Long-term effects of changes in cardiorespiratory fitness and body mass index on all-cause and cardiovascular disease mortality in men: the Aerobics Center Longitudinal Study.

Plain-language summary

This study set out to see how changes in fitness and in body weight affect a man's risk of dying, from any cause and from heart disease. It followed 14,345 men, average age 44, for about 11 years after tracking their treadmill-measured fitness and their body mass index over the previous 6 years. Men who gained fitness had a markedly lower risk of death than men who lost it, and every one-step improvement in measured fitness went with a lower risk. Change in body weight did not predict death once fitness change was accounted for. Men who lost fitness were at higher risk whatever their weight did.

Key findings

• Improving fitness was linked to a 39% lower risk of death from any cause and a 42% lower risk of death from heart disease compared to losing fitness.
• Every 1-MET (a measure of fitness) improvement lowered the risk of death by 15% (all-cause) and 19% (heart disease).
• BMI changes did not predict death risk after adjusting for fitness changes.
• Men who lost fitness had higher death risks no matter how their weight changed.