Metabolic Responses of Black and White Females During Rest and Exercise.

Lower mitochondrial respiration does not lead to decreased fat oxidation in young African American women without obesity

“…These data are in line with those of Hickner et al [18], who reported lower rates of fat oxidation, both absolute and normalized to FFM, at 40% and 65% of VO 2 peak in lean AAW compared with White women of similar age. Similarly, Chitwood et al [17], using treadmill exercise at 65% of VO 2 max, demonstrated higher RER during exercise, suggesting a greater reliance on carbohydrate oxidation and lower rates of fat oxidation in AAW compared with White women.…”

“…These data are in line with those of Hickner et al [18], who reported lower rates of fat oxidation, both absolute and normalized to FFM, at 40% and 65% of VO 2 peak in lean AAW compared with White women of similar age. Similarly, Chitwood et al [17], using treadmill exercise at 65% of VO 2 max, demonstrated higher RER during exercise, suggesting a greater reliance on carbohydrate oxidation and lower rates of fat oxidation in AAW compared with White women. Our finding that fat oxidation was not different when adjusting for workload to account for the lower VO 2 peak in AAW is in line with a report by Melby et al [37], who reported no differences in RER values between young lean AAW and White women during exercise at fixed power outputs (25 W, 50 W, and 75 W) for 15 minutes each.…”

“…Low fat oxidation was observed in young (21 years), lean (22% fat) AAW with family history of obesity compared with matched White women [17]. In another study, fat oxidation during low intensity exercise (15 W; ~40% VO 2 max) and higher intensity exercise (65% VO 2 max) was shown to be lower in AAW than in White women [18].…”