The Truth About Creatine – Separating Facts From Fiction – Part Two
By Lee A. Mancini, MD, CSCS, CSN
Recap
In part one, we took a closer look at one of the hottest supplements on the market, creatine. Creatine is also one of the most studied and researched supplements as well. In this issue we will examine creatine’s effects on anaerobic, its effects on aerobic endurance, and its side effects.
Proven Performance Effects – Anaerobic Sprints
Creatine also has an ergogenic effect on high intensity, repeated sprints. In looking at 61 studies of creatine supplementation on running, swimming, or rowing sprints lasting less than thirty seconds, 45 were found to show statistically significant evidence of creatine improving athletic performance. 7 Thirty cyclists performed eight 15 second sprints with rests of 1 minute, 3 minutes, or 6 minutes in between each sprint. The test group consumed 0.3g/kg bodyweight per day. The cyclists receiving creatine showed greater mean power in the one minute and 3 minute rest groups and greater peak power in the one minute rest group when compared to the other test and placebo groups. Creatine supplementation seems to aid in recovery of creatine phosphate stores in recovery periods less than six minutes but has no added benefit in periods of six or more minutes. 13
Supplementing with creatine in swimmers at 9g/day for five days was not shown to increase a single 50M freestyle sprint but did show a significant improvement on performing eight 50M sprints in succession with minimal rest in between. A study of 25M, 50M, and 100M single sprints showed six days of creatine supplementation at 20g/day did not significantly improve sprint times when compared to placebo. 14 Single bouts of high intensity cycling and swimming have shown no benefit from less than one week of creatine supplementation, but high intensity repeated efforts have shown improved performance with creatine vs. placebo. One study showed subjects given 9g/day of creatine for nine days had faster single 100M freestyle sprint times, faster 3 x 100M repeated effort sprint times, and greater work and power output on 3 x 20 second ergometer sprint times. 15 In nine studies looking at short sprints from six to 30 seconds in length, there is an average improvement of 1% over placebo with creatine supplementation. In a sprint that may last only 25 seconds, a decrease in time of 1% means 0.25 seconds, and at the world class level this is a huge difference since medals can be won or lost in 0.01 seconds. 4
Proven Performance Effects – Aerobic Sprints
What about creatine’s effect on longer anaerobic and aerobic endurance events? There have been 25 studies examining the effect on prolonged anaerobic endurance events ranging from 30 seconds to 3 minutes in length. Eight studies found no improvement in performance with creatine supplementation, while 17 did. Sixteen male elite rowers were tested in two areas. The first protocol had them row at 50Watts for 3 minutes, with an increase in power every 3 minutes by 50W until exhaustion. The second test was for maximum length of time they were able to row at 7 Watts/kg bodyweight. All subjects were tested without supplements and then were divided into placebo and creatine groups. The creatine group increased maximum power from 314 to 336 watts, while the placebo group went from 305 to 309. The creatine group also increased the time they could row at 7W/kg bodyweight by 12.1 seconds compared to only 2.4 seconds for the placebo group. 3 Improved times in 5M and 15M sprints were seen with creatine ingestion, but in longer runs of 6K creatine supplementation actually made the subjects run 26 seconds slower. 2 For longer distance endurance events the extra lean body mass from muscle and water retention may slow runners and swimmers down. 4 In examining the evidence it seems that the extra bodyweight that creatine adds in the form of lean body mass, slows down endurance athlete’s times.
Adverse Effects
The major reported side effect of creatine vs. placebo has been an upset gastrointestinal system. Other studies have shown no difference between the side effects in the creatine and placebo groups. There have been case reports of increased muscle cramping, believed to be because of creatine’s ability to bring water into the cell. Because creatinine is a major breakdown product of creatine, there has been concern about how creatine ingestion may affect renal function. It has been shown that increased consumption of creatine does lead to an increase in serum creatinine levels. One study examining creatine supplementation over a four year period found no adverse reactions, no change in cholesterol levels, no change in LFTs, no change in hGH levels, no change in cortisol levels, and no change in testosterone levels. 16 Another study of NCAA football players having taken creatine for three years showed no effect on kidney or liver function. Players had normal LFTs, normal creatinine, normal BUN, normal creatinine clearance, and normal urea levels after consuming creatine for three years. In another study there were no reported side effects as well. 17 Other restrospective studies have also found no significant adverse effects up to five years after ingesting creatine. 4 However, there have been no studies of the effect of creatine longer than five years.
Summary
Creatine is one of the mostly widely used supplements by athletes today. A survey revealed that over 30% of American professional sports teams in the NFL, MLB, NBA, and NHL actually supply creatine to their athletes. Close to 50% of NCAA Division I male athletes have used creatine. Nearly 10% of high school athletes have used creatine in the past, and 4.1% are currently using it. About three quarters of the high school athletes who have used creatine were informed about it from their friends, not their coaches, parents, or physicians. 18 This highlights the importance of the medical field and in particular the team sports doctor being informed of the most recent sports supplements. The body of evidence behind creatine shows that it does increase lean muscle mass, increase maximum strength, increase short high intensity anaerobic endurance but lacks evidence to support longer aerobic endurance. So it is an ergogenic aid with specifc benefits. Besides reports of increased muscles cramping and gastrointestinal issues, creatine has no side effects. Studies have shown that it has no harmful effect on kidney function, but users should be cautioned that no study longer than five years has been done. Finally, creatine is legal and is not banned by the IOC, the NCAA, or the major professional sports.
This is a selection from his new book The Doctor Of Fitness Guide To Supplements: For Athletes, Coaches, Parents, and Physicians. To order the book click here.
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
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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.
13. Cottrell, G.T., Coast, J.R., & Herb, R.A. (2002). Effect of recovery interval on multiple-bout sprint cycling performance after acute creatine supplementation. Journal of Strength and Conditioning Research, 16(1), pp. 109-116.
14. Dawson , B., Vladich, T., & Blanksby, B.A. (2002). Effects of 4 weeks of creatine supplementation in junior swimmers on freestyle sprint and swim bench performance. Journal of Strength and Conditioning Research, 16(4), pp. 485-490.
15. Grindstaff, P.D., Kreider, R., Bishop, R., Wilson , M., Wood, L., Alexander, C., & Almada, A. (1997). Effects of creatine supplementation on repetitive sprint performance and body composition in competitive swimmers. International Journal of Sports Nutrition, 7, pp. 330-346.
16. Crowe, M.J., O’Connor, D.M., & Lukins, J.E. (2003, June). The effects of ß-hydroxy-ß-methylbutryrate (HMB) and HMB/creatine supplementation on indices of health in highly trained athletes. International Journal of Sport Nutrition & Exercise Metabolism, 13(2), pp. 184-198.
17. Mayhew, D.L., Mayhew, J.L., & Ware, J.S. (2002, December). Effects of long-term creatine supplementation on liver and kidney functions in American college football players. International Journal of Sport Nutrition & Exercise Metabolism, 12(4), pp. 453-451.
18. Smith, J. MD, & Dahm, D.L. MD. (2000, December). Creatine use among a select population of high school athletes. Mayo Clinic Proceedings, 75(12), pp. 1257-1263.
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