Relationship between physical activity, body posture and morbidity risk in the elderly population

Study design

This is a descriptive, observational, and correlational study conducted to analyze postural characteristics and risk measurement variables with respect to non-communicable chronic diseases, along with their relationship to physical activity in an elderly population. The study was approved under Resolution 8430/1993 by the Ministry of Health and Social Protection of Colombia and by the Ethics Committee of Universidad Santo Tomás de Valdivia (Chile) with number 188 MZS;1364.2024, following the guidelines of the Declaration of Helsinki.

Participants

A total of 38 older adults from the “Potrerito” sports group in the city of Bello (Antioquia, Colombia) participated in this study. The participants usually engage in weekly physical activity focused on conditional physical capacities, with training sessions lasting 60 minutes throughout the week. Of the total participants, 28.9% were men and 71.1% were women. The inclusion criteria for the study required participants to be healthy individuals without recent injuries or bodily limitations in the past six months, and to voluntarily agree to participate in the study. The sociodemographic characteristics of the study population are presented in Table 1.

Instruments and procedures

Two interventions were carried out for the execution of the study. The first intervention involved an interview to collect sociodemographic data from the participants, including gender, age, and weekly physical activity. The second intervention included the assessment of variables related to body posture using the Portland State University (PSU) instrument.^14,15 To identify morbid risk, height and body mass variables were used to calculate the Body Mass Index (BMI), as well as waist and hip circumferences, to determine the waist-to-hip ratio. Before the tests began, the participants were provided with an informed consent document outlining the benefits and potential risks of the study, emphasizing the commitment to maintaining their anonymity. They were informed that photographs would be used exclusively for research purposes and that their data would be processed using codes to safeguard their identity. Evaluations were conducted after the participants read the document and had all their questions addressed, at which point they signed the informed consent form.

Evaluation of measurement variables and morbid risk

The evaluations were conducted starting at 7:00 am, from January 2nd to February 8th, 2024, at the times previously agreed upon with each participant. The protocol for data collection was developed according to the guidelines of the International Society for the Advancement of Kinanthropometry (ISAK) and was carried out by a Level 3 anthropometrist. The following measurements were taken: height, using a wall stadiometer (Height o meter^®, model Est-221HR, McCook, USA), with an accuracy of 0.5 cm, with the participants in an orthostatic position, feet together, back in contact with the stadiometer, and head in the Frankfort plane, applying traction on the head during the measurement; body weight, with a digital scale (OMRON^®, model HBF-226, Kyoto, Japan), with the participants standing on the scale, looking forward and with their arms at their sides; and body circumferences, with the participants positioned on a 40 cm high anthropometric box, with their arms crossed over their chest.

Waist circumference was measured at the narrowest point of the abdomen, between the lower lateral costal margin and the top of the iliac crest, while hip circumference was measured at the maximum posterior prominence of the gluteus using a retractable metal tape measure (Cescorf, Porto Alegre, Brazil). All measurements were taken twice, and if the difference between the first two measurements exceeded 1%, a third measurement was taken to ensure accuracy. The data were processed to obtain BMI measurements according to the Quetelet equation and the waist-to-hip ratio, based on the criteria from the World Health Organization.¹⁶

Postural assessment by Portland State University (PSU)

The Postural Correction Index (PCI) was established using the Portland State University instrument to assess posture globally and by regions, identifying postural deviations in the study participants. The intervention involved assessing variables related to body posture by using photographs of the participants taken from the sagittal and frontal planes, focusing on body regions such as the trunk, back, thighs, legs, and feet. These photographs were then compared with reference images from the PSU instrument, which requires subjective observation and comparison. The main objective was to detect asymmetries and possible postural deviations across body segments, enabling the evaluator to quantify the PCI through mathematical equations derived from the diagnostic results of the analyzed body regions. The scoring system was weighted as follows: 5 for no deviation, 3 for slight lateral deviation, and 1 for pronounced lateral deviation. The PCI is determined by adding the scores for each of the following regions: head and neck (HN) (five regions), thoracic and lumbar spine (TLS) (three regions), abdomen and hips (AH) (four regions), and lower limbs (LL) (four regions). After this evaluation, the total score is summed, divided by 75, and multiplied by 100 to calculate the percentage (see equation 1). The PCI procedures are well-documented in the scientific literature, and its methodology was replicated for repeatability in this study.^14,15

The assessments were conducted in a specially equipped room, featuring a retractable posture grid measuring 36 × 82 inches composed of printed blue lines on a white background made of flexible, long-lasting material. Subjects were positioned three meters away from a Sony Full-frame A7 camera (model ILCE-7M4K, Sony Corporation, Thailand), mounted on a COMAN tripod (model KX3939Q5S, China). Photographs were taken from the frontal and sagittal planes. To identify the type of plantar footprint, 210 mm thermal paper (FAX) was used. The participants’ feet were moistened with an alcohol-based antibacterial gel, and they stood for two minutes to obtain the plantar impressions (Figure 1).

