Abstract
Background
Professional swimmers are often affected by a high number of injuries due to their large amount of training. The occurrence of musculoskeletal pain during an important tournament has not been investigated.
Objective
The objective of the study was to assess the prevalence of musculoskeletal pain and its characteristics in professional swimmers. Secondary objectives included evaluating the swimmers’ injury history over the previous 12 months, and examining the association of the presence of pain with personal and training characteristics of the swimmers.
Design
Observational, cross‐sectional study
Method
Two‐hundred and fifty‐seven swimmers who participated in the Brazilian Swimming Championship were included in the study and answered a questionnaire about personal and training characteristics, presence of pain, and injuries in the previous 12 months. The relative risk of presence of pain was calculated for the following variables: gender, BMI, stroke specialty, swimmer's position, strength training, practice of another physical activity, and previous injuries.
Results
The prevalence of musculoskeletal pain was about 20%, with 60% of swimmers reporting at least one injury in the previous 12 months. The shoulder was the most commonly affected region and tendinopathy was the most common type of previous injury. No significant relationships were found between the presence of pain and personal or training characteristics.
Conclusions
The results demonstrated that the prevalence of musculoskeletal pain in professional swimmers participating in the most important Brazilian national tournament was approximately 20%, while the majority of participants reported previous injuries in many areas.
Level of Evidence
2c
Keywords: Aquatic sports, epidemiologic studies, injuries, swimming
INTRODUCTION
Swimming is broadly practiced around the world and people of all ages participate. The participants in this sport look for wellness and prevention of systemic diseases, principally in the cardiorespiratory system.1 However, the high exposure to practice of swimming may be a risk for the integrity of musculoskeletal system.2 The number of musculoskeletal injuries related to swimming may be an important consideration, mainly among professional swimmers, because they are more exposed by their amount of training compared to amateur swimmers.2‐5 Professional swimmers can swim around 10 to 14 kilometres a day, depending on stroke specialty and whether they are sprinters or distance swimmers.6 In the United States, it is estimated that in the last 25 years a total of 42000 swimmers competed at the elite level of the National Collegiate Athletic Association (NCAA).7 In the Federation Internationale de Natation (FINA) World Championship (2009), a total of 2592 athletes from 172 countries participated in the event.8
Despite the apparently high injury rates in swimming, few epidemiologic studies are found in the literature. Available studies usually evaluate injuries in specific joints, particularly the shoulder complex, specific stroke specialties, or injuries related to the biomechanics of the sport.6,9‐14 Information about injuries in swimmer who participate in elite tournaments is scarce. 8,13,15
Until now, to the authors knowledge, no studies have investigated the presence of musculoskeletal pain in swimmers competing in a large national tournament. Thus, the objective of the present study was to assess the prevalence of musculoskeletal pain and its characteristics in professional swimmers that participated from Brazilian Swimming Championship. Secondary objectives included evaluating the swimmers’ injury history over the previous 12 months, and to examining the association of the presence of pain with personal and training characteristics of the swimmers.
METHODS
This cross‐sectional study utilized swimmers who participated in the Brazilian Swimming Championship (39th Troféu José Finkel Edition, 2010) that occured in a short course pool (25 meters). The participants could only participate of the event if they achieved a qualifying time established by the Brazilian Aquatic Sports Federation. All 430 swimmers participants in the event were invited to participate in the study. If the participants accepted, they signed the consent form in accordance with the study's requirements and were included in the study.
