RELATION OF LEISURE-TIME PHYSICAL-ACTIVITY AND CARDIORESPIRATORY FITNESS TO THE RISK OF ACUTE MYOCARDIAL-INFARCTION IN MEN

Background. Previous studies have suggested that higher levels of regu lar physical activity and cardiorespiratory fitness are associated wit h a reduced risk of coronary heart disease. We investigated the indepe ndent associations of physical activity during leisure time and maxima l oxygen uptake (a measure of cardiorespiratory fitness) with the risk of acute myocardial infarction. Methods. During the period 1984 to 19 89, we performed base-line examinations in 1453 men 42 to 60 years old who did not report having cardiovascular disease or cancer. Physical activity was assessed quantitatively with a detailed questionnaire, an d maximal oxygen uptake was measured directly by exercise testing. Dur ing an average follow-up of 4.9 years, 42 of the 1166 men with normal electrocardiograms at base line had a first acute myocardial infarctio n. Results. After adjustment for age and the year of examination, the relative hazard (risk) of myocardial infarction in the third of subjec ts with the highest level of physical activity (> 2.2 hours per week) was 0.31 (95 percent confidence interval, 0.12 to 0.85; P = 0.02), as compared with the third with the lowest level (P = 0.04 for linear tre nd over all three groups). The relative hazard in the third with the h ighest maximal oxygen uptake (> 2.7 liters per minute) was 0.26 (95 pe rcent confidence interval, 0.10 to 0.68; P = 0.006) (P = 0.006 for lin ear trend), after adjustment for age, the year and season when the exa mination was performed, weight, height, and the type of respiratory-ga s analyzer used. After up to 17 confounding variables were controlled for, the relative hazards for the third of subjects with the highest l evel of physical activity (0.34; 95 percent confidence interval, 0.12 to 0.94; P = 0.04) and maximal oxygen uptake (0.35; 95 percent confide nce interval, 0.13 to 0.92; P = 0.03), as compared with the values in the lowest third, were significantly (P < 0.05) less than 1.0. Conclus ions. Higher levels of both leisure-time physical activity and cardior espiratory fitness had a strong, graded, inverse association with the risk of acute myocardial infarction, supporting the idea that lower le vels of physical activity-and cardiorespiratory fitness are independen t risk factors for coronary heart disease in men.