Local and central circulatory responses to sustained contractions and the effect of free or restricted arterial inflow on post‐exercise hyperaemia

Abstract

1. The cardiovascular responses to sustained contractions at tensions from 5 to 30% maximal voluntary contraction (MVC) have been examined. At 5 and 10% MVC blood pressure, heart rate and forearm blood flow all reached a steady state during the contraction; post-exercise hyperaemia did not show peak flows higher than those found during exercise. At tensions of 20 and 30% MVC, none of the measurements showed a steady state during the contractions, but increased steadily throughout the contraction; post-exercise hyperaemia characteristically showed peak flows in excess of any flow measured during contractions. The results obtained at a tension of 15% MVC did not show a steady-state during the contraction but the following hyperaemia showed a similar pattern to that seen at the lower tensions.2. Digital compression of the brachial artery after sustained handgrip contractions for periods of 3 or 6 min after the contraction ended resulted in only a small reduction, on average by 5-15%, of the post-exercise hyperaemia.3. Consideration of the evidence leads to the view that in physiological circumstances the post-exercise hyperaemia following sustained contractions bears a close relationship to the metabolism of the active muscles.