Effects of a 15-d Race on Plasma Steroid Levels and Leg Muscle Fitness in Runners

摘要

Endurance training has been documented to attenuate the concurrent development ofmuscular strength. Repeated endurance exercise apparently interferes with muscular adaptations to simultaneous heavy resistance training. Endurance training may also reduce existent strength-related performance. For example, a moderate jogging program was shown to decrease vertical jump performance. Costill et al. recently suggested that failure to replenish muscle glycogen levels to match the energy demands of intensified training may impair swimming performance. However, little is known about the effect of increased distance training on existing muscular strength and power in competitive endurance runners. Prolonged and intense training commonly reduces circulating testosterone concentration in distance runners (8). Decreased plasma testosterone levels during repeated prolonged exercise might favor protein catabolism for supplemental energy production and possibly lead to the degradation of skeletal muscle.