Scapular muscle activities during closed chain shoulder exercises

Over activation of the upper trapezius and inhibition of the serratus anterior are reported in patients with shoulder pathologies. Research supports focusing on exercises that activate the serratus anterior while inhibiting the upper trapezius. Exercises to facilitate this relationship are variations of the push]up plus which may be too challenging for patients in early rehabilitation. This studyfs purpose is to investigate shoulder muscular activation levels in particular upper trapezius/serratus anterior ratios (UT/SA) during 7 common shoulder rehabilitation exercises of varying intensity. We hypothesize greater UT/SA ratios in the more upright exercises (forward elevation, wall slides, and wall push]ups) compared to the ball roll, inferior glide, knee, and incline push]up. We hypothesis, there will be no group differences between symptomatic and asymptomatic subjects in muscle amplitudes or ratios. Twenty symptomatic and 20 asymptomatic subjects will be recruited and instrumented with EMG on 7 shoulder muscles. Participants will perform 10 repetitions of each exercise EMG data will be normalized to maximal muscle contractions, amplitude during each exercise will be determine with particular interest in the UT/SA ratio will be compared with a repeated measure ANOVA. The results of this study will aid clinicians in selecting meaningful exercises to improve scapular muscle imbalances.