**3. Inhibitory and facilitative effects of muscle tone in normal healthy subjects**

This section provides an overview of the effects of inhibition and facilitation by physical stimuli on skeletal muscle of healthy subjects. We shall then consider the current state surrounding the physical stimulus in the field.

## **3.1. Pressure stimulation**

**2.3. Our previous study 2**

202 Electrodiagnosis in New Frontiers of Clinical Research

ceps femoris muscles (Table 2).

Mean±standard deviation

\*p<0.05: pre-vibration vs post-vibration

**2.4. Previous studies by other authors**

diate effect was recorded after the intervention.

Mean±standard deviation

When vibration stimulation is applied on skeletal muscle, the amount of output and muscle activity of the stimulated skeletal muscle is decreased. This finding should help to bring on a

It may be possible to facilitate the activity of the muscle that is important to knee joint extension, namely vastus lateralis muscle, when vibration stimulation decreases its activity. In fact, we have confirmed that, when vastus lateralis muscle was stimulated by vibration, the reduction in the amount of muscle activity was observed in only vastus lateralis muscle among quadri‐

There may be a possibility of enhancing the activity of inner muscles, which were long assumed to be unsusceptible to strengthening, provided that you can selectively suppress just those muscles you want to suppress. It is hoped that our future studies will clarify this issue as well.

> **Pre-vibration Post-vibration** 250.0 ± 25.4 220.5 ± 16.2

> > **Pre-vibration Post-vibration**

**Table 1.** Muscle force of quadriceps femoris muscle before and after vibration stimulation (%BW).

Rectus femoris muscle 174.5 ± 29.2 121.2 ± 52.3 Vastus medialis muscle 143.8 ± 34.2 102.1 ± 68.5 Vastus lateralis muscle 113.6 ± 49.1 95.5 ± 37.8 \*

**Table 2.** Muscle activity of quadriceps femoris muscle before and after vibration stimulation (%iEMG).

*2.4.1. Spasticity of upper limb in stroke patients is suppressed by 5 to 10 minutes of vibration stimulation* If vibration stimulation of about 5 to 10 minutes is applied on the spastic muscle of a stroke patient's upper limb, the following will be observed: a decrease in the H/M ratio indicative of the excitability level of anterior horn cells in the spinal cord; improvement of motor function and of Modified Ashworth Scale indicative of the degree of spasticity; and improvement of Functional Ability Scale using Wolf Motor Function Test. In some treatment cases, an imme‐

The nervous system of a spastic stroke patient may be restructured and/or strengthened by adjusting the level of CNS excitability using a vibration stimulus in combination with training

change in the pattern of muscle activity during action (Table 1).

A decreased H/M ratio was observed by air pressure in the splint on triceps surae muscle of the lower limb (Robichaud et al., 1992) and radiocarpal flexor muscle of the upper limb (Agostinucci et al., 2006) both in healthy subjects.

Pressure stimulation causes a decrease in blood flow, leads to the state of lack of oxygen, and adversely affects the site of compression of the cell, tissue, or organ. What then would be an appropriate duration and compression strength to apply without bringing on undesirable effects? In a study of healthy Japanese youths, the condition of 5 minutes at 50 mmHg was recommended as appropriate (Miura et al., 2011). A pressure of up to 50 mmHg did not result in any statistically significant differences in blood flow compared with no-addition pressure stimuli. But at this time the excitability of soleus muscle motor neurons was inhibited in the spinal cord.