A questionnaire was developed, in which participants were asked about: 1) personal characteristics (age, gender, weight, height and swimming experience); 2) training routine (weekly distance training, stroke specialty, athlete's position, practice of another physical activity, and strength training); 3) presence of current musculoskeletal pain, pain characteristics, pain anatomic region, situation that caused the pain (practice or competition); and 4) injury history over the previous 12 months, with details regarding the respective situation, type, and region of injury. The following operational definition of injury used was: any musculoskeletal disorder related to swimming in previous 12 months, severe enough for the swimmer to seek medical attention or to prevent the swimmer from performing at least one training session or competition.16
The swimmer's position was defined as sprinter (if they typically competed in races of 200 metres or less) or distance (if they typically competed in races of greater than 200 metres). The swimmer's stroke specialty was classified according to the races they competed in (freestyle, backstroke, breaststroke, butterfly, and medley) and participants must to choose only one stroke specialty of his preference. Regarding presence of pain, athletes were asked if they were suffering any current pain of musculoskeletal origin, as well as the pain characteristics. To better identify the type and anatomic region of pain and previous injuries, a predefined list used by previous studies was adopted.17‐19
This study was approved by the Ethics Committee of the University of the City of São Paulo and also received approval from the Medical Department of the Brazilian Aquatic Sports Federation in accordance with the Helsinki Declaration of 1975 and the guidelines of Harris and Atkinson.20 All participating athletes signed the consent form in accordance with the study's requirements.
Statistical Analysis
The description of participants’ personal and training characteristics was descriptively analyzed using frequency distribution and percentages for categorical data (gender, body mass index [BMI], stroke specialty, swimmer's position, strength training, and previous injuries). Swimmers were categorized as freestyle or non‐freestyle, and more than half of the participants had freestyle as their stroke specialty. Continuous data (age, height, weight, swimming experience, and weekly distance) were reported in mean and standard deviation, since all data presented in a normal distribution. Normality evaluation of continuous data was done through a curve symmetry analysis.
For categorical data comparison, the Chi‐squared Test was utilized. For continuous data comparison, the Students t‐test for independent samples was used. The relative risk of presence of pain was also calculated for the following variables: gender, BMI, stroke specialty, swimmer's position, strength training, practice of another physical activity (another modality besides the swimming), and previous injuries. For all analyses, a 95% significance level was regarded as statistically significant and the analyses were performed using SPSS 17.0.
RESULTS
Two hundred and fifty‐seven (59.8%) swimmers accepted the invitation to participate in the study and completed the questionnaire. The description of swimmers’ personal and training characteristics are presented in Table 1.
Table 1.
Characteristics of swimmers included in the study.
| Total (n= 257) | Male (n= 140) | Female (n= 117) | |
|---|---|---|---|
| Age (years) | 20.1 (3.8) | 20.6 (3.7) | 19.4 (3.9) |
| Height (cm) | 176.2 (14.4) | 181.5 (16.8) | 169.9 (6.9) |
| Weight (kg) | 70.4 (12) | 77.7 (9.9) | 61.6 (7.7) |
| BMI | |||
| ≤ 25 | 92.6% (238) | 88.5% (123) | 98.3% (115) |
| >25 | 7.4% (19) | 11.5% (16) | 1.7% (2) |
| Swimming experience (years) | 13.2 (4.7) | 13.6 (4.7) | 12.6 (4.8) |
| Stroke specialty | |||
| Freestyle | 41.6% (107) | 40% (56) | 43.6% (51) |
| Backstroke | 18.3% (47) | 16.4% (23) | 20.5% (24) |
| Breaststroke | 15.6% (40) | 18.6% (26) | 12% (14) |
| Butterfly | 13.2% (34) | 13.6% (19) | 12.8% (15) |
| Medley | 11.3% (29) | 11.4% (16) | 11.1% (13) |
| Position | |||
| Distance | 32.7% (84) | 33.6% (47) | 31.6% (37) |
| Sprinter | 67.3% (173) | 66.4% (93) | 68.4% (80) |
| Week distance (km) | 57.1 (29.9) | 59.7 (32.5) | 53.9 (26.4) |
| Strength training | |||
| Yes | 93.4% (239) | 94.3% (132) | 91.5% (107) |
| No | 6.6% (18) | 5.7% (8) | 8.5% (10) |
| Another physical activity | |||
| Yes | 16.3% (42) | 16.4% (23) | 16.2% (19) |
| No | 83.7% (215) | 83.6% (117) | 83.8% (98) |
Continuous data are expressed in mean and standard deviation, and categorical data are expressed in percentage and number of participants.
