|
|
||||||||||
|
J Am Coll Cardiol, 2001; 37:153-156 © 2001 by the American College of Cardiology Foundation |
a Human Cardiovascular Research Laboratory, Department of Kinesiology and Applied Physiology, University of Colorado at Boulder, Boulder, Colorado, USA
b Divisions of Cardiology and Geriatric Medicine, Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado, USA
Manuscript received April 18, 2000; revised manuscript received July 24, 2000, accepted September 13, 2000.
Reprint requests and correspondence: Dr. Hirofumi Tanaka, Department of Kinesiology and Applied Physiology, Campus Box 354, University of Colorado at Boulder, Boulder, Colorado 80309-0354
tanakah{at}colorado.edu
| Abstract |
|---|
|
|
|---|
We sought to determine a generalized equation for predicting maximal heart rate (HRmax) in healthy adults.
BACKGROUND
The age-predicted HRmax equation (i.e., 220 age) is commonly used as a basis for prescribing exercise programs, as a criterion for achieving maximal exertion and as a clinical guide during diagnostic exercise testing. Despite its importance and widespread use, the validity of the HRmax equation has never been established in a sample that included a sufficient number of older adults.
METHODS
First, a meta-analytic approach was used to collect group mean HRmax values from 351 studies involving 492 groups and 18,712 subjects. Subsequently, the new equation was cross-validated in a well-controlled, laboratory-based study in which HRmax was measured in 514 healthy subjects.
RESULTS
In the meta-analysis, HRmax was strongly related to age (r = 0.90), using the equation of 208 0.7 x age. The regression equation obtained in the laboratory-based study (209 0.7 x age) was virtually identical to that obtained from the meta-analysis. The regression line was not different between men and women, nor was it influenced by wide variations in habitual physical activity levels.
CONCLUSIONS
1) A regression equation to predict HRmax is 208 0.7 x age in healthy adults. 2) HRmax is predicted, to a large extent, by age alone and is independent of gender and habitual physical activity status. Our findings suggest that the currently used equation underestimates HRmax in older adults. This would have the effect of underestimating the true level of physical stress imposed during exercise testing and the appropriate intensity of prescribed exercise programs.
| ||||||
Because maximal exercise testing is not feasible in many settings, HRmax is often estimated using the age-predicted equation of 220 age. However, the validity of the age-predicted HRmax equation has not been established, particularly in a study sample that included an adequate number of older adults (e.g., >60 years of age). The latter limitation is crucial in that older adults demonstrate the highest prevalence of cardiovascular and other chronic diseases. As such, this is the most prevalent population undergoing diagnostic exercise testing, representing a key clinical target for exercise prescription. Importantly, older adults are a population in which there is often a reluctance or an inability to measure HRmax directly, owing to concerns related to the physiologic stress imposed by strenuous exercise. Thus, ironically, the 220 age HRmax prediction equation is used in this population more than in any other.
Accordingly, the aim of the present study was to determine an equation for predicting HRmax in healthy, nonmedicated humans ranging widely in age. To address this aim, we first used a meta-analytic approach in which group mean HRmax values were obtained from the published data. Subsequently, we cross-validated the newly derived equation in a well-controlled, laboratory-based study. With each approach, we attempted to establish the generalizability of the equation by determining whether gender or habitual physical activity status exerted a significant modulatory influence on the HRmax-age relation.
