Prevalence of sports injuries in Para Athletics throwers - a retrospective cohort study

Introduction

Repetitive overhead sports, such as athletic throwing events, impose unique demands upon the upper limbs [1,2], due to their requirement for greater flexibility, muscular strength, coordination, synchronicity, and neuromuscular control [3,4]. It is crucial that the athlete achieves a balance between these attributes to maintain upper-body joint mobility and stability [4,5]. The throwing motions require high technical complexity, and great muscle power [6,7] and force production in a short time [8]; as such, they place considerable stress on tendons, muscles, ligaments and joints, thus increasing the risk of upper limb injuries [9]. Non-disabled throwing athletes are exposed to a high rate of shoulder tendinopathies and shoulder tendon ruptures, which have been attributed to the high demands exerted on the shoulder girdle and the repetitive use of training elements [10,11]. In addition, injury rates tend to be higher during competitions than during practice sessions [12].
Only a few studies have assessed the epidemiology of injuries in Para Athletics throwers (PATs), a Paralympic sport where athletes with visual, physical, and intellectual impairments compete in the throwing events, viz. shot-put, discus, javelin, and club throwing [13]. Previous research in other Para sports (e.g., goalball, swimming, judo) has found para athletes to be exposed to a relatively high burden of sports injuries and additional risk factors compared to non-disabled athletes [14]. Indeed, many para athletes use adaptive equipment in sports and their daily lives, and their existing impairments may affect joint stability, muscle strength, balance and nerve innervation. For example, athletes with spinal cord injury, who typically use a wheelchair, and experience loss of muscle innervation, instability and chronic pain, appear to be at greater risk of developing injuries in the shoulder, elbow, wrists and hands [15,16].
Functional classification plays a crucial role in categorizing para athletes [17], and can influence injury patterns; however, rather than comparing injury rates between different classifications, the present study focuses on the overall prevalence of injury in PATs. To create targeted injury prevention programs, it is first necessary to analyze injury epidemiology data, incidence rates and exposure risk hours in a particular sport, and define preventative strategies [18]. Most epidemiological research on track and field injuries to date has focused on non-disabled athletes [19-21], and little is known of those experienced by PATs.
A more comprehensive understanding of the epidemiology of sports injuries in PATs would be of value for researchers, coaches and athletes hoping to better optimize athletic performance and implement preventive strategies. Hence, the purpose of this study was to determine the prevalence of sports injuries and their related characteristics in PATs over a 12-month period. It was hypothesized that: a) TFTPA experience a higher prevalence of shoulder and elbow injuries compared to non-disabled athletes; b) TFTPA have an increased risk of developing repetitive strain injuries, such as tendinopathies; c) specific disabilities of TFTPA, such as spinal cord injuries, may exhibit distinct injury patterns.

Materials and methods

Study design

This research was performed as a retrospective cohort study. Data was gathered through an online questionnaire, which has proven to be an effective approach for the systematic collection of injury data across diverse populations, and for identifying patterns and risk factors specific to certain sports and impairments [22]. The questionnaire was adapted from a prior epidemiological study of sports injuries [23]. The questionnaire was reviewed and adapted to PATs by a board of experts including an experienced throws coach, an experienced researcher in the field of throwing, two experienced researchers in the field of sports injuries, a para sport researcher, and a physician. Following this, a pilot test was conducted with three PATs: one woman and two men. After receiving feedback from the pilot test, two questions were added: one about the duration of the impairment, and another on whether the participants were throwers before acquiring their impairment.

Participants

The following inclusion criteria were used: being a male or female PATs, aged over 18 years old, having a sport class in Para Athletics, and with at least one year of training in any Para athletics throwing event. The exclusion criteria comprised failure to provide informed consent for the study or failing to complete the entire questionnaire.
The present study assessed prevalence of a sports injury in PATs over a 12-month period, i.e. the proportion of athletes reporting an injury throughout a 12-month period.

Ethics

The study obtained approval from the ethics board at the University of Los Lagos (1210-022), following the principles outlined in the Declaration of Helsinki involving research into human subjects [21]. All athletes received written information about the study, outlining its voluntary nature, risks, benefits, and procedures to maintain confidentiality. All enrolled participants gave their written informed consent to take part.

Data collection

The online survey was distributed to PATs participating at a national or international Para throwing events between November 2022 and July 2023, by the first author through Google Forms. To include as many PATs participants as possible worldwide, the survey was made available in English, Spanish, and Portuguese.
The questionnaire was adapted based on the Para sport translation of the International Olympic Committee consensus on recording and reporting of data for injury and illness in sport. The following injury definition was used: “any condition that reduces an athlete’s normal state of full health, irrespective of its consequences for the athlete’s sports participation or performance or whether the athlete sought medical attention” [22].
The questionnaire comprised 82 questions, and took approximately thirty minutes to complete. The questions covered the following topics: (i) athlete demographics; (ii) details related to Para Athletics participation; (iii) training history; (iv) impairment-related information; (v) number of injuries in the past 12 months; and (vi) injury characteristics (e.g. injury site, type of injury, onset of injury, injury mechanism, time loss from sports and the impact of injuries on daily life).

Data categorization and statistical analysis

Since the data was non-normally distributed, it was reported as median with interquartile range (IQR). Demographic and injury prevalence data were analyzed and presented as percentages. Additionally, a 95% confidence interval (CI) was calculated for the prevalence values.
To compare the prevalence of injury between different athlete groups, the data were further categorized into the following sub-groups: sex (male and female), age group (18-25, 26-35, 36-46, 47-50), impairment type (intellectual impairment, blindness and low vision, short stature, neuromuscular disorders [e.g., post-polio, peripheral nerve injury], upper and lower limb amputation, spinal cord injury, cerebral palsy), age of impairment onset (1 to 8 years, 9 to 16 years, 17 to 34 years, and Congenital), and prior experience as a thrower (before or after acquiring the disability). The proportions of athletes reporting injuries in these sub-groups were compared using the Pearson’s chi-square test.
The injury data were then categorized according to location (neck, shoulder, upper arm, elbow, forearm, wrist, fingers, thoracic spine [upper back], lumbar spine [lower back], hip/groin, thigh, knee or leg), and the nature of the injury, viz. muscle injury (including strain, tear, rupture, intramuscular tendon or aponeurosis), muscle contusion or tendinopathy; injury mechanism (contact or non-contact injury) was also noted. The proportions of injuries in these sub-groups were also compared using the Pearson’s chi-square test.
Additionally, it was noted whether the onset of injury occurred during training or competition, as well as the total number of new injuries reported by each athlete throughout the study period. Any differences in the onset of injury and the number of new injuries between sub-groups were analyzed using the Mann-Whitney U-test.
Data was analyzed using IBM SPSS Statistics, version 23.0 for Windows (IBM Corp., Armonk, N.Y., USA). All data were checked for completeness and plausibility before being analyzed, and a significance level of p ˂ 0.05 was used for all statistical tests.

Results

Athlete demographics

The study included a total of 60 PATs, viz. 42 men (70%) and 18 women (30 %). Their place of residence was Argentina (n = 5), Australia (n = 1), Brazil (n = 2), Chile (n = 13), Colombia (n = 8), Costa Rica (n = 1), Ecuador (n = 3), Guatemala (n = 1), Mexico (n = 2), Moldova (n = 1), Morocco (n = 1), Netherlands (n = 1), Panama (n = 8), Paraguay (n = 1), Peru (n = 1), Romania (n = 1), Spain (n = 5), United Kingdom (n = 4), or United States of America (n = 1). Their ages ranged from 18 to 55 years, with a median age of 31 (IQR 23-42) years. The participants had one to thirty years of throwing experience with a median of six (IQR 3-8.7) years. Five of the participants were throwers before acquiring their disability. Of the total sample, 31.7% used a wheelchair as adaptive equipment. Specific demographic data are presented in Table 1.

