As far as I know, it doesn’t do anything to it. It does negatively affect creatine absorbtion.
According to whom?[/quote]
Back in 1996, researchers from Katholieke Universiteit Leuven in Belgium showed that caffeine interferes with some of the performance-enhancing effects of creatine .
They supplemented a group of nine healthy male volunteers for six days with creatine, creatine and caffeine, or a placebo. Creatine increased muscular performance by 10-23%.
However, when creatine was combined with caffeine, the caffeine appeared to “block” the performance-enhancing effects of creatine. Creatine and caffeine taken together both raised creatine levels in the muscle to the same extent as creatine alone. But it was only the latter treatment that improved performance.
In a later study, the same research group thinks they’ve found out why it happens . A group of ten men took part in five different trials. Each trial was separated by five weeks.
? Four days of creatine loading at 20 grams per day.
? Three days of caffeine intake at 5 milligrams per kilogram (2.2 pounds) of bodyweight.
? Creatine loading plus caffeine intake (a combination of the first two treatments).
? A single dose of 5 milligrams of caffeine per kilogram (2.2 pounds) of bodyweight before exercise.
Before and after each treatment, the researchers measured the contraction and relaxation time of the quadriceps (the muscles on the front of your thigh) during electrically stimulated muscle contractions.
Why is relaxation time important? The quicker a muscle can relax, the quicker it can contract again. This might offer a benefit during certain types of sport, especially those involving sprinting.
Five days of creatine loading shortened relaxation time. Three days of caffeine intake, on the other hand, with or without creatine, increased relaxation times by approximately 10%. But a single dose of caffeine had little impact on relaxation time compared to the placebo.
But this doesn’t mean that creatine and caffeine should never be used together. It’s important to remember that both studies used very large doses of caffeine (five milligrams of caffeine per kilogram of bodyweight).
For someone weighing 180 pounds (around 82 kilograms), that’s more than 400 milligrams of caffeine. To put this figure in context, one cup of coffee contains 65-115 milligrams of caffeine. Soft drinks contain 10?50 milligrams of caffeine per 12-ounce serving.
What’s more, previous research has used creatine dissolved in warm caffeinated drinks, such as coffee or tea. In other words, only high doses of caffeine have been shown to interfere with the performance-enhancing effects of creatine. A cup of coffee or tea won’t have the same negative impact.
- Graham, T.E., Hibbert, E., & Sathasivam, P. (1998). Metabolic and exercise endurance effects of coffee and caffeine ingestion. Journal of Applied Physiology, 85, 883-889
- Harris, R.C, Soderlund, K., & Hultman, E. (1992). Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clinical Science, 83, 367-374
- Hespel, P., Op’t Eijnde, B., & Van Leemputte, M. (2002). Opposite actions of caffeine and creatine on muscle relaxation time in humans. Journal of Applied Physiology, 92, 513-518
- Preen, D., Dawson, B., Goodman, C., Lawrence, S., Beilby, J., & Ching, S. (2002). Pre-exercise oral creatine ingestion does not improve prolonged intermittent sprint exercise in humans. Journal of Sports Medicine and Physical Fitness, 42, 320-329
- Robinson, T.M., Sewell, D.A., Hultman, E., & Greenhaff, P.L. (1999). Role of submaximal exercise in promoting creatine and glycogen accumulation in human skeletal muscle. Journal of Applied Physiology, 87, 598-604
- Vandebuerie, F., Vanden Eynde, B., Vandenberghe, K., & Hespel, P. (1998). Effect of creatine loading on endurance capacity and sprint power in cyclists. International Journal of Sports Medicine, 19, 490-495
- Vandenberghe, K., N. Gillis, M. Van Leemputte, P. Van Hecke, F. Vanstapel, and P. Hespel. (1996). Caffeine counteracts the ergogenic action of muscle creatine loading. Journal of Applied Physiology, 80, 452-457