title: Changes in peak fat oxidation in response to different doses of endurance training.
abstract: The effect of different doses of endurance training on the capacity to oxidize fat during exercise in sedentary, overweight men and assessment of variables associated with changes in peak fat oxidation (PFO) were evaluated. Young, sedentary, overweight men were randomized to either the high-dose (HIGH, 600 kcal/day, n = 17) or moderate-dose (MOD, 300 kcal/day, n = 18) endurance training groups or controls (CON, n = 15). PFO and peak oxygen uptake (VO2 peak) were measured using indirect calorimetry, body composition using dual-energy x-ray absorptiometry, and protein levels of mitochondrial enzymes determined by Western blotting. PFO increased in both MOD [1.2 mg/kg fat-free mass (FFM)/min, 95% confidence interval (CI): 0.08:2.3, P = 0.03] and HIGH (1.8 mg/kg FFM/min, CI: 0.6:2.9, P < 0.001) compared with CON. Skeletal muscle expression of citrate synthase, β-hydroxyacyl-CoA dehydrogenase, and mitochondrial oxphos complexes II-V increased similarly in MOD and HIGH. Stepwise multiple linear regression analysis with backward elimination of individual variables correlated with changes in PFO revealed increases in cycling efficiency, FFM, and VO2 peak as the remaining associated variables. In conclusion, PFO during exercise increased with both moderate- and high-dose endurance training. Increases in PFO were mainly predicted by changes in VO2 peak, FFM, and cycling efficiency, and less with skeletal muscle mitochondrial enzymes.
authors.affiliation: Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Rosenkilde
authors.forename: M H
authors.initials: MH
authors.lastname: Reichkendler
authors.forename: P
authors.initials: P
authors.lastname: Auerbach
authors.forename: T C
authors.initials: TC
authors.lastname: Bonne
authors.forename: A
authors.initials: A
authors.lastname: Sjödin
authors.forename: T
authors.initials: T
authors.lastname: Ploug
authors.forename: B M
authors.initials: BM
authors.lastname: Stallknecht
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002153:Calorimetry, Indirect; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D050177:Overweight / Q000378:metabolism* / Q000628:therapy; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010807:Physical Endurance; D052097:Quadriceps Muscle / Q000378:metabolism*; D057185:Sedentary Behavior; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D024101:Mitochondrial Proteins
keywords: exercise; fat metabolism; indirect calorimetry; skeletal muscle; substrate utilization