The Use of H reflex and F wave as a Quantitative Measure of Motor Neuron Excitability

The Use of H reflex and F wave as a Quantitative Measure of Motor Neuron Excitability

Effect of Volitional Muscle Relaxation on H reflex

　To test the effect of volitional inactivity and subsequent voluntary muscle contraction on the excitability of the anterior horn cells in the lower limb, we studied the time course of H reflex recorded from the soleus muscle in 11 healthy subjects after resting the muscle for one and two hours.¹⁾ The H-reflex amplitude declined (p＜0.05) after rest, remained the same after standardized exercise, and recovered after standing. Statistical analyses showed a significant difference in the degree of suppression induced by one- and two-hour periods of rest. We conclude that the excitability of the spinal motor neurons tested by H reflex undergoes a substantial diminution after a relatively brief cessation of volitional motor drive, recovering quickly upon resumption of normal muscle activity.

Effect of Volitional Muscle Relaxation on H reflex

　To test the effect of volitional inactivity and subsequent voluntary muscle contraction on the excitability of the anterior horn cells in the lower limb, we studied the time course of H reflex recorded from the soleus muscle in 11 healthy subjects after resting the muscle for one and two hours.¹⁾ The H-reflex amplitude declined (p＜0.05) after rest, remained the same after standardized exercise, and recovered after standing. Statistical analyses showed a significant difference in the degree of suppression induced by one- and two-hour periods of rest. We conclude that the excitability of the spinal motor neurons tested by H reflex undergoes a substantial diminution after a relatively brief cessation of volitional motor drive, recovering quickly upon resumption of normal muscle activity.