SIMMONS, D. N., M. J. BERRY, S. I. HAYES, and S. A. WALSCHLAGER. The relationship between %HRpeak and %V̇O2peak in patients with chronic obstructive pulmonary disease. Med. Sci. Sports Exerc., Vol. 32, No. 5, pp. 881–886, 2000.
Purpose: The relationship between the percent peak oxygen consumption (%V̇O2peak) and percent peak heart rate (%HRpeak) has been suggested as a method for exercise prescription. According to the American College of Sports Medicine (ACSM), 50, 60, 80, and 85% of V̇O2peak represent 62, 70, 85, and 90% of HRpeak, respectively. Recent research with young healthy adults has shown that this relationship is not as ACSM suggests. Furthermore, it has been suggested that this relationship be examined in populations with low functional capacity.
Methods: The present study evaluated the relationship between %HRpeak and %V̇O2peak in 125 patients with chronic obstructive pulmonary disease before and then after 3 months of exercise intervention.
Results: The mean percentages of HRpeak for the COPD patients at baseline were 70, 76, 87, and 90% at 50, 60, 80, and 85% of V̇O2peak. Percentages of HRpeak at 50, 60, and 80% of V̇O2peak were significantly different from those suggested by ACSM. The mean percentages of HRpeak after the 3-month exercise intervention were 71, 77, 87, and 90% at 50, 60, 80, and 85% of V̇O2peak. Percentages of HRpeak at 50, 60, and 80% of V̇O2peak were significantly different from those suggested by ACSM. There were no significant differences between the slopes and the intercepts of the two equations used to describe the relationship between %HRpeak and %V̇O2peak. Therefore, we pooled the data from the pre- and post-intervention tests to form the following equation to describe the relationship between %HRpeak and %V̇O2peak for COPD patients: %HRpeak = 0.55 ( ± 0.01)%V̇O2 peak + 43.2 (±1.4).
Conclusion: In conclusion, the relationship between %HRpeak and %V̇O2peak described by ACSM is not applicable to patients with COPD. Furthermore, this relationship does not change with exercise training and can be described by a single equation.
The prescription of exercise intensity in patients with chronic obstructive pulmonary disease (COPD) is not well defined (1,5,11,17). Specific questions concerning the prescription of exercise for COPD patients include what is the optimal exercise intensity and what is the best method for prescribing exercise intensity. The American College of Sports Medicine (ACSM) recommends four methods for prescribing exercise intensity in COPD patients. These include exercise at 50% of peak oxygen consumption (V̇O2peak), exercise at or above the anaerobic threshold, exercise at near-maximal intensity, and the use of ratings of dyspnea (2). If 50% of V̇O2peak is used as the method of exercise prescription, it then becomes necessary to determine how this intensity will be monitored during the exercise sessions. One method that has been suggested is to use a certain percentage of peak heart rate (%HRpeak). Because of the linear relationship between heart rate and oxygen consumption (V̇O2), the heart rate measured during exercise is a method of estimating V̇O2, and, therefore, can be used as an indicator of exercise intensity (18). More specifically, the assessment of exercise intensity, as reflected by %V̇O2peak, can be indirectly measured as a function of %HRpeak. According to the ACSM, 62, 70, 85, and 90% of HRpeak represent 50, 60, 80, and 85% of V̇O2peak, respectively, for the general population (2).
Swain et al. (20) recently examined the relationship between %HRpeak and %V̇O2peak in apparently healthy men and women. The investigation by Swain et al. differed from previous studies examining this relationship by the development of a regression equation that used %HRpeak as the dependent variable and %V̇O2peak as the independent variable. Furthermore, Swain et al. performed linear regressions for each participant and then formulated a mean regression equation from all these values as opposed to using all subject data to develop a single equation. These investigators found that the %HRpeak obtained by their subjects at a given %V̇O2peak were significantly greater than those suggested by the ACSM (2). Additionally, Swain et al. found that the subject’s fitness level affected the %HRpeak and %V̇O2peak relationship. Because of the effect that fitness level has on this relationship, Swain et al. (20) suggested that this relationship be studied in individuals with a low functional capacity.
Based on the recommendation of Swain et al. and because of the fact that the relationship between %HRpeak and %V̇O2peak has profound implications concerning exercise prescription in COPD patients, the purpose of this investigation was to examine the %HRpeak and %V̇O2peak relationship in these patients. Additionally, because fitness level has been shown to affect this relationship, a secondary purpose was to examine the effects of 3 months of exercise training in these patients on this relationship.