Determination of Onset Point of Mechanical Stimulation

The difference between latencies of the tonic vibration reflex or T-reflex and whole body vibration-induced muscular reflex may be related to the distance between their stimulation point and the muscle spindles. Achilles tendon is mechanically stimulated by using a local vibrator to elicit the tonic vibration reflex or a reflex hammer to elicit the T-reflex. Whole body vibration, however, stimulates the soleus muscle indirectly over the heel, not directly, since whole body vibration is administered in a position that the subjects are standing on the whole body vibration platform. In other words, while the local vibrator or the hammer stimulates the Achilles tendon, whole body vibration stimulates the sole of the foot. During whole body vibration, mechanical vibration stimuli need to go a long way to reach the soleus muscle spindle. Therefore, whole body vibration-induced muscular reflex latency may be longer than tonic vibration reflex or T-reflex latency. The aim this study is to define a method for determination of onset point of mechanical stimulation inducing muscle spindle-based reflex (e.g., tonic vibration reflex, T-reflex) by using intramuscular electromyography electrodes.