Hemodynamic impacts of entrainment of heart rate and stride rate

Synchronization of heart rate and step rate has been hypothesized to create a hemodynamically favorable situation where heart motion and bodily motion are in constant harmony so that stroke volume and cardiac output enhanced and oxygen delivery to the tissues is increased. The primary aim of the present investigation was to determine the impact of synchronization of step rate and heart rate on cardiovascular functions. Twenty-three apparently healthy subjects performed treadmill running in three different conditions, one that the step rate was matched with the heart rate (matched condition), one that the step rate was ∼10 steps greater or lower than heart rate (unmatched conditions). Beat-by-beat blood pressure was measured using the finger plethysmography, and stroke volume and cardiac output were calculated using the validated Model Flow method. Average heart rate and blood pressures were not different among the 3 conditions. There were no differences in double products among the 3 conditions. Stroke volume and cardiac output were greater (P < 0.05) in the matched condition than in the unmatched conditions. Our present results are consistent with the idea that synchronization of heart motion and bodily motion augments stroke volume and cardiac output, presumably through the mechanism similar to the arterial counterpulsation.