ABSTRACT
The relationship between relaxation time and muscle fiber composition was investigated in 16 males.<BR>A highly positive correlation was found between muscle fiber composition and relaxation time. In addition, higher proportions of fast-twitch fibers were associated with longer relaxation times, indicating that the fast-twitch fiber has a longer relaxation time than the slow-twitch fiber.<BR>Multiple regression analysis, which was conducted to investigate the suitability of relaxation time as a model for estimating muscle fiber composition, revealed that the T 1 and T 2 were significantly related to muscle fiber composition.<BR>Therefore, the results of the present study indicate that relaxation time obtained by MRI can be used to estimate muscle fiber composition.