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Mitochondrial Respiration is Associated with Lower Energy Expenditure and Lower Aerobic Capacity in African American Women
Author(s) -
Toledo Frederico G.S.,
Dubé John J.,
Goodpaster Bret H.,
StefanovicRacic Maja,
Coen Paul M.,
DeLany James P.
Publication year - 2018
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1002/oby.22163
Subject(s) - skeletal muscle , thermogenesis , resting energy expenditure , medicine , endocrinology , aerobic capacity , obesity , respiration , energy expenditure , zoology , biology , anatomy
Objective Reasons for the higher obesity prevalence in African American women (AAW) compared with Caucasian women (CW) are unknown. Energy expenditure and maximal aerobic capacity (VO 2 max) are lower in AAW. It was hypothesized that these differences are explained by skeletal muscle characteristics, particularly mitochondrial content and function. Methods Multivariate regression analyses were used to examine the relationships between energy expenditure (resting and during a hyperinsulinemic‐euglycemic clamp) and VO 2 max versus body composition, physical activity, and skeletal muscle mitochondrial measurements in AAW and CW. Results In AAW, VO 2 max was lower ( P < 0.0001). Body‐composition‐adjusted energy expenditure during the clamp was lower in AAW ( P < 0.002). Physical activity was similar in both groups. After adjusting for mitochondrial respiration, racial differences in energy expenditure and VO 2 max were no longer present. Another novel finding was that a thermogenic response to the clamp was observed in CW (+53 ± 22 kcal/d; P < 0.03) but not in AAW (−19 ± 24 kcal/d; P = 0.43). Conclusions AAW and CW show differences in adjusted energy expenditure and aerobic capacity that are largely accounted for by differences in skeletal muscle mitochondrial oxidative characteristics. Further research is needed to determine whether lower mitochondrial respiration and lower thermogenesis are risk factors for obesity in AAW.