Low rates of daily energy expenditure, increased energy intake, or a combination of both contribute to obesity in African-Americans. We examined whether African-Americans have lower rates of free-living daily energy expenditure than Caucasians. One hundred sixty-four (>55 yr) volunteers (37 African-American women, 52 Caucasian women, 28 African-American men, and 47 Caucasian men) were characterized for total daily energy expenditure, resting metabolic rate, and physical activity energy expenditure from the doubly labeled water method and indirect calorimetry. Absolute total daily energy expenditure was lower in women than men but was not different between African-Americans and Caucasians. However, we found race and gender differences in total daily energy expenditure after controlling for differences in fat-free mass. Total daily energy expenditure was 10% lower ( P < 0.01) in African-Americans compared with Caucasians due to a 5% lower resting metabolic rate ( P < 0.01) and 19% lower physical activity energy expenditure ( P = 0.08). Moreover, total daily energy expenditure was 16% lower ( P < 0.01) in women compared with men due to a 6% lower resting metabolic rate ( P = 0.09) and a 37% lower physical activity energy expenditure ( P = 0.06). Low rates of energy expenditure may be a predisposing factor for obesity, particularly in African-American women.

The purpose of this study was to determine the relationship between free-living daily physical activity and ambulatory measurements in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. Thirty-four older, nonsmoking PAOD patients with intermittent claudication (age=69.0 +/- 6.0 years, ankle/brachial index [ABI] =0.63 +/- 0.18) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. Energy expenditure of physical activity (EEPA) was determined by using doubly labeled water and indirect calorimetry techniques. Patients were also characterized on claudication distances and peak oxygen uptake during a graded treadmill test, 6-minute walking distance, weight, body mass index, and percent body fat. The claudication patients were sedentary, as EEPA was 362 +/- 266 kcal/day. EEPA was related to the 6-minute walk distance (369 +/- 68 meters; r=0.629, P<0.001), to the number of steps taken during 6 minutes (605 +/- 99 steps; r=0.485, P=0.008), to the treadmill distance to maximal claudication (313 +/- 131 meters; r=0.470, P=0.010), and to the time to relief of pain (6:21 +/- 3:57 min:sec; r=-0.417, P=0.017). None of the other ambulatory and body composition measurements were correlated with EEPA. In conclusion, a reduction in free-living daily physical activity was associated with a decrease in ambulatory ability and with more severe intermittent claudication in older PAOD patients.