Le complexe articulaire de l’épaule du nageur de haut niveau

Magnitude and direction of shoulder torque asymmetries between different angular velocities in competitive swimmers

Asymmetries in swimming can be the result of poor technique or coordination between limbs, reducing the ability to produce propulsive force and increasing resistive drag. Therefore, this study aimed to compare the magnitude and determine the consistency of isokinetic peak torque asymmetries between the angular velocities of in the shoulder joint movements of internal and external rotation, flexion, and extension. Twenty-one competitive swimmers performed concentric actions at 60°/s (3 repetitions) and 180°/s (20 repetitions) in the movements of internal and external rotation, flexion, and extension of the shoulders using an isokinetic dynamometer, with the peak torque and asymmetry index being common metrics across the tests. The results showed a greater magnitude of asymmetry in internal rotation (16.86 vs. 9.86; p = 0.007) and flexion (12.06 vs. 7.35; p = 0.008) at 60 vs. 180°/s, respectively. The agreement levels of the direction of asymmetries between angular velocities were fair to substantial (Kappa: 0.40 to 0.69). Evaluating isokinetic torque in different movements and angular velocities resulted in different levels of asymmetry. Muscle force asymmetries can impact propulsion efficiency and movement coordination during swimming. Understanding muscle asymmetries allows the development of targeted and individualised training programmes to correct strength imbalances.

Investigating The Association Between Supraspinatus Tendon Abnormality, Shoulder Pain and Isokinetic Strength in Elite Swimmers: A Cross-Sectional Study

Shoulder pain is common among elite swimmers due to the tremendous stress over shoulders during swimming. Supraspinatus muscle is one of the major prime movers and stabilizers of shoulder and is highly susceptible to overloading and tendinopathy. An understanding of the relationship between supraspinatus tendon and pain; and between supraspinatus tendon and strength would assist health care practitioners for developing training regime. The objectives of this study are to evaluate 1) the association between structural abnormality of supraspinatus tendon and shoulder pain and 2) the association between structural abnormality of supraspinatus tendon and shoulder strength. We hypothesized that structural abnormality of supraspinatus tendons positively associated with shoulder pain and negatively associated with shoulder muscle strength among elite swimmers. 44 elite swimmers were recruited from the Hong Kong China Swimming Association. Supraspinatus tendon condition was evaluated using diagnostic ultrasound imaging and shoulder internal and external rotation strength was evaluated by the isokinetic dynamometer. Pearson's R was used to study the correlation between shoulder pain and supraspinatus tendon condition and to evaluate the association between isokinetic strength of shoulders and supraspinatus tendon condition. 82 shoulders had supraspinatus tendinopathy or tendon tear (93.18%). However, there was no statistically significant association between structural abnormality of supraspinatus tendon and shoulder pain. The results showed that there was no association between supraspinatus tendon abnormality and shoulder pain and there was a significant correlation between left maximal supraspinatus tendon thickness (LMSTT) and left external rotation/ concentric (LER/Con) and left external rotation/ eccentric (LER/Ecc) shoulder strength (p < 0.05) while internal rotation/ external rotation (IR/ER) ratio can also be a significant predicator on LMSTT >6mm (R² = 0.462, F = 7.016, df = 1, p = 0.038). Structural change of supraspinatus tendon was not associated with shoulder pain, but could be a predictor on MSTT >6mm in elite swimmers.

Shoulder Muscle Imbalance as a Risk for Shoulder Injury in Elite Adolescent Swimmers: A Prospective Study

