Skeletal muscle mechanics in osteoporotic and nonosteoporotic postmenopausal women.
The purpose of this study was to evaluate single-joint, dynamic muscle function of osteoporotic (OST) and nonosteoporotic (N-OST) women. Knee flexor and extensor function in postmenopausal women (6th decade OST, n = 15; 7th decade OST, n = 10; 6th decade N-OST, n = 6; 7th decade N-OST, n = 5) were evaluated at five angular velocities from 60 degrees.s-1 to 300 degrees.s-1. All subject groups had similar anthropometric measurements, but the 6th decade N-OST group were more physically active than the age-matched OST group. The OST and N-OST women produced peak torque at similar knee angles. The 6th decade N-OST women produced significantly greater knee extensor mean peak torque and angle specific torque, and mean work than any of the other three groups (P < 0.05). However, knee flexor function was equivalent throughout the groups for most comparisons, except those between the 6th decade N-OST and 7th decade OST. While previous research has shown an early loss of flexor muscle function in aging women, our data indicated that women with osteoporosis also experience a deterioration in quadriceps muscle function not encountered within the N-OST subjects. It is possible that such a change is precipitated by reduced physical activity, and may mirror deterioration in bone mineral content.
Stanley
S N
SN
Faculty of Health Studies, Auckland Institute of Technology, New Zealand.
Marshall
R N
RN
Tilyard
M W
MW
Taylor
N A
NA
D000368:Aged; D000375:Aging / Q000502:physiology; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007717:Knee / Q000503:physiopathology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010024:Osteoporosis / Q000503:physiopathology*; D017698:Postmenopause / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results