The effect of chronic shoulder pain on maximal force of shoulder abduction

SummaryThe aim of this study was to determine if chronic shoulder pain had an effect on arm abduction strength and recruitment strategies of the serratus anterior, middle deltoid, and upper trapezius.MethodThe maximal isometric force at 30° arm abduction and the electromyographic activity of the serratus anterior, middle deltoid, and upper trapezius were recorded for 14 subjects with unilateral chronic shoulder pain and 11 healthy subjects.ResultsRelative to the group without pain, the group with chronic shoulder pain showed no significant difference in maximal force production during isometric arm abduction. The Mann–Whitney tests showed no differences in the activation of the serratus anterior, middle deltoid, and upper trapezius between the two groups.Discussion and conclusionSubjects with chronic shoulder pain of mild to moderate intensity showed no difference from healthy subjects in arm abduction maximal strength, and recruitment patterns of serratus anterior, middle deltoid, and upper trapezius.