Muscle strength imbalances between the internal and external rotators of the shoulder are frequent in swimmers, but their role in shoulder injury remains unknown. We aimed to evaluate the association of shoulder rotator strength and injury in elite adolescent swimmers. Eighteen adolescent swimmers performed preseason isokinetic tests of the internal and external rotator muscles in concentric (con) and eccentric (ecc) modes. Conventional (conER:conIR and eccER:eccIR) and functional ratios (eccER:conIR and eccIR:conER) were calculated. Thirteen swimmers completed a weekly questionnaire about swimming habits and shoulder injuries throughout the season. Preseason testing showed a significant negative association between the functional eccER:conIR ratio and years of practice (p < 0.05). Over the season, 46% of athletes experienced at least one shoulder injury. At the end of the season, peak torques increased for both internal and external rotator muscles strength, but only concentrically, resulting in a decrease in the eccER:conIR functional ratio (p < 0.05). The receiver operating characteristic curve analysis highlighted good predictive power for the preseason functional eccER:conIR ratio, as values below 0.68 were associated with a 4.5-fold (95% CI 1.33-15.28, p < 0.05) increased risk of shoulder injuries during the season.

The Effectiveness of a Dry-Land Shoulder Rotators Strength Training Program in Injury Prevention in Competitive Swimmers

Competitive swimmers usually undergo large mileage of daily training, in which propulsive force is produced mainly by the upper limbs. Some studies claim that dry-land shoulder rotators injury prevention programs before the in-water swim practice are paramount. However, the effect of shoulder strengthening prior to water training is unclear. This study aimed to analyse the acute effects of training programs conducted on dry land with the goal of preventing shoulder rotators injuries. A group of young swimmers (N = 23) was recruited to participate in this research. The peak torques of shoulder internal and external rotators were assessed before and after the completion of the compensatory strength training program. The isokinetic assessment was performed using two different protocols: 3 repetitions at 60^⍛/s and 20 repetitions at 180^⍛/s. Except for a trivial reduction in strength after the training program, there were no other significant differences in any of the studied variables (shoulders rotators endurance, strength and muscle balance). All results showed trivial to small effect sizes. Our findings suggest that a compensatory strength training program does not have a significant acute effect on the strength, endurance and muscle balance of shoulder rotators in young swimmers.

COMPARISON OF GLENOHUMERAL JOINT ROTATION RANGE OF MOTION IN YOUNG ATHLETES

ABSTRACT Introduction: Overhead-throwing athletes undergo changes in shoulder range of motion (ROM) due to sports activities, such as excessive amplitude, lateral rotation (LR) increase and medial rotation (MR) restriction. Asymmetry greater than 20° may render athletes more prone to injuries. There are similarities among sports featuring overhead throwing due to the considerable amount of movements involving maximum lateral rotation. In these sports, medial rotation (MR) restriction, excess of lateral rotation (LR) and shoulder pain are common, particularly in overhead-throwing athletes. Objective: To assess shoulder MR and LR ROM in athletes participating in different sports, considering the influence of these variables on injuries and functional performance. Methods: The rotation ROM of the glenohumeral joint was assessed in 477 young athletes, who were categorized in three sports groups: swimming, overhead-throwing and non-overhead throwing, distributed by age group. Analyses of Variance (ANOVA) were performed to verify if there were differences in MR and LR between groups and paired Student t test was used to verify differences between sides (asymmetry). Results: Youngest athletes showed significant shorter LR than the oldest, in both sides. This study demonstrated that the right side has less MR and greater LR in all groups. Conclusion: The findings showed that overhead-throwing and swimming groups have similarities in shoulder rotation ROM. Level of evidence III; Diagnostic Studies - Investigating a Diagnostic Test.

Isokinetic assessment of shoulder complex strength in adolescent elite synchronized swimmers

Children and adolescent participation in sport has increased in recent years. Synchronized swimming requires correct muscle balance in the shoulder complex. The purpose of this study was to establish isokinetic strength profiles and peak torque ratios of shoulder internal and external rotator muscles in a female high-level synchronized swimming team. Twenty-six adolescent female high-level synchronized swimmers, aged 12-14, participated in this study. Maximal bilateral shoulder concentric external and internal rotation force was measured at 60°/s (5 repetitions) and 180°/s (15 repetitions). The isokinetic concentric strength generated by the internal rotator muscles was significantly higher (p < 0.05) than by the external rotators in both limbs and at both velocities. Significant bilateral differences in the external rotation (ER):internal rotation (IR) strength ratio were noted at 60°/s. Isokinetic assessment is essential in sports medicine, since it is the only test capable of diagnosing any shoulder strength deficit.

