Muscle function in 164 men and women aged 20--84 yr.
OBJECTIVE
The purpose of the present study was to investigate the effect of aging in men and women on muscle functional properties, i.e., muscle force and force per unit of cross-sectional area (force/CSA).


METHODS
A total of 164 volunteers participated in this study and were divided into five groups according to their chronological age as follows: 20s (20--39 yr old), 40s, 50s, 60s, and 70s (70--84 yr old). Isokinetic (0, 60, 180, and 300 degrees.s(-1)) knee extensor and flexor peak torque, and CSA of the quadriceps femoris (QF) muscle of the mid-thigh were measured.


RESULTS
Peak torque during knee extension and flexion was inversely related to age in both men and women. This was the case irrespective of the speed of contraction in both genders (men: r = -0.797 to -0.756, all P < 0.001, women: r = -0.639 to -0.530, all P < 0.001). A significant correlation was observed between CSA of QF and peak torque during isometric knee extension in men (r = 0.827, P < 0.001) and women (r = 0.657, P < 0.001). During isometric contraction, the force/CSA exhibited a significant decrease with increasing age in men (r = -0.518, P < 0.001) but not in women (r = -0.207, NS).


CONCLUSIONS
These results thus suggest that muscle strength losses would be mainly due to a decline in muscle mass in both genders, whereas age-related decline in muscle function in men may also be the result of neural factors, such as muscle recruitment and/or specific tension.
Department of Life Sciences (Sports Sciences), Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan. akima@idaten.c.u-tokyo.ac.jp
H
H
Akima
Y
Y
Kano
Y
Y
Enomoto
M
M
Ishizu
M
M
Okada
Y
Y
Oishi
S
S
Katsuta
S
S
Kuno
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology*; D012737:Sex Factors