Injury prevalence

A total of 24 PATs reported an injury during the past 12 months, resulting in an overall prevalence of 40% over the period (n = 24; 95% CI: 27.5-53.4). This prevalence was 47.6% among men (95% CI: 32.0-63.5) and 22.2% among women (95% CI: 6.4-47.6) (Table 2).
Table 3 shows the prevalence of injuries for different impairment groups. The highest prevalence was observed in athletes with blindness/low vision and athletes with intellectual impairments: in both cases, the prevalence was 75% (95% CI: 19.4-99.4). No significant difference in the prevalence of injury was noted between sub-groups according to sex, age, impairment type, or age of onset (p>0.05; Chi-square tests). The most common disabilities reported were lower limb amputation (20%), spinal cord injury (25%), and cerebral palsy (16.7%). In total, 28.33% of the athletes reported regular chronic pain.

Frequency and type of injuries

In total, 79 injuries were reported by the 60 studied para athletes. The most frequently-affected body area was the upper limb, with the elbow (25.3%) being the most commonly-injured location, followed by the shoulder (22.8%) lumbar spine (lower back; 15.2%) and wrists (12.7%) (Table 4).
Regarding the nature of injury, the most prevalent types of injuries were muscle injuries (41.3%), followed by tendinopathies (19.6%), and contusions and muscle spasms, each representing 8.7% (Table 5). The majority of the reported injuries were new sports injuries. Male athletes reported significantly more new injuries throughout the year than female athletes (p = 0.016; Mann-Whitney U-test).
Table 6 displays the distribution of injuries during training, pre-competition (i.e. a few days before competing), and competition periods. The majority of injuries occurred during training (88.6%).
No statistically significant relationship was found between the prevalence of injuries and the following factors: previous status as a thrower before disability, performing a warm-up routine, performing stretching in the warm-up, performing static stretches or dynamic stretching in the warm up, the injury mechanism (contact or non-contact injury), and regular experience of pain (p>0.05; chi-square test). This lack of association was consistent regardless of whether the individuals were male or female. Additionally, the occurrence of an injury was not influenced by age, weight, height, time living with a disability, or years as a thrower before acquiring the disability. However, sex was found to be significantly related to the number of injuries in competitions (p = 0.021) and to the number of new sustained injuries (p = 0.016).

