the complete de-identified participant-level dataset has already been made publicly available [17] through the study's data repository, as cited in the Data Availability section of the manuscript. This publicly accessible dataset includes the individual outcome measures for all participants, allowing readers to examine participant-level responses, variability, and potential outliers directly. We believe that providing unrestricted access to the complete dataset offers greater transparency and facilitates independent verification and secondary analyses while maintaining participant confidentiality.

Standard feasibility metrics are also incompletely reported. The number of children screened, number eligible, number declining participation, per-participant attendance, completion of all sessions, and treadmill speed progression are not clearly described. These details are especially important because the study is framed as a feasibility study and would inform the planning of a future trial.

Response
We appreciate the reviewer's suggestion regarding the reporting of feasibility outcomes. This is an exploratory feasibility case series employing a convenience sample meeting specific inclusion criterion, hereby formal recruitment metrics such as the numbers screened, eligible, or declining participation were not applicable, as the primary feasibility objectives focused on intervention delivery, participant adherence, safety, and treatment tolerance.
To improve clarity, we have expanded the Results section to report that all enrolled participants completed the full intervention protocol, attended all ten treatment sessions, and experienced no dropouts or stimulation-related adverse events. In addition, the intervention description has been revised to clarify that treadmill speed was individualized and progressively increased according to each participant's tolerance while maintaining the predefined safety criteria.

4. Comment

If applicable, is the statistical analysis and its interpretation appropriate? Partly The statistical reporting requires substantial clarification before the preliminary efficacy claims can be interpreted reliably. The Table 1 footnote reports t(9) = 3.97, p = 0.003 for medio-lateral alignment. However, the study included five participants in a single-group pre–post design. For a subject-level paired t-test with n = 5, the degrees of freedom should be n − 1 = 4, not 9. The reported df = 9 is therefore inconsistent with the stated sample size and paired design. If df = 9 resulted from treating repeated walking trials as independent observations, this would raise a concern of pseudoreplication because repeated trials from the same child are not statistically independent. If trial-level data were analysed, the authors should use a method that accounts for clustering within participants, such as an appropriate repeated-measures or mixed-effects model. Multiple outcomes appear to have been assessed for statistical significance, including walking tolerance, motor function, postural alignment, gait variability, and several passive range-of-motion outcomes. No correction for multiple comparisons is reported, and no clear primary efficacy outcome is identified. This increases the risk of Type I error, particularly in a sample of only five participants. There are also internal reporting inconsistencies. The left ankle dorsiflexion effect size is reported as g = 1.42 in the abstract but g = 1.49 in Table 1. The abstract describes right ankle dorsiflexion as a moderate, non-significant improvement, whereas the Results section states that the treatment had a significant impact on both left and right ankle dorsiflexion. These inconsistencies should be corrected.

Response
We sincerely thank the reviewer for this thoughtful and constructive assessment of the statistical analysis. We carefully reconsidered the statistical approach considering the reviewer's comments and have substantially revised the manuscript.
Because this investigation was designed as an exploratory feasibility study with an extremely small sample size (n = 5), the statistical analysis focuses exclusively on descriptive statistics and Hedges' g effect size estimates to quantify the magnitude of the observed treatment effects.
Consequently, concerns regarding degrees of freedom, pseudoreplication, multiple comparisons, and Type I error no longer apply to the revised statistical analysis. All formal hypothesis testing, including paired t-tests, degrees of freedom, and associated p-values were removed.
In addition, the abstract and revised table 1 is now completely matched.

5. Comment:
The manuscript provides a data availability statement and refers to a repository under a Creative Commons Attribution 4.0 license. Data is available on ZENODO. This is a positive aspect of the paper and supports transparency. However, full reproducibility depends not only on the availability of the dataset but also on clarity of the analysis procedures. Because the manuscript does not clearly state which outcomes were analysed using paired t-tests, how repeated gait trials were handled, or how effect sizes were calculated, source data availability alone is not sufficient to ensure full reproducibility.

