The effect of exercise training on beta-adrenergic stimulation of fat metabolism in obese men.
OBJECTIVE
To investigate the in vivo effect of exercise training at high and low intensity on beta-adrenergic stimulated fat metabolism in obese men at rest.


METHODS
Twenty-three obese, healthy subjects were randomly divided in a low-intensity exercise training program (40% VO(2max), n=7), a high-intensity exercise training program (70% VO(2max); 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 beta-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 beta-adrenergic stimulation on relative fat oxidation in obese men at both intensities and in lean men. In addition, beta-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.


CONCLUSIONS
Low- and high-intensity exercise training in obese men failed to affect beta-adrenergic mediated relative fat oxidation in vivo. beta-Adrenergic-mediated lipolysis might be increased in obese men after HI exercise training only. The effect of low-intensity exercise training on beta-adrenergic-mediated fat metabolism was similar in lean and obese men. International Journal of Obesity (2001) 25, 16-23
Nutrition, Toxicology and Environmental Research Institute (NUTRIM), Department of Human Biology, Maastricht University, Maastricht, The Netherlands. D.vanAggel@HB.unimaas.nl
D P
DP
van Aggel-Leijssen
W H
WH
Saris
M
M
Homan
M A
MA
van Baak
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000328:Adult; D001823:Body Composition; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005990:Glycerol / Q000097:blood; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D050356:Lipid Metabolism; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism / Q000628:therapy*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D013997:Time Factors
D000318:Adrenergic beta-Agonists; D007545:Isoproterenol; D005990:Glycerol