Relationships Between Isokinetic Shoulder Evaluation and Fitness Characteristics of Elite French Female Water-Polo Players

Swimming and throwing are involved in water-polo player performance. These movements have a common biomechanical basis in the use of the internal shoulder rotation and adductor muscles. The aim of the study was to evaluate the relationship between shoulder isokinetic evaluation and throwing velocity as well as swimming performance in female water-polo players. Fifteen high level water-polo players completed two isokinetic shoulder evaluations to determine peak torque of shoulder rotators of the dominant shoulder (concentric and eccentric movements at an angular velocity of 60°·s-1 and concentric movements at an angular velocity of 240°·s-1) and shoulder extensors of both arms (concentric movements at an angular velocity of 60°·s-1 and 240°·s-1). Throwing velocity was measured using a radar gun placed 5 m behind the goal post. Front crawl swimming velocity was determined at 25 m, 100 m and 400 m distances. Concentric peak torque at 60°·s-1 and 240°·s-1 of internal rotators and eccentric peak torque at 60°·s-1 of external rotators were predictors of throwing velocity. The best model to explain the relationship between isokinetic evaluations and throwing velocity was obtained with concentric IR peak torque at 60°·s-1 and eccentric ER peak torque at 60°·s-1 (r2 = 0.52, p = 0.012). Relative total work done and peak torque of shoulder extensors were predictors of 25 m swimming velocity. Shoulder isokinetic evaluations correlate significantly with swimming performance and throwing velocity of female water-polo players. The results may help coaches to develop new strategies such as eccentric dry land training programs to increase both shoulder external rotators strength and throwing velocity.

Are there bilateral isokinetic shoulder rotator differences in basketball male players?

BACKGROUND

The internal (IR) and external (ER) rotator shoulder strength are often assess in the upper limb sports to prevent a risk of injuries. The purpose of this comparative study was to measure the agonist/antagonist balance of shoulder strength and to determine whether significant differences exist between the dominant and nondominant sides in basketball players compared to a control groups.

METHODS

During the championship, 23 elite male-basketball players (BB) and 23 healthy males (CG) were tested bilaterally on a Cybex Norm isokinetic dynamometer in a seated position with 45° shoulder abduction in the scapular plane at 60°.s-1 and 180°.s-1 in concentric (CON) and 60°.s-1 in eccentric (ECC) modes.

RESULTS

No significant differences were found for normalized values to body weight (N.m/kg-1) between the both groups and ER/IR, ECC/CON and functional deceleration ratios were similar. BB have a bilateral difference with higher ER of the dominant side comparatively to the opposite (P<0.05).

CONCLUSIONS

Unlike other sports that increase the performance of IR dominant side, the basketball player isokinetic profile could indicate a strengthening in the external rotators of the dominant side. This bilateral difference could be explained by the repetition of the specific movements in the ball control but this was not large enough for the ER/IR ratios to be significantly different with CG. The ratios analysis does not report an imbalance associated with a high risk of shoulder injuries.

Does a water-training macrocycle really create imbalances in swimmers' shoulder rotator muscles?

The continuous execution of swimming techniques may cause muscle imbalances in shoulder rotators leading to injury. However, there is a lack of published research studies on this topic. The aim of this study was to analyze the influence of a competitive swim period on the shoulder rotator-cuff balance in young swimmers. A randomized controlled pretest-posttest design was used, with two measurements performed during the first macrocycle of the swimming season (baseline and 16 weeks). Twenty-seven young male swimmers (experimental group) and 22 male students who were not involved in swim training (control group) with the same characteristics were evaluated. Peak torque of shoulder internal and external rotators was assessed. Concentric action at 1.04 rad s(-1) (3 repetitions) and 3.14 rad s(-1) (20 repetitions) was measured using an isokinetic dynamometer (Biodex System 3). External/internal rotators strength ratios were also obtained. For both protocols, there were significant training effects on internal rotator strength and external/internal rotator ratios (p ≤ .05). This trend was the same for both shoulders. Within-group analysis showed significant changes from baseline to 16 weeks for internal rotators strength and unilateral ratios of the experimental group. Swimmers' internal rotator strength levels increased significantly. In contrast, a significant decrease of the unilateral ratios was observed. Findings suggest that a competitive swim macrocycle leads to an increase in muscular imbalances in the shoulder rotators of young competitive swimmers. Swimming coaches should consider implementing a compensatory strength-training program.

