Abstract
Five male subjects were tested to investigate the effect of arterial occlusion upon contractile as well as electrophysiological responses during controlled muscular contractions induced by tetanic nerve stimulations at various frequencies for a period of one minute. The evoked mass action potentials from the triceps surae muscle group (the gastrocnemius and soleus) were continuosly recorded together with mechanical force output different circulatory conditions, i.e., free circulation, continuous occlusion (CO) and release of occlusion after 30 sec of continuous occlusion (OR) . Results indicated that 1) significant decreases in the evoked potential conduction velocity were found during CO and OR conditions, suggesting some degree of neuromuscular transmission impairment during aterial occlusion, 2) comparisons of CO and OR conditions revealed that significantly greater reduction in the evoked polential amplitude due to a reduced muscle membrane excitability was found shortly after the occlusion release, and 3) this reduction in the evoked potential was accompanied by a parallel decline in the developed force. These results support the notion that the amount of extracellular fluid volume can play an important role in prolonging the onset of intramuscular acidification, thus indirectly affecting muscle membrane excitability and contractile function.
