fitness and health

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American Medical Association, 515 N. State St, Chicago, IL 60610.

Volume 292(10) 8 September 2004 p 1232–1234

The Fitness, Obesity, and Health Equation: Is Physical Activity the Common Denominator?

Previous investigations, including studies from our group, have examined the individual and joint associations of cardiorespiratory fitness (CRF) and body habitus to health outcomes. Use of maximal exercise tests to quantify CRF provides an objective evaluation of an individual's recent activity patterns and accounts for 70% to 80% of the variance in detailed activity records. 7 Cardiorespiratory fitness is stronger than self-reported physical activity as a predictor of many health outcomes, most likely because fitness measurements are less prone to misclassification and because factors other than activity may influence both fitness and health through related biological factors. 8 For example, the age and examination year–adjusted relative risks for all-cause mortality in 1263 men with type 2 diabetes are 1.8 for inactivity but 2.9 for low fitness. 9

Obese individuals with at least moderate CRF have lower rates of cardiovascular disease (CVD) or all-cause mortality than their normal-weight but unfit peers. In fact, death rates in the former group are about one half those of the latter. 10 These results are similar whether BMI, percent body fat, body fat mass, or waist circumference is used as the body habitus measure 11 and are consistent for women and men 11,12 and for men with type 2 diabetes. 13 These results also pertain to nonsmokers and after exclusion of individuals with chronic disease or deaths within the first 5 years of follow-up. 11 Moreover, 150 minutes a week of moderate intensity physical activity is sufficient to avoid the low-fitness category. These results are consistent with those reported in 24 studies identified in a systematic review on physical activity, CRF, obesity, and health. 14

7. Paffenbarger RS Jr, Blair SN, Lee I-M, Hyde RT. Measurement of physical activity to assess health effects in free-living populations. Med Sci Sports Exerc. 1993;25:60–70.

8. Blair SN, Cheng Y, Holder JS. Is physical activity or physical fitness more important in defining health benefits? Med Sci Sports Exerc. 2001;33:S379-S399.

9. Wei M, Gibbons LW, Kampert JB, Nichaman MZ, Blair SN. Low cardiorespiratory fitness and physical inactivity as predictors of mortality in men with type 2 diabetes. Ann Intern Med. 2000;132:605–611.

10. Wei M, Kampert JB, Barlow CE, et al. Relationship between low cardiorespiratory fitness and mortality in normal-weight, overweight, and obese men. JAMA. 1999;282:1547–1553.

11. Lee CD, Blair SN, AS. Cardiorespiratory fitness, body composition, and all-cause and cardiovascular disease mortality in men. Am J Clin Nutr. 1999;69:373–380.

12. Farrell SW, Braun L, Barlow CE, Cheng YJ, Blair SN. The relation of body mass index, cardiorespiratory fitness, and all-cause mortality in women. Obes Res. 2002;10:417–423.

13. Church TS, Cheng YJ, Earnest CP, et al. Exercise capacity and body composition as predictors of mortality among men with diabetes. Diabetes Care. 2004;27:83–88.

14. Blair SN, Brodney S. Effects of physical inactivity and obesity on morbidity and mortality: current evidence and research issues. Med Sci Sports Exerc. 1999;31:S646-S662.