Aging process of leg muscle endurance in males and females.

In order to estimate muscle endurance during knee extension (KME) and plantar flexion (PME) using a simple method, holding times for the half-squatting posture for KME and for the calf-raising posture for PME were measured in 3,792 males and 3,620 females aged between 6 and 79 years. The regression lines of the aging process for KME and PME in both sexes were determined. Peak values were found at 13 years in males and 12 years in females for KME, and at 15 years in males and 16 years in females for PME. The mean values increased sharply with age up to each peak and then decreased abruptly to a low level at around 20 years, thereafter declining gradually. The values of KME as a percentage of the peak value were 71, 75 and 34 at the ages of 6, 20 and 70-79 years respectively in males, while the corresponding values were 80, 77 and 36 for females. The values of PME at these ages were 34, 93 and 69 in males and 54, 91 and 73 in females. The mean values for males were generally higher than those for females. These results suggest that endurance of the leg muscles differs according to age, sex and the region of the leg muscle. These data will be useful as standard values for evaluating endurance and for prescribing suitable exercise for the promotion of physical fitness.