THE EFFECTS OF MUSCLE FATIGUE ON AND THE RELATIONSHIP OF ARM DOMINANCE TO SHOULDER PROPRIOCEPTION

It is hypothesized that proprioceptive information plays an important role in joint stabilization and that muscle fatigue may alter proprioc eptive ability. The purpose oi this study was to determine what effect shoulder muscle fatigue has on glenohumeral proprioception and to exa mine the relationship between arm dominance and shoulder proprioceptio n. Eighty subjects without a history of glenohumeral pathology partici pated. Each was sealed on an isokinetic dynamometer with a randomly se lected shoulder positioned in 90 degrees oi abduction and elbow flexio n. With vision blinded, the arm was passively positioned in 75 degrees oi external rotation for 10 seconds, then passively returned to the n eutral starting position. Three trials each of active and passive repo sitioning (2 degrees/sec) were recorded. Following a fatigue protocol, both active and passive repositioning were reassessed. Testing order was randomized. A significant difference was detected between pre- and post-fatigue scores. No significant difference was detected between d ominant and nondominant extremities. No relationship between arm domin ance and shoulder proprioception was established. It is concluded that shoulder proprioception is diminished in the presence oi shoulder mus cle fatigue, suggesting clinical rehabilitation protocols must emphasi ze increasing muscular endurance.