Correspondence
Exercise for Women
N Engl J Med 1996; 335:1324-1325October 24, 1996
- Article
To the Editor:
On the surface, Manson and Lee (May 16 issue)1 presented balanced editorial comments on the benefits and costs of different exercise prescriptions. Their comments were first addressed to Williams's study in the same issue of the Journal, 2 showing a beneficial dose relation between the distance run and the high-density lipoprotein (HDL) cholesterol level in female runners; the authors then generalized their comments to different exercise and activity regimes for women. Manson and Lee pointed out the enhanced health and fitness benefits derived from following previous traditional recommendations (i.e., 20 minutes of exercise three times per week at 60 to 90 percent of the maximal heart rate) but advocated following the recent minimal guidelines from the Centers for Disease Control and Prevention and the American College of Sports Medicine (30 minutes of moderate activity on most days),3 presumably on the basis of a balance of health, fitness, and feasibility considerations.
One can take serious issue with how Manson and Lee have framed their arguments, from both exercise-science and public-policy perspectives. The authors cited hormonal and musculoskeletal problems associated with overuse and overtraining syndromes in female athletes to warn against the dangers of excessive exercise. The authors have confused the classic exercise-training variables of frequency and volume with intensity. The examples and disorders noted primarily result from excessive (one might say obsessive) frequency and volume of exercise at moderate to high intensity. Such inappropriate training is sometimes combined with dietary and caloric restrictions, further undermining health, typically in relatively young female athletes.
It is important to note that high frequency and volume are not necessary and, indeed, are often counterproductive in terms of cardiovascular fitness and increases in strength, even or perhaps especially at higher levels of fitness and strength, where the greater ability to apply stress in training demands more recovery time.4 Evidence supports the efficacy of higher-intensity training at any level of cardiovascular fitness and strength when it is coupled with modest or even minimal frequency and volume to maximize fitness, strength, and diverse health-related outcomes. (In this light, examining Williams's data for intensity, not just volume of exercise, would be of interest.5) When carried out in a planned, progressive way, such training is generally safe, need not be painful, and takes minimal time.4
Since such training can be safe, effective, and not unpleasant, Manson and Lee further confused the scientific and public-policy issues by subtitling their editorial “How Much Pain for Optimal gain?” They may unwittingly be undermining interest in and striving for more than the most limited fitness and health benefits.
5 ReferencesRichard A. Winett, Ph.D.
Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-04361
Manson JE ,Lee I-M . Exercise for women -- how much pain for optimal gain? N Engl J Med 1996;334:1325-1327
Full Text | Web of Science | Medline2
Williams PT . High-density lipoprotein cholesterol and other risk factors for coronary heart disease in female runners. N Engl J Med 1996;334:1298-1303
Full Text | Web of Science | Medline3
Pate RR ,Pratt M ,Blair SN , et al. Physical activity and public health: a recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402-407
CrossRef | Web of Science | Medline4
Westcott WL. Strength fitness: physiological principles and training techniques. 4th ed. Madison, Wis.: Brown and Benchmark, 1995.
5
Haskell WL. Dose-response issues from a biological perspective. In: Bouchard C, Shephard RJ, Stephens T, eds. Physical activity, fitness, and health: international proceedings and consensus statement. Champaign, Ill.: Human Kinetics, 1994:1030-9.
Author/Editor Response
The authors reply:
To the Editor: As Dr. Winett suggests, the term “physical activity” or “exercise” encompasses several components: frequency (how often one exercises), duration (how long each episode lasts), and intensity (how vigorous the activity is, whether measured on an absolute scale or in relation to individual capacity). Hence, the assessment of physical activity is complicated. Only in experimental studies can each of the three dimensions be manipulated. In experimental studies, however, only short-term health characteristics (e.g., blood pressure) have been evaluated. It is not feasible to conduct experiments for a sufficiently long time in sufficient numbers of subjects to evaluate the more important long-term health outcomes, such as cardiovascular events or mortality. Therefore, the association between physical activity and long-term health outcomes has been assessed, to date, only in observational studies.
Because people can exercise in so many different ways, the investigators conducting these studies have generally assessed physical activity by combining the three dimensions into a single unit of total energy expenditure, for ease of analysis. Recently, efforts have been made to tease out the contributions of physical activity of different intensities to long-term health outcomes1,2; however, the data are currently sparse. We know even less regarding the contributions of frequency and duration of exercise to such health outcomes. Clear, direct evidence at present indicates that physical activity (a combination of frequency, duration, and intensity) is beneficial in terms of long-term health outcomes, but the relative contributions of each of its dimensions remain uncertain. It also appears that a dose–response relation exists, with higher levels of physical activity being associated with greater benefits.3
Winett is incorrect in assuming that we wish to undermine those striving for greater fitness and health benefits. In fact, we state that “we do not mean to discount the additional health benefits that may accrue with more frequent, longer, and more intense physical activity, and we would not dissuade those who wish to exercise more.”4 We also stand by our original assertion that among American adults, most of whom are highly sedentary, recommending a less stringent program of physical activity (particularly with regard to duration and intensity) is more likely to be successful in achieving compliance.
4 ReferencesI-Min Lee, M.B., B.S., Sc.D.
JoAnn E. Manson, M.D., Dr.P.H.
Harvard Medical School, Boston, MA 021151
Morris JN ,Clayton DG ,Everitt MG ,Semmence AM ,Burgess EH . Exercise in leisure time: coronary attack and death rates. Br Heart J 1990;63:325-334
CrossRef | Web of Science | Medline2
Lee I-M , Hsieh C-c,Paffenbarger RS Jr . Exercise intensity and longevity in men: the Harvard Alumni Health Study. JAMA 1995;273:1179-1184
CrossRef | Web of Science | Medline3
Pate RR ,Pratt M ,Blair SN , et al. Physical activity and public health: a recommendation from the Centers for Disease Control and Prevention and the American College of Sports medicine. JAMA 1995;273:402-407
CrossRef | Web of Science | Medline4
Manson JE ,Lee I-M . Exercise for women -- how much pain for optimal gain? N Engl J Med 1996;334:1325-1327
Full Text | Web of Science | Medline
