Abstract To analyze age-related changes in the total number of muscle fibers, the changes of the cross-sectional area of the anterior tibial muscle and the decrement rates of the total round number of muscle fibers were analyzed in male huan subjects between 40 and 90 years of age. The results of the analysis in the age group 20s were used as controls. The atrophy rate of the muscle cross-sectional area ranged from 20.6% to 64.8% after the age of 40. The decrement rate of the total number of muscle fibers ranged from 6.0% to 40.5% after the age of 60. These findings and observations showed that the anterior tibial muscle showed markedly regressive change in male subjects after the age of 60.

Key Words: anterior tibial muscle, muscle fiber, aging, atrophy, male human