Fat Mass Localization Alters Fuel Oxidation during Exercise in Normal Weight Women.

1Laboratory of Metabolic Adaptations to Exercise in Physiological and Pathological conditions, Clermont University, Blaise Pascal University, Clermont-Ferrand, France
Medicine and science in sports and exercise (Impact Factor: 4.46). 03/2013; DOI: 10.1249/MSS.0b013e3182935fe3
Source: PubMed

ABSTRACT PURPOSE: Abdominal and lower body fat mass tissues exhibit particular metabolic profiles at rest and during exercise. However data are missing in normal weight women during exercise. The purpose of this study was to investigate the impact of low (LA/LB) and high (HA/LB) abdominal to lower body (A/LB) fat mass ratio on metabolic and hormonal responses during exercise in premenopausal normal weight women. METHODS: After preliminary testing (VO2max and body composition assessment), substrate oxidation (Respiratory Exchange Ratio, lipid and carbohydrate oxidation rates), metabolic (glycerol, free fatty acids, glucose) and hormonal (insulin, growth hormone, atrial natriuretic peptide, adrenaline and noradrenaline) responses were determined during exercise (45 min at 65% of VO2max) in 21 premenopausal normal weight women (10 HA/LB women vs 11 LA/LB women). RESULTS: Waist circumference was significantly higher in HA/LB women compared with LA/LB women (p<0.01). No difference in other anthropometric characteristics, VO2max and resting blood values was observed between the two groups. LA/LB subjects exhibited greater lipid oxidation rates compared with HA/LB women during exercise (p<0.01). This occurred with lower plasma insulin (p<0.05) and glucose (p<0.05) concentrations and higher plasma free fatty acids (p<0.05), glycerol (p<0.05), growth hormone (p<0.05), atrial natriuretic peptide levels (p<0.01) during exercise in the LA/LB group compared with the HA/LB group. CONCLUSION: The present study demonstrated that LA/LB women exhibited an increase in whole-body lipid mobilization and utilization during exercise compared with HA/LB counterparts. This greater reliance on lipid as fuel metabolism during exercise could be explained by substrate availability and metabolic and hormonal responses. It appeared that LA/LB women exhibited greater metabolic flexibility during an exercise bout of 45 min at 65% of VO2max on cycle ergometer.

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Available from: Laurie Isacco, Jul 27, 2014
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    ABSTRACT: Fat mass localization affects lipid metabolism differently at rest and during exercise in overweight and normal-weight subjects. The aim of this study was to investigate the impact of a low vs high ratio of abdominal to lower-body fat mass (index of adipose tissue distribution) on the exercise intensity (Lipoxmax) that elicits the maximum lipid oxidation rate in normal-weight women. Twenty-one normal-weight women (22.0±0.6 years, 22.3±0.1kg.m(-2)) were separated into two groups of either a low or high abdominal to lower-body fat mass ratio [L-A/LB (n=11) or H-A/LB (n=10), respectively]. Lipoxmax and maximum lipid oxidation rate (MLOR) were determined during a submaximum incremental exercise test. Abdominal and lower-body fat mass were determined from DXA scans. The two groups did not differ in aerobic fitness, total fat mass, or total and localized fat-free mass. Lipoxmax and MLOR were significantly lower in H-A/LB vs L-A/LB women (43±3% VO2maxvs 54±4% VO2max, and 4.8±0.6mgmin(-1)kg FFM(-1)vs 8.4±0.9mgmin(-1)kg FFM(-1), respectively; P<0.001). Total and abdominal fat mass measurements were negatively associated with Lipoxmax (r=-0.57 and r=-0.64, respectively; P<0.01) and MLOR [r=-0.63 (P<0.01) and r=-0.76 (P<0.001), respectively]. These findings indicate that, in normal-weight women, a predominantly abdominal fat mass distribution compared with a predominantly peripheral fat mass distribution is associated with a lower capacity to maximize lipid oxidation during exercise, as evidenced by their lower Lipoxmax and MLOR.
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