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

Abstract

Background: The combined associations of changes in cardiorespiratory fitness and body mass index (BMI) with mortality remain controversial and uncertain.

Methods and results: We examined the independent and combined associations of changes in fitness and BMI with all-cause and cardiovascular disease (CVD) mortality in 14 345 men (mean age 44 years) with at least 2 medical examinations. Fitness, in metabolic equivalents (METs), was estimated from a maximal treadmill test. BMI was calculated using measured weight and height. Changes in fitness and BMI between the baseline and last examinations over 6.3 years were classified into loss, stable, or gain groups. During 11.4 years of follow-up after the last examination, 914 all-cause and 300 CVD deaths occurred. The hazard ratios (95% confidence intervals) of all-cause and CVD mortality were 0.70 (0.59-0.83) and 0.73 (0.54-0.98) for stable fitness, and 0.61 (0.51-0.73) and 0.58 (0.42-0.80) for fitness gain, respectively, compared with fitness loss in multivariable analyses including BMI change. Every 1-MET improvement was associated with 15% and 19% lower risk of all-cause and CVD mortality, respectively. BMI change was not associated with all-cause or CVD mortality after adjusting for possible confounders and fitness change. In the combined analyses, men who lost fitness had higher all-cause and CVD mortality risks regardless of BMI change.

Conclusions: Maintaining or improving fitness is associated with a lower risk of all-cause and CVD mortality in men. Preventing age-associated fitness loss is important for longevity regardless of BMI change.

Figure 1

Hazard ratios of all-cause (A) and cardiovascular disease (B) mortality by fifths of changes in % body fat (data from 12 475 men), body weight, and maximal METs in 14 345 men. All data were adjusted for age, examination year, parental CVD, baseline value of each exposure, the combination patterns of each lifestyle factor (smoking status, alcohol intake, and physical activity) and each medical condition (abnormal electrocardiogram, hypertension, diabetes, and hypercholesterolemia) at the baseline and last examinations, the number of clinic visits between the baseline and last examinations, and baseline maximal METs and maximal MET change (for % body fat change and body weight change) or baseline weight and weight change (for maximal MET change).

Figure 2

Hazard ratios (95% confidence intervals) of all-cause (A) and cardiovascular disease (B) mortality by combinations of changes in fitness and BMI in 14 345 men. All data were adjusted for age, examination year, parental CVD, BMI, and maximal METs at baseline, the combination patterns of each lifestyle factor (smoking status, alcohol intake, and physical activity) and each medical condition (abnormal electrocardiogram, hypertension, diabetes, and hypercholesterolemia) at the baseline and last examinations, and the number of clinic visits between the baseline and last examinations. The number of men (number of all-cause deaths) in the fitness loss, stable, and gain groups were 717 (82), 1240 (91), and 2824 (208) in the BMI loss group; 1732 (101), 2129 (113), and 921 (63) in the stable BMI group; and 2333 (115), 1412 (79), and 1037 (62) in the BMI gain group, respectively. Also, the number of men (number of CVD deaths) in the fitness loss, stable, and gain groups were 658 (23), 1184 (35), and 2686 (70) in the BMI loss group; 1660 (29), 2050 (34), and 874 (16) in the stable BMI group; and 2259 (41), 1361 (28), and 999 (24) in the BMI gain group, respectively.