Effect of a 1-hour single bout of moderate-intensity exercise on fat oxidation kinetics

Metabolism. 2009 Dec;58(12):1778-86. doi: 10.1016/j.metabol.2009.06.008. Epub 2009 Jul 25.

Abstract

The present study aimed to examine the effects of a prior 1-hour continuous exercise bout (CONT) at an intensity (Fat(max)) that elicits the maximal fat oxidation (MFO) on the fat oxidation kinetics during a subsequent submaximal incremental test (IncrC). Twenty moderately trained subjects (9 men and 11 women) performed a graded test on a treadmill (Incr), with 3-minute stages and 1-km.h(-1) increments. Fat oxidation was measured using indirect calorimetry and plotted as a function of exercise intensity. A mathematical model (SIN) including 3 independent variables (dilatation, symmetry, and translation) was used to characterize the shape of fat oxidation kinetics and to determine Fat(max) and MFO. On a second visit, the subjects performed CONT at Fat(max) followed by IncrC. After CONT performed at 57% +/- 3% (means +/- SE) maximal oxygen uptake (Vo(2max)), the respiratory exchange ratio during IncrC was lower at every stage compared with Incr (P < .05). Fat(max) (56.4% +/- 2.3% vs 51.5% +/- 2.4% Vo(2max), P = .013), MFO (0.50 +/- 0.03 vs 0.40 +/- 0.03 g.min(-1), P < .001), and fat oxidation rates from 35% to 70% Vo(2max) (P < .05) were significantly greater during IncrC compared with Incr. However, dilatation and translation were not significantly different (P > .05), whereas symmetry tended to be greater in IncrC (P = .096). This study showed that the prior 1-hour continuous moderate-intensity exercise bout increased Fat(max), MFO, and fat oxidation rates over a wide range of intensities during the postexercise incremental test. Moreover, the shape of the postexercise fat oxidation kinetics tended to have a rightward asymmetry.

MeSH terms

  • Adult
  • Anaerobic Threshold / physiology
  • Body Composition / physiology
  • Calorimetry, Indirect
  • Carbohydrate Metabolism / physiology
  • Carbon Dioxide / blood
  • Exercise / physiology*
  • Exercise Test
  • Female
  • Heart Rate / physiology
  • Humans
  • Kinetics
  • Lipid Metabolism / physiology*
  • Male
  • Middle Aged
  • Mixed Function Oxygenases / metabolism
  • Oxidation-Reduction
  • Oxygen Consumption / physiology
  • Vasodilation / physiology
  • Young Adult

Substances

  • Carbon Dioxide
  • Mixed Function Oxygenases