The Mechanism of the Increased Maximum Work Performance of Small Muscle Groups Resulting from “Diverting Work” with Other Muscle Groups

The mechanism of increased work performance resulting from “diverting works” was examined. Muscle blood flow was measured in exercised and rested muscles by means of venous occlusion plethysmography and ¹³³Xe clearance. Measurements of muscle blood flow, blood pressure and work performance following “diverting work” and other stimuli were compared with values obtained during control rest periods. Stimuli which caused a substantial rise in arterial blood pressure (“diverting work”, change in heart level, pain) caused increases in blood flow and work performance in exercised muscles. Non‐pressor or mild pressor stimuli (non‐strenuous “diverting work”, CO₂ inhalation, apnea, cold) resulted in unchanged blood flow and work values in the exercised muscles. It is concluded that pressor stimuli produce increased muscle blood flow in maximally ischemic muscles due to release of muscle arteries from neurogenic and myogenic control. The increased muscle blood flow during periods employing pressor stimuli results in improved muscle restitution and hence increased work performances.