How Much Caffeine Is Enough Blog Banner
If you’ve been going to the gym for a while, you may have noticed that caffeine is the unofficial mascot of the fitness industry. Whether it’s in your client’s morning coffee, their pre-workout or the energy drink they’re clutching at 7pm (eeek), caffeine is everywhere.
But for all its popularity, there’s still a lot of confusion about how much caffeine actually improves performance and also, at what point it just becomes a jittery waste of a good training session. A new study from 2025 helps clear up some of the guesswork and it turns out, you might not need nearly as much as you think.
This is especially handy knowledge for personal trainers, S&C coaches and anyone studying nutrition coach courses, because caffeine is one of the few supplements that genuinely works, but only if it’s used wisely.
And for those looking at nutrition courses in general, understanding caffeine’s ergogenic effects and limits is a key part of bridging the gap between research and what real clients are actually doing in the gym.
So, let’s break it all down. How much caffeine is enough, when should it be taken, and how can it be used in such a way that it won’t wreck sleep, stomach or sanity.
The paper that sparked this conversation is a 2025 study by Montalvo-Alonso and colleagues. They looked at what happens when resistance-trained men consume a moderate dose of caffeine, just 3 mg per kilogram of body weight, before a session involving both strength and endurance tests.
Participants performed bench press and back squat exercises at varying intensities from 25% to 90% of 1RM, at two different times of day. These were in the morning when performance typically dips, and evening when we’re naturally stronger. The researchers wanted to see if caffeine would help and if it would alter muscle electrical activity, which was measured via EMG.
The results showed caffeine consistently improved strength, power and endurance across a range of exercises including the back squat in particular. This was regardless of time of day. At higher loads (75–90% 1RM), performance gains were significant. Even endurance training where sets were performed to failure at 65% 1RM saw improvements.
Interestingly, though, muscle activation didn’t change. EMG activity in the quads, pecs and triceps stayed flat. That means the performance boost came from somewhere else. Researchers surmised this is likely peripheral mechanisms such as improved calcium release, phosphodiesterase inhibition or sodium-potassium pump efficiency.
And yes, all of that happened with just 3 mg/kg caffeine. A dose most gymgoers blow past without blinking.
Let’s put that into perspective. For an average 75 kg client, a 3 mg/kg dose equals 225 mg of caffeine. That’s roughly:
It’s a Goldilocks dose. That’s enough to see performance benefits, without tipping into the land of heart palpitations and toilet runs.
Compare that to the high doses used in some studies of up to 6–9 mg/kg, or found in commercial pre-workouts which are often over 300 mg per scoop, and it’s easy to see how we’ve been conditioned to think “more is better”. In this case, more isn’t necessary as it works so well with less.
Here’s how different levels stack up based on what we know:
So, unless your client is an elite powerlifter chasing 1% gains on comp day, there’s rarely a need to go overboard.
Caffeine takes about an hour to kick in fully, so the sweet spot for consumption is roughly 60 minutes before training. This applies whether you’re working with a 6am bootcamp crew or a 4pm strength session.
In the Montalvo-Alonso study, caffeine effectively neutralised the usual morning dip in performance. Normally, we’re a bit weaker and slower in the early hours due to circadian rhythms (Guette et al., 2005). But with caffeine onboard, that drop-off was erased, at least for lower loads like 25% 1RM and endurance sets.
This will make a big difference to clients who only have time to train in the morning. A short coffee or caffeine gum could be the difference between a sluggish lift and a solid session.
That said, caffeine late in the day is a slippery slope. Even if your client says it doesn’t affect them, sleep latency and quality can still take a hit. If they consume 200mg or more in the evening, it will definitely have an impact. And we all know that poor sleep can sabotage recovery and progress.
We tend to associate caffeine with 1RM efforts or explosive lifts, but this study showed it also helps with muscular endurance, specifically sets to failure at 65% 1RM. Participants completed more reps and produced more power.
This is good news for hypertrophy-focused clients, group class participants or anyone chasing volume rather than just raw strength.
What’s more, the gains weren’t limited to just the back squat. While lower body exercises responded more consistently to caffeine, likely due to larger muscle mass, the bench press still showed improvement at lower intensities and in endurance sets.
So whether your client is chasing size, power or stamina, caffeine has a place, as long as the dose and timing are dialled in.
Before you go recommending a pre-gym espresso to every client, there are some important considerations.
Caffeine isn’t right for everyone. Clients with anxiety, panic disorders, hypertension or sleep issues may find that even moderate doses cause problems. Pregnant or breastfeeding clients should also be cautious.
Plus, some people are just highly sensitive to caffeine, while others are habitual high users. There’s also evidence that tolerance can blunt the effect over time (Filip et al., 2020). In those cases, it might be worth suggesting a short caffeine “deload” to reset sensitivity. Although this may be a hard sell to someone who loves their morning brew.
As with anything nutrition-related, get a full picture of their current intake, timing and lifestyle before recommending changes. A quick dietary recall or caffeine log can be surprisingly revealing.
The take-home message is simple. When it comes to caffeine, more isn’t always better. A low dose of around 3 mg/kg is often enough to support real, measurable performance gains across strength, power and endurance, especially in the morning.
If you’re a PT or nutrition coach looking to help your clients train smarter, understanding caffeine dosing is one of the easiest wins. And if you’re diving into nutrition courses to broaden your skillset, this is exactly the kind of evidence-based insight that helps separate helpful guidance from fitness folklore.
So before you suggest another scoop of pre-workout, check the dose, check the timing, and above all, check if it’s even needed.
Looking to help your clients train smarter, not just harder? The Nutrition & Exercise Specialist & Master Diplomas™ give you the advanced tools to do just that. In a recent study, a simple 3 mg/kg dose of caffeine boosted strength and power output by up to 11% in bench press and 12% in back squat endurance sets, and that’s without any change in muscle activation, showing just how vital nutrition strategies are in driving performance. Whether you’re guiding early morning lifters or high-volume hypertrophy clients, understanding how supplements like caffeine affect both strength and endurance can set your coaching apart. On these diplomas, you’ll dive deep into evidence-based nutrition and advanced training techniques to support real-world results. Learn more and enrol now at the link above.
Nutrition & Exercise Specialist/Master – Distance Study, In-Person & Live-Virtual
If you’re ready to offer expert, evidence-based advice on fuelling for both fat loss and peak performance, the Level 4 Nutrition for Weight Management & Athletic Performance course is for you. In a recent study, a modest 3 mg/kg dose of caffeine increased back squat power output by up to 11% at 25% 1RM and over 9% in muscular endurance tests, even reversing the usual decline seen in morning training sessions. These insights highlight the powerful role nutrition and precise supplementation can play in enhancing client outcomes. On this course, you’ll explore the science behind macronutrients, supplementation, metabolism and performance nutrition, helping you deliver tailored advice that goes far beyond basic calorie counting. Get started today.
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