*2.1.4. Conditions for vibration stimulation*

changes have in fact been brought on by the intervention, and not due to alterations in the

Vibration stimulation has been used as one of the treatment modes for conditions of muscle tone of skeletal muscle, including spasticity. Its effects have in fact been reported. Unlike manual therapy, vibration stimulation is an excellent treatment method because it is expected

Though its detailed mechanism has not been elucidated, vibration stimulation acts directly on

When skeletal muscle during a maximum contraction receives vibration stimulation, the muscle's action potential on EMG, nerve activity, and muscle output are reduced (Bongiovanni 1989, Kouzaki 2000, Stephen 2003, Konishi 2009). The inhibitory effect of muscle contraction is dependent on the conditions of vibration stimulation: the effect is greater if the frequency

In recent reports, when stroke patients with a spastic upper limb received vibration stimulation on the limb, their upper limb function was shown to improve with a suppression of muscle

In patients who underwent ACL reconstructive surgery or those with osteoarthritis, vibration stimulation to their quadriceps femoris muscle brought about neither an increase in neural activity as evaluated by integrated EMG nor a decrease in muscle output as evaluated by peak torque (Konishi 2002, Rice 2011). It is thought that this outcome was due to a failure in Ia

Muscle spindle senses a very small change in muscle length when a skeletal muscle receives vibration stimulation. And this information is transmitted to the fibers of group Ia or II, eventually to reach the spinal cord. In the spinal cord, the information serves as presynaptic inhibition through an interstitial cell and suppresses the alpha motor neuron (Gillies 1969,

In addition, sustained vibration stimulation will selectively excite group Ia fibers. That will then bring about, in nerve endings, depletion of neurotransmitters and a rising threshold of

the contracted muscle cells to relax them (Vukas 1978, Ljung 1972, Ljung 1975).

of the vibration stimulation is low, or if its amplitude is large (Desmedt 1978).

afferent feedback, including dysfunction of the gamma-loop.

physical condition such as electrode attachment and the like.

**2.1. Responses of skeletal muscle to vibration stimulation**

to show a certain effect regardless of who uses it.

*2.1.1. Physiological act on muscle cells*

*2.1.2. Inhibitory act on muscle contraction*

tone (Noma 2012, Caliandro 2012).

*2.1.3. Neurophysiological mechanism*

Shinohara 2005).

**2. Vibration stimuli**

200 Electrodiagnosis in New Frontiers of Clinical Research

The equipment that is used to apply vibration stimulation may vary from researcher to researcher, but the effect seems to be uniform as long as stimulation conditions are controlled in the same way. Stimulation conditions inevitably differ according to the research objective, but they are generally set at a frequency of 50-100 Hz and amplitude of 1-2 mm. The equipment is contacted at 20-30N on the body or tendon of the targeted skeletal muscle.

Effects that vibration stimulation has on the body depend on the duration of stimulation. The H/M ratio decreases immediately after the application of stimulation, and the inhibitory effect on spasticity has been confirmed in 5 minutes of stimulation (Noma 2012). Muscle output is reduced by a sustained stimulation of at least 20 minutes (Bongiovanni 1989, Kouzaki 2000, Stephen 2003, Konishi 2009).