The prevalence of musculoskeletal pain among 257 swimmer participants was 21% (n=54). The pain was most frequent during swimming practice but without performance limitation or after swimming. Around 70% of athletes reported that the pain was derived from training sessions. The anatomic region most commonly affected by pain was the shoulder, followed by the low back. Additional information about pain characteristics reported by the swimmers is provided in Table 2.
Table 2.
Prevalence and description of current pain reported by the swimmers.
| Total | Males | Females | |
|---|---|---|---|
| Presence of pain (n=257) | |||
| Yes | 21% (54) | 20.7% (29) | 21.4% (25) |
| No | 79% (203) | 79.3% (111) | 78.6% (92) |
| Pain situation (n=54) | |||
| Training | 68.5% (37) | 62.1% (18) | 72% (19) |
| Competition | 31.5% (17) | 37.9% (11) | 28% (6) |
| Pain characteristics (n=54) | |||
| Continuous | 3.7% (2) | ‐ | 8% (2) |
| With performance limitation* | 22.2% (12) | 24.1% (7) | 20% (5) |
| Without performance limitation# | 37% (20) | 37.9% (11) | 36% (9) |
| After competition/training | 29.7% (16) | 31% (9) | 28% (7) |
| Only during warm‐up | 3.7% (2) | 3.5% (1) | 4% (1) |
| Not reported | 3.7% (2) | 3.5% (1) | 4% (1) |
| Pain region (n=54) | |||
| Neck/Cervical | 7.8% (4) | 6.9% (2) | 8% (2) |
| Shoulder | 44.4% (24) | 41.4% (12) | 48% (12) |
| Elbow/wrist/hand/finger | 7.8% (4) | 13.8% (4) | ‐ |
| Hip/Thigh | 9.3% (5) | 10.4% (3) | 8% (2) |
| Knee | 5.5% (3) | 3.4% (1) | 8% (2) |
| Ankle/Foot | 1.8% (1) | 3.4% (1) | ‐ |
| Low back | 16.7% (9) | 17.3% (5) | 16% (4) |
| Others | 7.8% (4) | 3.4% (1) | 12% (3) |
Pain during competition/practice, with performance limitation.
Pain during competition/practice, without performance limitation.
A total of 144 swimmers (56%) reported previous musculoskeletal injuries in the previous 12 months. Table 3 shows a description of previous injuries’ characteristics. Around 60% of previous injuries affected the upper extremities, and the shoulder was the anatomic region most commonly affected in both genders (males, 41.4%; females, 48%). The second region most affected by previous injuries was the knee and tendinopathy was the most common type of knee injury most reported by swimmers.
Table 3.
Prevalence and description of previous injuries in last 12 months in swimmers.
| Total | Males | Females | |
|---|---|---|---|
| Previous injury (within 12 months) | (n=257) | ||
| Yes | 56% (144) | 57.9% (81) | 53.8% (63) |
| No | 44% (113) | 42.1% (59) | 46.2% (54) |
| Injury situation | |||
| Practice | 91% (131) | 90.1% (73) | 92.1% (58) |
| Competition | 9% (13) | 9.9% (8) | 7.9% (5) |
| Type of injury | |||
| Tendinopathy | 58.7% (61) | 55.7% (34) | 62.9% (27) |
| Muscular lesion | 7.7% (8) | 9.8% (6) | 4.6% (2) |
| Dislocation | 3.8% (4) | 6.7% (4) | ‐ |
| Arthritis/Synovitis/Bursitis | 3.8% (4) | 1.6% (1) | 7% (3) |
| Ligamentar rupture | 2.9% (3) | 1.6% (1) | 4.6% (2) |
| Meniscal/Cartilage | 6.7% (7) | 8.2% (5) | 4.6% (2) |
| Sprain | 1.9% (2) | ‐ | 4.6% (2) |
| Others | 14.5% (15) | 16.4% (10) | 11.7% (5) |
| Injury region | |||
| Neck/Cervical | 6.2% (9) | 6.2% (5) | 6.3% (4) |
| Shoulder | 46.5% (67) | 50.6% (41) | 41.3% (26) |
| Elbow/Wrist/Hand/Finger | 2.8% (4) | 1.2% (1) | 4.8% (3) |
| Hip/Thigh | 4.2% (6) | 2.5% (2) | 6.3% (4) |
| Knee | 16% (23) | 14.8% (12) | 17.5% (11) |
| Leg | 2.1% (3) | 1.2% (1) | 3.2% (2) |
| Ankle/Foot | 4.9% (7) | 2.5% (2) | 7.9% (5) |
| Low back | 6.2% (9) | 11.1% (9) | ‐ |
| Others | 11.1% (16) | 9.9% (8) | 12.7% (8) |
The comparison of continuous variables between swimmers with pain and without pain is shown in Table 4. It should be noted that there were no statistically significant differences for any of the variables between swimmers with and without pain.
