Abstract des Autors

To investigate the influence of skeletal muscle fiber composition on the mechanical characteristics of human skeletal muscle under isometric and dynamic conditions, ten well-trained track athletes with differing muscle fiber composition (M. vastus lateralis) were used as subjects to perform maximum isometric and dynamic knee extension with maximum speed employing increasing load. To determine the mechanical properties of knee extensors a special dynamometer was used. The load was increased by adding weight discs to the electromagnetic part of dynamometer. The load increased from 0,33 to 2,33 Kgm2in six stages. The total population of subjects was divided into two groups onthe basis of whether individuals had more or less than 50 per cent of fast twitch fibers. Both groupsinvolved five subjects. The force-velocity curve might be separated on the basis of muscle fiber composition. The subjects who had a predominance of fast twitch fibers were able to perform higher power output. Significant correlation between percentage of fast twitch fiber and power as well as velocity was found when greater loads were employed. When thepercentage of fast twitch fiber and fast twitch fiber cross-sectional area were combined, significant correlation was proved between the mentioned para- meter and power using the two lowest loads.