Effect of Creatine Supplementation and Resistance-Exercise Training on Muscle Insulin-Like Growth Factor in Young Adults, published in the International Journal of Sports Nutrition in 2008, aimed to look at whether or not creatine supplementation actually made any difference in the strength and size gains of young men and women participating in an eight week resistance-exercise training program. The study sample consisted of 24 young men and 18 young women that had previously been involved with at least 30 minutes of structured activity 3-4 times a week, but had less than one year of resistance training experience. Eighteen of the above mentioned participants were vegetarian for at least three years, adding to the scope of the study. The researchers also hoped to understand if creatine supplementation had a different effect on the gains made by vegetarians, as opposed to non-vegetarians. (Burke et al, 2008)
Previous research and anecdotal information have led to the idea that creatine supplementation can help improve strength and size gains in those participating in a resistance training program. “Theoretically, creatine supplementation might enhance the metabolic adaptations from regular resistance-exercise training sessions, leading to greater production of insulin-like growth factor-I (IFG-I) over time.” (Burke et al., 2008) Basically, the addition of a creatine supplement has the potential to allow your body to enhance its reactions to your workouts, letting you work harder and/or longer, producing more strength and more muscle growth. Prior to the above mentioned study, the research team hypothesized that “creatine supplementation during resistance training would increase IGF-I over placebo, and vegetarians on creatine would experience greater gains than non-vegetarians". (Burke et al, 2008)
Following medical approval, a Physical Activity Readiness Questionnaire, a three day dietary journal and blood tests, the study began. The loading phase consisted of four doses a day of creatine, .25 g/kg of lean tissue mass for 7 days. They were to take the doses in the morning, afternoon, post workout and before bed. The maintenance phase was to be taken post workout (when it has the opportunity to increase muscle maintenance the most) and was .006 g per kg of lean tissue mass for 49 days, to coincide with 8 weeks of resistance training. The exercise program consisted of four days a week of all over body exercises that were heavy load and heavy volume. The routines worked through seven cycles, with each cycle varying from 3-5 sets of 4-12 repetitions. Training logs were used to keep track of the workout volume completed by each participant. (Burke et al, 2008)
There were no actual differences in the volume of training over the course of the entire 8 weeks of the study between the placebo or dosed groups. The creatine did lead to greater training volume for the creatine group during the second and seventh week. The researchers also found that over the study vegetarians consumed 3-400 fewer calories less per day and consumed about 60g of protein fewer than the non-vegetarian group, whether they were getting the placebo or not. While the average gain in IGF-I was 55% for the placebo group, the creatine dosed group had a 78% gain in IGF-I. (Burke et al, 2008) The creatine group had a greater increase in both strength and size. To break down the creatine dosed group, the vegetarians gained an average of 2.4 kg of lean body mass, while the non-vegetarians gained 1.9kg of lean tissue. (Burke et al, 2008) It is possible that because the vegetarians were eating a fewer amount of the essential amino acids and they entered the study with lower creatine amounts, their bodies may have been set up to absorb the benefits at a higher rate than the non-vegetarians, however, they did not indicate higher levels of IGF-I than the non-vegetarian group. “A diet low in essential amino acids reduces IGF-I production…suggesting that essential amino acids are necessary to maximize IGF-I production.” (Burke et al, 2008)
The benefits of creatine supplementation come from an increase in “high energy phosphate metabolism and training intensity”. (Burke et al, 2008) The bump in the high energy phosphate metabolism allowed for the increased volume seen in weeks 2 and 7. In conclusion, the study showed that young men and women who participate in a high volume, heavy load resistance program do indeed benefit from creatine supplementation. However, it is important to understand the correct dosages and ensure adequate nutrition and water intake to avoid any of creatine’s possible side effects, such as low blood sugar, high blood pressure and kidney stones.
Creatine. (2014, July 15). . Retrieved July 15, 2014, fromhttp://www.mayoclinic.org/drugs-supplements/creatine/safety/hrb-20059125
Burke, D. G., Candow, D. G., Chilibeck, P. D., MacNeil, L. G., Roy, B. D., Tarnopolsky, M. A., & Ziegenfuss, T. (2008). Effect of Creatine Supplementation and Resistance-Exercise Training on Muscle Insulin-Like Growth Factor in Young Adults. International Journal Of Sport Nutrition & Exercise Metabolism, 18(4), 389-398.
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