Abstract

The influence of exercise training on reflex excitability was assessed by tendon tap (T-) and Hoffman (H-) reflex responses in 8 long distance runners and 8 sedentary control subjects. During testing, subjects maintained a constant 2 of maximum voluntary contraction. Short latency myoelectric responses (EMG) were quantified taking the percent gain of the reflex response at 1.1 times threshold (Th) for the H-reflex and 2.0 times Th for the T-reflex with respect to reflexes elicited at Th stimulus intensity. Recordings were made from soleus and tibialis anterior muscles. There were no significant differences found between the percent gain in reflex responses of athletes vs. those of controls. However, the probability of the appearance of an M-wave, caused by direct activation of efferents, was found to be significantly greater in controls than in athletes. This findings may represent a physiological expression of differences in efferent diameters between the two populations as has been suggested in the research literature. Verf.-Referat