Response:
We sincerely thank the reviewer for recognizing the value of our open data repository in supporting research transparency. We agree that complete reproducibility requires not only access to the raw data but also a clear description of the analytical procedures.
Accordingly, we have revised the Statistical Analysis section to explicitly describe our estimation-based analytical approach. Because this was an exploratory feasibility study with an extremely small sample size (n = 5), formal hypothesis testing was removed, and all outcome measures were evaluated using descriptive statistics and Hedges' g effect size estimates. We have also clarified that gait outcomes were obtained by averaging two 10-m walking trials performed before and after the intervention, with these averaged values subsequently used for the effect size calculations. Together with the publicly available de-identified participant-level dataset deposited in Zenodo, these revisions provide sufficient methodological detail to allow independent verification and reproduction of the reported analyses.

6. comment Are the conclusions drawn adequately supported by the results?
Partly

The conclusion that the intervention appears safe is supported by the reported absence of side effects or stimulation intolerance. However, the conclusion regarding feasibility should be more cautious because standard feasibility indicators, such as screening numbers, eligibility, recruitment flow, adherence, attendance, and protocol progression, are incompletely reported.

The conclusion that the intervention produced significant improvements in medio-lateral alignment and ankle dorsiflexion should also be interpreted cautiously. The reported degrees-of-freedom error, unclear handling of repeated gait trials, absence of correction for multiple outcome testing, and p-value reporting weaken confidence in the statistical significance claims.

The Discussion also appears to attribute observed changes to specific mechanisms, such as tDCS-related reduction in spasticity or treadmill-related lateral force effects. Because this was a combined-intervention, single-group case series without a control group, the study cannot separate the effects of tDCS, treadmill training, maturation, practice effects, or measurement variability. These mechanistic explanations should therefore be framed as speculative and hypothesis-generating rather than demonstrated findings.

The recommendation for future larger randomized controlled trials is appropriate and well aligned with the feasibility nature of the study. However, the manuscript should avoid overstating preliminary efficacy until the statistical and reporting issues are corrected.

Response:
We thank the reviewer for these valuable comments. We have revised the manuscript accordingly. To better reflect the exploratory nature of this feasibility study, we removed all statements implying statistical significance and now present the findings as treatment effect estimates based on Hedges' g. The Discussion and Conclusion have been revised to avoid overstating efficacy, and mechanistic explanations are now clearly presented as speculative and hypothesis-generating rather than causal. We have also clarified that this convenience-sample feasibility study primarily evaluated intervention feasibility, safety, adherence, and treatment tolerance. Finally, the recommendation for future adequately powered randomized controlled trials has been retained and further emphasized.
Competing Interests: No competing interests were disclosed. Close
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Version 2 (revision) 11 Jul 26
Version 1 29 Apr 26	read

Umair Ahmed, University of Lahore, Lahore, Pakistan

Romasa Sarwar, Link Medical Interface, Lahore, Pakistan

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04 Jun 2026 | for Version 1

Umair Ahmed, University of Lahore, Lahore, Pakistan

Romasa Sarwar, Physiotherapy, Link Medical Interface, Lahore, Punjab, Pakistan

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Approved With Reservations

Electrode size (cm²) is not reported
Impedance monitoring during sessions is not mentioned
Ramp-up and ramp-down durations are not stated
It is not explicitly confirmed whether tDCS stimulation ran concurrently for the full 10-minute treadmill period
Recommendation: A dedicated tDCS parameter table following Peterchev et al. (2012) reporting standards should be added.

Is the work clearly and accurately presented and does it cite the current literature?

Partly
Is the study design appropriate and is the work technically sound?

Partly
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Yes

References

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Neurological physiotherapy and rehabilitation; stroke rehabilitation; gait, balance and fall prevention; pediatric and adult neurorehabilitation; digital health, AI-assisted rehabilitation, and predictive analytics in physiotherapy; clinical trials and evidence-based rehabilitation interventions.

