Sprint performance is related to muscle fascicle length in male 100-m sprinters

The purpose of this study was to investigate the relationship between muscl e fascicle length and sprint running performance in 37 male 100-m sprinters . The sample was divided into two performance groups by the personal-best 1 00-m time: 10.00-10.90 s (S10; n = 22) and 11.00-11.70 s (S11; n = 15). Mus cle thickness and fascicle pennation angle of the vastus lateralis and gast rocnemius medialis and lateralis muscles were measured by B-mode ultrasonog raphy, and fascicle length was estimated. Standing height, body weight, and leg length were similar between groups. Muscle thickness was similar betwe en groups for vastus lateralis and gastrocnemius medialis, but S10 had a si gnificantly greater gastrocnemius lateralis muscle thickness. S10 also had a greater muscle thickness in the upper portion of the thigh, which, given similar limb lengths, demonstrates an altered "muscle shape." Pennation ang le was always less in S10 than in S11. In all muscles, S10 had significantl y greater fascicle length than did S11, which significantly correlated with 100-m best performance (r values from -0.40 to -0.57). It is concluded tha t longer fascicle length is associated with greater sprinting performance.