Eight male subjects were examined to determine the physiological effects of static stretching upon muscle soreness which was induced experimentally by heel rases (10 rep., 10 sets) with a 70% MVC equivalent weight attached on an universal shoulder press equipment. Electrophysiological parameters, e.g., maximal mass action potential (M-wave), H-wave, and H/M ratio for determination of alpha motoneuron's excitability were measured during standing rest (control), 24hr post experimental fatigue, and immediate post static stretching by means of computer-aided EMG analyses. The posterior tibial nerve was electrically stimulated for this purpose. In some cases, changes in the resting EMG's up to 48hr post experimental fatigue were subjected to frequency power spectral analysis so as to determine the degree of muscle fatigue and resting action potential amplitude. Results demonstrated that 1) the static stretching (3 sets of 20 sec duration) brought about a statistically significant reduction in the H/M ratio of the experimental leg, 2) the experimentally induced muscle soreness was associated with a higher resting action potential amplitude and a lower mean power frequency, suggesting the existence of some degree of muscle spasm and a possible synchronization of tonic motoneurons, and 3) the static stretching showed quite noticeable effects of restoring these electrophysiological parameters back to the control level. These result are entirely consistent with earlier studies and further suggest that the inverse myotatic reflex (Ib inhibition), which originates in the Golgi tendon organs, may be the basis for the relief of muscle soreness by static stretching.

DESCENTE SPORTS SCIENCE Vol.8/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE