how much caffeine you actually need to run faster (we did the math)

the tldr because we respect your time: caffeine actually works, and it's one of the only legal supplements that isn't a scam. the sweet spot is 3–6 mg per kg of body weight. your coffee is great but wildly inconsistent, gum absorbs fastest, gels are best for race day, nasal sprays are a complete waste of money. and if caffeine makes you anxious instead of fast? that might be genetic, not a you problem.

coming in part 2: how to calculate your exact caffeine dose (with real examples) · before you do the math, check what you're already taking · why caffeine works for your friend but not for you (it's genetic) · your caffeine protocol (the summary)

I can't be the only one who goes to bed already excited to wake up and drink my coffee. It's become my thing, even more so since moving to Melbourne, where I'm surrounded by world-leading roasteries and coffee snobs. The happy smell, satisfaction of a good crema and the feeling of coming to life after the first sip is genuinely the best part of my morning, even more so after 10 months of sleepless nights with our latest family addition.

Anyway, I've been looking for an excuse to drink more of it without turning into a jittery mess, especially since getting back into running after a 3-year hiatus recovering from myocarditis, POTS, and postpartum life. Between the deliriously tired baby brain and trying to find enough energy to get through my little "mental health 5ks" as my time starts to creep back down each week (yay), I needed to know if my coffee habit was actually helping or just making me feel like it was.

Because I'm a nerd, and I have a sports dietitian sister, I obviously had to dive into the research (which she of course vetted). I wanted to know exactly how much to drink to actually perform, but also stop me from turning into an anxious mess chugging water at 2pm.

So I went deep into the science, including a brand new 2025 study that finally tested caffeine on female athletes, and a bunch of data comparing how fast different sources actually hit your system.

The question: is a gum, a gel, or my beloved Melb espresso the best way to PR (hit a personal record)?

There's a molecule in your brain called adenosine, which is basically the brake pedal for your nervous system. From the moment you wake up, it builds and builds, binding to receptors that tell your body "bestie, we are tired, let's rot on the couch."

Caffeine looks almost identical to adenosine. So when you drink it, it rushes to your brain and parks itself in those receptors before the real adenosine can get there.

Your brain then genuinely thinks it's not tired. Dopamine and glutamate (your "go" neurotransmitters) start running the show, and suddenly you feel alert and focused and ready to run through a wall, because your brain has effectively muted the fatigue signal.

Your coffee is basically gaslighting your nervous system, it's not actual energy, it's more like a blocker.

yes. across basically every metric.

Researchers combined the results of 21 different studies (so a LOT of data) and found caffeine improved endurance, strength, power, agility, and jumping performance. It also made hard efforts feel easier, which in exercise science terms means it lowers your RPE, basically how hard the effort feels to you, on a scale of 1 to 10.

Same effort, but feels less terrible = the dream.

the bit that matters to the girls: up until very recently, almost all caffeine research was done on men, which meant women were left guessing whether the same protocols actually applied to us. That's starting to change. A 2025 study tested caffeine specifically on highly trained female athletes and found that just 3 mg/kg significantly improved jump height, agility, and game intensity. It's one of the first studies to confirm what a lot of us already suspected, and the more research like this that gets done, the better the guidance gets for everyone.

So no, your iced latte before a run isn't a placebo. There's science behind it.

Coffee is the best delivery system, I will defend Melbourne espresso with my life, but the problem is it's wildly inconsistent.

When researchers tested 97 espressos from different cafes, caffeine content ranged from 25 mg to 214 mg per serving, which is a massive range when your performance dose might only be 180mg.

Another study found a 6-fold difference across commercial espressos, which is kind of unhinged when you think about how confidently we all say "I had two coffees" as if that means the same thing twice.

So for training, coffee is fine, enjoy the vibes. But for race day when you actually need precision, you should probably know what you're taking, unless you've trialled and tested the exact coffee making routine a dozen times yourself.

Also, if the acidity bothers your stomach, adding milk can help neutralise it, simple fix before you give up your morning happy moment.

not all caffeine sources are created equal. some are precise, some are chaos, and one is genuinely a scam.

There are way more ways to get caffeine into your system than just your morning coffee. You can get in through gums, gels, pills, energy drinks and nasal sprays (yes, really). The problem is they all absorb differently, dose differently, and hit differently. So here's a breakdown of how reliable they actually are, because when you're trying to do the math on your performance dose, the delivery method matters just as much as the number.

🟢 caffeinated gum—the speed hack

Caffeinated gum absorbs through your cheek cells, which means it bypasses the whole digestive system and hits your bloodstream faster than any other option. 5 minutes of chewing releases about 80% of the caffeine, and 10 minutes gets you closer to 90%.

One caveat though, it's not perfectly precise. One study found a 50mg piece only delivered ~41mg, which is about 18% less than the label. That's still way more predictable than a mystery espresso, but it's worth knowing when you're doing your math.

🟢 gels (maurten, gu, etc.)—the race day pick

Caffeinated gels are pre-packaged, precisely dosed, and they double as fuel because you're getting carbs too, which makes them the strongest option for long runs and endurance events. The catch is that they're concentrated and too many might upset your stomach mid-race, so if you have a sensitive gut, ease in during training before relying on them on race day.

🟡 coffee—the og

Coffee isn't portable and isn't precise, but it brings joy and that counts for something. The higher acidity might trigger reflux during hard efforts though, and adding milk can help if that's an issue for you.

🟡 caffeine pills—the minimalist

Caffeine pills are portable, clearly labelled, and make the math easy. The risk is that they're tiny enough to make it terrifyingly easy to accidentally double your dose, so always read the label before taking them.

🔴 energy drinks—proceed with caution

A single 16oz can often packs 54g of sugar, which is already over the WHO's daily recommendation, and it also contains a tonne of other additives, artificial sweeteners, taurine, and whatever else they've thrown in, that might impact your performance and health. Unless you're hours deep into a really long race, the caloric load is probably unnecessary.

🔴 nasal sprays—save your money

Caffeinated nasal sprays sound cool and biohack-y, but researchers tested them and found no significant improvement in performance. Next.

Now you know what caffeine does, whether it actually works, why your coffee order is a gamble, and which delivery method is best for what. In part 2 we'll do the actual math, your exact dose by body weight, the hidden caffeine sources you're probably not counting, and the genetic reason caffeine might work for your friend but not for you.

— xx, athlete girl

the research behind this article:

Guest N. S. et al. (2021). Journal of the International Society of Sports Nutrition. · Nieto-Acevedo, R. et al. (2025). Nutrients. · Crozier T. W. M. et al. (2012). Food & Function. · Desbrow B. et al. (2007). Food and Chemical Toxicology. · Al-Shaar L. et al. (2017). Front Public Health. · WHO sugar consumption recommendation. · De Pauw K. et al. (2017). International Journal of Sports Physiology and Performance. · Morris C. et al. (2019). Food & Function. · Sadek P. et al. (2017). J Caffeine Research. · Wickham K. A., Spriet L. L. (2018). Sports Medicine.