Effect of Oral Creatine Supplementation on Human Muscle GLUT4 Protein Content After Immobilization

B. Op 't Eijnde, B. Ursø, E.A. Richter, P.L. Greenhaff, P. Hespel

Disclosures

Diabetes. 2001;50(1) 

In This Article

Results

Muscle GLUT4 concentrations were expressed relative to the corresponding baseline values that were set equal to 1 (Fig. 1). Muscle GLUT4 content at baseline was similar between the groups. In the placebo group, 2 weeks of immobilization decreased GLUT4 content on an average of 22% (range -10 to -35%, P < 0.05). Conversely, in the creatine group, muscle GLUT4 protein was stable (+9% NS). In the placebo group, the rehabilitation training restored muscle GLUT4 content within 3 weeks to the baseline value, where it remained. However, in the creatine group, muscle GLUT4 content progressively increased during the 10-week rehabilitation period to a value that was ~40% higher than in the placebo group at the end of the study (P < 0.05).

Effect of creatine supplementation on muscle GLUT4 protein content during immobilization and subsequent rehabilitation training. Data are means ± SE (n = 8) and are expressed relative to the baseline value that was set to be equal to 1. Muscle samples were taken from the vastus lateralis muscle before and after 2 weeks of immobilization and after 3 and 10 weeks of rehabilitation of the right leg. During immobilization and rehabilitation, subjects ingested creatine monohydrate (black bar) or placebo (white bar). See research design and methods for further details. *Significant treatment effect compared with placebo, P < 0.05; §significant time effect compared with the preimmobilization value.

The initial muscle glycogen concentration was 407 ± 43 mmol/kg dry weight (DW) in the placebo group versus 379 ± 19 mmol/kg DW in the creatine group (NS) (Fig. 2). Immobilization did not change muscle glycogen concentration in either group. However, during the initial 3 weeks of rehabilitation training, muscle glycogen markedly increased in the creatine group (P < 0.05), whereas it did not significantly change in the placebo group. Thus, after 3 weeks, muscle glycogen concentration was higher (P < 0.05) in the creatine group (660 ± 70 mmol/kg DW) than in the placebo group (520 ± 60 mmol/kg DW). However, during the final 7 weeks of rehabilitation training, muscle glycogen reverted to baseline values in both groups.

Effect of creatine supplementation on muscle glycogen concentration during immobilization and subsequent rehabilitation training. Data are means ± SE (n = 8). Muscle samples were taken from the vastus lateralis muscle before and after 2 weeks of immobilization and after 3 and 10 weeks of rehabilitation of the right leg. During immobilization and rehabilitation, subjects ingested creatine monohydrate (black bar) or placebo (white bar). See research design and methods for further details. *Significant treatment effect compared with placebo, P < 0.05; §significant time effect compared with the preimmobilization value.

The muscle phosphocreatine and free creatine concentrations at baseline were similar between both groups (Table 1). During immobilization, phosphocreatine concentration decreased to ~15% below the baseline value in the placebo group (P < 0.05). This decrease was negated by creatine supplementation (P < 0.05). In the placebo group, muscle phosphocreatine concentration returned to the preimmobilization baseline level within the initial 3 weeks of the rehabilitation period, after which it remained stable. On the other hand, in the creatine group, compared with the placebo group, the muscle phosphocreatine concentration increased to ~12% above baseline value after 3 weeks of rehabilitation (P < 0.05). However, this increase above baseline in phosphocreatine was reversed during the final stage of the rehabilitation period. Throughout the study, the muscle free creatine concentrations were not significantly different between the placebo and the creatine groups. In the placebo group, muscle total creatine concentration was not significantly changed compared with the baseline value during either immobilization or rehabilitation. Yet in the creatine group, compared with the placebo group, the muscle total creatine concentration was higher at the end of the immobilization period, as well as after 3 weeks of rehabilitation (P < 0.05). However, along with the declining muscle phosphocreatine levels, muscle total creatine returned to baseline by the end of the study.

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