Electromyographic analysis of selected shoulder muscles during rehabilitation exercises.

BACKGROUND: Overhead work-activities and repetitive use of arm in occupational tasks are known risk factors to cause shoulder injury that often develops to functional disability. Rehabilitation exercises (REs) are capable of slowing this development.

OBJECTIVE: The main objective of the present work is to experiment with common REs and to identify those which produce significant integrated electromyography (iEMG) activation of selected shoulder muscles namely, posterior deltoid, infraspinatus, teres minor, upper trapezius, middle trapezius and lower trapezius.

METHODS:   Ten healthy male occupational workers, exposed to the risk of shoulder injury, performed six REs while iEMG activities of concerning muscles are recorded using Biopac MP 150 system. REs are cross-examined statistically to select those which yield higher iEMG activations.

RESULTS: Results indicate that upper trapezius presents the highest iEMG activity in exercise 6 (standing ER at 90∘ abduction and 90∘ elbow flexion). Middle trapezius and lower trapezius show highest activation in exercise 1 (prone horizontal abduction at 90∘ with full external rotation with thumb right up). Also, posterior deltoid, infraspinatus, and teres minor have the highest iEMG activity in this exercise.

CONCLUSIONS: Results provide basic information to select appropriate rehabilitation programs for occupational workers exposed to the risk of shoulder injury.