Abstract
The purpose of this study is to develop a measurement system of muscle hardness using ultrasound image device. The system was applied to measurement of muscle hardness before and after stretching. An ultrasound image device probe holder which has three force sensors was constructed. The probe holder could measure force of the probe to the skin during acquiring an ultrasound image. The hardness of the gastrocnemius medialis was measured before and after stretching. Two images were obtained with and without compressing force of 1 kgf to the skin. Subjects were instructed to stand on a stretching board of which angle was 3 degree lower than the ankle joint range of motion. A two minutes stretching was performed three times with a one minute break between the stretching. The images were obtained again. The thickness of muscle was measured from the image and the strain was calculated as difference of thickness before and after stretching. The Young's modulus of the muscle was calculated from the stress and strain. The Young's modulus decreased after stretching. It was concluded that the developed system could be applied to measurement of muscle hardness before and after stretching.
