Cardiorespiratory Fitness and Adiposity as Mortality Predictors in Older Adults

CONTEXT Although levels of physical activity and aerobic capacity decline with age and the prevalence of obesity tends to increase with age, the independent and joint associations among fitness, adiposity, and mortality in older adults have not been adequately examined. OBJECTIVE To determine the association among cardiorespiratory fitness (“fitness”), adiposity, and mortality in older adults. DESIGN, SETTING, AND PATIENTS Cohort of 2603 adults aged 60 years or older (mean age, 64.4 [SD, 4.8] years; 19.8% women) enrolled in the Aerobics Center Longitudinal Study who completed a baseline health examination during 1979-2001. Fitness was assessed by a maximal exercise test, and adiposity was assessed by body mass index (BMI), waist circumference, and percent body fat. Low fitness was defined as the lowest fifth of the sex-specific distribution of maximal treadmill exercise test duration. The distributions of BMI, waist circumference, and percent body fat were grouped for analysis according to clinical guidelines. MAIN OUTCOME MEASURE All-cause mortality through December 31, 2003. RESULTS There were 450 deaths during a mean follow-up of 12 years and 31 236 person-years of exposure. Death rates per 1000 person-years, adjusted for age, sex, and examination year were 13.9, 13.3, 18.3, and 31.8 across BMI groups of 18.5-24.9, 25.0-29.9, 30.0-34.9, and ≥35.0, respectively (P = .01 for trend); 13.3 and 18.2 for normal and high waist circumference (≥88 cm in women; ≥102 cm in men) (P = .004); 13.7 and 14.6 for normal and high percent body fat (≥30% in women; ≥25% in men) (P = .51); and 32.6, 16.6, 12.8, 12.3, and 8.1 across incremental fifths of fitness (P