Low back pain functional disability and associated factors: A cross-sectional study in Peruvian amateur athletes

Introduction

Low Back Pain Functional Disability is an alteration generated by a musculoskeletal problem at the lumbar level that can manifest with pain.¹ Globally, there are no figures estimated by official institutions such as the World Health Organization; however, there are authors who affirm that the disability caused by low back pain reaches figures between 5.45 and 6.73 million people affected between the years 1990 and 2016.² Other international studies have shown that this condition is present in a higher prevalence rate among athletes, compared to the general population, even doubling said rate.³ In the case of America, the evidence at the Latin American level is quite limited; however, in the United States, low back pain and its functional disability is the second most crucial health problem in the loss of years of healthy life.⁴ In Peru, musculoskeletal diseases occupy the sixth place of disease burden. In the specific case of low back pain, there are no national registries that show its prevalence or incidence in the general population; however, various studies show that it is a common reason for the loss of workdays,⁵ calculating losses of 149 million work days per year due to low back pain.⁶ However, low back pain and the functional disability generated are more prevalent in certain risk groups, such as those who handle heavy loads, workers with non-ergonomic positions, and people dedicated to sports activities.⁷

Approximately it is estimated that 80% of people experience at least one episode of back pain during their lives.⁸ This rate varies between 1% and 30% among people dedicated to sports activities depending on age, training program and the type of sport practiced.^9–11 Sports are classified according to static-dynamic activity in 3 levels: Low (e.g., golf, cricket, and bowling), medium (American football, rugby, jumping), and high (cycling, triathlon, boxing, and canoeing).¹² Among highly competitive athletes, low back pain is one of the most common causes of game loss and lifelong disability.³ Disability assessment is one of the most critical components of the health care service, and self-reported measures of disability are currently the most common way to assess patients with back pain.¹³ In this sense, various specific indices have been developed to assess the functional status of the lower back in the population at risk.¹⁴ The most popular are the Roland-Morris Disability Questionnaire¹⁵ and the Oswestry Low Back Pain Disability Index.¹⁶ However, these scales were designed to assess back pain in the general population with low physical and functional activity performance.¹⁷ These tools may have some limitations in assessing the specific physical demands, deficits, and temporary disabilities of athletes and their specific exercise and activity levels; Furthermore, the expectations of athletes regarding their functional status and therapeutic results differ significantly from those of the general population.¹⁸ However, despite the limitations above, there are instruments such as the Micheli Functional Scale (MFS) to assess pain and functional levels in young athletes¹⁸ and the Athlete Disability Index (ADI) to assess functional disability of the lower back in athletes.³

In Peru, the most formally practiced sports are soccer and volleyball. However, sports such as tennis, basketball, and athletics are being promoted by the Peruvian Sports Institute. Tennis includes movements that involve muscle tension, rotation, and stretch-shortening cycles with the participation of different muscle groups in the legs, shoulders, hips, and back, among others.¹⁹ The ballistic and repetitive trunk movements required in tennis have been associated with radiological abnormalities in the lumbar spine²⁰ and with evidence of low back pain in elite young tennis players.²¹ It has even been observed that excessive mechanical force can injure the vertebrae in the lower back.²² Basketball is characterized as a fast and intense sport involving accelerations, sudden stops or landings from a jump, body contacts, and handling of the ball during fast movements.²³ These movements can increase the risk of low back pain. However, little scientific evidence associates low back pain exclusively with basketball. The prevalence of low back pain in basketball players is very high. Close to 50% have been reported in players who have practiced the sport for 12 consecutive months.²⁴ Low back pain is known to be the third most frequent ailment among basketball players, preceded by ankle and knee injuries.²⁵ Athletics is made up of many sports that involve movements such as the role of internal rotation of the upper arm in striking and the influence of elastic energy and muscle pre-stretch on stretching and shortening actions,²⁶ which are subject to dysfunctional movements if they are not supervised.²⁷ This scenario increases the risk of low back pain. It can be exacerbated by characteristics attributed to the athlete, such as flexibility, lower limb length discrepancy, sacroiliac movement dysfunction, and preseason training intensity.²⁸

Our research aimed to determine the frequency of low back pain functional disability and the identification of associated factors. We believe that early identification of low back pain and functional disability associated with the practice of sports in amateur athletes can improve primary prevention strategies in amateur athletes, reducing the risk of recurrent musculoskeletal injuries in their professional sports life.

