objective:To determine what effect diet-induced ~12 kg weight loss in combination with exercise training has on body composition and resting energy expenditure (REE) in premenopausal African-American (AA) and European-American (EA) women. Methods and Procedures: This study was a longitudinal, randomized weight loss clinical intervention, with either aerobic (AT), resistance (RT), or no exercise training (NT). Forty-eight AA and forty-six EA premenopausal overweight (BMI between 27 and 30) women underwent weight loss to a BMI <25. Body composition (densitometry), REE (indirect calorimetry), maximal oxygen uptake (VO 2 max), and muscular strength (isometric elbow flexion) were evaluated when subjects were in energy balance. Results: AA women lost less fat-free mass (FFM, P ≤ 0.05) (47.0 ± 4.6 to 46.9 ± 5.0 kg) than EA women (46.4 ± 4.9 to 45.2 ± 4.6 kg). Regardless of race, RT maintained FFM (P ≤ 0.05) following weight loss (46.9 ± 5.2 to 47.2 ± 5.0 kg) whereas AT (45.4 ± 4.2 to 44.4 ± 4.1 kg) and NT (47.9 ± 4.7 to 46.4 ± 5.1 kg) decreased FFM (P ≤ 0.05). Both AT and NT decreased in REE with weight loss but RT did not. Significant time by group interactions (all P ≤ 0.05) for strength indicated that RT maintained strength and AT did not. Discussion: AA women lost less FFM than EA women during equivalent weight losses. However, following weight loss in both AA and EA, RT conserved FFM, REE, and strength fitness when compared to women who AT or did not train.

Premenopausal women overestimate PA estimates on questionnaires. Overestimation of PA in weight-reduced black women is greater than in weight-reduced white women and never-overweight black and white women.

Objective: To determine the relationship between body composition/fat distribution and parity after adjusting for potential confounders: age, smoking, and physical activity. Design: Cross-sectional. Subjects: A total of 170 Caucasian women between the ages of 18 and 76 years, who were non-smokers with no cardiovascular disease, diabetes, metabolic, or endocrine disorders. Measurements: Physical activity assessment (Baecke Physical Activity Questionnaire), anthropometric measures, and body composition (dual-energy X-ray absorptiometry, computed tomography). Results: Although percent body fat was related to parity (r ¼ 0.26, Po0.01), after adjusting for age, physical activity index, and smoking, the parity-percent body fat relationship was no longer significant. Multiple regression analysis for modeling intra-abdominal adipose tissue demonstrated that parity and intra-abdominal adipose tissue were significantly related after adjusting for percent body fat, physical activity index, and smoking (partial r ¼ 0.18, P ¼ 0.02, unstandardized b ¼ 5.2272.26, intercept ¼ À37.32724.63). Conclusion: Our data suggest that intra-abdominal adipose tissue increases with increasing parity, even after adjusting for potential confounders: age, percent body fat, physical activity, and smoking.

HUNTER, GARY R., NUALA M. BYRNE, BARBARA A. GOWER, BOVORN SIRIKUL, AND ANDREW P. HILLS. Increased resting energy expenditure after 40 minutes of aerobic but not resistance exercise. Obesity. 2006;14:2018 -2025. Objective: Resting energy expenditure (REE) is increased 24 hours after high-intensity aerobic exercise lasting 60 minutes, whereas results have been inconsistent after resistance training and aerobic exercise of shorter duration. The objective of the study was to compare the effects of 40 minutes of high-intensity aerobic vs. resistance exercise on REE 19 to 67 hours after exercise. Research Methods and Procedures: REE was compared 19, 43, and 67 hours after 40 minutes of aerobic training (AT; 80% maximum heart rate) or resistance training (RT; 10 repetitions at 80% maximum strength, two sets and eight exercises). Twenty-three black and 22 white women were randomly assigned to AT, RT, or no training (controls). Exercisers trained 25 weeks. REE was measured after a 12-hour fast. Results: There was a significant time ϫ group interaction for REE when adjusted for fat-free mass and fat mass, with post hoc tests revealing that the 50-kcal difference between 19 and 43 hours (1310 Ϯ 196 to 1260 Ϯ 161 kcal) and the 34-kcal difference between 19 and 67 hours (1310 Ϯ 196 to 1276 Ϯ 168 kcal) were significant for AT. No other differences were found, including RT (19 hours, 1256 Ϯ 160; 43 hours, 1251 Ϯ 160; 67 hours, 1268 Ϯ 188 kcal). Urine norepinephrine increased with training only in AT. After adjusting for fat-free mass, REE ⌬ between 19 and both 43 and 67 hours was significantly related to urine norepinephrine (r ϭ 0.76, p Ͻ 0.01 and 0.68, p Ͻ 0.03, respectively). Discussion: Consistent with findings on longer duration AT, these results show that 40 minutes of AT elevates REE for 19 hours in trained black and white women. This elevation did not occur with 40 minutes of RT. Results suggest that differences are, in part, due to increased sympathetic tone.

Recent data have shown that individuals with low insulin sensitivity (S(I)) also have reduced whole body maximal oxygen uptake. The objectives of this study were to determine 1) whether muscle mitochondrial function was independently related to S(I) after being adjusted for known determinants of S(I) and 2) whether lower S(I) among African-American (AA) vs. Caucasian-American (CA) women was due to lower muscle mitochondrial function among AA women. Subjects were 37 CA and 22 AA premenopausal women (age: 33.6 +/- 6.3 yr). Mitochondrial function [time constant of ADP (ADP(tc))] was assessed during a 90-s unilateral isometric contraction using (31)P magnetic resonance spectroscopy, S(I) with an intravenous glucose tolerance test, body composition by dual-energy X-ray absorptiometry, and visceral adipose tissue (VAT) with computed tomography. ANOVA was used to compare AA and CA groups, and multiple linear regression modeling was used to identify independent predictors of S(I). Between-race comparisons indicated that muscle oxidative capacity was lower among AAs vs. CAs (ADP(tc): 25.6 +/- 9.8 vs. 21.4 +/- 9.9 s). Multiple linear regression models for the dependent variable S(I) contained 1) VAT and race and 2) VAT, race, and ADP(tc). Significant independent effects for all predictor variables were observed in both the first (r(2) = 0.345) and second (r(2) = 0.410) models. The partial correlation for race was lower in the second model (-0.404 vs. -0.300), suggesting that muscle mitochondrial function contributed to the racial difference in S(I). Lower muscle mitochondrial function among AAs may in part explain lower S(I) among them.