The Influence of Aerobic Exercise Training on the Double Product Break Point in Low-to-Moderate Risk Adults
The double product (DP) is the product of the heart rate (HR) and systolic blood pressure (SBP). The double product break point (DPBP) is a physiologic threshold that occurs at similar exercise intensities to that of the ventilatory threshold (VT). The influence of aerobic exercise training on the DPBP has not yet been examined. The purpose of this study was to examine whether aerobic exercise training (ET) increases the exercise intensity at which the DPBP occurs, and whether it increases in a similar fashion to the VT. Seven males and 11 females, all sedentary (mean ± SD: age = 29.9 ± 10.5 yr) underwent supervised cardiopulmonary exercise testing using a cycle ergometer ramp protocol at baseline and after eight weeks of vigorous ET on a cycle ergometer. The VT was determined by gas analysis and the V-slope method. Experienced observers using standardized instructions visually determined the DPBP. Following ET, VO2peak, maximal workload, and body composition variables all showed significant positive changes. The VO2 at which the DPBP and VT occurred increased significantly from baseline to follow-up (p <.001). At baseline and at follow-up, the DPBP and VT did not differ. The DPBP and VT were significantly correlated to each other at both time points. Results suggest that the DPBP responds to ET in a similar fashion to that of the VT, and may be an easier and more useful marker of the VT for exercise training purposes.