Supplement Savvy - 4-12-04!

This week I'll compare different loading and maintenance protocols on creatine uptake...


Creatine Supplementation: A Comparison of Loading and Maintenance Protocols on Creatine Uptake By Human Skeletal Muscle

Creatine is the most widely researched dietary supplement to date. There are currently more than 500 studies on the supplement. While not all are related specifically to performance, there is enough supportive research available to make creatine the base of many individual's supplement protocols.

So while it's nothing new to report how creatine will increase body weight or strength gains, there is still debate as to the best way to supplement with creatine. Is it still efficacious to go through the loading phase? What's the necessary dose of creatine to provide a potential benefit?

Is it necessary to cycle on and off of creatine? Is creatine safe? The list can go on about some of the perceived unknowns about this supplement and each will be covered in this and future columns. This week, I'll discuss a recent study comparing loading and maintenance protocols with creatine monohydrate.

It is typically recommended that when using creatine, you should first consume a "loading phase" consisting of 5 gram doses of creatine 4-6 times/day for 5-7 days to fully "saturate" the muscles. After that, it is recommended that individuals consume 5 grams of creatine per day to maintain these levels.

This recommendation is supported by research. Several studies have demonstrated this dosing protocol to increase total skeletal muscle creatine storage by 20-40%, subsequently enhancing performance. Further, the magnitude of performance improvement is related to the size of skeletal muscle stores.

However, it sure would be convenient (and cheaper) if the same results could be attained with a lesser dose. Hey, what do ya' know, researchers also thought this might be nice to find out and decided to investigate this question.

There were two purposes of this study. First, researchers wanted to determine the differences between three different "loading" protocols: 1) 5 grams creatine 4 times/day, 2) 5 grams creatine 4 times/day plus glucose, taken with the 2nd and 4th creatine dose (research has shown glucose enhances creatine uptake into muscle), or 3) 5 grams of creatine 4 times/day in conjunction with 60 minutes of repeated sprint performance (research has shown exercise enhances creatine uptake into the muscle).

Second, after these initial "loading" phases, the researchers provided varying doses of creatine (0, 2 or 5 grams/day) to the subjects, who were randomly assigned to the different creatine groups, over a 6-week period.

The 18 male subjects in this study were all physically active at baseline and were not eligible for the study if they had ever creatine loaded or currently taking a nutritional supplement.

Muscle biopsies were taken (i.e., researchers take a little piece out of a particular muscle--usually the quadriceps-to measure a specific variable) pre- and post-loading, as were urine samples to measure urine creatine concentrations (to determine how much creatine was actually absorbed). So what did they find?

All three loading protocols significantly elevated intramuscular creatine levels, but the glucose plus creatine group saw the greatest improvement (60% greater than creatine alone). The thought here is that glucose causes an increase in insulin. Subsequently, insulin helps shuttle the nutrients (in this case, creatine) into the skeletal muscle.

When comparing the various maintenance doses after 6 weeks, it was not surprising that the 0 gram/day creatine was significantly lower than after the loading phase. However, the intramuscular creatine levels did not return to baseline values, which show that it takes longer than 6 weeks for a "washout" period.

Other research has demonstrated it takes as little as 4 weeks. Interestingly, there were no significant differences between the 2 and 5g creatine/day groups in terms of intramuscular creatine levels at the end of the 6- week maintenance period.

So while we knew that creatine is effective, at least in most, this study has demonstrated that the dose that's typically recommended is not necessarily needed. Previous research has even shown that the loading phase is unnecessary when compared to a "maintenance" type dose over a 30 day period. While the loading dose produces results more quickly than a maintenance dose, those differences washout over a 30 day time span.

This study also supports previous findings that taking glucose (or other simple carbohydrate) with creatine will enhance the uptake by the muscle. From this work and others, it is prudent to recommend skipping the loading phase and instead take a smaller dose of creatine than typically recommended (2 grams/day) with some simple carbohydrate.

Considering the results from some of the previous studies I've discussed, a nice post-workout drink would be some simple carbohydrate with 6 grams of essential amino acids (or about 20 grams of a complete protein, such as whey) and a couple grams of creatine.

Source:
International Journal of Sport Nutrition and Exercise Metabolism, 2003, 13, 97-111.