To examine the effects of physical training on muscle power outputs of 24 healthy females (aged 42-63 yr.) and 9 active males (63-81 yr.) were studied in the present study. Thirteen females performed isotonic strength training of knee extension three times a week for 12 weeks (Ex. I) and the other females participated in isokinetic strength training of elbow flexion five times a week for (Ex. Dynamic (isokinetic) muscle strength measured using a Cybex II dynamometer at angular velocities of 60, 120, 180 240 and 300°sec increased significantly with the training in both groups of every velocity. There was no change in anthropometric parameters related to an increase in muscle strength. Performances of dynamic and static muscle power outputs were compared between one male international champion jumper trained for years and 8 males as the reference group (Ex. III). Biopsy specimen was taken from the vastus lateralis muscle of the dominant thigh of the jumper. Cross-sectional area of each fiber were 3.43 (type I), 3.32 (type IIA) and 2.34 (type IIB) μm²×10³, respectively and found to be an age-related muscle fiber atrophy. Isokinetic muscle strength of the jumper measured as the same manner in Ex. I and II, were larger than the reference group, especially at faster angular velocities. From the torque-time curve of maximal isometric knee extension the jumper had the highest value per body weight from the onset to near the peak level. It might be concluded that the skeletal muscles of middle-aged females and masters athlete remain trainable and that the training effects would rather be attributable to neural factors than to morphological one.

DESCENTE SPORTS SCIENCE Vol.7/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE