The effect of scapular protraction on isometric shoulder rotation strength in normal subjects.

To measure the effect of scapular protraction on isometric shoulder rotation strength, 20 normal subjects completed 2 maximal isometric internal and external rotation contractions in 2 scapular positions (scapula neutral [SN] and scapula protracted [SP]) from 3 arm positions (90 degrees internal rotation [IR], 45 degrees internal rotation [MR], and 90 degrees external rotation [ER]). Scapular protraction reduced shoulder rotation strength in 5 of 6 test positions (P < .0004), with significant interactions between scapular position and arm position (P < .