People who take popular sports supplement creatine and lift weights do not build muscle any faster than those who do resistance training without the supplement, new research shows.
A UNSW-led clinical trial which put 54 people through a 12-week resistance training program found no difference between those who took the supplement at the recommended dose and those who did not, the research published in Nutrients shows.
Both groups in the randomised control trial put on an average of two kilograms of lean body mass during the program, which involved three supervised resistance training sessions per week.
"We've shown that taking five grams of creatine supplement per day does not make any difference to the amount of lean muscle mass people put on while resistance training," said senior author Dr Mandy Hagstrom, from UNSW's School of Health Sciences.
"The benefits of creatine may have been overestimated in the past, due to methodological problems with previous studies," she added.
Creatine is a naturally occurring compound which supplies energy to muscles. It is produced by the liver, pancreas and kidneys, and found in protein-rich foods. Previous research shows creatine supplements help build muscles, enhance athletic performance, and may even have cognitive benefits.
However, previous trials have started supplementation and exercise programs on the same day, making it difficult to separate the effect of each on muscle gains, Dr Hagstrom said. They've also overlooked the potential for creatine to cause water retention, though more research is needed to confirm this.
So, in this trial, those in the supplement group started on creatine one week before the exercise program began, taking five grams per day, which is at the upper end of the recommended maintenance dose of three to five grams.
"We had what we call a wash-in phase, where half of the participants started taking the supplement, without changing anything else in their daily life, to give their body a chance to stabilise in terms of its response to the supplement," Dr Hagstrom said.
The effect of creatine with and without resistance training
During that first week people taking creatine gained more lean body mass, particularly women, gaining an average of 0.5 kilograms more than the control group. However, the extra gains they made varied greatly, and soon dropped back to match those of the control group.
"The people taking the creatine supplement saw changes before they even started exercising, which leads us to believe that it wasn't actual real muscle growth, but potentially fluid retention," Dr Hagstrom said.
"Then once they started exercising, they saw no additional benefit from creatine which suggests that five grams per day is not enough if you're taking it for the purposes of building muscle."
By comparison, previous trials with no wash-in period found those on creatine gained one kilogram more muscle, than those not taking the supplement, during trials spanning four to 12 weeks.
More research needed on creatine doses The trial suggests people need to take more creatine than is commonly thought to get the desired benefit of additional muscle gains, the experts say.
Just how much more will need to be the subject of further research, but 10 grams could be the dose to test first, given it's already shown to be safe and promising for both brain and bone health, Dr Hagstrom said. A longer study would also be beneficial, said first author Dr Imtiaz Desai, from UNSW's School of Health Sciences and Neuroscience Research Australia (NeuRA). As would measuring body water content, tracking the menstrual cycle – which can affect fluid retention – and creatine absorption, which was not feasible for this trial.
"It would be really interesting to see if creatine has more of a long-term benefit," said Dr Desai. "When you start weight training, you have those beginner gains in strength and those start tapering off around the 12-week mark and become slower, so it's possible the support from creatine might come at a later stage." In the meantime, the researchers hope it will give people more realistic expectations on creatine use, and prompt them to question claims made in the marketing of some supplements. "For your average person taking creatine to boost their gains in the gym, this will hopefully change their perception about what it can help them achieve," Dr Desai said. "For professional athletes, particularly those who must be at a particular weight for their sport, the findings may inform how and when they take the supplement." As for researchers, it's hoped the study may encourage others to start to use a wash-in phase, to better understand the impact of supplements with and without exercise.
About the trial
The participants, aged 18 to 50, were all relatively healthy people who were doing less than the recommended minimum of 150 minutes of moderate intensity exercise per week.
They were put through the same training program and had their measurements taken at multiple stages using dual energy x-ray absorptiometry, a non-invasive imaging technique that measures bone mineral density and body composition. They were also required to keep a food log three days prior to each assessment, which showed no significant differences in their diets. Those on creatine did bypass a loading phase, which includes taking 20 to 25 grams daily for up to one week. While it is common to start with a loading phase, it can cause gastrointestinal issues and is not necessary to reach saturation levels - the maximum that the body can store at any one time.
