Heart rate reserve is equivalent to%??VO2Reserve, not to%??VO2max

Abstract

Percentage of heart rate reserve (%HRR) is widely considered to be equivalent to% of maximal oxygen consumption (%˙VO_2max) for exercise prescription purposes. However, this relationship has not been established in the literature, and a theoretically stronger case can be made for an equivalency between%HRR and%˙VO₂Reserve (%˙VO_2R)(i.e., the difference between resting and maximal ˙VO₂). The current study hypothesized that%HRR is equivalent to%˙VO_2R, not%˙VO_2max, and that the discrepancy between%HRR and%˙VO_2max would be inversely proportional to fitness level. Sixty-three adults performed incremental maximal exercise tests on an electrically braked cycle ergometer. HR and ˙VO₂ at rest, at the end of each stage of exercise, and at maximum were used to perform linear regressions on%HRR versus%˙VO_2max, and%HRR versus%˙VO_2R for each subject. For%HRR versus%˙VO_2max, the mean intercept and slope were -11.6 ± 1.0 and 1.12 ± 0.01, respectively, which were significantly different (P < 0.001) from 0 and 1, respectively. For%HRR versus%˙VO_2R, the mean intercept and slope were -0.1± 0.6 and 1.00 ± 0.01, respectively, which were not distinguishable from the line of identity. There was a significant(P < 0.01) inverse relationship between fitness level(˙VO_2max) and the discrepancy between%HRR and%˙VO_2max. In conclusion,%HRR should not be considered equivalent to%˙VO_2max. Rather,%HRR is equivalent to%˙VO_2R, and this relationship should be used in exercise prescription.