Bidirectional Voluntary Heart Rate Control During Static Muscular Exercise: Metabolic and Respiratory Correlates

Following three sessions of instructed HR control with exteroceptive HR feedback (Group IFB) or without feedback (Group IC), subjects were required, on a fourth session, to increase and decrease HR whilst engaging in isometric arm exercises at 10%, 30%, and 50% of their maximal voluntary contractions. Significant increases and decreases from resting levels in HR were recorded during the first three sessions in which no exercise demands were made. When required to control HR whilst exercising, significant increases in HR above exercise‐only baselines were recorded but subjects were unable to decrease HR significantly below exercise‐only baselines. The extent of “voluntary’ HR control was inversely related to the concurrent level of isometric exercise and was unaffected by the provision of exteroceptive HR feedback. Since all significant variations in HR were accompanied by significant parallel variations in oxygen consumption and breathing patterns, it is concluded that subjects were unable to modulate the HR response to exercise.