Physical training effects on muscle morphology in sedentary males at different ages.

The purpose of this pilot study was to investigate the influence of physical training on muscle morphology and strength in different age groups in order to learn about the exogenous influence (e.g., inactivity) on the these characteristics in old age. Eighteen sedentary males ranging in age from 22-65 yr were involved in a low resistance and high repetition strength training program twice a week for 15 wk. Muscle biopsies were taken and strength measurements were performed before and after the training period. Age-related muscle fiber atrophy, seen before training, was diminished after the training period because of an increase in fiber size in older subjects. Muscular strength values, however, were lower with increasing age before and after training, indicating that strength decline in old age is not primarily due to muscle fiber atrophy.