title: Creatine supplementation influences substrate utilization at rest.
abstract: The influence of creatine supplementation on substrate utilization during rest was investigated using a double-blind crossover design. Ten active men participated in 12 wk of weight training and were given creatine and placebo (20 g/day for 4 days, then 2 g/day for 17 days) in two trials separated by a 4-wk washout. Body composition, substrate utilization, and strength were assessed after weeks 2, 5, 9, and 12. Maximal isometric contraction [1 repetition maximum (RM)] leg press increased significantly (P < 0.05) after both treatments, but 1-RM bench press was increased (33 +/- 8 kg, P < 0.05) only after creatine. Total body mass increased (1.6 +/- 0.5 kg, P < 0.05) after creatine but not after placebo. Significant (P < 0.05) increases in fat-free mass were found after creatine and placebo supplementation (1.9 +/- 0.8 and 2.2 +/- 0.7 kg, respectively). Fat mass did not change significantly with creatine but decreased after the placebo trial (-2.4 +/- 0.8 kg, P < 0.05). Carbohydrate oxidation was increased by creatine (8.9 +/- 4.0%, P < 0.05), whereas there was a trend for increased respiratory exchange ratio after creatine supplementation (0.03 +/- 0.01, P = 0.07). Changes in substrate oxidation may influence the inhibition of fat mass loss associated with creatine after weight training.
authors.affiliation: Department of Nutrition, Arizona State University, Mesa, Arizona 85212, USA.
authors.forename: M Erik
authors.initials: ME
authors.lastname: Huso
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Hampl
authors.forename: Carol S
authors.initials: CS
authors.lastname: Johnston
authors.forename: Pamela D
authors.initials: PD
authors.lastname: Swan
mesh_terms: D000328:Adult; D001823:Body Composition; D050260:Carbohydrate Metabolism; D003404:Creatinine / Q000493:pharmacokinetics* / Q000652:urine; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D005223:Fats / Q000378:metabolism; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D012119:Respiration; D012146:Rest / Q000502:physiology*; D014891:Weight Lifting / Q000502:physiology
chemical_list: D005223:Fats; D003404:Creatinine