November 5, 2001
1- Featured Article:
Does creatine benefit women?
This Month’s Featured Article:
Does creatine benefit women?
The short answer is “yes”. The long answer is also “yes, but differently from men”. Creatine supplementation has two well-documented effects. The first is that creatine increases our muscle energy reserves, allowing us to train harder. The second is that creatine induces muscle swelling through increased water retention, increasing our body mass and size. Interestingly, this second effect, also known as muscle volumizing, might cause our muscles to actually amass proteins. Unfortunately, since most creatine studies have focussed on males (18 and 35 years of age), it wasn’t clear whether creatine benefits females in the same way.
In this issue of the Creatine Newsletter we discuss two recent studies that asked the question “does creatine also benefit women?”
Study #1: Peter Hespel, Belgium
In 1997 Peter Hespel’s group in Belgium showed that creatine supplementation enhances muscle energetics in females. This effect was similar to the previously demonstrated effect in males that depends on an increase in muscle phosphocreatine levels.
The sample group consisted of 19 healthy, but sedentary females. Their ages ranged from 19-22 years. Half of them took creatine tablets, while the other half took maltodextrine tablets. The creatine group commenced supplementation with a loading phase of 20 grams of creatine per day for five days, followed by a maintenance phase of 5 grams of creatine per day for a period of 10 weeks. This was a relatively long-term study.
Strength increased by ~20% and fat-free mass increased by ~60% in the creatine group. These values were similar in magnitude to those previously described in male subjects. In addition, this study found that creatine supplementation maintained strength for an additional 10 weeks after training had stopped.
Creatine increases fat free mass and repetitive exercise performance in women. Creatine also appears to enhance exercise performance when not accompanied by training.
Study #2: Mark Tarnopolsky, Canada (Hot Off the Press!).
This September Mark Tarnopolsky’s group in Toronto published a study comparing the turnover rates of proteins in males and females in response to creatine supplementation. Motivated by the finding that fat-free mass increases following creatine use, these authors sought to determine if this effect is solely due to increased muscle hydration or whether increases in muscle protein content also contribute. They were also interested in determining whether creatine supplementation benefits males and females to the same extent.
The sample consisted of 13 males and 14 female subjects. On average they were 23 years of age. They were asked to abstain from taking any other supplements during the study period. The design was similar to the previous study. Half of the subjects (males and females) were given placebo; the other half were loaded with 20 grams of creatine monohydrate powder a day for 5 days, followed by a maintenance dose of 5 grams of creatine for a period of 3-4 days. This was a short-term study.
This study found that while the rate of new protein production did not change in response to creatine use, the rate of protein degradation decreased. It thus appeared that creatine suppressed protein degradation. In scientific jargon this would be known as an “anti-catabolic” (anti-breakdown) effect and would eventually lead to greater protein levels in supplementing individuals. This effect would also contribute to the increase in fat-free mass commonly observed with creatine use. Unfortunately, while this protein-sparing effect was apparent in males, it was virtually absent in females. The reason for this gender disparity is currently unresolved.
Interestingly, muscle creatine (and phosphocreatine) levels increased to the same extent in both males and females, explaining why fat-free mass also increases in both sexes. Remember that water follows creatine into skeletal muscle resulting in muscle volumizing and consequently in an increase in fat-free mass. In other words, the relative proportion of fat to total muscle mass, including water, decreases with creatine use. This increase in fat-free mass, however, is typically less pronounced in women, which also makes sense since the protein sparing effect of creatine is virtually absent in women.
This study concluded that creatine supplementation spares proteins from being degraded. Furthermore, the authors hypothesized that this was an effect downstream of muscle volumizing and is supported by experiments showing that infusing males (through their veins) with dilute saline (to induce cell swelling) exhibited similar protein sparing effects. In other words, cell swelling alone also spares proteins from being degraded. Therefore, this effect has little to do with creatine per se.
Creatine enhances exercise output and lean muscle mass in both males and females. Furthermore, creatine may also spare the breakdown of proteins as a result of strenuous exercise. This effect appears to be more pronounced in males than in females. The reason for this disparity is still an open issue, but may involve the different hormone environments typical of males and females.
Vandenberghe K., Goris M., Van Hecke P., Van Leemputte M., Vangerven L., Hespel P. (December 1997) Long-term creatine intake is beneficial to muscle performance during resistance-training. Journal of Applied Physiology Volume 83:6: pages 2055-2063.
Parise G., Mihic S., MacLennan D., Yarasheski K.E., Tarnopolsky M.A. (September 2001). Effects of acute creatine monohydrate supplementation on leucine kinetics and mixed-muscle protein synthesis. Journal of Applied Physiology Volume 91:3: pages 1041-1047.
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