Creatine is a substance made from amino acids in the body, but can also be taken as a supplement in powder, capsule or serum form. Its physiological role is to supply phosphate to muscles working anaerobically, a process that cannot persist for long before muscle failure occurs; it therefore participates in short, intense bursts of exercise such as weightlifting, jumping and sprinting.
Restoring ATP
The body's main source of fuel in anaerobic or "all-out" exercise is adenosine triphosphate, or ATP. In supplying energy for mechanical work, ATP gives up a phosphate group to become ADP. Creatine, in its phosphorylated form, gives up its own phosphate to ADP to regenerate ATP and keep the cycle alive. In this way, creatine supplementation allows intermittent all-out work to continue for somewhat longer than the usual 10 or so seconds.
All-Out Treadmill Running
A study by Bosco et al. at the University of Rome showed that supplementation using 20 g of creatine daily for five days resulted in statistically significant improvement in time for treadmill running exhaustion in trained subjects. Runners maintaining a speed of 20 km/hr -- about 4 minutes 50 seconds per mile -- up a fixed five percent grade grade stayed on the treadmill an average of 13% longer than before supplementation. The duration of this exercise was about 60 seconds, or 35% longer than it takes the fastest runners in the world to run a quarter mile on the track.
Water Retention
Runners and others taking creatine serum or creatine in any form are likely to retain water to some extent, an effect many users mistakenly attribute to increased muscle mass. This is believed to result from a tendency of water to flow into body cells owing to their increased creatine content, as creatine is an osmotically active substance and therefore "sucks" fluids from areas of low creatine concentration to areas of higher creatine concentration. This may provoke muscle cramps, dehydration and heat intolerance in people who supplement using creatine syrup.
Endurance exercise
Since performance in the longer running events is not dependent to any appreciable extent on anaerobic metabolism, an increase in the performances of endurance athletes using creatine syrup would not be expected. In fact, this is what researchers have found. Scientists at California State University, San Marcos tested 24 runners who ingested either creatine syrup or a placebo before a treadmill test and an outdoor 5,000-meter time trial performed one after the other. Those in the creatine serum group did not, contrary to the claims of the serum's manufacturer, demonstrate any ergogenic benefit in this form of exercise.
References
- "Journal of Strength and Conditioning Research"; Is running performance enhanced with creatine serum ingestion?; T.A. Astorino et al.; November 2005
- Rice University: Creatine Supplementation in Athletes: Review by Mark Jenkins
- Quackwatch.com: Creatine Supplementation
- "International Journal of Sports Medicine"; Effect of oral creatine supplementation on jumping and running performance; C. Bosco et al.; July 1997
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