**Clarified issue 1: Anterior horn cells in the spinal cord are suppressed by vibration stimu‐ lation from its onset to about 3 minutes into stimulation.**

As a result of vibration stimulation on the triceps surae of healthy adults, the H/M ratio continues to decrease from 1 to 3 minutes after stimulus onset. After 4 minutes into stimulation, though the ratio continues to decrease somewhat, no significant difference was found between values at after 4 minutes and the value at 3 minutes of stimulation.

From these findings, it has been clarified that excitability of alpha motor neurons gets sup‐ pressed immediately after the intervention with vibration stimulation. Also clarified was that the decline of the H/M ratio reaches a steady state after 3 minutes of stimulation from its onset.

## **Clarified issue 2: It is recommended that vibration stimulation be applied on tendon.**

If vibration stimulation is to be adopted in clinical settings, it is essential that an appropriate set of stimulus conditions should be considered for each of the clinically different cases. A site of stimulation is certainly one of the factors for the treating therapist to take into account.

Based on the results of our study, the H/M ratio was significantly lower after the onset of vibration stimulation on both muscle belly and the tendon (p<0.01). In addition, when stimulus to the belly was compared with stimulus to the tendon, the H/M ratio was significantly lower in the latter (p<0.05). In other words, to suppress muscle tone using a vibration stimulus, it is recommended that a stimulus be applied on the tendon.
