Creatine works for those who are responders. Research has also shown that creatine is safe if there are no pre-existing health issues (kidney disorders, liver problems, etc). Regardless of the positive data on this supplement; the most well-researched supplement to date (with over published 500 studies), there are still those who have their concerns.
One of the major concerns typically heard from some health professionals and the like is that creatine causes cramping, primarily from dehydration. This was a legitimate concern with creatine use, because while it's not precisely known what the exact mechanism is for how creatine exerts its effects, one suggested mechanism is via water retention in the cells, which may ultimately result in protein synthesis.
This additional water retention in the cells causes concern for the potential connection to dehydration.
A few studies have demonstrated that this is not the case, but it is never enough for many critics. I do understand the need to critic science and particularly dietary supplements; there are more "snake oil" type products out there than legit ones and more charlatans to promote them than scientists.
With that said, let's take a look at one study which considered the effect of creatine supplementation on various physiological parameters related to heat stress.
The Effects of Creatine Supplementation on Cardiovascular, Metabolic, and Thermoregulatory Responses During Exercise in the Heat in Endurance—Trained Humans
International Journal of Sport Nutrition and Exercise Metabolism, 2004, 14, 443-460.
Twenty-one endurance trained male subjects volunteered for this study. No subjects were accustomed to training in the heat (which obviously allows the body to deal with this stressor) and none had taken creatine within the previous 8 weeks (it takes approximately 30 days after creatine supplementation for the body to return to baseline levels, so this 8 weeks ensured these athletes were at baseline levels).
The subjects were familiarized with the experimental protocol prior to any testing; this was to determine the intensity and work rate necessary to elicit fatigue in a 40-60 minute window that would be utilized in the study. This was a double-blind, randomized trial, in which subjects were split into either a placebo or creatine group.
The Creatine Group
The creatine group received a "typical" loading protocol where they consumed 5 g or creatine 4 times/day and 35 grams of a carbohydrate solution for 7 days.
The Placebo Group
The placebo group received 40 grams carbohydrate 4 times/day (160 grams total) for 7 days.
All subjects then underwent the same measurements:
- Body fat testing using what's called a bioimpedance analyzer (allows bodyfat and extra-cellular water to be assessed)
- Body Temperature
- Heart Rate
- Skin temperature
- First of all, time to exhaustion did increase significantly in the creatine group, but the body mass increased significantly following creatine supplementation. Again, not surprising as this is common among creatine responders.
- There were no significant differences in any of the cardiovascular measures before of after supplementation.
- There was a significantly different change in temperature in the creatine vs. the placebo group.
- There was a significant reduction in the sweat rate of the creatine group vs. the placebo group.
- Plasma volume did fall during exercise, as is expected, but there was no difference between groups.
Basically, the moral of the story is that creatine did not negatively effect hydration as many think. In fact, creatine induced hyperhydration thereby resulting in a more efficient thermoregulatory response.