Respond to this report

Responses (1)

Author Response

11 Jul 2026

Hikmat Hadoush, Department of Physiotherapy, University of Sharjah, Sharjah, United Arab Emirates

On behalf of this study authors, we sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised in the 2nd revised draft (submitted), point to point response and changes are shown below.

1. Comment Is the work clearly and accurately presented and does it cite the current literature?

The manuscript is generally understandable and addresses a clinically relevant topic. The rationale for bilateral anodal tDCS is clearly introduced and is linked to prior evidence suggesting bilateral sensorimotor involvement in children with cerebral palsy. The topic is relevant, and most of the cited literature is appropriate to the intervention and population.
However, several presentation and citation issues require correction. The abstract reports the effect size for left ankle dorsiflexion as g = 1.42, whereas Table 1 reports g = 1.49 for the same outcome. One of these values appears to be incorrect and should be reconciled. In addition, p-values are reported for some outcomes in the abstract but are not consistently presented in Table 1, making it difficult to cross-reference the significance claims against the tabulated results.
There is also an unresolved sentence fragment in the Discussion: “Hereby, there However, this study applied bilateral anodal tDCS...”, which requires editorial correction. Reference 9, concerning wet cupping therapy in adults with chronic medical conditions, has no clear relevance to tDCS, treadmill training, gait, or cerebral palsy and appears to be misplaced. The Introduction also refers to Nevalainen et al. as a 2015 study, whereas the reference list appears to cite Nevalainen et al. as 2012. This citation inconsistency should be checked and corrected.

Response:
We sincerely thank the reviewer for the positive evaluation of our study and for recognizing the clinical relevance of investigating bilateral anodal tDCS combined with treadmill training in children with cerebral palsy. We appreciate the careful review and have addressed all of the presentation and citation issues raised.

Effect size inconsistency (g = 1.42 vs. g = 1.49):

Thank you for identifying this discrepancy. The value reported in the abstract (1.42) resulted from an earlier draft and has now been corrected to match Table 1. The abstract, tables, and manuscript have all been thoroughly cross-checked to ensure consistency.

Consistency of p-values between the Abstract and Table 1:

Response
We thank the reviewer for highlighting this inconsistency. Upon careful reconsideration of the statistical analysis, we revised our reporting approach to better align with the exploration nature of this feasibility study. Given the very small sample size (n = 5), we removed formal hypothesis testing and the associated p-values from both the Abstract and Table 1. Instead, the results are now reported consistently using Hedges' g effect size estimates, which represent the primary measure of treatment effects in this pilot study. This estimation-based approach is consistent with current recommendations for pilot and feasibility studies, where emphasis is placed on estimating the magnitude of intervention effects and identifying potential clinical signals rather than on formal statistical significance testing. Consequently, the Abstract and Table 1 are now fully consistent in their presentation of the study findings.

Editorial sentence fragment in the Discussion:

Response
We appreciate the reviewer for identifying this typographical error. The fragmented sentence:
"Hereby, there However, this study applied bilateral anodal tDCS..."
has been corrected to:
The Discussion section has also been carefully proofread to eliminate similar editorial issues.

Irrelevant Reference 9:

This reference has been removed and replaced with the appropriate publication describing ipsilateral anodal tDCS in children with cerebral palsy. The number of all subsequent references has been updated accordingly.

Nevalainen et al. citation year (2015 vs. 2012):

Thank you for noting this inconsistency. The correct publication year is 2012. The Introduction has been revised accordingly, and all in-text citations have been checked against the reference list to ensure complete consistency throughout the manuscript.

2. Comment:

The single-group feasibility case series design is acceptable for an early-stage investigation of safety, feasibility, and preliminary signal detection. The bilateral tDCS montage is rationally justified by prior neurophysiological evidence suggesting bilateral sensorimotor disruption in cerebral palsy. This is a technically interesting and potentially novel aspect of the study.

