Exercise for rotator cuff tendinopathy: Proposed mechanisms of recovery.

Rotator cuff (RC) tendinopathy is a common recurrent cause of shoulder pain, and resistance exercise is the first-line recommended intervention. Proposed causal mechanisms of resistance exercise for patients with RC tendinopathy consist of four domains: tendon structure, neuromuscular factors, pain and sensorimotor processing, and psychosocial factors. Tendon structure plays a role in RC tendinopathy, with decreased stiffness, increased thickness, and collagen disorganization. Neuromuscular performance deficits of altered kinematics, muscle activation, and force are present in RC tendinopathy, but advanced methods of assessing muscle performance are needed to fully assess these factors. Psychological factors of depression, anxiety, pain catastrophizing, treatment expectations, and self-efficacy are present and predict patient-reported outcomes. Central nervous system dysfunctions also exist, specifically altered pain and sensorimotor processing. Resisted exercise may normalize these factors, but limited evidence exists to explain the relationship of the four proposed domains to trajectory of recovery and defining persistent deficits limiting outcomes. Clinicians and researchers can use this model to understand how exercise mediates change in patient outcomes, develop subgroups to deliver patient-specific approach for treatment and define metrics to track recovery over time. Supporting evidence is limited, indicating the need for future studies characterizing mechanisms of recovery with exercise for RC tendinopathy.

Body roll differences in freestyle swimming between swimmers with and without shoulder pain.

Several studies have identified body roll as an important variable that affects shoulder pain due to its potential to modify upper limb kinematics. This study aimed to investigate potential differences in body roll between swimmers with and without shoulder pain. Twenty-four competitive swimmers participated in the study, 12 with unilateral shoulder pain and 12 without. Body roll was measured using two tri-axial accelerometers, one at the shoulder and one at the hip, during three trials of 100 m front crawl swimming at three different speeds. The results showed no significant difference in peak body roll angle between groups for the breathing side at the shoulders or hips. However, for the non-breathing side, swimmers with shoulder pain rolled significantly less at the hips (49º vs 57º, p = 0.018, r = 0.931) while no significant difference was found at the shoulders. These findings suggest that a potential relationship between hip rotation and shoulder pain may exist, such that hip roll is diminished to the non-breathing side in swimmers with unilateral shoulder pain. Given that a cause-effect relationship cannot be inferred from this cross-sectional study, future studies should attempt to identify the mechanisms that link body roll to the aetiology and pathomechanics of shoulder pain.