Abstract
OBJECTIVE: We examined the relationships among and differences between muscle size and strength, specific tension (MQ(ST)), echo intensity (MQ(EI)), and functional performance in physically active younger and older women.
METHODS: Measurements included maximal voluntary isometric knee extension contractions (MVICs), maximal velocity sitto-stand (STS) movements, and muscle cross sectional area (mCSA), MQ(S)(T), and MQ(EI) of the rectus femoris (RF).
RESULTS: There were no differences in MQ(ST) (p = 0.96) or physical activity levels (p = 0.29). MQ(ST) and MQ(EI) were not related in the younger women, but were related in the older women (r = 0.50). MVIC was related to mCSA (r = 0.75) in the older women, but was not significantly related to MQ(ST) or MQ(EI) in either age group.
DISCUSSION: Physical activity may maintain MQ(ST) in aging. We suggest that studies examining changes in skeletal muscle with aging utilize both traditionally calculated muscle quality (specific tension) and ultrasound EI.