However, the technical reporting is incomplete. The tDCS protocol states the current intensity and electrode locations, but electrode size in cm² is not provided; therefore, current density cannot be calculated. Impedance monitoring, impedance thresholds, and ramp-up/ramp-down procedures are also not reported. These details are important for safety interpretation and technical reproducibility.

Response
We agree that additional technical information is essential for reproducibility and safety interpretation. Accordingly, the Methods section has been expanded to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area) and the corresponding current density (0.0625 mA/cm²). We have also clarified that stimulation was delivered using a gradual 3-second ramp-up and 3-second ramp-down procedure.
In addition, we added that electrode-skin impedance was monitored continuously throughout each session and maintained below the manufacturer's recommended safety threshold before stimulation commenced. These additions improve the reproducibility of the intervention and align the protocol with current reporting recommendations for tDCS studies.

There is also inconsistency between the reported gait assessment method and Figure 2. The Methods section describes tri-axial accelerometry, whereas Figure 2 depicts a Vicon/Nexus motion-capture setup. It is unclear whether Vicon data were collected, whether they contributed to the reported outcomes, or whether the figure is unrelated to the data presented. This should be clarified.

Response
We appreciate the reviewer for identifying this source of confusion. The gait outcomes reported in the present study were obtained exclusively from the tri-axial accelerometer system, which was used to calculate gait alignment and gait variability variables. A new appropriate figure is replaced the previous one with the appropriate illustration of the accelerometer-based gait assessment system used in the current study, and the accompanying legend has been revised accordingly.

The GMFM version is also inconsistently identified. The abstract refers to GMFM-66, whereas the Methods section and Table 1 refer to GMFM-IS. These are not interchangeable labels and may involve different scoring approaches. The correct instrument and scoring method should be confirmed and reported consistently.

Response
The abstract, method section, and Table 1 are now matched as GMFM-IS was the scale has been used.

3. Comment:

The manuscript provides some useful intervention details, including the number of treatment sessions, treadmill familiarisation sessions, treadmill speed basis, current intensity, and approximate electrode locations. However, several key details needed for replication are missing.

The tDCS electrode size, current density, impedance values or thresholds, and ramp-up/ramp-down procedures are not reported. Without these details, another research group could not fully reproduce the stimulation protocol.
Protocol Reporting
- Electrode size (cm²) is not reported
- Impedance monitoring during sessions is not mentioned
- Ramp-up and ramp-down durations are not stated
- It is not explicitly confirmed whether tDCS stimulation ran concurrently for the full 10-minute treadmill period
Recommendation: A dedicated tDCS parameter table following Peterchev et al. (2012) reporting standards should be added.
Response
We have expanded the intervention description in the method section to include the electrode dimensions (4 × 4 cm saline-soaked sponge electrodes; 16 cm² contact area), current density (0.0625 mA/cm²), stimulation ramp-up and ramp-down periods (3 seconds each), impedance monitoring procedures, and in treadmill section we confirmation that bilateral anodal tDCS was delivered continuously throughout the entire 10-minute treadmill training period. These additional details improve reproducibility of the stimulation protocol.
In addition, a new Table 2 was created as recommended by the reviewer.

The statistical methods also require clarification. It is not clearly stated which outcomes were subjected to paired t-tests and which outcomes were interpreted using effect sizes only. This distinction should be explicitly stated in the Methods section or in a detailed table footnote.

Response
We thank the reviewer for this helpful observation. We agree that the statistical approach required clearer description. The Statistical Analysis section has been revised to explicitly state that this study is an exploratory feasibility study with an extremely small sample size (n = 5), the primary interpretation of the findings was based on Hedges' g effect size estimates rather than statistical significance alone. This approach is consistent with recommendations for pilot and feasibility studies, where estimation of treatment effects and assessment of clinical signals are generally considered more informative than formal hypothesis testing. Besides, Table 1 has also been revised.

