Abstract
Background: The American College of Sports Medicine recommends 20–60 minutes of aerobic exercise three to five days a week at an intensity of 40/50–85% of maximal aerobic power (VO2MAX) reserve, expending a total of 700–2000 kcal (2.93–8.36 MJ) a week to improve aerobic power and body composition.
Objective: To ascertain the minimum effective dose of exercise.
Methods: Voluntary, healthy, non-obese, sedentary, postmenopausal women (n = 121), 48–63 years of age, were randomised to four low dose walking groups or a control group; 116 subjects completed the study. The exercise groups walked five days a week for 24 weeks with the following intensity (% of VO2MAX) and energy expenditure (kcal/week): group W1, 55%/1500 kcal; group W2, 45%/1500 kcal; group W3, 55%/1000 kcal; group W4, 45%/1000 kcal. VO2MAX was measured in a direct maximal treadmill test. Submaximal aerobic fitness was estimated as heart rates at submaximal work levels corresponding to 65% and 75% of the baseline VO2MAX. The body mass index (BMI) was calculated and percentage of body fat (F%) estimated from skinfolds.
Results: The net change (the differences between changes in each exercise group and the control group) in VO2MAX was 2.9 ml/min/kg (95% confidence interval (CI) 1.5 to 4.2) in group W1, 2.6 ml/min/kg (95% CI 1.3 to 4.0) in group W2, 2.4 ml/min/kg (95% CI 0.9 to 3.8) in group W3, and 2.2 ml/min/kg (95% CI 0.8 to 3.5) in group W4. The heart rates in standard submaximal work decreased 4 to 8 beats/min in all the groups. There was no change in BMI, but the F% decreased by about 1% unit in all the groups.
Conclusions: Walking (for 24 weeks) at moderate intensity 45% to 55% of VO2MAX, with a total weekly energy expenditure of 1000–1500 kcal, improves VO2MAX and body composition of previously sedentary, non-obese, postmenopausal women. This dose of exercise apparently approaches the minimum effective dose.
Full Text
The Full Text of this article is available as a PDF (119.9 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Blair S. N., Kohl H. W., Gordon N. F., Paffenbarger R. S., Jr How much physical activity is good for health? Annu Rev Public Health. 1992;13:99–126. doi: 10.1146/annurev.pu.13.050192.000531. [DOI] [PubMed] [Google Scholar]
- Branch J. D., Pate R. R., Bourque S. P. Moderate intensity exercise training improves cardiorespiratory fitness in women. J Womens Health Gend Based Med. 2000 Jan-Feb;9(1):65–73. doi: 10.1089/152460900318984. [DOI] [PubMed] [Google Scholar]
- Deurenberg P., Weststrate J. A., van der Kooy K. Is an adaptation of Siri's formula for the calculation of body fat percentage from body density in the elderly necessary? Eur J Clin Nutr. 1989 Aug;43(8):559–567. [PubMed] [Google Scholar]
- Duncan J. J., Gordon N. F., Scott C. B. Women walking for health and fitness. How much is enough? JAMA. 1991 Dec 18;266(23):3295–3299. [PubMed] [Google Scholar]
- Durnin J. V., Womersley J. Body fat assessed from total body density and its estimation from skinfold thickness: measurements on 481 men and women aged from 16 to 72 years. Br J Nutr. 1974 Jul;32(1):77–97. doi: 10.1079/bjn19740060. [DOI] [PubMed] [Google Scholar]
- Haskell W. L. J.B. Wolffe Memorial Lecture. Health consequences of physical activity: understanding and challenges regarding dose-response. Med Sci Sports Exerc. 1994 Jun;26(6):649–660. doi: 10.1249/00005768-199406000-00001. [DOI] [PubMed] [Google Scholar]
- Howley E. T., Bassett D. R., Jr, Welch H. G. Criteria for maximal oxygen uptake: review and commentary. Med Sci Sports Exerc. 1995 Sep;27(9):1292–1301. [PubMed] [Google Scholar]
- Jakicic J. M., Wing R. R., Butler B. A., Robertson R. J. Prescribing exercise in multiple short bouts versus one continuous bout: effects on adherence, cardiorespiratory fitness, and weight loss in overweight women. Int J Obes Relat Metab Disord. 1995 Dec;19(12):893–901. [PubMed] [Google Scholar]
- Kukkonen-Harjula K., Laukkanen R., Vuori I., Oja P., Pasanen M., Nenonen A., Uusi-Rasi K. Effects of walking training on health-related fitness in healthy middle-aged adults--a randomized controlled study. Scand J Med Sci Sports. 1998 Aug;8(4):236–242. doi: 10.1111/j.1600-0838.1998.tb00198.x. [DOI] [PubMed] [Google Scholar]
- Morris J. N., Hardman A. E. Walking to health. Sports Med. 1997 May;23(5):306–332. doi: 10.2165/00007256-199723050-00004. [DOI] [PubMed] [Google Scholar]
- Murphy M. H., Hardman A. E. Training effects of short and long bouts of brisk walking in sedentary women. Med Sci Sports Exerc. 1998 Jan;30(1):152–157. doi: 10.1097/00005768-199801000-00021. [DOI] [PubMed] [Google Scholar]
- Pate R. R. Physical activity and health: dose-response issues. Res Q Exerc Sport. 1995 Dec;66(4):313–317. doi: 10.1080/02701367.1995.10607917. [DOI] [PubMed] [Google Scholar]
- Ready A. E., Naimark B., Ducas J., Sawatzky J. V., Boreskie S. L., Drinkwater D. T., Oosterveen S. Influence of walking volume on health benefits in women post-menopause. Med Sci Sports Exerc. 1996 Sep;28(9):1097–1105. doi: 10.1097/00005768-199609000-00004. [DOI] [PubMed] [Google Scholar]