Caffeine and Performance in Women

Caffeine is one of the most consumed psychoactive elements worldwide¹, to the point that it is estimated that around two billion cups of coffee are drunk every day in the world². Such a high consumption can be due to numerous reasons: the taste of a good coffee, the feeling of alertness it produces, the health benefits that have been described when consuming it... But we are not going to deny it, many athletes also consume caffeine in large part for its ergogenic effects, that is, to improve performance. Caffeine is also one of the few nutritional supplements that has the most evidence regarding its benefits for performance, as we have talked about on previous occasions (you can read more here).

 Caffeine and Performance: What We Already Know

The evidence regarding the benefits of caffeine on performance is clear, to the point that a highly reputable international association such as the International Society of Sports Nutrition (ISSN) has taken a position on the matter, supporting the use of this substance³. In fact, caffeine has been shown to be effective in both endurance and strength sports. For example, a meta-analysis published in the prestigious journal Sports Medicine that included 46 studies, found that caffeine consumption (3 – 6 mg/kg) leads to an increase in power of around 3%⁴ during endurance tests. Doesn't that seem like much? Well, it is much more than we can achieve even with weeks of training. Similarly, another recently published meta-analysis found that caffeine improves performance in both strength actions (such as weight lifting) and actions that require high levels of power (such as performing a jump)⁵.

As we can see, caffeine has been shown to be effective in improving performance in practically any type of sport. In addition, as we commented on this website, caffeine appears to be effective in nearly everyone; even in people who are very used to taking it or in people whose genetics could indicate that they are little or 'non-responders' to caffeine. However, in this field of research we still find many unanswered questions, and one of them concerns a segment of the population that is largely forgotten both in the world of sport and research: women.

 Caffeine and performance in women, how does it affect them?

Although fortunately women are increasingly present in high-performance sport, women have traditionally been underrepresented in sports-science research. And this is also evident in studies related to caffeine. For example, a recent review on the effect of caffeine on performance found that of the more than 5.000 participants included in the 362 studies analyzed, only 13% were women⁶. This finding is hugely relevant, as we are drawing conclusions regarding the effects of caffeine on performance based on studies that have been conducted almost entirely on men, but not on women, and the results could be very different due to physiological differences between the sexes. But is caffeine also effective in women? Is it as effective as in men?

Few studies have looked at the differences between men and women regarding the effects of caffeine, although there are some. Specifically, a recent systematic review analyzed the 10 studies that had been published on the subject to date, and observed that they all found the same benefits in both men and women in 'aerobic' performance indicators (such as, for example, a time trial) or the fatigue index measured in actions such as a Wingate test. Good news. However, 7 studies looked at variables related to anaerobic performance (e.g., a sprint, maximal strength, or a jump), and 4 of these studies found greater benefits in men than in women. Therefore, caffeine appears to be beneficial in both men and women, although men appear to benefit even more in some explosive actions⁷. However, of the many existing supplements (including some such as taurine, beta-alanine, beetroot juice or creatine), caffeine is still one of the most beneficial for improving a wide spectrum of actions in women, from more aerobic efforts to explosive efforts⁸.

 Hormonal Cycle and Caffeine in Women

Another variable that distinguishes men from women is their hormonal status, mainly due to menstruation. During the different phases of the menstrual cycle, there are important hormonal variations that can affect the pharmacokinetics of caffeine (specifically its elimination from the body) and, therefore, impact its effects⁹. But do these hormonal variations really affect the effects of caffeine? A group of Spanish researchers has tried to answer this question by analysing several women who came to their laboratory on no less than 6 occasions ^10–12. Each participant attended in the three phases of their menstrual cycle (early follicular, late follicular or pre-ovulatory and middle luteal) and in each phase they attended two days: in one they consumed caffeine (3 mg/kg 60 minutes before exercise) and in the other a placebo. The results were clear: compared to placebo, caffeine resulted in an improvement in maximal aerobic power in an incremental test ¹¹, peak power and average power in a 15-second sprint ¹² and average squat execution speed performed with a load equivalent to 60% of a maximum repetition (although not at 20%, 40% or 80%)¹⁰. In addition, these improvements were observed in practically each of the phases of the menstrual cycle studied, with no differences between the phases.

 Conclusions

In summary, caffeine consumption is an effective strategy to improve athletic performance not only in men, but also in women. In addition, these benefits seem to be seen in a similar way regardless of the phase of the menstrual cycle they are in. Therefore, we have even more evidence in favor of using caffeine in training and competitions.

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References

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