Abstract

Attempts were made to clarify whether or not fiber composition of the m. vastus lateralis could be predicted with running performance. Biopsy samples from 32 well-trained and 17 untrained adult males were examined for the percentage area of fast-twitch (FT) and slow-twitch (ST) fibers which might be related to the physical performance better than the fiber type distribution. In addition, each subject completed 50-m sprint and 12-min run tests. A multiple regression analysis revealed that in the trained males predictive accuracy for the percentage area of FT fibers (areaFT) from the ration of a 50-m sprint speed to a 12-min run speed (50 m/S/12 min/S) was higher than that from most of other variables. A positive correlation between 50 m/S/12 min/S and areaFT also existed for the untrained subjects. The linear regression equations of areaFT (Y) on 50 m/S/12 min/S (X) were X = 68.6 + 76.2X (r = 0.896, p < 0.05) and Y = -47.5 + 61.1X (r = 0.798, p < 0.05) for the trained and untrained males, respectively. There was no significant difference in the regression equations between the trained and untrained males. For all subjects, the equation was Y = -59.8 + 69.8X (r = 0.876, p < 0.05) and the standard error of estimate of areaFT on 50 m/S/12 min/S was 8.86. These results suggest that the performances of a 50-m sprint and a 12-min run are valuable indicators in, accurately, easily and noninvasively, predicting the percentage area of FT and ST fibers of the m. vastus lateralis from adult male. Verf.-Referat