Morphological and functional differences in the elbow extensor muscle between highly trained male and female athletes

The purpose of this study was to investigate the difference in the morphological and functional aspects of the triceps brachii muscle between highly trained male and female athletes who were members of the 1996 Japanese Olympic teams in each of three different events: soccer, gymnastics and judo. The thickness (TBmt) and fibre pennation angle (TBpen) of the triceps brachii muscle and force output during elbow extensions were determined using a B-mode ultrasound apparatus and an isokinetic dynamometer, respectively. The TBmt and its value relative to upper arm length (TBmt/l(ua)) were significantly larger in the men than in the women in all the events except judo. In all the subjects, a significant correlation was found between TBmt/l(ua)) and TBpen (r = 0.721, P < 0.05). The existence of the sex difference in TBpen within the same event was in agreement with that observed in TBmt/l(ua) except for the soccer players. The TBpen of the soccer players were similar in both sexes although a significant sex differences was found in TBmt/l(ua). The isokinetic forces measured using the two velocities 60 degrees x s(-1) (F60) and 180 degrees x s(-1) (F180) were significantly correlated to the cross-sectional area (CSA) of the triceps brachii muscle estimated from TBmt (r = 0.702, P < 0.05 for F60, and r = 0.776, P < 0.05 for F180). No significant sex differences were found in either F60/CSA or F180/CSA in any of the events. From these results, it could be assumed, at least in the Olympic athletes tested in this study, that the fibre angulation of the triceps brachii muscle was almost the same in the two sexes if allowance was made for the difference in the muscle size, and the sex difference in force generation capability of the triceps brachii muscle could in the main be attributed to the difference in CSA rather than in the architectural characteristics.