Muscle hardness measurement has substantial potential for treating muscular dysfunction. Measures of muscle hardness at particular sites are used as indices of injury prevention, injury diagnosis and recovery maintenance in the field of rehabilitation and sports medicine. Muscle hardness has traditionally been measured at a single time point, such as before and after treatment. However, continuous measurement at multiple sites during exercise could provide valuable information for treating muscle conditions. In the current study, we examined muscle hardness using wearable indentation testers. In a pilot experiment, we measured changes in muscle hardness at several points during static stretching, and examined the similarity of the effect for decreasing muscle hardness at multiple sites.