No effect of creatine supplementation on human myofibrillar and sarcoplasmic protein synthesis after resistance exercise.
Muscle hypertrophy during resistance training is reportedly increased by creatine supplementation. Having previously failed to find an anabolic effect on muscle protein turnover at rest, either fed or fasted, we have now examined the possibility of a stimulatory effect of creatine in conjunction with acute resistance exercise. Seven healthy men (body mass index, 23 +/- 2 kg/m2, 21 +/- 1 yr, means +/- SE) performed 20 x 10 repetitions of leg extension-flexion at 75% one-repetition maximum in one leg, on two occasions, 4 wk apart, before and after ingesting 21 g/day creatine for 5 days. The subjects ate approximately 21 g maltodextrin + 6 g protein/h for 3 h postexercise. We measured incorporation of [1-13C]leucine into quadriceps muscle proteins in the rested and exercised legs. Leg protein breakdown (as dilution of [2H5]phenylalanine) was also assessed in the exercised and rested leg postexercise. Creatine supplementation increased muscle total creatine by approximately 21% (P < 0.01). Exercise increased the synthetic rates of myofibrillar and sarcoplasmic proteins by two- to threefold (P < 0.05), and leg phenylalanine balance became more positive, but creatine was without any anabolic effect.
Louis
Magali
M
Université Catholique de Louvain, France.
Poortmans
Jacques R
JR
Francaux
Marc
M
Berré
Jacques
J
Boisseau
Nathalie
N
Brassine
Eric
E
Cuthbertson
Daniel J R
DJ
Smith
Kenneth
K
Babraj
John A
JA
Waddell
Tom
T
Rennie
Michael J
MJ
D000328:Adult; D001706:Biopsy; D001783:Blood Flow Velocity; D002247:Carbon Isotopes; D003401:Creatine / Q000008:administration & dosage* / Q000032:analysis; D003903:Deuterium; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D015444:Exercise; D006801:Humans; D007700:Kinetics; D007866:Leg / Q000098:blood supply; D007930:Leucine / Q000378:metabolism; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000737:chemistry; D009210:Myofibrils / Q000187:drug effects / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism; D011134:Polysaccharides / Q000008:administration & dosage; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*
D002247:Carbon Isotopes; D004044:Dietary Proteins; D009124:Muscle Proteins; D011134:Polysaccharides; D010649:Phenylalanine; C008315:maltodextrin; D003903:Deuterium; D007930:Leucine; D003401:Creatine