• Aging;
  • muscle metabolism;
  • muscle ultrastructure;
  • training

The effects of a 12-week program of physical training on skeletal muscle (vastus lateralis) characteristics in 5 old men were investigated. Heart rates during submaximal bicycle exercise were decreased after training, indicating an improved cardiovascular function. As judged from enzyme activity measurements, the anaerobic capacity as well as the mitochondrial oxidative capacity were increased by the training. Fatty acid oxidation capacity remained unchanged, while the glycolytic potential tended to be increased, suggesting a somewhat different pattern of adaptation as compared to that seen in young subjects. Volume fractions of mitochondria and lipid droplets were unchanged with training, supporting the view that in old men, increases in oxidative capacity take place within the existing mitochondrial volume. It was concluded, that the aging human skeletal muscle remains trainable, and that the training response is similar, but possibly not identical, to that seen in younger age groups.