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Effects Of Creatine Ingestion On Muscle Thickness.

This particular study measured the effects of creatine ingestion on muscle thickness in males and females.

Creatine monohydrate is probably the most popular supplement to date. In fact, sales of this supplement alone have topped $400 million. It's no surprise - creatine works!

I have talked about creatine in this column several times, but each month I receive my scientific journals, there is yet another study about this supplement trying to determine different outcomes from taking the supplement than have already been discovered.

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This particular study measured the effects of creatine ingestion on muscle thickness in males and females.

Effect Of Creatine Ingestion After Eexercise On Muscle Thickness In Males & Females
MSSE, 36(10), 1781-1788, 2004

Creatine monohydrate is effective at inducing hypertrophy in about 75% of users. Some research suggests that its effects come from enhancing protein synthesis, while other suggest it enhances hypertrophy by drawing water into cells, thereby providing additional size to muscles.

Creatine more than likely indirectly enhances protein synthesis because if it allows you to move more weight in the weight room, you'll subsequently increase protein synthesis thereby facilitating muscle growth.

Although creatine is absorbed rather easily into the system, there are a number of ways to enhance creatine absorption even faster. Most folks mix their creatine with simple carbohydrates and sometimes protein; both enhance insulin release which will in turn enhance the uptake.

Similarly, folks whose muscles are already saturated will absorb very little, while folks who do not have a tremendous amount of creatine stored will absorb much more. The same goes for many other nutrients too; if your body needs them, it will be more efficient at absorbing them; however, on the contrary, if you have sufficient doses, more of the nutrients will be excreted.

The primary purpose of this particular study was to determine whether greater increases in muscle thickness could be achieved by ingesting creatine, compared with placebo, immediately after exercise of muscle groups after a period of 6-weeks of training. Second, was to determine if males and females differ in their response since few studies have considered the female response to creatine.

Twenty-one subjects (11 men and 10 women) participated in this study. Subjects were randomized to either creatine or placebo groups (creatine groups received 0.2 g/kg creatine/day). Some of the requirements for subjects participation were that none supplemented with creatine in the past month, none were vegetarians (remember that meat and fish are the best sources of creatine, so it's assumed that vegetarians would respond better to supplemental creatine since they do not have a high dietary intake).

Subjects then trained each side of their body on different days. They first trained the one side of their body two days of the week and then the other side of their body on another two. The subjects then received creatine after exercising only one side of their body, so the comparison could be made from one side to the next.

Muscle thickness was measured before and after the study for all limbs. Percent change in arm thickness for the creatine group was greater than the placebo group, but this was not statistically significant (statistics are used because if it is not statistically significant, it is more likely due to "chance" that the differences are apparent).

It was in this particular study, the results approached significance, but were not statistically significant - means the values were very close to significant. Therefore, it's up to the researchers and readers to determine if these values were clinically significant even though they were not statistically significant. Basically, are the changes valuable even though statistics do not show them to be significant?

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The second important finding of this study was that creatine supplementation during resistance training increased lean tissue mass in males but not females. Typically studies over 5-weeks are long enough to show a response; however, maybe the 6-weeks wasn't long enough.

So what have we learned from this study? Well, first of all some of you may be wondering what the necessity of doing a study on one side of the body. Think about its utility in folks who may have broken or injured a limb on one side. Creatine may be useful during the healing process to bring the limb(s) up to speed with the "normal" side.

Unfortunately the results didn't show that there was/is a statistically significant differenc between the creatine or placebo groups. Moreover, there was no significant increase in lean body mass in the females. Of course there are physiological differences between males and females, so it appears that these differences are affecting the way creatine is utilized and metabolized in the body.

There may have been a different outcome in untrained individuals, as some studies have shown this population responds very well to creatine. Then again, they also respond very well to training in general, so I don't recommend creatine to newbies who are just learning about resistance training.

What Have We Learned From This Study & What Can We Take Away To Enhance Our Knowledge?

  • In this small study, creatine does not appear to affect the muscle thickness of muscles. Again, however, this study may have been too short to notice any measurable differences. Moreover, there were very few subjects, making it more difficult to detect any differences.

  • Creatine did not increase lean body mass in females like it did in males. Previous work has shown creatine can enhance muscle mass in females, so the exact reason for the lack of change is not apparent. Again, this was a short study, with few subjects; both could have contributed to the lack of response.


Before considering creatine or any other dietary supplements, it is most important to get your diet and training in order. Diet and training first - supplements second.

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