EFFECT OF TRAINING ON THE CALF MUSCLE ENERGY-METABOLISM - A P-31 NMR-STUDY ON 4 ELITE DOWNHILL SKIERS CHALLENGED WITH A STANDARDIZED EXERCISE PROTOCOL

This study evaluates the effects of a 6 months' training period on the bioenergetics of the calf muscle of elite athletes by means of phosphorus-31 Nuclear Magnetic Resonance Spectroscopy (P-31-NMR). Four downhill skiers, belonging to the Spanish National Team, performed a standardized exercise protocol using their right leg inside a wide-bore 2.35 Tesla magnet. The inorganic phosphate/phosphocreatine (Pi/PC) ratio and intracellular pH (pHi) were measured at steady-state during an exercise protocol composed of 5 work levels between 20 % and 80 % of the maximum voluntary contraction (MVC), before and after the training period. The measured values, which were markedly scattered at the beginning, regrouped after training. This was caused by a shift towards lower Pi/PC ratios and by a lower pHi acidification in three of the four subjects. This result suggests that P-31-NMR is a good tool to evaluate changes in the muscle aerobic capacity of athletes induced by training.