RUNNING-INDUCED CHANGES IN H-REFLEX AMPLITUDES IN NON-TRAINED MEN

Effect of 5-weeks running training on modulation of the H-reflex amplitude on soleus muscle in non-trained men was studied. It was established that modulation of the H-reflex amplitude occurs in two phases. In the course of the first 3 weeks of running training (first phase) statistically significant (p < 0.05) increase in H-reflex amplitudes and the maximum H-reflex to the maximum M-response amplitudes ratio (10%) were registered. In contrast to the first phase, decrease in investigated parameters up to initial values were observed during the next 2 weeks of the training (second phase). An increase in the of the soleus H-reflex amplitude, is probably due to the enhanced drive in descending pathways, increased motoneuron excitability and changes in presynaptic Ia afferent inhibition, whereas decrease in the amplitude of the H-reflex might occurs presumably due to motor learning. Apparently, that the repetitive task, which automatically performed and controlled on a spinal or brainstem level can be reflected in the normalization and stabilization of the H-reflexes registered after running training in later period.