Muscular Contraction Ability Develops in the Lower Trapezius Muscle of the Dominant Arm in Team Hand-Ball Players

Eleven male university team hand-ball players (22 shoulders) with 5 or more years of competitive team hand-ball experience who had no history of injuries were included in this study. We compared the thickness of the trapezius muscle between their dominant arm and non-dominant arm, to clarify the correlation between the muscle thickness and muscular strength during internal and external rotation in the shoulder joints used to throw a handball. We measured the thickness of the middle and lower trapezius muscles at an abduction angle of 90° descending by the ultrasonic LOGIQ e and measured internal and external rotational muscular strength of the glenohumeral joint by BIODEX. The players showed significantly greater thickness of the lower trapezius muscle during constriction in the dominant arm than that in the non-dominant arm. Furthermore, a positive correlation was observed between muscle thickness of the lower trapezius muscle and the muscular strength during internal rotation of the glenohumeral joint. It is highly probable that the height of the constricting ability in the lower trapezius muscle in the dominant arm is related to the prevention of throwing injuries.