L'évaluation en laboratoire et sur le terrain vers la prévention des blessures à l’épaule chez les athlètes de sports aquatiques et d’armée du bras

In athletes competing in aquatic or overhead sports, chronic shoulder injuries are a major obstacle to performance and are among the most common injuries. The repetitive shoulder rotations required by these sports can cause kinematic and muscular adaptations that can lead to the development of chronic injuries at the shoulder. However, since the incidence of shoulder injuries is often multifactorial, there is no consensus on the risk factors and the best predictive screening tests for these injuries. The objectives of this thesis were to deepen the knowledge about shoulder function during maximal and repetitive efforts, and to evaluate the diagnostic validity of field evaluation methods aimed at identifying functional deficits of the upper limbs. The first study highlighted the important role in shoulder stability of the subscapular and serratus anterior. In addition, analysis of the electromyographic envelopes (EMG) suggests that eccentric and high speed contractions would allow faster recruitment of shoulder girdle muscles. It also appears that muscle recruitment patterns are associated with muscle lengthening, yet in some cases, these relationships differ depending on whether the muscle acts as prime mover or stabilizer. The second study provided valuable information on the kinetics of fatigue in the muscles of the shoulder girdle during repeated dynamic internal and external maximal rotations. The pectoralis major, medial deltoid, superior trapezius, infraspinatus and subscapularis showed signs of fatigue, particularly during their agonist phase, which was associated with a decrease in the maximum developed torque. Fatigue in the periscapular and rotator cuff muscles suggest that shoulder stability may be compromised in the presence of acute fatigue and could increase the risk of shoulder impingement. Finally, the third article and the complementary results suggest that the Kerlan-Jobe orthopaedic clinic shoulder and elbow score is an interesting screening tool to identify athletes with a shoulder injury, but that the Closed kinetic chain upper extremity stability test should not be used as a stand-alone test for this purpose. In particular, the use of a k-means algorithm made it possible to identify injured athletes more accurately than by using cut-off criteria. In short, the results of this thesis suggest to gradually include eccentric highspeed exercises and to develop the muscular endurance capacity of the scapular and rotator cuff muscles as part of rehabilitation and shoulder strengthening programs. In addition, the combination of EMG time-frequency transformation methods and statistical parametric mapping allows analysis of changes in instantaneous median power frequency during dynamic contractions which could be applicable to future studies monitoring muscle fatigue during repetitive sport movements. Finally, there is still a need to develop physical performance measures of the shoulder with good diagnostic validity. The use of machine learning methods could improve detection of chronic shoulder injuries in aquatic and overhead athletes by allowing clinicians to make decisions based on a multifactorial and nonlinear interpretation of clinical, self-reported and performance measures.

Keyphrases: Electromyography, Shoulder, Subscapularis, Rotator cuff, Isokinetics, Time-frequency, Statistical parametric mapping, Nonlinear analysis, Overhead, K-means