Objective: To determine whether pain reduction induced by supervised exercises over several months results in increased maximal force and muscle activation.
Design: Before-after trial.
Participants: Ten patients with unilateral rotator tendinosis and more than 3 months' duration of pain.
Intervention: Supervised exercises for 3 to 6 months.
Outcome measures: Maximal abduction force, muscle activation by surface electromyogram (EMG), and pain were assessed during brief maximal voluntary isometric contractions (MVC) before and after fatigue. EMG and pain were assessed during sustained submaximal contraction, performed with the shoulder 45 degrees abducted. The testing protocol was performed before and after supervised exercises.
Results: In the afflicted shoulder, resting pain was reduced after supervised exercises and no longer differed from the unafflicted side. The increase in pain during contraction was almost the same before and after treatment. MVC force increased, but significant side differences remained. EMG increased for trapezius and deltoid muscles in both afflicted and unafflicted arms. Fatigue development and recovery was unaltered by the exercise regimen.
Conclusions: Pain reduction after supervised exercises was associated with an improved MVC force, but the side difference in maximal force generation was maintained. Muscle activity during maximal contraction increased in both the afflicted and unafflicted sides.