Influence of body position on shoulder rotator muscle strength during isokinetic assessment

Abstract

The purpose of this study was to compare the effect of two different positions of shoulder internal rotation (IR) and external rotation (ER) on isokinetic concentric and eccentric peak torque as well as conventional and dynamic ratios. Nineteen athletes (Eigth judo and eleven tennis players), (20.3 ± 5.2 yrs) performed 5 maximal unilateral isokinetic concentric shoulder IR and ER repetitions at 60 � /s and 120 � /s. The subjects also performed 3 and 5 maximal eccentric shoulder ER repetitions at 60 � /s and 120 � /s respectively. The tests were performed in two seated positions: 1) with the shoulder abducted in the scapular plane, and 2) with the shoulder flexed in the saggital plane. S houlder dynamic control ratio (DCR) and conventional ratio were also assessed. The scapular plane position showed significa ntly (p < 0.05) greater peak torque (PT) values than the saggital plane position during concentric IR at both speeds. However, the saggital plane position PT values were significantly greater during concentric and eccentric ER in both speeds. Additionally, the DCR and the conventional ratio values were significantly g reater for the saggital plane shoulder position. These results sug gest that test position is an important control variable in i sokinetic shoulder IR and ER testing.