The Truth About Creatine – Separating Facts From Fiction – Part One
By Lee A. Mancini, MD, CSCS, CSN
Introduction
In the past ten years creatine has become one of the hottest and most popular supplements. With creatine in the news so much, there have also been many misconceptions spread about what it is, what it does, and its side effects.
The History Of Creatine
Many people believe creatine has only been around for a decade or so, but nothing could be further from the truth. Actually, creatine was first discovered in 1832 by the scientist Chevreul. He named it for the Greek word for flesh. This was because creatine is a compound found in animal protein: red meat, chicken, fish, and other sources. Creatine is a tripeptide consisting of arginine, glycine, and methionine. The body requires about 2g/day. Nearly all of the 2g/day is supplied from a well-balanced diet; the rest the body makes in the liver, pancreas, and kidney.1 Creatine is found in all of the body’s tissues from the liver, the heart, the kidneys, the testes, and the brain as well. However, over 95% of creatine is found in skeletal muscle. One third of creatine is found as a free form compound; the rest is bound to a phosphate group.
Actions
Creatine is involved in ATP synthesis. If you can remember back to high school biology, ATP is the body’s source of instant energy. In cells, creatine phosphate combines with ADP and is converted into ATP and creatine by the enzyme creatine kinase. Ingested creatine levels peak in the body 60 to 90 minutes after oral intake. By increasing the levels of creatine, this leads to greater resynthesis of creatine phosphate by 12-18%. Creatine phosphate is the body’s primary immediate source of ATP. During intense anaerobic exercise, ATP is consumed in the first ten seconds.2 The more ATP available, the more strength and power a muscle can produce, and the longer an athlete can maintain higher maximum power output. Creatine also serves to buffer the muscle pH by using a hydrogen ion to resynthesize ATP. This delays muscle fatigue and shifts an individual’s lactate threshold.3 Creatine also increase whole body nitrogen retention, increases water retention at the cellular level, and increases myofibrillar protein synthesis. What this means is that ingesting creatine increases skeletal muscle size.
Proven Performance Effects – Strength Gains
Creatine is one of the most recently studied supplements with over 96 scientific studies having been done. Also most of the research, 93% of the studies, has been done in the past ten years. Most creatine studies use a dose which consists of a loading period of four to seven days of 20g per day, followed by a maintenance dose of 5g per day for the rest of the study length.4 Chronic resistance training has been shown to produce gains in lean body mass of zero to one kg per month. One week supplementing with creatine can produce one to two kg of lean body mass in studies.5,6,7 One study compared taking a carbohydrate supplement, a combination of carbohydrates and protein, and creatine, showed that the creatine group gained 1.1 to 2.3kg more lean body mass than the other groups. There was also a significantly greater increase in strength as well. The take home point here is that we know that weight training alone produces gains in strength and lean body mass; but when one supplements with creatine one gains an additional two to five pounds of muscle.
Combining creatine with protein supplementation was shown to lead to a greater increase in lean muscle mass when compared to a placebo as well as creatine alone.8 Combining creatine with protein supplementation led to a 10% increase in muscle mass and strength gains when compared to protein alone. The strength and lean body mass effects lasted even four weeks after creatine use was discontinued.9 In looking at a meta-analysis of creatine supplementation studies, there is proof that creatine supplementation does increase lean muscle mass by 0.36% per week over placebo or about a 2.2 kg increase in lean body mass over a six to eight week period.
It has been well documented in the literature that creatine does increase maximal strength. Meta-analysis of creatine studies showed a 1.09% per week increase in subject strength over placebo.10 Eight studies examined the effect on creatine of 1-3RM bench press strength and found an average increase of 6.85kg or 15.07 lbs over the placebo groups. Four studies looking at 1RM arm flexor strength showed a 29.9% increase in strength with creatine ingestion compared to a 16.5% increase for the placebo group. Six studies detailed an average increase of 9.76kg or 21.47 lbs in back squat 1RM.4 A study by the United States Army consisted of four separate tests: a mood profile questionnaire, a marksmanship test, three obstacle course runs, and five sets of failure at 70% of a subject’s 1RM on the bench press. The creatine group had an increase in 1.4kg lean body mass and a decrease in body fat of 0.5% over the placebo group. In terms of athletic performance, the creatine group performed 14% more total reps on the bench press test but did not have any statistical significance in performance on the obstacle course, in marksmanship, or in mood.11 While the evidence supports the fact that creatine supplementation does improve strength, there have been some studies that have not found this to be the case. One ten-week study of college football players found no difference in 1RM squat, anaerobic muscle endurance, body fat loss, or lean body mass between placebo and two different methods of creatine dosing.12
That’s enough information for now, next time we will discuss the effect of creatine on anaerobic and aerobic endurance.
Send any questions or ideas for topics of future interest to questions@DoctorOfFitness.com.
Note: Lee A. Mancini graduated from Harvard as a two-sport athlete with honors in biology. Board certified in sports medicine and family practice, he works at the Family Health Center and UMass Sports Medicine Center in Worcester . He trains select clients as a certified strength and conditioning specialist and sports nutritionist. If you are interested in hiring him to design an individualized program, click here for our paid consultation services.
References
1. Koch, J.J. (2002). Performance-enhancing substances and their use among adolescent athletes. Pediatrics in Review, 23, pp. 310-317.
2. Juhn, M.S. (2003). Popular sports supplements and ergogenic aids. Sports Medicine, 33(12), pp. 921-939.
3. Chwalbinska-Moneta, J. (2003, June). Effect of creatine supplementation on aerobic performance and anaerobic capacity in elite rowers in the course of endurance training. International Journal of Sport Nutrition & Exercise Metabolism, 13 (2), pp. 173-184.
4. Dempsey, R.L., Mazzone, M.F., & Meurer, L.N. (2002, November). Does oral creatine supplementation improve strength? A meta-analysis. The Journal of Family Practice, 51(11), pp. 945-951.
5. Kreider, R.B. (1999, February). Dietary supplements and the promotion of muscle growth with resistance exercise. Sports Medicine, 27(2), pp. 97-111.
6. Schwenk, T.L., & Costley, C.D. (2002). When food becomes a drug: Nonanabolic nutritional supplement use in athletes. The American Journal of Sports Medicine, 30, pp. 907-916.
7. Branch, J.D. (2003, June). Effect of creatine supplementation on body composition and performance: A meta-analysis. International Journal of Sport Nutrition & Exercise Metabolism, 13(2), pp. 198-207.
8. Green, A.L., Hultman, E., Macdonald, I.A. (1996). Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in humans. American Journal of Physiology, 271(5), pp. E821-E826.
9. Lemon, P.K. (2000). Beyond the zone: Protein needs of active individuals. Journal of the American College of Nutrition, 19(5), pp. 513S-521S.
10. Nissen, S.L., & Sharp, R.L. (2003, February). Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. Journal of Applied Physiology, 94(2), pp. 651-659.
11. Warber, J.P., Tharion, W.J., Patton, J.F., Champagne, C.M., Mitotti, P., & Lieberman, H.R. (2002). The effect of creatine monohydrate supplementation on obstacle course and multiple bench press performance. Journal of Strength and Conditioning Research, 16(4), pp. 500-508.
12. Wilder, N., Gilders, R., Hagerman, F., & Deivert, R.G. (2002). The effects of a 10-week, periodized, off-season resistance-training program and creatine supplementation among collegiate football players. Journal of Strength and Conditioning Research, 16(3), pp. 343-352.
|
