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Article
March 4, 1988

Activity and Risk of Coronary Heart Disease

Author Affiliations

Los Angeles County—University of Southern California Medical Center Los Angeles

Los Angeles County—University of Southern California Medical Center Los Angeles

JAMA. 1988;259(9):1328. doi:10.1001/jama.1988.03720090020021
Abstract

To the Editor.  —The article entitled "Leisure-Time Physical Activity Levels and Risk of Coronary Heart Disease and Death" from the Multiple Risk Factor Intervention Trial1 raises important issues. The "treatment effect" of a higher level of physical activity seems to be well supported by the data.However, prior studies have shown that physical activity that is heavy enough to produce a training effect results in an increase in left ventricular mass and a reduction of resting pulse rates. In individuals with normal coronary blood flow, these factors should be offsetting. In those with a high risk of developing a coronary event, blood flow might not be adequate for an increase in left ventricular mass.Was the level of physical activity as estimated in this trial in the high-activity group sufficient to produce a training effect and therefore to potentially increase left ventricular mass? Were any measurements taken that might

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