Gluteus and posterior thigh muscle sizes in sprinters: Their distributions along muscle length.

Muscle hypertrophy can occur non-uniformly in athletes who repetitively perform particular movements, presumably leading to a unique muscle size distribution along the length. The present study aimed to examine if sprinters have unique size distributions within the gluteus and posterior thigh muscles. Nineteen male sprinters and 20 untrained males participated in the present study. T1-weighted magnetic resonance images of the hips and right thigh were obtained in order to determine whole and regional (proximal, middle, and distal) volumes of the gluteus maximus and individual posterior thigh muscles. The results showed that the volumes of all the examined muscles relative to body mass were significantly larger in sprinters than in untrained males (all  < 0.001,  = 1.40-3.29). Moreover, the magnitude of the difference in relative volume between sprinters and untrained males was different between the regions within the gluteus maximus ( = 0.048, partial  = 0.187), semitendinosus ( = 0.004, partial  = 0.331), and adductor magnus ( = 0.007, partial  = 0.322), but not within the other posterior thigh muscles ( = 0.091-0.555, partial  = 0.025-0.176). The magnitude of the difference in relative volume between the sprinters and untrained males was greatest in the distal regions within the gluteus maximus and semitendinosus, while the proximal region within the adductor magnus. These findings indicate that sprinters have unique size distributions within the gluteus maximus, semitendinosus, and adductor magnus, which may be attributed to their competitive and training activities. HighlightsSprinters showed larger gluteus maximus and individual posterior thigh muscles than untrained males.The magnitude of difference varied within the gluteus maximus, semitendinosus, and adductor magnus.The greatest difference was found in distal regions within the gluteus maximus and semitendinosus, while proximal region within the adductor magnus.