Abstract des Autors

Muscles that are used intensively show a progressive decline of performance which is denoted muscle fatigue and a largely reversible phenomenon. In voluntary contractions, muscles are activated by complex pathways starting centrally in the cortex and through the motor neurons leading to the excitation of the contractile apparatus of the muscle fiber in the peripheral. The degree of fatigue and the activation event causing fatigue depends on the type, intensity, and duration of the muscle activities, involving both central and peripheral originated factors (Allen et al., 2008). High-intensity exercise (e.g., cross-country sprint skiing) has repeatedly been shown to induce peripheral impairments of muscle cellular function (Zory et al., 2006; Place et al., 2010). Among the peripheral factors, the contractile function of single muscle fibers has been proposed to be a significant factor. However, few studies have been conducted in order to elucidate the effect of exercise on the contractile apparatus function. Therefore, the purpose of the present study was to examine the effects of repeated sprint skiing on the contractile apparatus of single muscle fibers obtained from a group of elite cross-country skiers. We hypothesize that repeated high-intensity exercise in highly trained subjects will impair the contractile apparatus maximum force output and possibly Ca2+ sensitivity.