Discussion

This aim of the study was to determine the prevalence of injury among PATs. It was found that a) PATs experience high prevalence of upper-body injuries, b) muscle strains and tendinopathies are repetitive injuries, c) the majority of injuries occurred during training sessions, and d) men had a significantly higher number of injuries in training and new injuries.
Two-fifths of the surveyed athletes reported sustaining an injury during the preceding year, confirming previous findings that PATs experience a higher prevalence of shoulder and elbow injuries [26,27]. This is not surprising as in PATs, the upper limbs tend to engage a wider range of motion (ROM) during throws [28]. In addition, throwing events are particularly demanding, with high technical complexity, and this may force the athletes to struggle to maintain correct movement mechanics; they may compensate with suboptimal movement patterns, leading to muscle and tendon injuries. Our findings are in line with those of a systematic review of 18 studies in para athletes, indicating that the rates of injury in the upper-body are the highest among all body parts [29].
Our findings indicate that male PATs are at increased risk of elbow and shoulder injuries then women; however, these results must be interpreted with caution considering the disparity between the sexes in the sample and the limited number of female PATs. Even so, several factors may contribute to the observed difference in prevalence, such as differences in upper-body muscle mass [30,31] or cultural factors [32]. Our findings nevertheless highlight the need for further research with more balanced samples.
The data underscore the importance of developing specific injury prevention strategies for PATs and prompt further investigation into the underlying causes of these increased injury rates. More recently, a prospective cohort study from the Paralympic games in Rio 2016 showed that pre-competition injury rates were higher compared to competition injury rates, with the shoulder joint being the most frequently-injured anatomical area [27]. While the study [27] included track and field para athletes in the analysis, it was found that five-a-side football, judo, and seven-a-side football had a higher injury risk. Moreover, a previous prospective cohort study from the Paralympic games in London 2012 including track and field para athletes showed that the highest incidence rate of injuries during competitions occurred in the thigh for ambulant athletes and in the shoulder for wheelchair athletes [33], similar to previous reports [26,27].
The prevalence of upper-body injuries among PATs suggests the need for structured injury prevention programs aimed at reducing the incidence of injury and minimizing the time lost due to training-related injuries. Hence, to lower the risk of injury, a primary goal of the PATs should be to increase the ROM during the throwing motion, as this should increase the work-producing path or rate of acceleration on the implement [34]. This is particularly important for seated athletes, as a significant correlation has been noted between shoulder girdle ROM and measured distance of the throw [35]; it has been found that the combination of a large ROM of the shoulder girdle with a high average angular speed for each upper-body segment during the delivery phase of the throw [36] may increase the risk of upper-body injury in PATs. As such, coaches and athletes should be wary of potential shoulder injury during training and competition, and aim to follow training programs aimed at improving the ROM and strength of upper-body musculature to prevent injury.
Our data indicate that the most common injuries in PATs were muscle injuries followed by tendinopathies. These findings partially confirm the second hypothesis, which states that PATs athletes have an increased risk of developing repetitive strain injuries, such as tendinopathies. Although a high prevalence of tendinopathies and muscle injuries was noted in the studied group, the data did not provide conclusive evidence that these injuries were mostly due to muscle imbalances. It has been suggested that overhead athletes (i.e., baseball, badminton, volleyball, tennis) are prone to shoulder, elbow, lower back, and wrist injuries due to muscle imbalances on either the dominant or non-dominant side [37]. In addition, it was also found that neither age, body characteristics, time living with the disability, training experience before acquiring the disability, training frequency nor the time spent training per week were associated with the injury rate. As such, our findings may be attributed to the multifactorial nature of sport injuries, whose treatment may require a paradigm shift from identifying risk factors to recognizing patterns of risk [38]. However, to fully understand these patterns of injury and their underlying causes, more in-depth analyses are needed, ideally based on prospective studies with randomized samples.
It has been found that injury rates are lower in younger para athletes [39], and that a high percentage of para athletes train and/or compete with the presence of pain, with only a handful following injury prevention programs [40]; however, our present data do not confirm any relationship between number of injuries, experience, age of the PATs, and specific disabilities. Nonetheless, spinal cord injury, lower limb amputation, and cerebral palsy were found to be associated with a higher incidence of injury, although not significantly (p>0.05). Contrary to our third hypothesis, and previous findings [41], the nature of the specific disability experienced by the PATs, such as spinal cord injury, does not appear to indicate a distinct injury pattern.
Interestingly, the number of injuries sustained during competitions, and the number of new injuries sustained were found to be significantly related to the sex of the PATs. These findings contradict those of an epidemiology study by Willick et al. [39], which found injury rates to be similar between male and female athletes from the Paralympic games in London 2012. Nevertheless, sex might be a valuable clue for predicting injury rate among PATs, although more research is required to confirm this.

Limitations

The present study is retrospective in nature, and the participants may have difficulty accurately recalling their injuries, leading to potential data inaccuracies. Furthermore, the participants, especially the female group, were restricted to specific athletic divisions; hence, there is a need for caution when extrapolating results to all PATs. In addition, it is unknown whether the PATs followed any injury prevention program during the previous years. Finally, the questionnaire did not undergo comprehensive validation (e.g., validity and reliability), which may compromise the accuracy of the data collected. It would also have been desirable to recruit a wider range of participants by providing a questionnaire translated into other languages (e.g. French, German, Arabic), which would further strengthen the findings.
Despite these limitations, this study introduces valuable insights into the epidemiology of sports related injuries in PATs, underscoring the importance of further prospective studies aimed at confirming these findings. Notably, this is the first study to investigate the injury rate in PATs. Our findings suggest that the upper-body musculature is the most vulnerable to injury in this group although this is influenced by sex. Consequently, coaches are encouraged to implement injury prevention training programs to reduce injury rates and enhance throwing performance.

Conclusions

The musculature of the upper-body appears to be the most susceptible region to injury among PATs, although this may depend on other factors, such as sex. In this group, injuries are most likely to occur in the shoulder and elbows, with muscle strains and tendinopathies being most common. Injury is more prevalent in men than women during training. These findings emphasize the importance of implementing tailored injury prevention programs addressing the specific needs of PATs to reduce injury rates and enhance throwing performance.

Funding

This research received no external funding.

Conflicts of interest

The authors declare no conflict of interest.

References