The effect of shoulder inferior mobilization on scapular and shoulder muscle activity during resisted shoulder abduction: a repeated-measures study on asymptomatic individuals

Mobilisation is used for improving range of motion and reducing pain in patients with shoulder disorders. It is currently unclear what the underlying mechanisms of that technique are. This study aimed to assess the effect of inferior shoulder mobilisation on scapular and shoulder muscle activity, during resisted shoulder abduction in asymptomatic individuals. This is a repeated-measures, cross-over, randomised controlled study. Twenty-two participants were recruited. The order of intervention was randomised. Participants performed 5 repetitions of resisted shoulder abduction before and after the control or mobilisation conditions. Surface electromyography recorded activity of: anterior, middle and posterior deltoids; infraspinatus; upper and lower trapezius; serratus anterior; and latissimus dorsi muscles. We observed significant reductions in activity levels (infraspinatus, middle and posterior deltoid, and serratus anterior muscles) following the mobilisation during the eccentric phase of shoulder abduction. This may be related to differences in neural control between concentric and eccentric contractions.