Sui X et al. (2007) Cardiorespiratory fitness and adiposity as mortality predictors in older adults. JAMA 298: 2507–2516

The burgeoning elderly population and the increasing prevalence of obesity and physical inactivity in the US are putting a substantial burden on health-care services. Obese, inactive, middle-aged adults are at high risk of early death, but few studies have investigated the link between obesity, physical activity levels, and survival in older adults. Sui et al. looked at the relationship between these elements and at the impact of fitness by studying 2,603 adults aged 60 years or older who were taking part in the Aerobics Center Longitudinal Study.

During the 12-year follow-up, 450 of the participants died. Analysis of data including BMI, waist circumference and percentage body fat revealed that mortality correlated with BMI and waist circumference, but not with percentage body fat. The death rate per 1,000 person-years in individuals with a BMI in the range 18.5–24.9 kg/m2 was 13.9, compared with 31.8 in the group with a BMI over 35 kg/m2. Waist circumferences of ≥88 cm for women and ≥102 cm for men were risk factors for mortality after adjustment for smoking, baseline health status, and BMI. Poor fitness was strongly associated with mortality even after adjustment for potential confounding factors, including various measurements of adiposity.

The authors conclude that older adults who retain fitness are likely to live longer than those who are unfit, irrespective of the weight and fat distribution of the individual. They suggest that mortality in this age-group could be reduced by the promotion of regular physical activity.