| Methods |
|---|
|
|
|---|
3 times/week for over one year; 2) active, referring to occasional or irregular performance of aerobic exercise
2 times/week; and 3) sedentary, referring to no performance of any aerobic exercise. Data from treadmill and cycle ergometers were evaluated together and separately. There were no differences in the results between the two analyses. Therefore, data from both exercise modes were pooled and are presented together. This meta-analysis included a total of 351 studies involving 492 subject groups (161 female and 331 male groups) and 18,712 subjects. Because we have previously shown that weighted results by sample size were not significantly different from unweighted results (6), no weighting scheme was used in the present meta-analysis. Laboratory-based study. Five-hundred fourteen subjects (237 men and 277 women) were studied (age range 18 to 81 years). All of the subjects were apparently healthy and free of overt coronary artery disease, as determined by a medical history questionnaire. Subjects >50 years of age were further evaluated by physical examination and by rest and maximal exercise electrocardiography ECG (3). None of the subjects smoked or used any medications other than hormone replacement (postmenopausal women). To eliminate the potentially confounding influence of severe obesity, only subjects with a body mass index <35 kg/m2 were included. Two different groups were studied: endurance exercise-trained and sedentary. The endurance-trained subjects (n = 229) had been training for at least the past two years. The subjects in the sedentary group (n = 285) performed no regular physical exercise. Before participation, the subjects gave their written, informed consent to participate in this investigation. This study was reviewed and approved by the Human Research Committee at the University of Colorado at Boulder.
Maximal heart rate was determined by a continuous, incremental treadmill protocol, as previously described in detail by our laboratory (4). Heart rates were continuously monitored with electrocardiography. Minute oxygen consumption (
O2) also was measured using on-line, computer-assisted, open-circuit spirometry (4). After a warm-up period of 6 to 10 min, each subject ran or walked at a comfortable but brisk speed. The treadmill grade was increased 2.5% every 2 min until volitional exhaustion. At the end of each stage, the subjects were asked to rate their perception of effort using a Borg category scale (6 to 20 rating). Maximal heart rate was defined as the highest value recorded during the test. To ensure that each subject achieved maximal exertion, at least three of the following four criteria were met by each subject: 1) a plateau in
O2 with increasing exercise intensity (<100 ml); 2) a respiratory exchange ratio of at least 1.15; 3) a maximal respiratory rate of at least 35 breaths/min; and 4) a rating of perceived exertion of at least 18 units on the Borg scale (5).
Statistical analysis. Linear regression analyses were performed to determine the association among variables. In all cases, age was used as the predictor variable. Pearson product-moment correlation coefficients were used to indicate the magnitude and direction of relations among variables. The slopes of regression lines were compared using analysis of covariance. Forward stepwise multiple regression analyses were used to identify significant independent determinants for the age-related declines in HRmax. To do so, only those variables that had significant univariate correlations with HRmax (e.g., age, body mass) were entered in the model. All data were reported as the pooled mean value ± SD. The statistical significance level was set, a priori, at p < 0.01 for all analyses.
| Results |
|---|
|
|
|---|
80% of the individual variance in HRmax.
|
|
| Discussion |
|---|
|
|
|---|
Comparison with the traditional equation.
The original reports proposing the 220 age HRmax equation appear to be reviews by Fox and Haskell in the 1970s (7,8). The age-predicted equation was determined "arbitrarily" from a total of 10 studies. The highest age included was <65 years, with the majority of subjects being
55 years old. Because of these limitations, there have been some attempts to establish a more appropriate equation to predict HRmax (911). However, similar to the original reports by Fox and Haskell (7,8), these studies probably or definitely included subjects with cardiovascular disease who smoked and/or were taking cardiac medications. Each of these conditions influences HRmax independent of age (10,12,13). Therefore, the present study is the first to determine the age-predicted equation for healthy, unmedicated and nonsmoking adult humans. Another unique aspect of the present study is that each subject achieved a verified maximal level of effort, as established by conventional maximal exercise criteria (e.g., a plateau in
O2, maximal respiratory exchange ratio >1.15).
We obtained the regression equation of 208 0.7 x age to predict HRmax in the present study. When this equation was compared with the traditional 220 age equation (Fig. 3), it is clear that the traditional equation overestimates HRmax in young adults, intersects with the present equation at age 40 years and then increasingly underestimates HRmax with further increases in age. For example, at age 70 years, the difference between the two equations is
10 beats/min. Considering the wide range of individual subject values around the regression line for HRmax (SD
10 beats/min), the underestimation of HRmax could be >20 beats/min for some older adults. Although the present HRmax equation provides a more accurate estimation of HRmax on average, as with previous equations, it may not precisely predict true HRmax in some individuals, because of the standard deviation. As such, despite the convenience and ease of use of age-predicted HRmax, direct measurements of HRmax should be used as an indicator of physical stress whenever possible. Alternatively, individuals may choose to use more subjective end points of exercise, such as breathlessness and/or a fatigue level considered to be "somewhat hard" to "hard" on the Borg perceived exertion scale (2).
