A reexamination of the effects of creatine on muscle protein synthesis in tissue culture.

Fry, D. Michael; Morales, Manuel F.

doi:10.1083/jcb.84.2.294

Cited by 30 publications

(17 citation statements)

References 12 publications

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“…If it is the result of a direct effect of creatine, it should stimulate muscle protein synthesis or decrease muscle protein breakdown. Increased creatine availability has been reported in studies of animal skeletal and cardiac muscle in vitro to stimulate protein synthesis (15,16,33), although other investigators (11) were unable to confirm this.…”

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confidence: 72%

No effect of creatine supplementation on human myofibrillar and sarcoplasmic protein synthesis after resistance exercise

Louis

Poortmans²,

Francaux³

et al. 2003

American Journal of Physiology-Endocrinology and Metabolism

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. No effect of creatine supplementation on human myofibrillar and sarcoplasmic protein synthesis after resistance exercise. Am J Physiol Endocrinol Metab 285: E1089-E1094, 2003. First published June 24, 2003 10.1152/ajpendo.00195.2003.-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 Ϯ 2 kg/m 2 , 21 Ϯ 1 yr, means Ϯ SE) performed 20 ϫ 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 ϳ21 g maltodextrin ϩ 6 g protein/h for 3 h postexercise. We measured incorporation of [1-13 C]leucine into quadriceps muscle proteins in the rested and exercised legs. Leg protein breakdown (as dilution of [ 2 H5]phenylalanine) was also assessed in the exercised and rested leg postexercise. Creatine supplementation increased muscle total creatine by ϳ21% (P Ͻ 0.01). Exercise increased the synthetic rates of myofibrillar and sarcoplasmic proteins by two-to threefold (P Ͻ 0.05), and leg phenylalanine balance became more positive, but creatine was without any anabolic effect. skeletal muscle; protein turnover THE USE OF CREATINE SUPPLEMENTATION as an ergogenic aid has increased markedly, especially among athletes requiring high power outputs during so-called explosive events. In investigating the possible mechanisms for the claimed improvements in performance, many workers have reported that creatine supplementation is accompanied by a significant increase in lean body mass (1,2,4,9,14). There is evidence that the increase in muscle mass does not simply represent an increase in total body water but is mainly intracellular, suggesting that the body cell dry mass has increased (10). Also, there are a number of reports showing increases in muscle fiber area as a result of consuming creatine while training using resistance exercise (29, 30) or during treatment of patients with muscle atrophy (13, 28).The mechanism of the creatine-associated effect on muscle mass is unknown. If it is the result of a direct effect of creatine, it should stimulate muscle protein synthesis or decrease muscle protein breakdown. Increased creatine availability has been reported in studies of animal skeletal and cardiac muscle in vitro to stimulate protein synthesis (15,16,33), although other investigators (11) were unable to confirm this.In starting to investigate the possible effects on human muscle, we began by studying the effect of creatine supplementation on human muscle protein turnover at rest in the fasted and fed conditions (20). In that study, we measured myofibrillar protein synthesis and leg protein breakdown in healthy young men before and after 5 days of dietary creatine supplementation sufficient to r...

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confidence: 72%

No effect of creatine supplementation on human myofibrillar and sarcoplasmic protein synthesis after resistance exercise

Louis

Poortmans²,

Francaux³

et al. 2003

American Journal of Physiology-Endocrinology and Metabolism

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“…If it is the result of creatine per se acting as a modulator of muscle mass, we can hypothesize that it should act either by stimulating muscle protein synthesis or by decreasing muscle protein breakdown. Increased creatine availability has been reported in studies of animal skeletal and cardiac muscle to stimulate protein synthesis (14,15,37), although others were unable to confirm this (10).…”

mentioning

confidence: 85%

Creatine supplementation has no effect on human muscle protein turnover at rest in the postabsorptive or fed states

Louis

Poortmans

Francaux

et al. 2003

American Journal of Physiology-Endocrinology and Metabolism

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. Creatine supplementation has no effect on human muscle protein turnover at rest in the postabsorptive or fed states. Am J Physiol Endocrinol Metab 284: E764-E770, 2003. First published December 10, 2002 10.1152/ajpendo.00338.2002.-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 Ϯ 7 yr, body mass index 22 Ϯ 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 H5]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 ⅐ kg body wt Ϫ1 ⅐ h Ϫ1 ). Creatine supplementation increased muscle total creatine by ϳ30% (P Ͻ 0.01). Feeding had significant effects, doubling MPS (P Ͻ 0.001) and depressing MPB by ϳ40% (P Ͻ 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. skeletal muscle; protein synthesis; protein breakdown OVER THE LAST TEN OR SO YEARS, the use of creatine supplementation as an ergogenic aid has increased markedly, especially among athletes requiring high power outputs during so-called explosive events. In investigating the possible mechanisms for the claimed increase in performance, many workers have reported that creatine supplementation is accompanied by a significant increase in lean body mass (1,2,4,8,13). Although the increase has been explained by some as an increase in total body water, there is evidence that this is mainly intracellular, suggesting that the body cell dry mass was increased (9). Furthermore, a number of workers have reported increases in muscle fiber area as a result of consuming creatine while training using resistance exercise (28, 32) or during treatment of patients with muscle atrophy (12, 26).The mechanism of the creatine-associated effect on muscle mass is unknown. If it is the result of creatine per se acting as a modulator of muscle mass, we can hypothesize that it should act either by stimulating muscle protein synthesis or by decreasing muscle protein breakdown. Increased creatine availability has been reported in studies of animal skeletal and cardiac muscle to stimulate protein synthesis (14,15,37), although others were unable to confirm this (10).Information concerning possible effects of creatine per se on protein metabolism in human beings is sparse. Part of the above hypothesis was tested by Parise et al. (19), who measured mixed-muscle protein synthesis and whole body protein turnover in young sedentary subjects in the postabsorptive state after oral cre...

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“…Some studies suggest that effect may be due to an increase in muscle protein synthesis [24], whereas others have demonstrated that this phenomenon is a consequence of water accumulation in the intramuscular medium caused by the high osmotic power of creatine [25]. These divergent results justify the importance of new studies to evaluate the effects of this supplementation on body composition in specific manner.…”

Section: Introductionmentioning

confidence: 95%

Effects of creatine supplementation on the performance and body composition of competitive swimmers

Mendes

Pires

Oliveira

et al. 2004

The Journal of Nutritional Biochemistry

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A reexamination of the effects of creatine on muscle protein synthesis in tissue culture.

Cited by 30 publications

References 12 publications

No effect of creatine supplementation on human myofibrillar and sarcoplasmic protein synthesis after resistance exercise

No effect of creatine supplementation on human myofibrillar and sarcoplasmic protein synthesis after resistance exercise

Creatine supplementation has no effect on human muscle protein turnover at rest in the postabsorptive or fed states

Effects of creatine supplementation on the performance and body composition of competitive swimmers

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