We investigated the relationship between the electrical and the mechanical responses of the frog sartorius in situ in isometric reflex contraction. All the thigh muscles other than the sartorius were dennervated. Mechanical stimulations were applied mainly on the dorsal skin of the ipsilateral foot. The electrical response led from the surface electrode was integrated by means of the Miller integrator. The mechanical response was recorded by the mechano-electric transducer, and its impulse was measured by the planimeter.
A very high positive correlation was found between the integrated value of the EMG and the mechanical impulse. It was found that the quantitative measurement of the electrical response of the muscle could be made in more accurate and efficient way by the Miller integrator than the other methods discussed in this paper.