|
Factors influencing HRmax. We found that the rate of decline in maximal heart rate was not associated with either gender or physical activity status. More importantly, a large portion of variability was explained by age alone. These results collectively indicate that the same age-based equation can be used for various groups of healthy adults to estimate their HRmax values. We wish to emphasize, however, that because we excluded individuals with overt cardiovascular disease and smokers (10,12,13), the present equation may not be applicable to these subjects.
Mechanisms. The mechanism underlying the age-related reduction in HRmax is not clear. It has been postulated that the primary mechanism is related to an age-related decline in intrinsic heart rate (i.e., independent of autonomic influences) (14,15). In this context, it is interesting to note that the rate of decline in HRmax observed in the present study is very similar to that reported previously for intrinsic heart rate determined after cardiac autonomic blockade (0.6 0.8 beats/min per year) (14,15). Moreover, consistent with the present findings, gender (14) and habitual physical activity (16) do not appear to influence intrinsic heart rate in humans. These results collectively suggest that a decrease in HRmax with age may primarily be due to the reduction in intrinsic heart rate.
Conclusions. The results of the present study fail to validate the traditional equation for predicting HRmax across the adult age range in healthy humans. Specifically, the traditional equation underestimates HRmax past age 40 years, markedly so in older adults. On the basis of the cross-confirmatory findings of our meta-analysis and complementary prospective study, we present a new equation for future use that should provide more precise results. These findings have important clinical implications related to exercise testing and prescription.
| Footnotes |
|---|
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
M.-C. Gomez-Cabrera, E. Domenech, M. Romagnoli, A. Arduini, C. Borras, F. V Pallardo, J. Sastre, and J. Vina Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance Am. J. Clinical Nutrition, January 1, 2008; 87(1): 142 - 149. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Tanaka and D. R. Seals Endurance exercise performance in Masters athletes: age-associated changes and underlying physiological mechanisms J. Physiol., January 1, 2008; 586(1): 55 - 63. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Sugawara, H. Komine, K. Hayashi, M. Yoshizawa, T. Otsuki, N. Shimojo, T. Miyauchi, T. Yokoi, S. Maeda, and H. Tanaka Systemic {alpha}-adrenergic and nitric oxide inhibition on basal limb blood flow: effects of endurance training in middle-aged and older adults Am J Physiol Heart Circ Physiol, September 1, 2007; 293(3): H1466 - H1472. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Brage, U. Ekelund, N. Brage, M. A. Hennings, K. Froberg, P. W. Franks, and N. J. Wareham Hierarchy of individual calibration levels for heart rate and accelerometry to measure physical activity J Appl Physiol, August 1, 2007; 103(2): 682 - 692. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. R. Stob, C. Bell, M. A. van Baak, and D. R. Seals Thermic effect of food and beta-adrenergic thermogenic responsiveness in habitually exercising and sedentary healthy adult humans J Appl Physiol, August 1, 2007; 103(2): 616 - 622. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Haykowsky and W. Tymchak Superior Athletic Performance Two Decades after Cardiac Transplantation N. Engl. J. Med., May 10, 2007; 356(19): 2007 - 2008. [Full Text] [PDF] |
||||
![]() |
