Lipid oxidation according to intensity and exercise duration in overweight men and women.
OBJECTIVE
Our objective was to compare the effect of different exercise intensities on lipid oxidation in overweight men and women.


METHODS
Nine young, healthy, overweight men and women were studied (age, 31.4 +/- 2.3 and 26.7 +/- 2.1 years; BMI, 27.9 +/- 0.4 and 27.2 +/- 0.5; for men and women, respectively). On one study day, the subjects first performed 30 minutes of cycling exercise at 30% of their maximal oxygen uptake (Vo(2max); E1 session), followed by 30 minutes of exercise at 50% Vo(2max) (E2 session). On a second study day, a similar E1 session was followed by 30 minutes of exercise at 70% Vo(2max) (E3 session). From the gas exchange measurements, the respiratory exchange ratio (RER) and the fat oxidation rate (FOR) were calculated. Plasma concentrations of glycerol and non-esterified fatty acids (NEFAs) were assayed.


RESULTS
RER was significantly lower for women during only the E1 session. For both sexes, RER decreased over time during the E2 and E3 sessions. During the E1 session, the FOR per kilogram of lean mass (LM) was higher among women, and it did not change over time despite an increase in plasma NEFAs. FOR per kilogram of LM was higher during the E2 exercise for both sexes. During E2 and E3 sessions, as the exercise time was prolonged, the FOR/kg LM increased simultaneously with the increase in the plasma glycerol.


CONCLUSIONS
Lipid oxidation during exercise is optimized for moderate and lengthy exercise. The enhancement of lipid oxidation occurring over time during moderate- and high-intensity exercises could be, in part, linked to the improvement of lipid mobilization. This fact is discussed to shed light on exercise modalities as a tool for the management of overweight.
Pillard
Fabien
F
Service d'Exploration de la Fonction Respiratoire et d'Exploration Fonctionnelle en Médecine du Sport, Hôpital Larrey, TSA 30030, 31059 Toulouse cedex 9, France. pillard.f@chu-toulouse.fr
Moro
Cédric
C
Harant
Isabelle
I
Garrigue
Eric
E
Lafontan
Max
M
Berlan
Michel
M
Crampes
François
F
de Glisezinski
Isabelle
I
Rivière
Daniel
D
D000328:Adult; D000886:Anthropometry / Q000379:methods; D015992:Body Mass Index; D015444:Exercise; D005260:Female; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008297:Male; D050177:Overweight / Q000175:diagnosis* / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D012737:Sex Factors; D013997:Time Factors
D008055:Lipids; D005990:Glycerol; D010100:Oxygen