Should I prescribe exercise to a patient with an immobilized shoulder? An electromyographic study in patients with unilateral shoulder pain and healthy volunteers.

Abstract

There is limited evidence about exercise performance during postoperative immobilization. This study aimed to quantify the muscle activity in the immobilized shoulder girdle in an abduction and neutral rotation position during a battery of contralateral activities and ipsilateral exercises of the upper limb in healthy volunteers and patients with unilateral shoulder pain (USP). Thirty participants were included and grouped as without (<i>N</i> = 17) or with USP (<i>N</i> = 13). Muscle activity (percentage of maximum voluntary isometric contraction (%MVIC)) of the serratus anterior (SA), upper trapezius (UT), lower trapezius (LT) and infraspinatus muscles was assessed during five contralateral activities (during comfortable speed, fast speed and comfortable speed with additional load) and seven ipsilateral exercises. No differences in % MVIC were found between healthy volunteers and patients with USP on immobilized upper limb exercises and with the contralateral shoulder girdle. General muscle activity was low (<15% MVIC) to moderate (21-40% MVIC). This similarity was maintained at different speeds and with additional load. Adapted lawnmower exercise showed a favorable UT/LT activation ratio. The study results support the use of all evaluated shoulder exercises, as they have shown low muscle activity, which is important for early rehabilitation phases.