ABSTRACT
The gastrocnemius muscles are composed predominantly of type II B and II A fibers while the soleus muscle is composed of type I fibers. However, the relationships between the calcaneal bone stiffness and the triceps surae muscles consisting of the different types of skeletal muscle fibers are unknown. The purpose of this study was to investigate the relationships between the calcaneal bone stiffness and the gastrocnemius or soleus muscle thickness in 73 postmenopausal women. We measured the speed of sound (SOS) and the broad band ultrasound attenuation (BUA), using a ultrasonic measurement of the calcaneal and the gastrocnemius or soleus muscle thickness used to measure the B-mode ultrasound anatomy. There was a significant differences in age between the high-and low-SOS groups. In the high-BUA group, the body mass index, the lower leg girth and the triceps surae muscle thickness were significantly higher than those in the low-BUA group. This data indicated that SOS is related to ageing and BUA is related to the body mass or the muscle thickness. The other side, stiffness and SOS were significantly correlated with the gastrocnemius muscle thickness, but not with the soleus muscle mass. Therefore, this study suggests that the calcaneal bone stiffness is closely related to the muscle thickness, which may be related especialy to the fast twitch muscle.