January 2001, Volume 25, Issue 1, Pages 16 - 23

Paper

The effect of exercise training on -adrenergic stimulation of fat metabolism in obese men DPC van Aggel-Leijssen, WHM Saris, M Homan & MA van Baak Nutrition, Toxicology and Environmental Research Institute (NUTRIM), Department of Human Biology, Maastricht University, Maastricht, The Netherlands     Correspondence to: DPC van Aggel-Leijssen, Maastricht University, Department of Human Biology, PO Box 616, 6200 MD Maastricht, The Netherlands. E-mail: D.vanAggel@HB.unimaas.nl

Keywords

low-intensity exercise;   isoprenaline;   respiratory exchange ratio;   lipolysis;   sympathetic nervous system

Abstract

OBJECTIVE: To investigate the in vivo effect of exercise training at high and low intensity on -adrenergic stimulated fat metabolism in obese men at rest. METHOD: Twenty-three obese, healthy subjects were randomly divided in a low-intensity exercise training program (40% VO2max, n=7), a high-intensity exercise training program (70% VO2max; n=8), or a non-exercising control group (n=8). The exercise training program lasted for 12 weeks with a training frequency of 3 times per week. Before and after the intervention body composition and maximal aerobic capacity were measured as well as fat metabolism at rest and during -adrenergic stimulation by isoprenaline. For comparison, six lean subjects served as a control group. They participated in a low-intensity exercise training program and underwent the same measurements as the obese subjects. RESULTS: Relative fat oxidation decreased significantly during infusion of an increasing dose of isoprenaline in the obese low-intensity and high-intensity exercise training groups as well as in the lean group (P<0.01). Exercise training failed to influence the effect of -adrenergic stimulation on relative fat oxidation in obese men at both intensities and in lean men. In addition, -adrenergic-mediated lipolysis did not seem to be different after low intensity exercise training in lean and obese men. Lipolysis might be increased after high-intensity exercise training in obese men. CONCLUSION: Low- and high-intensity exercise training in obese men failed to affect -adrenergic mediated relative fat oxidation in vivo. -Adrenergic-mediated lipolysis might be increased in obese men after HI exercise training only. The effect of low-intensity exercise training on -adrenergic-mediated fat metabolism was similar in lean and obese men. International Journal of Obesity (2001) 25, 16-23

Received 21 December 1999; Revised 23 June 2000; Accepted 7 August 2000

^© Macmillan Publishers Ltd 2001