ReviewMethodological and practical application issues in exercise prescription using the heart rate reserve and oxygen uptake reserve methods
Introduction
Regular physical exercise has been considered an effective strategy for improving public health and quality of life1 and this view is supported by the negative association between physical fitness and the development of chronic diseases.2 On the other hand, increasing sedentary rates3 and the associated increasing prevalence of hypokinetic diseases,4 especially obesity,5 highlights that there still is a need for identifying effective methods of prescribing exercise.
Endurance training has extensively been shown to be a valuable strategy for inducing physiological adaptations associated with improved health,6, 7, 8 however, optimal exercise prescription to maximize such adaptations remains elusive. The main characteristics of exercise prescription that have been widely adopted include the intensity, duration, frequency and mode of exercise.9 Exercise intensity has been given particular attention in the literature because of its relative efficacy in improving cardiorespiratory fitness10, 11 and in weight management programs, the latter being due to higher rates of energy expenditure during12 and after13 exercise. Recent studies have shown that under isocaloric training conditions, high-intensity exercise is more effective in reducing percentage body fat and fat mass than low-intensity exercise.8, 14 Thus, in addition to cardiorespiratory fitness, there appears to be a dose-response relationship between training intensity and the degree of favorable changes in body composition. The dose-response relationship related to exercise intensity also is evident for other training adaptations associated with improved health.15 High-intensity aerobic training has been reported to be more effective than low-to-moderate intensity training in eliciting favorable changes in physical endurance capacity, anaerobic threshold, total cholesterol, low-density lipoprotein cholesterol, serum triglycerides, waist circumference, insulin sensitivity, and glucose control.16, 17, 18, 19, 20, 21 It should be noted that high-intensity exercise is likely associated with somewhat greater total energy expenditure than low-intensity exercise and may partly explain the differences in the degree of adaptations in physiological variables indicative of health status.12 However, effective exercise prescription should not only ensure a sufficient training stimulus to yield the relevant health benefits,22 but should do so without over-exertion and unnecessary discomfort, thereby promoting safety and exercise adherence. It is clear that the characteristics of optimal exercise programs for healthy populations23 and those with chronic diseases, such as coronary heart disease,24 obesity,25 hypertension,26 type 2 diabetes,27 and osteoporosis,28 will differ markedly. Although the optimal type and amount of physical exercise has not been established for these different populations,22 such concern is perceptible in the various recommendations and official stands that address this matter.9, 29, 30
Exercise intensity can be prescribed according to the American College of Sports Medicine (ACSM) guidelines based upon ratings of perceived exertion (RPE), the metabolic equivalent (MET), estimated or measured maximal heart rate (HRmax), and maximal oxygen uptake (VO2max).9 The method based on the relationship between different percentages of HRmax and VO2max has been the most commonly used strategy for exercise prescription31 and has traditionally been favored by the ACSM (Table 1).33, 34, 35 Criticisms of this method,38 however, have more recently led the ACSM to recommend replacing the percentages of HRmax and VO2max with the percentage of the heart rate reserve (%HRR) and percentage of the VO2 reserve (%VO2R).9, 37
In spite of the general acceptance of the %HRR–%VO2R method of exercise prescription there are important methodological issues that might limit its use. The main issue concerns the error in determining exercise intensity due to measurement bias introduced by methodological differences in the determination of resting VO2 and VO2max, and in the subsequent application of the %HRR, %VO2max, and %VO2R relationships in exercise prescription. The aim of this critical review was therefore to discuss experimental studies that investigated the relationships between %HRR, %VO2max and %VO2R, with special reference given to the methodology used for the determination of the resting VO2 and VO2max and its moderating effect on these relationships. The applicability of %HRR, %VO2max and %VO2R relationships for exercise prescription is also discussed.
Section snippets
Literature search criteria
Bibliographic research databases [MEDLINE (1966–2010), LILACS (1982–2010), Cochrane Database of Systematic Reviews (1993–2010) and SCIELO (1997–2010)] were used to search for experimental studies that investigated the relationships between %HRR, %VO2max and %VO2R. The following search terms were used by themselves or combined: “hrr”, “heart rate reserve”, “vo2r”, “oxygen uptake reserve”, “vo2max”, “maximal oxygen uptake”, “exercise prescription”, “exercise intensity”. Fifteen pertinent studies
Historical perspective of the heart rate reserve and VO2 reserve concepts
Historically, the ACSM exercise prescription guidelines focused mainly upon percentages of VO2max (Table 1). In 1991, for example, the ACSM recommended an exercise intensity of between 40% and 85% VO2max for training programs aimed at developing the cardiorespiratory fitness of adults. The exercise workload, training volume and caloric expenditure corresponding to the target VO2 could then be derived from metabolic equations.35 However, the ACSM recognized that there are limitations to the use
Conclusions
The majority of the reviewed studies stated that percentages of HRR are closer to percentages of VO2R than to percentages of VO2max, thereby increasing the accuracy of exercise prescription. However, this finding has not been consistent and methodological limitations limit the confidence one can place on the findings. The methodological limitations involved using VO2max test protocols that were not conducive to eliciting a true VO2max, not determining resting VO2 using recommended guidelines,
Conflict of interest
There are no potential conflicts of interest to disclose.
Acknowledgements
We thank Luciana Dumphreys for reviewing the English version of the paper. We would also like to thank Steven Gaskill, PhD, for kindly providing unpublished data. This study was partially supported by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ, process E-26/150.751/2007) and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, process 305729/2006-3).
References (80)
- et al.
Impact of exercise intensity on body fatness and skeletal muscle metabolism
Metabolism
(1994) - et al.
Comparison of cardioprotective benefits of vigorous versus moderate intensity aerobic exercise
Am J Cardiol
(2006) - et al.
Effectiveness of high-intensity interval training for the rehabilitation of patients with coronary artery disease
Am J Cardiol
(2005) - et al.
The relationship between heart rate reserve and oxygen uptake reserve in heart failure patients on optimized and non-optimized beta-blocker therapy
Clinics (Sao Paulo)
(2008) - et al.
Best practice methods to apply to measurement of resting metabolic rate in adults: a systematic review
J Am Diet Assoc
(2006) - et al.
Comparison of the ramp versus standard exercise protocols
J Am Coll Cardiol
(1991) - et al.
Physical education's role in public health
Res Q Exerc Sport
(1991) - et al.
Changes in physical fitness and all-cause mortality: a prospective study of healthy and unhealthy men
JAMA
(1995) Trends in leisure time physical inactivity by age, sex and race/ethnicity -United States, 1994–2004
MMWR Morb Mortal Wkly Rep
(2005)- et al.
Low levels of leisure-time physical activity and cardiorespiratory fitness predict development of the metabolic syndrome
Diabetes Care
(2002)