Table 4.
Comparisons of between swimmers with and without pain.
| Without pain | With pain | p‐value | |
|---|---|---|---|
| Age (years) | 19.9 (3.8) | 20.1 (4) | 0.09 |
| Height (cm) | 176.8 (9.3) | 177.2 (9.6) | 0.69 |
| Weight (kg) | 70.6 (11.1) | 70.9 (11.7) | 0.79 |
| Swimming experience (years) | 13 (4.7) | 13.8 (4.8) | 0.17 |
| Week distance (km) | 57.8 (31.1) | 54.2 (25.3) | 0.61 |
Data are expressed in mean and standard deviation. Comparisons were conducted with the Student‐t Test for independent samples
With regard to relative risk for musculoskeletal pain, note that the relative risk values were not statistically different among groups for any of the variables (Table 5).
Table 5.
Comparison of categorical data between swimmers with and without pain.
| Without pain | With pain | p‐value | RR (CI) | |
|---|---|---|---|---|
| Gender | 0.9 | |||
| Male | 79.3 (111) | 20.7 (29) | 1 | |
| Female | 78.6 (92) | 21.4 (25) | 1.03 (0.64 – 1.66) | |
| BMI | 0.94 | |||
| ≤ 25 | 77.7(185) | 22.3 (53) | 1 | |
| > 25 | 94.4 (17) | 5.6 (1) | 0.25 (0.04 – 1.70) | |
| Stroke specialty | ‐ | ‐ | 0.88 | |
| Freestyle | 79.4 (85) | 20.6 (22) | 1 | |
| Non‐Freestyle | 78.7 (118) | 21.3 (32) | 1.11 (0.68 – 1.79) | |
| Position | 0.23 | |||
| Distance | 83.3 (70) | 16.7 (14) | 1 | |
| Sprinter | 76.9 (133) | 23.1 (40) | 1.38 (0.80 – 2.40) | |
| Strength training | 0.14 | |||
| No | 64.7 (11) | 35.3 (6) | 1.65 (0.82 – 3.44) | |
| Yes | 79.9 (191) | 20.1 (48) | 1 | |
| Another physical activity | 0.61 | |||
| No | 79.7 (169) | 20.3 (44) | 1 | |
| Yes | 76.2 (32) | 23.8 (10) | 1.17 (0.64 – 2.15) | |
| Previous injury | 0.25 | |||
| No | 82.3 (93) | 17.7 (20) | 1 | |
| Yes | 76.4 (110) | 23.6 (34) | 1.33 (0.81 – 2.19) |
Data are expressed in percentage and number of swimmers. The p‐value were obtained using the Chi‐squared Test.
RR= relative risk, CI= confidence interval
DISCUSSION
The results of the present cross‐sectional study demonstrated that approximately 20% of swimmers reported musculoskeletal pain during the Brazilian Swimming Championship (39th Troféu José Finkel Edition, 2010). Around 60% of participants reported previous injuries. Tendinopathy was the most common type of previous injury and the shoulder the most affected anatomic region in both males and females. When analysing the relative risk of presence of pain for personal and training characteristics, it should be noted that there were no statistically significant differences for any of the variables between those who had pain and those who did not.
