Evaluation Model for Muscle Hardness Using Wearable Indentation Tester

Naomi Okamura, Wataru Fukuda,
Mariko Tsukune, Takayuki Inami,
Yo Kobayashi,Yasuo Kawakami,
○Masakatsu Fujie

 Evaluation of muscle hardness in daily life is useful to prevent sports injuries. With the advent of the ultrasound elastography, non-invasive estimation of muscle hardness became available. However, the ultrasound elastography is a too large and complex system to be used in daily sports life. Therefore, smaller and simpler instruments that can evaluate muscle hardness have to be developed. In a previous study, we proposed a wearable muscle indentation tester and investigated the feasibility of evaluating muscle hardness during static stretching. The wearable muscle indentation tester is easy to use in daily sports life but the measured data is affected by other tissues around the muscle. In this study, we investigate features of the wearable muscle indentation tester compared to the ultrasound elastography to reveal the accuracy of the data from the wearable muscle indentation tester.

Static stretching is one of the most popular ways to decrease muscle hardness. With static stretching of the rectus femoris, we have confirmed that muscle hardness decreases significantly in the time during the stretching using the data measured by the wearable muscle indentation tester. The data measured by the shear wave ultrasound elastography also showed a similar change of muscle hardness in the rectus femoris. This suggests that the wearable muscle indentation tester is able to measure the muscle hardness of the rectus femoris. Currently, we are also attempting to measure the muscle hardness of the gastrocnemius and investigate the adaptability for different types of muscles.