Effect of creatine supplementation on phosphocreatine resynthesis, inorganic phosphate accumulation and pH during intermittent maximal exercise.
Level 4 - case-series / case-control
Uncontrolled before-and-after interventional study
PubMed 12043832 · doi:10.1080/026404102317366681
What was done
Nine healthy males completed an intermittent maximal plantar flexion exercise protocol before and after 6 days of creatine supplementation (20 g/day). The protocol consisted of five 8-second bouts separated by 30-second recovery intervals, followed by a sixth 8-second bout (1-minute recovery) and a seventh 16-second bout (2-minute recovery). Muscle phosphocreatine resynthesis, inorganic phosphate accumulation, and pH were monitored every 16 seconds using phosphorus-31 magnetic resonance spectroscopy (31P-MRS).
What was found
After creatine ingestion, muscle power output increased by approximately 5% (P < 0.05) across bouts 3 to 7. Phosphocreatine resynthesis during 10 minutes of recovery increased significantly (P < 0.05). At 30 seconds of recovery, higher phosphocreatine concentrations were accompanied by reduced inorganic phosphate accumulation and higher muscle pH. Exercise power restoration strongly correlated with pre-exercise phosphocreatine, inorganic phosphate, and pH values.
Why it matters
The findings demonstrate in vivo that creatine supplementation preserves power output during repeated maximal contractions by accelerating phosphocreatine recovery, mitigating intracellular inorganic phosphate accumulation, and buffering against muscle acidosis.
Limits
The sample size was very small (n = 9) and restricted to healthy young males. The study lacked a placebo group or randomization, making it impossible to rule out learning effects or non-specific time-dependent improvements across repeat testing sessions.
Cited by
- supports Mitochondria typically take 3 to 5 minutes to recover and resynthesize depleted intramuscular phosphocreatine stores after maximal exertion.