High doses of creatine have adverse effects
The Irish Times
Health Supplement, p. 13
13 May 2008
DOES IT WORK? Creatine is an essential component of the energy system – but athletes should be wary of its effects, writes Dónal O’Mathúna.
WITH THE OLYMPIC Games just around the corner, performance- enhancing drugs will most likely be in the news again. While steroids, blood doping and many other drugs are banned, creatine is not. This has made it one of the most popular dietary supplements used to improve sports performance. Creatine is also widely advertised for recreational athletes and for older people seeking to maintain muscle mass and strength. Yet the American College of Sports Medicine recommends that no one under 18 use creatine supplements. This position has been endorsed recently by Dr Pat Duggan, chairman of the GAA’s Medical, Scientific and Welfare Committee. The extent of creatine’s use in Ireland is uncertain, although the Irish Sports Council is currently investigating the area.
The importance of creatine for exercise has been known for over 100 years. On average, everyone needs about 2g daily, which we obtain both in our diet (from meat, milk or fish) and by making it within our bodies. This is why creatine would be very difficult to ban from competition. Creatine is an essential component of the energy system that fuels short, intense exercise like sprinting or weight-lifting. About 10 seconds of intense exercise uses up the creatine-linked energy stores, and it takes a couple of minutes of rest to replenish them.
Creatine’s use as a performance-enhancing supplement came to public attention in the 1990s. Since then, over 100 studies have examined it in a variety of controlled training sessions, but not in competition. For high-intensity, short-duration, repetitive training, average improvements of around 10 per cent were seen in those taking creatine, compared with a placebo. Such “interval” training could involve sprinting for five to 10 seconds, resting briefly, and sprinting again. Some weight-training is done this way also.
When the exercise lasted 30-90 seconds, much less benefit was found. Exercise longer than 90 seconds showed no improvements with creatine. Also, the beneficial effects were more pronounced for upper-body training compared to lower-body or overall exercise. While it appears that people can train harder when taking creatine, very few studies have examined its impact on actual sports performance or competition.
Those taking creatine may be able to train harder, but it also causes weight gain, typically 1-3kg. This is primarily due to water retention in the muscles. Muscle cramping is also reported to occur more frequently, though this has not been studied widely. Stomach cramps and feeling bloated are also reported.
More serious concerns have been expressed about creatine’s impact on the kidneys. This arises partly because of the large doses recommended. Clear guidelines on the best dose don’t exist, but many athletes start with a “loading dose” of 15-20g daily for five days, followed by 2-5g daily.
Anyone at risk of kidney problems could have difficulties with these doses. The International Olympic Committee has also warned that some creatine products have been contaminated with banned drugs which would lead to an athlete being disqualified.
Use of creatine supplements has been shown to help highly trained athletes perform better in one specific type of training: doing repeat sessions of all-out exertion lasting less than 30 seconds with a few minutes recovery.
Such benefits are in keeping with what is known about how muscles use creatine to fuel high-intensity, short-lasting exercise. Questions remain as to whether those improvements lead to better performances in competition.
Those who are training less intensely, or doing longer endurance events are unlikely to benefit from creatine. In addition, people vary widely in how they respond to creatine supplements, with some having no benefit. Given the side effects that can occur with creatine supplements, competitive athletes should first ensure they consume adequate creatine-rich foods.
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