Individual participant data are not presented in the manuscript. Given the very small sample size of five children, group means and standard deviations alone are insufficient to understand response variability, outliers, or consistency of response across participants.

Response
We thank the reviewer for this valuable suggestion. In accordance with the journal's open data policy and the editorial recommendations for F1000Research, the complete de-identified participant-level dataset has already been made publicly available [17] through the study's data repository, as cited in the Data Availability section of the manuscript. This publicly accessible dataset includes the individual outcome measures for all participants, allowing readers to examine participant-level responses, variability, and potential outliers directly. We believe that providing unrestricted access to the complete dataset offers greater transparency and facilitates independent verification and secondary analyses while maintaining participant confidentiality.

Standard feasibility metrics are also incompletely reported. The number of children screened, number eligible, number declining participation, per-participant attendance, completion of all sessions, and treadmill speed progression are not clearly described. These details are especially important because the study is framed as a feasibility study and would inform the planning of a future trial.

Response
We appreciate the reviewer's suggestion regarding the reporting of feasibility outcomes. This is an exploratory feasibility case series employing a convenience sample meeting specific inclusion criterion, hereby formal recruitment metrics such as the numbers screened, eligible, or declining participation were not applicable, as the primary feasibility objectives focused on intervention delivery, participant adherence, safety, and treatment tolerance.
To improve clarity, we have expanded the Results section to report that all enrolled participants completed the full intervention protocol, attended all ten treatment sessions, and experienced no dropouts or stimulation-related adverse events. In addition, the intervention description has been revised to clarify that treadmill speed was individualized and progressively increased according to each participant's tolerance while maintaining the predefined safety criteria.

4. Comment

If applicable, is the statistical analysis and its interpretation appropriate? Partly The statistical reporting requires substantial clarification before the preliminary efficacy claims can be interpreted reliably. The Table 1 footnote reports t(9) = 3.97, p = 0.003 for medio-lateral alignment. However, the study included five participants in a single-group pre–post design. For a subject-level paired t-test with n = 5, the degrees of freedom should be n − 1 = 4, not 9. The reported df = 9 is therefore inconsistent with the stated sample size and paired design. If df = 9 resulted from treating repeated walking trials as independent observations, this would raise a concern of pseudoreplication because repeated trials from the same child are not statistically independent. If trial-level data were analysed, the authors should use a method that accounts for clustering within participants, such as an appropriate repeated-measures or mixed-effects model. Multiple outcomes appear to have been assessed for statistical significance, including walking tolerance, motor function, postural alignment, gait variability, and several passive range-of-motion outcomes. No correction for multiple comparisons is reported, and no clear primary efficacy outcome is identified. This increases the risk of Type I error, particularly in a sample of only five participants. There are also internal reporting inconsistencies. The left ankle dorsiflexion effect size is reported as g = 1.42 in the abstract but g = 1.49 in Table 1. The abstract describes right ankle dorsiflexion as a moderate, non-significant improvement, whereas the Results section states that the treatment had a significant impact on both left and right ankle dorsiflexion. These inconsistencies should be corrected.

Response
We sincerely thank the reviewer for this thoughtful and constructive assessment of the statistical analysis. We carefully reconsidered the statistical approach considering the reviewer's comments and have substantially revised the manuscript.
Because this investigation was designed as an exploratory feasibility study with an extremely small sample size (n = 5), the statistical analysis focuses exclusively on descriptive statistics and Hedges' g effect size estimates to quantify the magnitude of the observed treatment effects.
Consequently, concerns regarding degrees of freedom, pseudoreplication, multiple comparisons, and Type I error no longer apply to the revised statistical analysis. All formal hypothesis testing, including paired t-tests, degrees of freedom, and associated p-values were removed.
In addition, the abstract and revised table 1 is now completely matched.

