Association between forearm muscle thickness and age-related loss of skeletal muscle mass, handgrip and knee extension strength and walking performance in old men and women: a pilot study.

Very little information is available concerning the relationship between handgrip strength and muscle size in the upper and lower extremities, especially the forearm muscle itself. To investigate the relationships among ultrasound-measured forearm muscle thickness from the radius and ulna bone interface with handgrip strength, knee extension strength, walking speed and absolute/relative total skeletal muscle mass (TMM), 32 Japanese men and 21 Japanese women ages 70-83 years had muscle thickness (MT) measured by ultrasound. In the forearm, two MTs (forearm-radius and forearm-ulna MT) were measured. TMM was estimated from an ultrasound-derived prediction equation. Handgrip-strength was significantly correlated with forearm-ulna MT in both men and women. There were no significant correlations between forearm MT and walking speed in either sex. In men, both forearm-radius and forearm-ulna MT were significantly correlated with TMM and TMM index. In women, a significant correlation was only observed between forearm-ulna MT and TMM index. Our results suggest that forearm-ulna MT may be a useful parameter for evaluating handgrip strength and TMM index in older Japanese men and women.