Most savvy supplement users are aware of the basic dosing protocol for creatine supplementation. Namely, a loading phase (~20g/day) for approximately 1 week followed by a maintenance phase (~5g/day) for 4-8 weeks. But one perplexing issue about creatine supplementation is that dosing has traditionally been prescribed based on absolute amounts rather than in relative terms like grams per kg of lean mass.
Relative Dosing of Creatine
Creatine is largely stored in muscle tissue, and therefore it makes sense that an individual’s capacity to store additional creatine in their muscle is inadvertently related to their lean muscle tissue mass. Using this philosophy, researchers from Baylor University in Texas recently tested the response to creatine supplementation in a group of young adults (avg age 20 years) using a relative dosing regimen.
Rather than prescribe creatine based on absolute amounts, they took a group of young males, split them in two and gave half a dose of creatine monohydrate based on their lean mass. The study also measured changes in urine, serum and muscle tissue creatine, with the aim of gathering data to better answer questions concerning the body’s ability to store extra creatine.
Creatine Monohydrate Dosing Regime
As is normal practice, each group started with a 1-week loading phase, which was followed by a 4-week maintenance phase and also a 4-week wash out phase. During the loading phase, each subject received 0.3g/kg lean mass/day of creatine monohydrate, which was taken in 4 divided doses throughout the day. On average, this equated to 18.8g/day for each subject in the active arm of the study, which is not too far off the general recommendation of 20g/day. During the maintenance phase, the relative dose dropped down to 0.075g/kg lean mass/day, which equated to an average of 4.77g/day; also very close to the general 5g per day recommendation.
Subjects in the control (placebo) group received equal amounts in the form of maltodextrin; a carbohydrate with a similar appearance and taste to creatine monohydrate.
Resistance Training Program
Throughout the course of the 9-week study, all subjects took part in a periodised 4-day/week resistance training program. The program was split into two upper-body and two lower-body workouts each week. Repetitions wise, they performed three sets of 10 repetitions to failure (i.e. ~70-80% of 1RM).
Changes in Urine, Serum and Muscle Creatine Levels
Some of the most interesting findings of the study concern the changes in urine, serum and intramuscular levels of creatine throughout the study. After just 4 days of supplementation on the loading dose, subjects taking creatine showed over a 1000-fold increase in their urinary excretion of creatine (as shown below).
When taken together with the changes in serum and intramuscular levels of creatine (shown below), the authors reasoned that the dose used during the loading phase was too high, exceeded the body’s functional capacity for it to be metabolised, thus resulting in wastage via urinary excretion and the saturated intramuscular levels.
This was despite using a relative dose based on each subjects’ lean muscle mass rather than absolute amounts.
So how does one ascertain the optimal dose of creatine monohydrate? The authors that this would be reflected as an increase in intramuscular creatine stores with minimal increase in urinary excretion of creatine.
Given the findings of the current study, it is obvious that further research needs to be carried out using an even lower relative dose. For those who enjoy self experimentation, try 0.2g/kg lean mass/day during the loading phase and see if you notice any lesser results.
Creatine Responders & Non-Responders
The authors of the study also make the important point that there are bound to be responders and non-responders when it comes to creatine. To illustrate their point, they highlight the case of one individual who only saw an increase of 18 mmol/kg dry weight in intramuscular creatine levels compared with the average of 30 mmol/kg dry weight for the creatine group. These differences are also reflected in the strength data responses, with some subjects attaining greater strength than others. Percentage composition of type II muscle fibers is one factor that has been suggested as an additional factor affecting an individual’s response to creatine supplementation.
This study serves as a timely reminder of the need to regularly re-evaluate long held beliefs concerning supplementation. Sometimes more is not always best.
Andre TL, et al. Effects of five weeks of resistance training and relatively dosed creatine monohydrate supplementation on body composition and muscle strength, and whole-body creatine metabolism in resistance-trained males. International Journal of Kinesiology & Sports Science. 2016;4(2):27-35.