Methods

Results

Table 1 shows the descriptive characteristics of 130 amateur athletes from the Peruvian Sports Institute at the Ica campus, of which 63.9% were male. The mean age was 23.9 ± 8.2 years. Regarding the anthropometric characteristics, the average weight and height were 64.8 ± 10.8 kg and 1.65 ± 0.08 m, respectively. The body mass index had a mean of 23.8 ± 3.9 kg/m² (min: 16.7 and max: 36.3). The presence of social habits such as cigarette and alcoholic beverage consumption was low. The frequency of athletes in table tennis, basketball, and athletics was 23.0%, 38.5%, and 38.5%, respectively.

Table 2 shows the characteristics of pain and functional disability due to low back pain. We found that all the athletes reported low back pain, and depending on the type, it was of neuropathic and non-neuropathic origin in equal proportions. The mean perceived pain score was 3.5 ± 1.8 (min: 0, max: 7 points) according to the DN4 instrument. 61.5% reported low back pain lasting approximately 1 to 3 continuous months. Functional disability due to low back pain presented a mean percentage score of 17.3 ± 18.3% (min: 0.0% - max: 69.4%). Functional disability due to low back pain occurred in 30% (CI95: 22.3-38.7%), of which 56.4% had a moderate disability, and 30.8% presented severe disability. No athlete with a disability that generated sports withdrawal was observed.

Table 3 shows the results of the association with functional disability due to low back pain in bivariate analysis. We identified that gender, age, obesity, duration of low back pain, and pain were factors associated with functional disability due to low back pain. We observed that functional disability was higher among women and older athletes. Likewise, those who manifested pain for up to 12 months represented almost all athletes with low back pain functional disability. In addition, athletes with neuropathic pain had a higher frequency of functional disability than those with non-neuropathic pain. The type of sport practiced was not a determining factor in functional disability due to low back pain. Additionally, we compared the athlete’s disability index scores for table tennis, basketball, and athletics with medians of 6.9, 9.7, and 13.8, finding no significant differences (p = 0.470, Kruskal-Wallis test).

Table 4 identifies the factors associated with low back pain functional disability in multivariate analysis. We evidenced that, for each increased year of life, the risk of occurrence of functional disability due to low back pain increases significantly by 5% (PR: 1.05, CI95: 1.01-1.09). Female athletes have approximately twice the risk of low back pain functional disability compared to male athletes (PR: 2.21, CI95: 1.08-4.50). Athletes with non-neuropathic pain had a 65% lower risk of functional disability due to low back pain than those with neuropathic pain (PR: 0.35, CI95: 0.16-0.80). No type of sport was associated with low back pain functional disability.

Discussion

Our results show that sports such as table tennis, basketball, and athletics are not significantly associated with the occurrence of low back pain functional disability; however, other factors do promote its condition, including age, female sex, and perceived pain in the lumbar region. Although our study population consisted of amateur athletes between the ages of approximately 16 and 35, it is essential to consider that there are structural differences in the spine of an adolescent compared to an adult. The spine of a child or adolescent at the level of the nucleus pulposus is moderately hydrophilic and more significant than that of an adult. It allows more effective absorption of force and its central distribution to the adjacent vertebrae.³² With adulthood, the composition of the nucleus pulposus begins to change and generates a distribution of force to more peripheral areas of the disc.³³ Therefore, age is a determining factor in spinal injury, especially at the lumbar level. Injuries and fractures are more common in the adolescent spine, with numbers as high as 47% of young athletes, and are believed to be caused by incomplete bone maturation present in the neural arch.^34,35

We found that 30% of athletes have low back pain functional disability at different levels (moderate, severe, and very high). This figure is much lower than that reported in other investigations. Noormohammadpour et al. reported that close to 90% of the athletes had mild lumbar functional disability using the Oswestry and Roland Morris scale,³⁶ not finding categories of severe and very high disability. Reiss et al. also found higher scores for lumbar functional disability among Jiu-Jitsu athletes (10 points) compared to control subjects (6 points), using the Quebec scale.³⁷ As observed in previous research, the disability rate is very high compared to our findings. This situation could explain by the instruments used (e.g., Oswestry, Roland-Morri’s questionnaire, and Quebec scale), which are oriented towards evaluation. Of low back pain functional disability in the general population. These instruments are beneficial in situations related to clinical conditions in the patient,³⁸ and they have not been designed to evaluate athletes.³⁶ The etiopathogenesis of pain is different in athletes compared to the general population. Therefore, the functional capacity is also different. This situation could lead to overvaluation and incorrect classification of lumbar functional disability among athletes.