Figure 1. Determination of the type of plantar footprint.

Statistical analysis

All analyses were conducted using the Jamovi^® statistical software, version 1.6. The data for the variables are presented as the means and their standard deviations. The normality of the data was verified using the Shapiro-Wilk test. To compare, evaluate, and determine significance between values, the Student’s t-test for independent samples, and the Mann-Whitney U test were employed. The effect of one variable on another was identified through the Spearman correlation test. Correlation coefficients were determined according to the Hopkins scale (2002).¹⁷ To verify the reliability of the PSU instrument, the Cronbach’s alpha test was used. All analyses were conducted with a significance level of p ≤ 0.05 to accept or reject the hypotheses.

Predictive variables for non-communicable chronic diseases (NCDs)

Studies on the waist-to-hip ratio (WHR) reveal significant differences between men and women in terms of health risks. Generally, men have a higher WHR and consequently, a greater propensity for health risks as compared to women. Our findings confirm this trend, showing that men have an average WHR that is 10% higher than that of women (see Table 1), with abnormal WHR values (men: 0.75 to 0.90; women: ≤0.80) exceeding those reported by Muaidi & Ahsan (2019).²⁰

Regarding the Body Mass Index (BMI), the averages of our participants fall into the overweight range for both genders. However, longitudinal studies, such as one conducted in Korea with 75,586 people, have shown that the effect of a high BMI on mortality is lower in the elderly as compared to the overall adult population.²¹ Additionally, another study conducted in Brazil, based on the WHO classification, found that elderly individuals who were overweight showed a protective effect against mortality (risk ratio of 0.58), as compared to those with a normal BMI, even among the elderly with myopenia, although this difference was not statistically significant.²²

BMI, waist circumference (WC), and WHR, are important anthropometric measurements associated with non-communicable diseases (NCDs) and mortality risk.²³ At the postural level, a higher BMI has been found to be linked to incorrect postures, both in standing position and during dynamic work.²⁴ WHR, in turn, correlates with foot posture index scores.²⁵ Overall, combining multiple anthropometric indices can provide a more comprehensive assessment of health risks related to NCDs and body posture in the elderly population.

Physical activity and body posture in the elderly

Physical activity offers significant benefits to older individuals, particularly in terms of posture and balance. Some studies have shown that older adults who engage in regular physical activity have a better seating posture, vertical alignment, and balance, as compared to their sedentary counterparts.⁶ Our findings revealed that physical activity levels were related to 40% of the components of the posture index, with a notable effect on the upper body (trunk), while excluding the lower back (lumbar). These results are positively associated with findings indicating vertebral growth in active older adults,²⁶ who also exhibited improved postural control and sensory integration.²⁷ Although some age-related postural changes persist, such as forward head posture and pelvic anteversion, physically active older adults may show less pronounced flexor postures due to strengthened extensor muscles. Exercise, particularly resistance and impact training, can improve bone strength and reduce the risk of falls in individuals with osteoporosis.²⁸

This study has some limitations, including a relatively small sample size and the lack of a longitudinal follow-up to observe the effects of physical activity over time. Additionally, the assessment of posture focused on static parameters, without considering dynamic variations that may influence the results. Future research should involve larger samples and longitudinal designs to validate and expand these findings. It would also be beneficial to investigate the impact of different types of physical activity on posture and balance, as well as to incorporate dynamic measurements to gain a more comprehensive understanding of the interactions between physical activity and posture in older adults.

Ethics and consent

The study was approved by the Ethics Committee of the Universidad Santo Tomás de Valdivia (Chile) under Resolution No. 231366443/2023 SEREMI DE SALUD dated March 31, 2023, with number 188 MZS;1364.2024, as it was a non-invasive low-risk study in accordance with Resolution 8430/1993 by the Ministry of Health and Social Protection of Colombia. Since participant images were used, anonymity was guaranteed, and consent was signed with this clarification.