Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans

Abstract

Muscle disuse due to physical inactivity, ageing and many disease conditions results in muscle atrophy and reduced muscle functional capacity, which may impair activities of daily living. Strategies that may prevent or reverse these effects are of considerable functional significance to the individual. Recent evidence suggests that oral creatine supplementation is an effective intervention to prevent or reverse neuromuscular degeneration in humans.Since Harris and his co-workers (1992) 1. We investigated the effect of oral creatine supplementation during leg immobilization and rehabilitation on muscle volume and function, and on myogenic transcription factor expression in human subjects. A double-blind trial was performed in young healthy volunteers (n = 22).A cast was used to immobilize the right leg for 2 weeks. Thereafter the subjects participated in a knee-extension rehabilitation programme (3 sessions week _1 , 10 weeks). Half of the subjects received creatine monohydrate (CR; from 20 g down to 5 g daily), whilst the others ingested placebo (P; maltodextrin).3. Before and after immobilization, and after 3 and 10 weeks of rehabilitation training, the crosssectional area (CSA) of the quadriceps muscle was assessed by NMR imaging. In addition, an isokinetic dynamometer was used to measure maximal knee-extension power (W max ), and needle biopsy samples taken from the vastus lateralis muscle were examined to asses expression of the myogenic transcription factors MyoD, myogenin, Myf5, and MRF4, and muscle fibre diameters.4. Immobilization decreased quadriceps muscle CSA (~10 %) and W max (~25 %) by the same magnitude in both groups. During rehabilitation, CSA and W max recovered at a faster rate in CR than in P (P < 0.05 for both parameters). Immobilization changed myogenic factor protein expression in neither P nor CR. However, after rehabilitation myogenin protein expression was increased in P but not in CR (P < 0.05), whilst MRF4 protein expression was increased in CR but not in P (P < 0.05). In addition, the change in MRF4 expression was correlated with the change in mean muscle fibre diameter (r = 0.73, P < 0.05).5. It is concluded that oral creatine supplementation stimulates muscle hypertrophy during rehabilitative strength training. This effect may be mediated by a creatine-induced change in MRF4 and myogenin expression.

Efficacy of 3 days/wk resistance training on myofiber hypertrophy and myogenic mechanisms in young vs. older adults

“…Why only myf-6 protein and not the other MRF proteins accumulated with resistance training is unknown. Of interest, however, is the finding in a recent resistance training study that changes in myf-6 protein expression correlated with changes in myofiber size, whereas changes in myogenin and MyoD did not (27). The bulk of the increase in myf-6 protein was localized to men in the present study, and young men experienced the greatest myofiber hypertrophy.…”

Acute molecular responses of skeletal muscle to resistance exercise in able-bodied and spinal cord-injured subjects

“…Hespel et al (29) found that VL myogenin protein levels were unchanged after 2 wk of cast immobilization and after 3 wk of knee-extension rehabilitation exercise. In that study, myogenin and myogenic regulatory factor-4 protein levels were increased after 10 wk of progressive exercise rehabilitation, a time point when significant muscle hypertrophy was evident.…”

Nutritional Interventions as Potential Strategy to Minimize Exercise-Induced Muscle Injuries in Sports

“…The hypertrophic response has been attributed to increased myosin heavy chain protein expression [130], changes in the expression of myogenic regulatory factors (MRF4 and myogenin) [131,132], increased mitotic activity of satellite cells and swelling-induced protein synthesis [133][134][135][136][137] followed by net protein deposition. The most popular mechanism to explain the efficacy of creatine on muscle performance refers to a better match between ATP supply and fibers demands during physical exercise due to the enhancement of the resting high energy phosphate levels (total creatine, phosphocreatine, creatine and ATP) observed following supplementation.…”