How to Dose Creatine Supplements
The primary source of energy for the phosphagen system is a compound called adenosine triphosphate (ATP). ATP provides energy when it loses a phosphate to become adenosine diphosphate (ADP). The release of the extra phosphate also releases energy that can be used to perform work (i.e., contract muscles). The phosphagen system has a limited capacity because the store of ATP is limited. As stated previously, after approximately 10 seconds, the body has to shift to the anaerobic glycolytic system because the phosphagen system is depleted. Creatine phosphate is part of the phosphagen system. Creating phosphate can donate a phosphate to ADP to reform ATP. The reaction is: CP + ADP = C + ATP. So creatine phosphate stores can increase the capacity of the phosphagen system. Research has shown that supplementing with creatine increases muscle creatine phosphate stores. This leads to greater phosphagen system capacity and reduced fatigue in activities that rely on the phosphagen system (i.e., repeated sprints, more repetitions on multi-set strength protocols). Research on creatine supplementation has provided more guidance on dosing for increasing tissue creatine concentrations.
The graph above compares two different supplementation strategies. The first strategy (A, the top graph) shows muscle creatine levels when subjects ingested 20g of creatine per day for 6 days, then discontinued supplementation. Notice that levels peaked at 7 days, then slowly declined, but did not reach pre-supplementation levels, even on day 35. Group 2 ingested 20g of creatine per day, then 2g per day as a maintenance dose. Creatine levels increased and remained high throughout the duration of the study. The study also showed that during the loading phase, each successive day resulted in less muscle creatine uptake as the muscles became saturated. Higher doses would likely result in more waste and urinary excretion and not more muscle loading. The data highlights two effective supplementation strategies:
- 20g per day for 6 days, repeated every month
- 20g per day, followed by 2g per day indefinitely
The researchers speculate that it is likely that 3g per day indefinitely is likely to saturate the muscles with creatine and maintain high muscle creatine indefinitely as well.
Soderlund K, Timmons JA, and Greenhaff PL, Muscle creatine loading in men, Journal of Applied Physiology 81:232-237, 1996.