Effect of training with eccentric muscle contractions on skeletal muscle metabolites.

Abstract

AbstractThe effect of training with eccentric contractions on skeletal muscle metabolism was in‐vestigated with human subjects engaged in cycling exercise. Experiments involving extended (30 min) exercise at high relative intensities were performed before and after a 5‐week period of training (25–30 min per day, 22 days). Muscle biopsies (lateral portion of m. quadriceps femoris) were taken at rest, after 4 min exercise, and termination of exercise. Expired air was collected periodically for determination of respiratory exchange. Vo 2 and heart rate were lowered by training (e.g., after 26 min of exercise: from an average of 0.96 to 0.74 1 × m‐l and 115 to 96 beats × min‐1, respectively). Muscle metabolite concentration evidenced no significant changes but respiratory exchange ratio (R) was decreased (after 10 and 26 min, from an average of 0.85 to 0.80 in both instances). Metabolic determinations offered no explanation for the lowered 02 cost of exercise nor evidence for or against the hypothesis that the muscles utilize the mechanical energy recived during eccentric exercise.