Search

Background Injury prevalence data, muscle strength, and fatiguability differ between males and females. In addition, arm spatial orientation affects muscle activation and strength of the shoulder muscles. Nevertheless, little research has been conducted in relation to the shoulder rotator muscles comparing men and women. Therefore, the main aim of of this study was to perform a comparative investigation between two arm spatial orientations (45° and 90° of abduction in the frontal plane) during a fatigue assessment of the internal rotator (IR) and external rotator (ER) shoulder muscles. Secondly, the interaction between sex and dominance with muscular performance was assessed. Methods Forty healthy sedentary participants, 20 males and 20 females took part in this study. Participants performed a fatigue resistance protocol consisting of 30 consecutive maximal concentric contractions of the IR and ER shoulder muscles in a supine position at a speed of 180°/s. The upper limb was abducted to an angle of 45° or 90° in the frontal plane and each participant was tested on the dominant and nom-dominant side, counterbalanced in order of administration. Performance measures of Induced Fatigue (IF; %), Cumulated Performance (C.Perf; J) and Best Repetition (BR; J) were calculated and used for analysis. IF represents the % difference between the amount of work done over the last 3 and first 3 repetitions, BR represents the largest amount of work done during a single contraction, and C.Perf represents the total amount of work done during all repetitions. Results Muscle group was the only factor to display significant variation when not considering other factors, with higher values for C.Perf (mean difference = 353.59 J, P P P = 0.0046). There was a significant difference between both angles, with higher values observed at 90° compared to 45° of abduction for C.Perf by ~ 7.5% (mean difference = 75 to 152 J) and ~ 10.8% (mean difference = 5.1 to 9.4 J) for BR in the ER, in males and females respectively (P P Discussion Differences in shoulder performance fatiguability between sexes are affected by arm position, arm dominance and muscle groups. In agreement with the literature, performance values in males were approximately 50% higher than in females. However, the amount of IF was no different between both sexes. Based on findings in literature, it could be suggested that this is due to differences between males and females in motor control and/or coordination strategies during repetitive tasks. In addition, we also observed the IR muscles to be significantly stronger than the ER muscles. It has long been established in literature that these observations are due to the muscle-size differences between both muscle groups, where the IR muscles can produce a larger amount of force due to the larger cross-sectional area. Results of our study found similar ER:IR ratios compared to previous reports. Conclusion Therefore, these findings are useful for clinicians when monitoring rehabilitation programs in sedentary individuals following shoulder injuries.

The serve is an important stroke in any high level tennis game. A well-mastered serve is a substantial advantage for players. However, because of its repeatability and its intensity, this stroke is potentially deleterious for upper limbs, lower limbs and trunk. The trunk is a vital link in the production and transfer of energy from the lower limbs to the upper limbs; therefore, kinematic disorder could be a potential source of risk for trunk injury in tennis. This research studies the case of a professional tennis player who has suffered from a medical tear on the left rectus abdominis muscle after tennis serve. The goal of the study is to understand whether the injury could be explained by an inappropriate technique. For this purpose, we analyzed in three dimensions the kinematic and kinetic aspects of the serve. We also performed isokinetic tests of the player's knees. We then compared the player to five other professional players as reference. We observed a possible deficit of energy transfer because of an important anterior pelvis tilt. Some compensation made by the player during the serve could be a possible higher abdominal contraction and a larger shoulder external rotation. These particularities could induce an abdominal overwork that could explain the first injury and may provoke further injuries. Key pointsIn the proximal-distal sequence, energy is transmitted from lower limbs to upper limps via trunk.The 3D analysis tool is an indispensable test for an objective evaluation of the kinematic in the tennis serve.Multiple evaluations techniques are useful for fuller comprehension of the kinematics and contribute to the awareness of the player's staff concerning pathologies and performance.

Tendinopathy is characterized by pain in the tendon and impaired performance sometimes associated with swelling of the tendon. Its diagnosis is usually clinical but ultrasonography and magnetic resonance imaging can refine the diagnosis. Tendinopathy is highly prevalent and is one of the most frequently self reported musculoskeletal diseases in physical workers and sports people. Nevertheless, it is very difficult to carry out general epidemiologic studies on tendinopathy because of the varying sports cultures and sports habits in different countries. The aetiology of tendinopathy seems to be multi-factorial, involving intrinsic and extrinsic factors. The role of inflammation is still debated but the absence of inflammatory cells does not mean that inflammatory mediators are not implicated. Different theories have been advanced to explain pain and chronicity mechanisms, but these mechanisms remain largely unknown. "Conventional "treatments are generally employed empirically to fight pain and inflammation but they do not modify the histological structure of the tendon. However, these treatments are not completely satisfactory and the recurrence of symptoms is common. Currently, eccentric training remains the treatment of choice for tendinopathy, even though some studies are contradictory. Moreover, many interesting new treatments are now being developed to treat tendinopathy, but there is little evidence to support their use in clinical practice. Key pointsThe word "tendinopathy "is the correct term for the clinical diagnosis of pain accompanied by impaired performance, and sometimes swelling in the tendon.The aetiology of tendinopathy seems to be a multi-factorial process, involving promoting factors that are intrinsic or extrinsic, working either alone or in combination.US (with color Doppler) and MRI are usually prescribed when tendinopathy is unresponsive to treatment and entails lingering symptoms.Eccentric training is currently considered to be the most efficient treatment for tendinopathy; nevertheless, in order to be effective, this treatment needs specific modalities: slow speed, low intensity and gradual intensification, with minimum 20 to 30 sessions of exercises often being needed.Many interesting new treatments are now being developed to treat tendinopathy, but currently there is little evidence to support their use in clinical practice.