Abstract des Autors

The present experiments were carried out to assess the relationship between the mechanical behaviour of the leg extensor muscles in 12 male athletes during activities of a ballistic type and torque production, during: (1) torque production during isokinetic contraction; (2) ballistic type activities (vertical jumps from static position = SJ, with counter-movement = CMJ and after a fall from different heights = DJ) and (3) a new anaerobic test (Bosco 1983a). This consisted of performing continuous jump work for a certain period of time. Peak torque was related to SJ (r = 0.71); to CMJ (r = 0.74); to best DJ (r = 0.60), to 15 s anaerobic power (r = 0.70) and 60 s anaerobic power (r = 0.68). The power output during ballistic activities was much higher than the power measured during zero acceleration performances. The difference noted was explained in the light of the fact that, when jumping, three different extensor muscle groups in each leg contract with re-use during the concentric phase of elastic energy stored during the eccentric phase. The relationship between isokinetic contraction and ballistic motion is discussed in terms of fiber type recruitment and their velocity dependency.