Tuesday, September 21, 2010

Creatine Cycling - Yes or No?

In a review (Wallimann. 2010) of the effects of creatine on muscle function, Prof. Dr. Theo Wallimann suggests that in view of the results of rat studies, the old hypothesis that creatine has to be cycled to be effective, needs further investigation before it may eventually be discarded:
[...] we have found that chronic creatine supplementation of rats, at very high dosage, down-regulates in vivo the expression and/or accumulation of the CreaT in skeletal muscle, but not in brain and heart [58]. Although the amounts of creatine taken by athletes, 20 grams / day during a 10 days loading phase and 5 grams as a maintenance dose during the following three months (amounting to approximately 0.1 gram of Cr /kg body weight/ day), is significantly lower than the amounts given in the above experiments to the rats (approximately 0.5 grams /kg body weight /day), the finding made with laboratory animals nevertheless may have consequences with respect to creatine supplementation schedules for humans. In the future, however, detailed studies on humans are needed to optimize the creatine supplementation schedules in use with respect to the observed down-regulation of CreaT expression and/or accumulation in animal experiments. According to most recent results, using "normal" Cr supplementation schedules with humans, CreaT seems also to be down-regulated, especially in combination with exercise (Greenhaff et al. unpublished), but, over the time course of this human trial, creatine transporter function did not seem to become a limiting factor for maintaining normal intracellular creatine levels. Nevertheless, as suggested earlier [86], a one month pause, after three months of continuous creatine supplementation, would still seem to be a reasonable thing to do.
Anecdotally, I have always considered myself a creatine non-responder until - about one year ago - I found an open bottle of creatine monohydrate in my supplement stash and, without expecting anything, started taking a mediocre amount of 5g/day - 1 week later I knew, that "non-responding" is obviously a matter of how depleted your creatine stores are at the beginning of supplementation. Unfortunately, the gains did not keep coming, although I have been taking 3-5g/day ever since. So maybe, it is time to stop and deplete the stores again?