ERGOMETRIC AND METABOLIC ADAPTATION TO A 5-S SPRINT TRAINING-PROGRAM

The effects of 7 weeks of sprint training (repeated 5-s all-out sprint s) on maximal power output (W-nu,W-max) determined during a force-velo city test and a 30-s Wingate test (W-peak) were studied in ten student s [22 (SD 2) years] exercising on a cycle ergometer. Before and after training, muscle biopsies were taken from vastus lateralis muscle at r est for the ten subjects and immediately after a training session for five of them. Sprint training induced an improvement both in peak perf ormances by 25% (W-nu,W-max and W-peak and in the 30-s total work by 1 6%. Before sprint training, the velocity reached with no load (nu(0)) was related to the resting muscle phosphocreatine (PCr) stores (r=0.87 , P<0.001). The training-induced changes in nu(0) were observed only w hen these PCr stores were lowest. This pointed to a possible limiting role of low PCr concentrations in the ability to reach a high velocity . The improvement in performances was linked to an increase in the ene rgy production from anaerobic glycolysis. This result was suggested in muscle by the increase in lactate production measured after a trainin g session associated with the 20% higher activity of both phosphofruct okinase and lactate dehydrogenase. The sprint training also increased the proportion of slow twitch fibres closely related to the decrease i n fast twitch b fibres. This result would appear to demonstrate an app ropriate adaptive reaction following high-intensity intermittent train ing for the slow twitch fibres which exhibit a greater oxidative capac ity.