Respiratory fitness, free living physical activity, and cardiovascular disease risk in older individuals: a doubly labeled water study.

The objective of this study was to examine the importance of cardiorespiratory fitness vs. physical activity energy expenditure on selected cardiovascular disease risk factors in older individuals. One hundred and seventeen older individuals, 53 men (68 +/- 9 yr) and 63 women (67 +/- 7 yr), participated in the study. This cohort was divided into 4 groups: 1) high cardiorespiratory fitness and high physical activity, 2) high cardiorespiratory fitness and low physical activity, 3) low cardiorespiratory fitness and high physical activity, and 4) low cardiorespiratory fitness and low physical activity. Cardiorespiratory fitness (VO2max) was determined from a graded exercise test, physical activity energy expenditure was measured by doubly labeled water and indirect calorimetry, body composition was determined by dual energy x-ray absorptiometry, and dietary practices were determined by a 3-day recall. Cardiorespiratory fitness exerted greater effects on the cardiovascular disease risk profile than physical activity. That is, older individuals with higher levels of cardiorespiratory fitness, regardless of their physical activity levels, showed lower levels of fasting insulin (P < 0.01), triglycerides (P < 0.05), total cholesterol (P < 0.05), total to high density lipoprotein cholesterol ratio (P < 0.05), low density lipoprotein (P < 0.05), and lower waist circumference (P < 0.01). Moreover, individuals with a high cardiorespiratory fitness but low physical activity energy expenditure displayed a more favorable cardiovascular disease risk profile than individuals with low cardiorespiratory fitness and high physical activity energy expenditure. The results suggest that higher levels of cardiorespiratory fitness have greater cardioprotective effects than higher levels of free living physical activity in older individuals. Although these findings do not discount the health benefits of being physically active, it is possible that greater emphasis should be placed on aerobic exercise to increase cardiorespiratory fitness in the elderly.