Effect of weight reduction, obesity predisposition, and aerobic fitness on skeletal muscle mitochondrial function.
We used (31)P magnetic resonance spectroscopy to measure maximal mitochondrial function in 12 obesity-prone women before and after diet-induced weight reduction and in 12 matched, never-obese, and 7 endurance-trained controls. Mitochondrial function was modeled after maximum-effort plantar flexion from the phosphocreatine recovery time constant (TC(PCr)), the ADP recovery time constant (TC(ADP)), and the rate of change in PCr during the first 14 s of recovery (OxPhos). Weight reduction was not associated with a significant change in mitochondrial function by TC(PCr), TC(ADP), or OxPhos. Mitochondrial function was not different between postobese and never-obese controls by TC(PCr) [35.1 +/- 2.5 (SE) vs. 34.6 +/- 2.5 s], TC(ADP) (22.9 +/- 1.8 vs. 21.2 +/- 1.8 s), or OxPhos (0.26 +/- 0. 03 vs. 0.25 +/- 0.03 mM ATP/s), postobese vs. never-obese, respectively. However, TC(ADP) was significantly faster (14.5 +/- 2. 3 s), and OxPhos was significantly higher (0.38 +/- 0.04 mM ATP/s) in the endurance-trained group. These results suggest that maximal mitochondrial function is not impaired in normal-weight obesity-prone women relative to their never-obese counterparts but is increased in endurance-trained women.
Larson-Meyer
D E
DE
Division of Physiology and Metabolism, Department of Nutrition Sciences, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Newcomer
B R
BR
Hunter
G R
GR
McLean
J E
JE
Hetherington
H P
HP
Weinsier
R L
RL
D000328:Adult; D004198:Disease Susceptibility; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D009682:Magnetic Resonance Spectroscopy; D008931:Mitochondria, Muscle / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology*; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*