Healthnotes Newswire — Two studies from July’s issue of Medicine and Science in Sports and Exercise have examined the evidence behind creatine, a nutritional supplement commonly used by athletes as a performance-enhancing agent.

In the first of these two studies, seven days of supplementation with approximately 25 grams of creatine per day (the so-called “loading dose”) led to a modest, but statistically significant, increase in body weight and improvement of sprint times.¹ These results are similar in magnitude to those found in other studies of creatine use.^{2 3}

The second study provided insight into one of the ways creatine works.⁴ Biopsies revealed that athletes taking creatine for five days were able to store more energy (in the form of a complex chain of sugar molecules called glycogen) in their muscles than those who were not taking creatine. While that effect would not explain an improvement in sprint times (short-term “bursts” of muscular activity do not depend on glycogen), studies have shown that athletes who store more glycogen in their muscles perform better in endurance sports.⁵

Perhaps most important in these new studies was what researchers didn’t find: side effects. Although previous studies have also not found significant adverse effects at commonly used levels of intake, some authors have cautioned that more study of the short- and long-term effects of creatine is necessary before a conclusion about its safety can be drawn.⁶

Since reports appeared in 1998 that baseball players Mark McGwire and Sammy Sosa were taking creatine, it has become a widely used nutritional supplement. Creatine use has also become controversial, particularly since the reports of the deaths of three young wrestlers, allegedly from the combination of taking excessive amounts of the supplement and rapidly losing weight.

The results of these new studies, and those preceding them, imply that the performance-enhancing activity of creatine is minimal, and probably not noticeable to anyone other than competitive athletes. These studies also give additional support for the apparent safety of creatine when used over the short-term, in commonly used amounts.