ARCHITECTURAL CHARACTERISTICS OF DOMINANT LEG MUSCLE IN JUNIOR SOCCER PLAYERS

Abstract

Preferential use of dominant over non-dominant limb produces muscle hypertrophy in the dominant limb. The purpose of this study was to investigate the muscle architectural characteristics associated with dominant leg use in junior soccer players. The gastrocnemius medialis (MG) muscle was tested at the 30% proximal level of the lower leg length in 26 junior soccer players [mean (SD), age:16.5 (0.6) yr] and 20 control college students [age:18.5 (0.5) yr]. Sectional images of muscle and aponeurosis were visualized in a two-dimensional plane with the use of B-mode ultrasound (Aloka SSD-500, Japan). Muscle thickness was determined as the distance between the adipose tissue-muscle interface and intermuscular interface. The fascicle pennation angle was measured from the angle between the echo of the deep aponeurosis of MG muscle and interspaces among the fascicles of that muscle. The length of fascicles across the deep and superficial aponeurosis was measured as a straight line, manually. Lower leg circumference and MG muscle thickness were significantly (p < 0.05) greater in soccer players than the controls. The percent difference (dominant minus non-dominant legs) in muscle thickness and fascicle length were significantly (p < 0.01) larger in soccer players than in controls but the percent difference in pennation angle was similar between groups. The difference (dominant leg minus non-dominant leg) in muscle thickness was significantly correlated (r = 0.55; p < 0.05) to the difference in muscle fascicle length in soccer players but not in controls. In conclusion, the preferentially use of one limb over another, as seen in junior soccer players, results in a greater difference in muscle thickness between the dominant and non-dominant legs. This difference in muscle thickness was associated with a longer fascicle length of the dominant leg. Thus it appears possible that fascicle length may be further influenced by physical training in the dominant legs.