A. M Hill, J. D Buckley, K. J Murphy, and P. R. Howe Combining fish-oil supplements with regular aerobic exercise improves body composition and cardiovascular disease risk factors Am. J. Clinical Nutrition, May 1, 2007; 85(5): 1267 - 1274. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Ukropcova, O. Sereda, L. de Jonge, I. Bogacka, T. Nguyen, H. Xie, G. A. Bray, and S. R. Smith Family History of Diabetes Links Impaired Substrate Switching and Reduced Mitochondrial Content in Skeletal Muscle Diabetes, March 1, 2007; 56(3): 720 - 727. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. P. Weiss, S. B. Racette, D. T. Villareal, L. Fontana, K. Steger-May, K. B. Schechtman, S. Klein, A. A. Ehsani, J. O. Holloszy, and Washington University School of Medicine CALERIE G Lower extremity muscle size and strength and aerobic capacity decrease with caloric restriction but not with exercise-induced weight loss J Appl Physiol, February 1, 2007; 102(2): 634 - 640. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Lucotti, E. Setola, L. D. Monti, E. Galluccio, S. Costa, E. P. Sandoli, I. Fermo, G. Rabaiotti, R. Gatti, and P. Piatti Beneficial effects of a long-term oral L-arginine treatment added to a hypocaloric diet and exercise training program in obese, insulin-resistant type 2 diabetic patients Am J Physiol Endocrinol Metab, November 1, 2006; 291(5): E906 - E912. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. R. Carnethon, M. Gulati, and P. Greenland Prevalence and Cardiovascular Disease Correlates of Low Cardiorespiratory Fitness in Adolescents and Adults JAMA, December 21, 2005; 294(23): 2981 - 2988. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. J. Ridout, B. A. Parker, and D. N. Proctor Age and regional specificity of peak limb vascular conductance in women J Appl Physiol, December 1, 2005; 99(6): 2067 - 2074. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. J.W. Chow, K. Ananthasubramaniam, R. A. deKemp, M. M. Dalipaj, R. S.B. Beanlands, and T. D. Ruddy Comparison of treadmill exercise versus dipyridamole stress with myocardial perfusion imaging using rubidium-82 positron emission tomography J. Am. Coll. Cardiol., April 19, 2005; 45(8): 1227 - 1234. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. L. Huggett, D. M. Connelly, and T. J. Overend Maximal Aerobic Capacity Testing of Older Adults: A Critical Review J. Gerontol. A Biol. Sci. Med. Sci., January 1, 2005; 60(1): 57 - 66. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. N. Proctor, K. U. Le, and S. J. Ridout Age and regional specificity of peak limb vascular conductance in men J Appl Physiol, January 1, 2005; 98(1): 193 - 202. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. A Varady, N. Ebine, C. A Vanstone, W. E Parsons, and P. J. Jones Plant sterols and endurance training combine to favorably alter plasma lipid profiles in previously sedentary hypercholesterolemic adults after 8 wk Am. J. Clinical Nutrition, November 1, 2004; 80(5): 1159 - 1166. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Loftin, M. Sothern, C. Van Vrancken, A. O'Hanlon, and J. Udall Effect of Obesity Status on Heart Rate Peak in Female Youth Clinical Pediatrics, July 1, 2003; 42(6): 505 - 510. [Abstract] [PDF] |
||||
![]() |
J. C. Baldi, J. L. Aoina, H. C. Oxenham, W. Bagg, and R. N. Doughty Reduced exercise arteriovenous O2 difference in Type 2 diabetes J Appl Physiol, March 1, 2003; 94(3): 1033 - 1038. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Kindermann, B. Schwaab, N. Finkler, S. Schaller, M. Bohm, and G. Frohlig Defining the optimum upper heart rate limit during exercise. A study in pacemaker patients with heart failure Eur. Heart J., August 2, 2002; 23(16): 1301 - 1308. [Abstract] [PDF] |
||||
![]() |
I. Eskurza, A. J. Donato, K. L. Moreau, D. R. Seals, and H. Tanaka Changes in maximal aerobic capacity with age in endurance-trained women: 7-yr follow-up J Appl Physiol, June 1, 2002; 92(6): 2303 - 2308. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Atwal, J. Porter, and P. MacDonald Cardiovascular effects of strenuous exercise in adult recreational hockey: the Hockey Heart Study Can. Med. Assoc. J., February 1, 2002; 166(3): 303 - 307. [Abstract] [Full Text] |
||||
![]() |
M. A. Mittleman The double-edged blade of recreational hockey Can. Med. Assoc. J., February 1, 2002; 166(3): 331 - 332. [Full Text] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |