Abstract
Stiffness of the leg muscle after physical exercise was measured objectively and quantitatively with a newly devised muscle hardness meter. It is well known that strenuous exercise may cause some stiffness of muscles by questionnaire or palpation. However, there are only a few reports concerned with objective measurement of muscle stiffness. We measured the time course of leg muscle stiffness after unilateral toe standing. In the case of unilateral toe standing on a flat floor, muscle hardness of the loaded side was elevated after physical exercise and diminished gradually. However muscle stiffness of the opposite non-loaded side also elevated. These results indicate that in the case of unilateral toe standing on a flat floor, the soleus muscle on the other side must be suspended and not touch the floor surface. This suspension may add a load to the soleus muscle on the other side. Avoiding these effects in the following unilateral toe standing was performed on a platform for completely relaxing the other leg muscle. In this condition the soleus stiffness elevated at only the loaded site. These results suggest that the device developed in our laboratory was very sensitive to muscle loading.
