Relationship between% heart rate reserve and%??VO2reserve in treadmill exercise

Abstract

For exercise prescription purposes, it is often assumed that % heart rate reserve (%HRR) provides equivalent intensities to %VO2max. However, a recent study from this laboratory demonstrated that during cycling exercise %HRR is not equivalent to %VO2max, but is instead equivalent to a percentage of the difference between resting and maximal VO2, i.e., % VO2reserve (%VO2R). The current study examined these relationships during treadmill exercise. Fifty adults performed Bruce protocol treadmill tests to exhaustion. For each subject, data obtained at rest, at the end of each stage, and at maximum were used to determine linear regressions of %HRR versus %VO2max, and of %HRR versus %VO2R. For %HRR versus %VO2max the mean intercept and slope were -6.1+/-0.7 and 1.10+/-0.01, respectively, with a mean r of 0.990+/-0.002. For %HRR versus %VO2R, the mean intercept and slope were 1.5+/-0.6 and 1.03+/-0.01, respectively, with a mean r of 0.990+/-0.002. Both regressions differed statistically from the line of identity (i.e., intercept of 0 and slope of 1). However, the regression of %HRR versus %VO2R was significantly closer (P < 0.001 ) to the line of identity than was the regression of %HRR versus %VO2max. We conclude that %HRR should be considered as an indicator of %VO2R, not %VO2max, when prescribing treadmill exercise, as was previously concluded for cycling exercise.

Influence of Cardiopulmonary Exercise Testing Protocol and Resting VO2Assessment on %HRmax, %HRR, %VO2maxand %VO2R Relationships

“…The resting VO2 was taken as the average of the last 10 min of (steady-state) data. The other two approaches (resting VO2sitting and resting VO2standing) were carried out before the cardiopulmonary exercise tests, 6 using similar criteria adopted by previous studies that aimed to investigate the relationship between the %HRmax, %HRR, %VO2R and %VO2max [10,11,13,18,23,25,30,32,40,41]. Participants were instructed not to engage in any form of physical exercise in the previous 24 h, to abstain from alcohol, soft drinks and caffeine in the 8 h preceding the test and to fast for 3 h. In the laboratory, participants laid quietly for 10 min.…”

“…The fasting period can influence the RMR reproducibility due to the thermic effect of food, and a minimum of 4 to 6h has been suggested [12]. With the exception of two studies [11,30], the available research adopted fasting periods of 1h [40,41] or 3h [10,18,23,32]. Two others did not report the fasting period [13,25].…”

“…According to the American College of Sports Medicine [3], 40, 50, 60, 80, and 85% VO2max corresponds, respectively, to 55, 62, 70, 85, and 90% HRmax [15,20,22,33,36]. However, some studies have suggested that the relationship proposed by the ACSM overestimates the %HRmax associated with any given %VO2max, especially at intensities lower than 80-85% VO2max [10,18,23,30,35,38].…”

“…The HRR and VO2R are a measure of the difference 4 between the resting and maximal values for heart rate and VO2, respectively [2]. Several studies reported that the %HRR and %VO2R were more strongly related than the %HRmax and %VO2max, and therefore, should provide more accurate exercise prescription [40,41]. The ACSM [1] subsequently published an official stand recommending the %HRR-%VO2R method.…”

“…The mean ± SD values of the intercepts and slopes were determined for each linear regression model and the Pearson correlation for each relationship was determined. The Student t-test for paired samples was also used to test whether the intercepts and slopes of the regression models were significantly different from 0 and 1, respectively [40,41], and to test possible differences between the regression lines, as described in detail elsewhere [47]. Two-tailed statistical significance for all hypothesis tests was accepted as p < 0.05.…”