title: Influence of lipolysis and fatty acid availability on fuel selection during exercise.
abstract: The aim of the present study was to investigate the influence of substrate availability on fuel selection during exercise. Eight endurance-trained male cyclists performed 90-min exercise at 70% of their maximal oxygen uptake in a cross-over design, either in rested condition (CON) or the day after 2-h exercise practised at 70% of maximal oxygen uptake (EX). Subjects were given a sucrose load (0.75 g kg(-1) body weight) 45 min after the beginning of the 90-min exercise test. Lipolysis was measured in subcutaneous abdominal adipose tissue (SCAT) by microdialysis and substrate oxidation by indirect calorimetry. Lipid oxidation increased during exercise and tended to decrease during sucrose ingestion in both conditions. Lipid oxidation was higher during the whole experimental period in the EX group (p = 0.004). Interestingly, fuel selection, assessed by the change in respiratory exchange ratio (RER), was increased in the EX session (p = 0.002). This was paralleled by a higher rate of SCAT lipolysis reflected by dialysate glycerol, plasma glycerol, and fatty acids (FA) levels (p < 0.001). Of note, we observed a significant relationship between whole-body fat oxidation and dialysate glycerol in both sessions (r (2) = 0.33, p = 0.02). In conclusion, this study highlights the limiting role of lipolysis and plasma FA availability to whole-body fat oxidation during exercise in endurance-trained subjects. This study shows that adipose tissue lipolysis is a determinant of fuel selection during exercise in healthy subjects.
authors: Inserm UMR1048, Institute of Metabolic and Cardiovascular Diseases, Obesity Research Laboratory, CHU Rangueil, 1 Avenue Jean Poulhès, BP84225, 31432, Toulouse Cedex 4, France, Cedric.Moro@inserm.fr.
authors: Cedric
authors: C
authors: Moro
authors: Isabelle
authors: I
authors: Harant
authors: Pierre-Marie
authors: PM
authors: Badin
authors: François-Xavier
authors: FX
authors: Patarca
authors: Jean-Claude
authors: JC
authors: Guilland
authors: Virginie
authors: V
authors: Bourlier
authors: Dominique
authors: D
authors: Langin
authors: Isabelle
authors: I
authors: De Glisezinski
mesh_terms: D000328:Adult; D001642:Bicycling; D018592:Cross-Over Studies; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D008066:Lipolysis; D008297:Male; D017551:Microdialysis; D010101:Oxygen Consumption; D055815:Young Adult
chemical_list: D005227:Fatty Acids