High aerobic fitness in late adolescence is associated with a reduced risk of myocardial infarction later in life: a nationwide cohort study in men

Abstract

Aims

Cardiovascular disease is the leading cause of morbidity and mortality worldwide, and signs of atherosclerosis are present in all large arteries already in adolescence. We investigated the association between high physical fitness in late adolescence and myocardial infarction (MI) later in life.

Methods and results

The study cohort comprised 743 498 Swedish men examined at the age of 18 years during conscription 1969–84. Aerobic fitness (W_max) and muscle strength at conscription were measured using standardized methods. Myocardial infarctions occurring in the cohort were tracked through national registers. During a median follow-up period of 34 years, 11 526 MIs were registered in the cohort. After adjusting for age, body mass index (BMI), diseases, education, blood pressure, and socio-economic factors, one standard deviation increase in the level of physical fitness (W_max) was associated with an 18% decreased risk of later MI [hazard ratio (HR) 0.82, 95% confidence interval (CI) 0.80–0.85]. The beneficial effects of W_max were significant across all recognized BMI groups, ranging from lean (BMI < 18.5) to obese (BMI > 30) (P < 0.05 for all). However, obese men (BMI > 30) in the highest fourth of W_max had a higher risk of MI than did lean men (BMI < 18.5) in the highest (HR 4.6, 95% CI 1.9–11.2), and lowest (HR 1.7, 95% CI 1.2–2.6) fourth of W_max.

Conclusions

We report a significant graded association between aerobic fitness in late adolescence and MI later in life in men. However, obese men with a high aerobic fitness had a higher risk of MI than lean men with a low aerobic fitness.

Myocardial infarction, Physical fitness, Adolescent men