Creatine is one of the most well-researched supplements on the market. It has potential benefit for athletic performance, body composition and even cognitive function. It’s no surprise creatine is a hugely popular supplement.

However, like most supplements, the majority of studies supporting its use are carried out only on males. Eagle-eyed readers will notice there are a number of physical and physiological differences between the sexes. So, I thought I would investigate whether creatine was as effective for females, and whether it had other female-specific benefits.

As the great Shania Twain said, let’s go girls.

Creatine 101: Who Is She?

Creatine is a naturally occurring molecule found in the body, most notably in the muscle tissue [1]. We can get creatine through our diet, through meat and fish. Creatine is not found in plants[2]. However, vegans and veggies need not fear, as we can produce small amounts of creatine ourselves in the liver from amino acids[3].

Within skeletal muscle, creatine is joined with phosphate to form phosphocreatine (PCr). This is initiated by an enzyme called creatine kinase. PCr is used to generate adenosine triphosphate (ATP), which creates energy. ATP is used to fuel the mitochondria, which as we hopefully recall from secondary school biology, is the powerhouse of the cell.

The PCr-energy system generates a lot of energy, very quickly[3], and fuels short bursts of high-intensity activity. Think sprinting, high-jumps, or testing your one rep max deadlift.

However, whilst the PCr-energy system certainly generates a lot of energy quickly, it’s also a finite resource. We run out of our creatine reservoir very quickly, and it is slow to replenish. Think about it – you can’t sustain your maximum sprint pace for very long!

So, overall:

• We can get creatine from our diet or produce it ourselves from amino acids
• Creatine is primarily stored in skeletal muscle
• It can be used to generate a lot of energy quickly
• The body uses up creatine supplies quickly and it can be slow to replenish

Not Just Small Men: Differences in Creatine Response in Women

With a baseline understanding of the role of creatine in the body, it’s time to discuss the physiological differences between the sexes that potentially influence the impact of supplementation. It must be noted that most of the information here comes from an insanely detailed review published in Amino Acids [4]. Well worth the read if you’re a massive nerd like me.

Difference #1: Overall Muscle Mass

The average man has significantly more muscle mass than the average woman[5]. As creatine is stored primarily in the muscle, it may suggest that females have smaller creatine storage capacity.

Difference #2: Creatine Production & Excretion Rates

Females produce 70-80% less creatine than their male counterparts. All hope is not lost however, as our rate of excretion is 20% lower than males[6].

Difference #3: Bleeding from Your Internal Organs Once A Month

The menstrual cycle is constantly overlooked and unaccounted for in many aspects of life, and in nutrition studies it’s no different. The majority of studies investigating the effect of creatine supplementation on females fail to consider our delicate lady parts, and this really does put a dampener on the conclusions we can draw.

As girlos, our muscles favour fat to carbohydrate for fuel during exercise [7]. That’s a significant difference in metabolism! Similarly, different stages of the menstrual cycle can inhibit creatine kinase release[8], as can female sex hormones[6]. Shockingly, this is not very well-studied, so for now we have more questions than answers.  

With glaring differences in muscle mass, production rates and sex hormones, it’s almost like you can’t generalise results from all-male studies across the board? Well, I suppose they do say nOt aLL mEn…

Part II will discuss what the literature says about the benefits of creatine, and discuss the considerations for females who want to get on the gain train. Let me know if there’s anything else you want me to touch on!

References

1. Wyss, M., Kaddurah-Daouk, R. (2000) ‘Creatine and creatinine metabolism’, Physiological Reviews, 80(3), pp. 1107-1213.
2. Wu, G. (2020) ‘Important roles of dietary taurine, creatine, carnosine, anserine and 4-hydroxyproline in human nutrition and health’, Amino Acids, 52, pp. 329-360.
3. Guimarāes-Ferreira, L. (2014) ‘Role of the phosphocreatine system on energetic homeostasis in skeletal and cardiac muscles’, Einstein (Sāo Paulo), 12(1), pp. 126-131.
4. Ellery, S.J., Walker, D.W., Dickinson, H. (2016) ‘Creatine for women: a review of the relationship between creatine and the reproductive cycle and female-specific benefits of creatine therapy’, Amino Acids, 48, pp. 1807-1817.
5. Janssen, I., Heymsfield, S.B., Wang, Z.M., Ross, R. (2000) ‘Skeletal muscle mass and distribution in 468 men and women aged 18-88 yr’, Journal of Applied Physiology, 89(1), pp. 81-88.
6. Brosnan, J.T., Brosnan, M.E. (2007) ‘Creatine: endogenous metabolite, dietary, and therapeutic supplement’, Annual Review of Nutrition, 27, pp. 241-261.
7. Mittendorfer, B., Horowitz, J.F., Klein, S. (2002) ‘Effect of gender on lipid kinetics during endurance exercise of moderate intensity in untrained subjects’, American Journal of Applied Physiology and Endocrinology Metbolism, 283(1), pp. 58-65.
8. Oosthuyse, T., Bosch, A.N. (2017) ‘The Effect of Gender and Menstural Phase on Serum Creatine Activity and Muscle Soreness Following Downhill Running’, Antioxidants, 6(1), p. 16.