According to our results, all athletes, without exception, presented low back pain at different levels of pain and origin, which denotes a severe problem with pain control and management. Other investigations have shown a very high prevalence of low back pain among athletes; for example, Fett et al. reported a prevalence of low back pain of 88.5% in elite athletes.³⁹ In general, the rate of low back pain among athletes is very high, according to international evidence, compared to the general population; however, from the point of view of sports medicine, pain is a manifestation attributed to sports practice that is reduced and eliminated by various pain control programs. However, the constant manifestation of pain and its level leads to the loss of functionality of the lumbar region in the athlete; this, in turn, generates limitations in sports practice and may even end in sports retirement.³²

The prevalence of low back pain and its functional disability may vary depending on the sport being practiced. For example, it has been described that up to 11% of gymnasts and 50% of soccer players presented low back pain. Recurrence of the type of injury that causes the pain again may be sport-specific. For example, herniated lumbar discs are more common in soccer players and weightlifters, disc degeneration and spondylolysis are more common in gymnasts, and traumatic lumbar spine injuries are more common in wrestlers and hockey players.⁴⁰ However, there are sports that have a lower risk of low back pain and functional disability. Table tennis is a sport that was taken as the reference group in our study, considering that the risk of low back pain is low, even in highly elite athletes.²¹ However, the frequency of low back functional disability among table tennis players was the lowest compared to the other two sports evaluated. In fact, due to the movements involved in basketball and athletics, the risk level of low back pain is much higher, especially in those who also handle heavy loads and have low back flexibility problems.⁴¹

People involved in impact sports appear to have risk factors for specific spinal pathologies that correlate with the load and repetition demands of specific activities. For example, elite athletes who engage in longer, more intense training have a higher incidence of the degenerative disc disease and spondylolysis than athletes who do not. On the other hand, the data suggest that amateur athletes can be protected from low back injuries prior to physical conditioning.⁴¹ Athletes are often well conditioned with greater flexibility and higher pain thresholds than the general population. These characteristics can serve as protective factors; however, athletes with high demands on the lumbar spine usually do not tolerate functional limitations in their activities. Low back pain among athletes is approximately 30%, which can even be higher in elite athletes, such as Olympic competitors. Low back pain can even be attributed to lumbar disc degeneration.⁴²

The study had some limitations, including the need for temporality, typical of a cross-sectional design, and the number of athletes evaluated. Although our study seeks to identify factors associated with low back functional disability, in order not to bias our results, we used a generalized linear model including potential confounders to adjust the association measures. We could not include instruments for the biomechanical study of athletes, which would have been necessary to understand better the etiopathogenesis of low back pain and functional disability.

Timely identification of low back pain and functional disability among athletes makes it possible to improve primary prevention programs aimed at reducing sports injuries. In the case of amateur athletes starting a sports season, they must undergo a physical and medical evaluation, which allows the identification of specific risk factors, such as previous injuries that have not been completely rehabilitated or muscle weakness and inflexibility. It is recommended that physical conditioning be carried out over several weeks, with a gradual increase in the frequency and intensity of training, to achieve a safe adaptation according to the demands of the sport. The growth process in the athlete is a crucial factor that must be considered in the training stage since young athletes are prone to lose muscle flexibility and imbalance, which predisposes them to injury.⁴³ In this sense, the medical staff, evaluators, and even the coach must be aware of the changes in the spinal development of the young athlete to help diagnose and treat spinal injuries in a timely manner.

Conclusions

Amateur athletes who practice table tennis, basketball, and athletics have a high frequency of low back pain functional disability. Likewise, low back pain is present in all athletes, with significant differences by type of sport practiced. Female athletes are more prone to low back pain functional disability, and the risk of this increases significantly with age. In this sense, it is essential to identify the main risk factors for injuries among athletes.