5. Comment:
The manuscript provides a data availability statement and refers to a repository under a Creative Commons Attribution 4.0 license. Data is available on ZENODO. This is a positive aspect of the paper and supports transparency. However, full reproducibility depends not only on the availability of the dataset but also on clarity of the analysis procedures. Because the manuscript does not clearly state which outcomes were analysed using paired t-tests, how repeated gait trials were handled, or how effect sizes were calculated, source data availability alone is not sufficient to ensure full reproducibility.

Response:
We sincerely thank the reviewer for recognizing the value of our open data repository in supporting research transparency. We agree that complete reproducibility requires not only access to the raw data but also a clear description of the analytical procedures.
Accordingly, we have revised the Statistical Analysis section to explicitly describe our estimation-based analytical approach. Because this was an exploratory feasibility study with an extremely small sample size (n = 5), formal hypothesis testing was removed, and all outcome measures were evaluated using descriptive statistics and Hedges' g effect size estimates. We have also clarified that gait outcomes were obtained by averaging two 10-m walking trials performed before and after the intervention, with these averaged values subsequently used for the effect size calculations. Together with the publicly available de-identified participant-level dataset deposited in Zenodo, these revisions provide sufficient methodological detail to allow independent verification and reproduction of the reported analyses.

6. comment Are the conclusions drawn adequately supported by the results?
Partly

The conclusion that the intervention appears safe is supported by the reported absence of side effects or stimulation intolerance. However, the conclusion regarding feasibility should be more cautious because standard feasibility indicators, such as screening numbers, eligibility, recruitment flow, adherence, attendance, and protocol progression, are incompletely reported.

The conclusion that the intervention produced significant improvements in medio-lateral alignment and ankle dorsiflexion should also be interpreted cautiously. The reported degrees-of-freedom error, unclear handling of repeated gait trials, absence of correction for multiple outcome testing, and p-value reporting weaken confidence in the statistical significance claims.

The Discussion also appears to attribute observed changes to specific mechanisms, such as tDCS-related reduction in spasticity or treadmill-related lateral force effects. Because this was a combined-intervention, single-group case series without a control group, the study cannot separate the effects of tDCS, treadmill training, maturation, practice effects, or measurement variability. These mechanistic explanations should therefore be framed as speculative and hypothesis-generating rather than demonstrated findings.

The recommendation for future larger randomized controlled trials is appropriate and well aligned with the feasibility nature of the study. However, the manuscript should avoid overstating preliminary efficacy until the statistical and reporting issues are corrected.

Response:
We thank the reviewer for these valuable comments. We have revised the manuscript accordingly. To better reflect the exploratory nature of this feasibility study, we removed all statements implying statistical significance and now present the findings as treatment effect estimates based on Hedges' g. The Discussion and Conclusion have been revised to avoid overstating efficacy, and mechanistic explanations are now clearly presented as speculative and hypothesis-generating rather than causal. We have also clarified that this convenience-sample feasibility study primarily evaluated intervention feasibility, safety, adherence, and treatment tolerance. Finally, the recommendation for future adequately powered randomized controlled trials has been retained and further emphasized.

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Competing Interests

No competing interests were disclosed.

Alongside their report, reviewers assign a status to the article:

Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested

Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.

Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions

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Gait and motor functions in cerebral palsy after bi-anodal transcranial direct current stimulation combined with treadmill training: A feasibility clinical study

Abstract

Background

Objective

Method

Results

Conclusion

Keywords

Revised Amendments from Version 1

Introduction

Figure 1. The tDCS protocols.

Methods

Study design & participants

Treadmill training & tDCS intervention

Table 2. Bilateral anodal tDCS parameters.

Outcome measures

Figure 2. Tri-axial accelerometer-based gait assessment and data processing.

Data analysis

Results

Table 1. Outcome measures.

Discussion

Conclusion

Data availability

References

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