CREATINE SUPPLEMENTATION AUGMENTS THE INCREASE IN SATELLITE CELL AND MYONUCLEI NUMBER IN HUMAN SKELETAL MUSCLE INDUCED BY STRENGTH TRAINING.
****, sorry for the caps, was too lazy to type the stuff again。
Inst of Sports Medicine Copenhagen.
The present study investigated the influence of creatine and protein supplementation on satellite cell frequency and myonuclei number in human skeletal muscle during 16 wks of heavy-resistance training. In a double-blinded design thirty-two healthy, male subjects (19-26 years) were assigned to strength training (STR) while receiving a timed intake of creatine (STR-CRE) (n=9), protein (STR-PRO) (n=8), placebo (STR-CON) (n=8) or serving as a non-training control group (CON) (n=7). Supplementation was given daily (STR-CRE : 6-24 g , STR-PRO: 20 g protein, STR-CON: placebo). Furthermore, timed protein/placebo intake were administered at all training sessions. Muscle biopsies were obtained at wks 0, 4, 8 (wk 8 not CON) and 16 of resistance training (3 days/wk). Satellite cells were identified by immunohistochemistry. Muscle mean fibre (MFA) area was determined after histochemical analysis. All training regimes were found to increase the proportion of satellite cells, however, significantly greater enhancements were observed with creatine supplementation at wk 4 (compared to STR-CON) and at wk 8 (compared to STR-PRO and STR-CON) (p<0.01-0.05). At wk 16, satellite cell number was no longer elevated in STR-CRE, while it remained elevated in STR-PRO and STR-CON. Furthermore, creatine supplementation resulted in an increased number of myonuclei per fibre and increases of 14-17% in MFA at wks 4, 8 and 16 (p<0.01). In contrast, STR-PRO showed increase in MFA only in the later (16 wks, +8%) and STR-CON only in the early (wk 4, +14%) phases of training, respectively (p<0.05). In STR-CRE a positive relationship was found between the percentage increases in MFA and myonuclei from baseline to week 16, respectively (r=0.67, p<0.05). No changes were observed in the control group (CON). In conclusion, the present study demonstrate for the first time that creatine supplementation in combination with strength training amplifies the training-induced increase in satellite cell number and myonuclei concentration in human skeletal muscle fibres, thereby allowing an muscle fibre growth in response to strength training.
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