April 18, 1990

Exercise, Fitness, and Mortality

Author Affiliations

Crozer-Chester Medical Center Upland, Pa

Crozer-Chester Medical Center Upland, Pa

JAMA. 1990;263(15):2047. doi:10.1001/jama.1990.03440150051013

To the Editor.—  Blair et al1 provide evidence that low levels of physical fitness, defined by treadmill exercise performance, are a risk factor for future cardiovascular mortality, cancer mortality, and all-cause mortality in a population of predominantly white, middle-aged men and women. They suggest that if all unfit persons became fit there would be a significant reduction in the death rate.The observed decrease in cancer mortality is intriguing. Possibly preclinical cancer can influence performance on the treadmill by humoral, metabolic, and/or other factors. If so, the exclusion from analysis of cancer deaths that occur within 4 years of baseline should eliminate the probability of a confounding preclinical cancer effect. If most cancer mortality occurred during the first few years after treadmill testing, it would be suggestive of the poor treadmill performance that results from a preclinical cancer effect. Perhaps the authors can provide data on cancer mortality in