This is first study that has investigated and described a 20% prevalence of musculoskeletal pain in professional swimmer participants in a large Brazilian national tournament. Several previous authors have also evaluated professional swimmers, but with a longitudinal prospective design.8,15,21 Wolf et al21 reported an injury incidence of four injuries per 1,000 exposures in swimmers from the National Collegiate Athletic Association (NCAA) team followed during five seasons, while Chase et al15 found an incidence of 5.5 per 1,000 hours exposure in swimmers also from the NCAA. Mountjoy et al8 evaluated the occurrence of new injuries sustained during the World Swimming Championship, and their incidence was 66 injuries per 1,000 athletes.
The present study also evaluated the rate of injuries in the previous 12 months, and 144 (56%) swimmers reported at least one musculoskeletal injury within the previous 12 months. This injury rate is similar to the results of Aguiar et al,22 which, despite the use of a different definition of injury, found an injury rate in the previous 12 months of 56.3% in swimmer participants in minor national tournaments. This similar result can be explained by the characteristics that are alike in both studies, such as age, swimming experience, and BMI.
The shoulder was the anatomic region most commonly affected by both musculoskeletal pain at the time of the survey, and by previous injuries (within 12 months) in swimmers in this study. Despite the different ways of monitoring swimmers in their studies, as in a longitudinal prospective way of evaluating new injuries,8,15,21,23 or only the previous injuries,22 these previous authors also cited the shoulder as the region most affected by swimming injuries. This finding was expected, as the shoulder is responsible for around 90% of propulsive power in swimmers.6 When this is associated with the training overloads to which professional athletes are exposed, then this makes the shoulder a region very susceptible to overuse injuries.
The type of previous injuries most reported by swimmers was tendinopathy, similar to the findings in Aguiar et al.22 Tendinopathy is usually related to excessive loads imposed by sports activities and is characterized as an overuse injury.24 The tendon, when exposed to repetitive harmful movements, exceeds its physiologic limit, causing the rupture of collagen fibers and tendon degeneration.25 Overuse injuries were also the most frequent in the studies by Kerr et al,23 Mountjoy et al8 and Chase et al,15 indicating that as in other sports,17,26,27 such as athletics and running, these type of injuries occur most frequently as in swimming. Future studies about preventive measures in swimming should attempt to overuse injuries, specially the tendinopathies, and how the amount of exposure by the athletes could be related to these injuries.
One hypothesis of this study was that variables, such as swimming experience, weekly distance, stroke specialty, swimmer's position, and previous injuries, could be associated with the presence of musculoskeletal pain in the swimmers. However, there were no statistically significant differences found between swimmers with pain and without pain for any of these variables. Previous authors have reported some factors associated with injuries. For instance, Aguiar et al22 reported that age and swimming experience were associated with previous injuries in swimmers in minor national tournaments. Wolf et al21 and Chase et al15, in prospective studies, noted the association between occurrence of new injuries with backstroke specialty and previous injuries, respectively. These different findings from the present study may be explained by the use of different injury definitions utilized by each study. Another explanation is that sports injuries usually are characterized by a multifactorial causes, maybe the questions included in the current study's questionnaire were not sufficient to detect possible differences between swimmers with pain and without pain.
As a limitation of the present study, one swimming team that had a large number of participants in the tournament refused to participate in the study, explaining why the study had 59.8% of attendance from the swimmers participants in the championship. Another limitation is the use of a questionnaire about previous injuries and swimming distance, since the participants could underreport both information, explaining why the present study did not find association between presence of pain and previous injuries or swimming distance. Despite limiting the questioning to injuries sustained in the last 12 months, it is not possible to discard the recall bias, since a previous study28 demonstrated that when a retrospective injury registration is used, participants can forget to record previous injuries and injury rate could be underestimated.
CONCLUSION
The results of the current study demonstrated that the prevalence of musculoskeletal pain in professional swimmer participants in the most important Brazilian national tournament was 20%, while around 60% of participants reported previous injuries. These results indicate that a substantial problem exists involving elite swimmers and further studies should address preventive measures through randomized controlled trials. Because overuse injuries of the shoulder were most common, attention to preventive measures should be given to these types of injuries, especially tendinopathies of the shoulder.
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