Creatine supplementation has no effect on human muscle protein turnover at rest in the postabsorptive or fed states.
Dietary creatine supplementation is associated with increases in muscle mass, but the mechanism is unknown. We tested the hypothesis that creatine supplementation enhanced myofibrillar protein synthesis (MPS) and diminished muscle protein breakdown (MPB) in the fed state. Six healthy men (26 +/- 7 yr, body mass index 22 +/- 4 kg/m(2)) were studied twice, 2-4 wk apart, before and after ingestion of creatine (21 g/day, 5 days). We carried out two sets of measurements within 5.5 h of both MPS (by incorporation of [1-(13)C]leucine in quadriceps muscle) and MPB (as dilution of [1-(13)C]leucine or [(2)H(5)]phenylalanine across the forearm); for the first 3 h, the subjects were postabsorptive but thereafter were fed orally (0.3 g maltodextrin and 0.083 g protein. kg body wt(-1) x h(-1)). Creatine supplementation increased muscle total creatine by approximately 30% (P < 0.01). Feeding had significant effects, doubling MPS (P < 0.001) and depressing MPB by approximately 40% (P < 0.026), but creatine had no effect on turnover in the postabsorptive or fed states. Thus any increase in muscle mass accompanying creatine supplementation must be associated with increased physical activity.
Louis
Magali
M
Université catholique de Louvain, Université Libre de Bruxelles, Brussels 1200, Belgium.
Poortmans
Jacques R
JR
Francaux
Marc
M
Hultman
Eric
E
Berre
Jacques
J
Boisseau
Nathalie
N
Young
Vernon R
VR
Smith
Kenneth
K
Meier-Augenstein
Wolfram
W
Babraj
John A
JA
Waddell
Tom
T
Rennie
Michael J
MJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D000596:Amino Acids / Q000493:pharmacokinetics; D001835:Body Weight; D003401:Creatine / Q000008:administration & dosage*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D005542:Forearm / Q000098:blood supply; D006801:Humans; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism*; D019518:Postprandial Period / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects
D000596:Amino Acids; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D009124:Muscle Proteins; D000255:Adenosine Triphosphate; D003401:Creatine