Optimizing Shoulder Exercise Selection: Arm Rotation Versus Abduction Exercises for Increasing Acromiohumeral...

Shoulder muscle groups contributing to arm rotation compared with arm abduction may differentially load the humeral head and scapula during arm elevation. Our primary aim was to compare the effects of progressive resistance exercises targeting either arm rotation or arm abduction on the acromiohumeral distance at 3 static angles of active scapular arm abduction in individuals with secondary subacromial impingement syndrome.

Randomized controlled clinical trial.

Fifty-four volunteers diagnosed with secondary subacromial impingement syndrome were randomly assigned to 3 parallel groups. Both intervention groups performed shoulder progressive resistance exercises every other day over 6 weeks; intervention group I focused on arm rotation, whereas intervention group II focused on arm abduction. The control group maintained their regular activities of daily living for 6 weeks. Using an ultrasound device, the acromiohumeral distance was measured at 3 static angles of active scapular abduction: 0°, 45°, and 60°. The outcome measures were assessed in the intervention groups 1 day before and 1 day after progressive balance exercises and in the control group twice, at 6-week intervals.

Significant between- and within-group interaction effects were identified for the acromiohumeral distance at 45° and 60° of active scapular arm abduction (P < .001, ηp2>.281). However, no significant between- and within-group interaction effect was observed for the acromiohumeral distance with no arm abduction (P = .085, ηp2=.092).

Six weeks of progressive resistance exercises targeting arm rotation, compared with arm abduction, increased the acromiohumeral distance at 45° and 60° of active scapular arm abduction.