Elite swimmers with unilateral shoulder pain demonstrate altered pattern of cervical muscle activation during a functional upper-limb task

STUDY DESIGN

Cross-sectional cohort study.

OBJECTIVE

To investigate the differences in the level of activation of neck-shoulder muscles between elite swimmers with and without shoulder pain during a functional upper-limb task.

BACKGROUND

Previous studies have reported altered motor control of the neck-shoulder muscles in patients with chronic neck-shoulder pain. Whether the activation of neck-shoulder muscles is altered among elite swimmers who have shoulder pain is unknown.

METHODS

Surface electromyography from the sternocleidomastoid, upper trapezius, and anterior scalene (SCL) muscles was recorded bilaterally in 17 elite swimmers (9 men, 8 women; mean ± SD age, 21 ± 3 years) with unilateral shoulder pain, and 17 age- and sex-matched elite swimmers without pain. Root-mean-square values were calculated and normalized to assess the level of muscular activation 5 seconds before, 120 seconds into, 150 seconds into, and 10 seconds after a functional upper-limb task.

RESULTS

The data revealed significant differences between groups for the root-mean-square of both SCL muscles (F = 3.733, P = .016) but not for the sternocleidomastoid and upper trapezius muscles. Swimmers with shoulder pain had higher normalized root-mean-square values in both SCL muscles at 120 seconds (78% on average) and 150 seconds (86% on average) into the task and at 10 seconds after the task (40% on average), as compared with swimmers without shoulder pain (P<.05).

CONCLUSION

The elite swimmers with shoulder pain demonstrated greater activation of the SCL muscles during a functional task and a lower ability to relax the SCL muscles after completion of the task than elite swimmers without shoulder pain. The present findings suggest an altered pattern of cervical muscle activation in elite swimmers with shoulder pain during performance of a functional task.

Elite swimmers with and without unilateral shoulder pain: mechanical hyperalgesia and active/latent muscle trigger points in neck-shoulder muscles

Our aim was to investigate the presence of mechanical hypersensitivity and active trigger points (TrPs) in the neck-shoulder muscles in elite swimmers with/without unilateral shoulder pain. Seventeen elite swimmers with shoulder pain; 18 swimmers without shoulder pain; and 15 elite athletes matched controls were recruited. Pressure pain thresholds (PPT) were assessed over the levator scapulae, sternocleidomastoid, upper trapezius, infraspinatus, scalene, subscapularis and tibialis anterior muscles. TrPs in the levator scapulae, upper trapezius, infraspinatus, scalene, sternocleidomastoid and subscapularis muscles were also explored. Swimmers with shoulder pain showed significant lower PPT in all muscles compared with controls (P<0.01). No differences in PPT were found between swimmers with and without shoulder pain, underlining widespread mechanical hypersensitivity. The mean number of TrPs for elite swimmer with and without shoulder pain was, respectively, 4.7 ± 1 (2.1 ± 1.5 active; 2.6 ± 1.4 latent) and 4.7 ± 1.3 (1.3 ± 1.3 active; 3.4 ± 1.5 latent), whereas healthy athletes only showed latent TrPs (2.4 ± 1.2). Elite swimmers with shoulder pain showed higher number of active TrPs than swimmers without pain, whereas it was the opposite for the number of latent muscle TrP (P<0.05). The reported mechanical hypersensitivity suggests that active TrPs play a role in the development of shoulder pain in elite swimmers.