Women and men appear to benefit equally from the ergogenic effects of coffee

You wake up, wander to your kitchen, and click the brew button on your coffee pot. The nutty and earthy aromatics fill the air and you quickly pour the freshly brewed joe into your mug. Upon first sip, you taste bitter, yet rich, flavor, and soon feel a rush of energy. Roughly 45 minutes later^[1], the primary ingredient in coffee, caffeine, takes full effect on your central and peripheral nervous systems^[2]. Caffeine is now one of the most widely utilized performance-enhancing chemicals in athletic communities because WADA lifted their tight regulations around the compound from 1984-2004. The general public also loves coffee; (85% of adults^[3] report consuming some form of caffeine daily, while athlete consumption is roughly at 75-90%^[4]. Studies have shown the consumption of three to eight milligrams of caffeine per kilogram of bodyweight (in the form of a pill or powder) can act as an ergogenic aid for executive function^[5], anaerobic^[6] and aerobic^[7] exercise, and resistance training^[8].

However, the literature is equivocal when it comes to investigating possible differences in the effects of caffeine between men and women. A 2019 systemantic review found only ten studies^[9] that compare sex differences of varying caffeine doses on athletic performance. The lack of evidence on this topic isn’t surprising when looking at the totality of literature that has been conducted in women participants. Only 35-37%^[10] of all studies^[10] in sports and exercise medicine journals have been done in women. Furthermore, the results are mixed concerning caffeine’s ergogenic efficacy in women: some studies show positive effects^[11], while others find little to no benefit^[12]. A recent review,^[9] whose results are summarized in Figure 1, found four studies (out of 10) concluding that men respond to a greater extent after caffeine ingestion than women. It is speculated that this is a casualty of oral contraceptive pills^[13], sex-specific hormones^[14], or the variances one sees in performance across the menstrual cycle^[15]. However, a paper recently covered in this digest didn’t find any impact of the menstrual cycle on the effects of caffeine, although it probably had too small of a sample size to reveal differences that, while small in magnitude, could matter to competitive athletes.

In addition, there is a quagmire in the literature questioning if caffeine derived from coffee has similar effects as anhydrous caffeine (e.g., caffeine pills). It has been previously theorized that the chlorogenic acid in coffee^[16] attenuates the ergogenic effects of caffeine (although other researchers state the opposite^[17]). Additionally, how the coffee is brewed will dictate both the caffeine and chlorogenic acid concentrations. For example, a medium roast Robusta bean will contain more caffeine than the same bean lightly roasted. Paper-filtered coffee will have significantly less caffeine^[18] than espresso derived from a machine. And, if you wanted to possibly minimize the lipid content of unfiltered coffee^[19], your best bet is instant coffee.

To address these limitations of the evidence, the present study explored the effects of caffeinated coffee, decaffeinated coffee-like beverage (placebo), and a control (no beverage) on five kilometer cycling time trial performance across men and women.

Caffeine is one of the most commonly used performance-enhancing substances available for consumer use. Despite this popularity, the literature is equivocal when it comes to utilizing coffee as a medium for caffeine ingestion. Also, the studies in women investigating the efficacy of caffeine on performance has resulted in mixed findings. The study under review investigated sex differences in the effect of caffeinated coffee on cycling time trial performance.