The Self-Control of the Cardiovascular Response to Exercise Using Feedback of the Product of Interbeat Interval and Pulse Transit Time

Feedback of the product of interbeat interval and pulse transit time (this product being a close correlate of the product of heart rate and systolic blood pressure) was compared with relaxation training and simple habituation to the experimental task. The subjects were 36 healthy volunteers tested both when inactive and when cycling on a bicycle ergometer. Subjects receiving product feedback were markedly more successful in minimizing the decrease in interbeat interval and pulse transit time caused by exercise (i.e., their rate pressure product rose less). Subjects who received relaxation training or simply exercised showed similar changes in interbeat interval and pulse transit time. In the inactive subject, the superiority of product feedback was much less evident but it did enable subjects to increase pulse transit time (i.e., decrease systolic blood pressure) compared to the other two conditions, which again did not differ. It is proposed that the superiority of product feedback may relate to its value as an index of sympathetic input to the heart and that such feedback may find clinical application in the treatment of angina pectoris.