Abstract des Autors

A group of 15 untrained male subjects pedalled on a friction-loaded cycle ergometer as fast as possible for 5-7 s to reach the maximal velocity (vmax) against different braking forces (F-B). Power was averaged during a complete crank rotation by adding the power dissipated against F-B to the power necessary to accelerate the flywheel. For each sprint, determinations were made of peak power output (Wpeak), power output attained at vmax (W-vmax) calculated as the product of vmax and F-B and the work performed to reach vmax expressed in mean power output (W-vmax). The relationships between these parameters and F-B were examined. A biopsy taken from the vastus lateralis muscle and tomodensitometric radiographs of both thighs were taken at rest to identify muscle metabolic and morphometric properties. The Wpeak value was similar for all F-B. Therefore, the average of values was defined as corrected maximal power (Wmax). This value was 11% higher than the maximal power output uncorrected for the acceleration. Whereas the Vmax determination did not require high loads, the highest W-vmax value (Wmax) was produced when loading was heavy, as evidenced by the W-vmax to F-B parabolic relationship. For each subject, the braking force (F-B,Wmax) giving Wmax was defined as optimal. The F-B,Wmax, equal to 0.844(SD 0.108) N/kg body mass, was related to thigh muscle area. The maximal velocity (vm,Wmax) reached against this force seemed to be related more to intrinsic fibre properties (% fast twitch b fibre area and adenylate kinase activity). Thus, from the Vmax determination, it is suggested that it should be possible to predict the conditions for optimal exercise on a cycle ergometer. Verf.-Referat