Pre-Workout Guide — What Is In It and Should You Take It?
Pre-workout supplements promise energy, focus, pumps and performance, and they are one of the best-selling categories in sports nutrition. The tubs are impressive: long ingredient lists, scientific-sounding names, and claims of explosive workouts. The reality is more modest: a handful of ingredients work, most are under-dosed, and the effect that most users feel is almost entirely caffeine.
This guide opens up the label: what is in pre-workout, what the evidence says about each ingredient, the safe doses, and who should avoid these products entirely. The headline is that a cup of coffee, taken 30–60 minutes before training, gives you most of what a pre-workout does — at a fraction of the price and with a much shorter ingredient list.
Use the calculator
Start with the numbers: try our one rep max calculator to work out your own figures before applying anything on this page. The worked examples below use round numbers so you can follow the maths; the calculator uses your real weight, height, age and goal.
Related reading: one rep max calculator, protein calculator, Whey Protein Guide, Supplements Worth Taking, full guides section.
The formula behind pre-workout
The only ingredient in pre-workout with a dose that can be calculated precisely is caffeine: the evidence-based dose for performance is 3–6 mg per kilogram of body weight, taken 30–60 minutes before exercise (Guest et al., 2021, Journal of the International Society of Sports Nutrition). For a 70 kg person that is 210–420 mg — roughly two to four cups of coffee, and far more than the 150–200 mg in a typical pre-workout serving. The other ingredients have their own evidence-based doses: creatine 3–5 g per day (every day, not just before training), beta-alanine 3.2–6.4 g per day (split into doses, taken daily for weeks), citrulline malate 6–8 g, and beta-alanine's tingling side effect (paraesthesia) is harmless but unpleasant. The calorie maths is trivial — most pre-workouts contain almost no calories — but the energy equation still frames the context: the Mifflin-St Jeor equation (Mifflin et al., American Journal of Clinical Nutrition, 1990) — 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women, times an activity factor — estimates maintenance calories, and no pre-workout changes that arithmetic. The safety floors (1,200 kcal/day women, 1,500 kcal/day men) are about the diet, not the supplement, but they matter here because pre-workout is often marketed alongside extreme dieting — and the combination of heavy stimulants and very low calories is a real risk.
The key points
Caffeine is the ingredient that works. Caffeine is the most effective legal performance enhancer available: a 2021 position stand (Guest et al.) found it improves strength, power, endurance and focus at 3–6 mg/kg, taken 30–60 minutes before exercise. The effect is real but modest — a few percent, not a transformation — and it is the same caffeine whether it comes from a £40 tub or a cup of coffee. Most pre-workouts contain 150–300 mg per serving, which is below the evidence-based dose for anyone over 60 kg. If you feel a pre-workout 'working', you are feeling caffeine.
Creatine works — but not as a pre-workout ingredient. Creatine is the most evidence-backed supplement in sports nutrition: 3–5 g a day, every day, reliably increases strength and muscle gain over weeks. But it does not work acutely — a single dose before training does nothing, because it works by saturating the muscles over days and weeks. Putting creatine in a pre-workout is marketing, not science: the dose in most pre-workouts is also too small (1–2 g) and the timing is irrelevant. Take creatine separately, 3–5 g a day, every day, mixed into anything.
Beta-alanine works slowly, and it tingles. Beta-alanine (3.2–6.4 g a day, taken daily for at least four weeks) improves performance in efforts lasting 1–4 minutes, by buffering acid in the muscles. It is the ingredient that causes the tingling, itching sensation (paraesthesia) that many users associate with a pre-workout 'kicking in' — but the tingle is a side effect, not a sign it is working, and it does not work from a single dose. Most pre-workouts contain 1.5–3.2 g, which is under-dosed for a single serving and useless without daily use.
Most other ingredients are under-dosed or unproven. Citrulline malate (6–8 g is the evidence-based dose; most products contain 2–4 g), BCAAs (unnecessary if total protein is adequate), tyrosine (some evidence for focus under stress, but the dose and context matter), and a long tail of herbal extracts with little or no human evidence. The pattern is consistent: the label lists impressive ingredients at doses too small to work, so that the marketing can claim the benefit without paying for the dose. Read the dose, not the ingredient list.
Stimulant load is the real risk. The danger of pre-workout is not the individual ingredients but the total stimulant load: caffeine plus synephrine (bitter orange), yohimbine, and other stimulants, sometimes at doses that are not fully disclosed in proprietary blends. Combined with heavy exercise, dehydration and a hot gym, high stimulant doses can cause a racing heart, high blood pressure, anxiety, nausea and, rarely, serious cardiac events. People with heart conditions, high blood pressure, anxiety disorders or caffeine sensitivity should avoid these products, and nobody should take more than one serving or combine them with other stimulants.
Proprietary blends hide the doses. Many pre-workouts list a 'proprietary blend' — a total weight for several ingredients without individual doses — which means you cannot tell whether any ingredient is present at an effective dose. It is a deliberate opacity, and it is a reason to avoid the product: if a company will not tell you the dose, assume it is too small. Choose products with full label disclosure, or skip the tub and use coffee plus separate creatine — which is cheaper, fully dosed, and transparent.
At a glance
| Ingredient | Evidence | Effective dose | Typical pre-workout dose | Verdict |
|---|---|---|---|---|
| Caffeine | Strong | 3–6 mg/kg, 30–60 min before | 150–300 mg | Works — usually under-dosed |
| Creatine monohydrate | Strong | 3–5 g/day, every day | 1–2 g (and timing irrelevant) | Works — take separately |
| Beta-alanine | Moderate | 3.2–6.4 g/day for 4+ weeks | 1.5–3.2 g | Works slowly — under-dosed |
| Citrulline malate | Moderate | 6–8 g | 2–4 g | Possibly — under-dosed |
| BCAAs | Weak (if protein adequate) | — | 2–5 g | Unnecessary |
| Tyrosine | Weak-moderate | 2 g under stress | 0.5–1 g | Unproven at this dose |
| Synephrine / yohimbine | Risky | — | Varies | Avoid — stimulant risk |
| Herbal extracts | Very weak | — | Varies | Marketing |
A worked example: coffee versus the tub
Take a 75 kg lifter who buys a pre-workout at £40 for 25 servings (£1.60 per serving), containing 200 mg of caffeine, 2 g of creatine, 1.6 g of beta-alanine and 3 g of citrulline malate. The evidence-based caffeine dose for him is 3–6 mg/kg, or 225–450 mg — so the tub gives him the bottom of the range, and he would need one and a half servings to reach the middle. The creatine dose is less than half the 3–5 g a day he needs, and it does nothing acutely anyway. The beta-alanine is half the minimum daily dose and useless without daily use for weeks. The citrulline is half the effective dose. Now the alternative: a cup of coffee (about 100 mg of caffeine per cup, so two cups = 200 mg, or three cups = 300 mg, taken 30–60 minutes before training) costs about 10p, and a separate creatine supplement (3–5 g a day, every day) costs about 10p a day. The coffee-plus-creatine approach gives him a full caffeine dose, a full creatine dose, and costs about 20p a session instead of £1.60 — saving about £35 a month for a better-dosed result. His maintenance calories by Mifflin-St Jeor — 10 × 75 + 6.25 × 178 − 5 × 30 + 5 = 750 + 1,112 − 150 + 5 = 1,717 kcal/day, times 1.55 for moderately active = about 2,661 kcal/day — are unchanged by either option, because pre-workout contains almost no calories. The supplement does not change the arithmetic; it only changes the price.
How to use this guide
If you want a performance boost before training, start with coffee: 2–3 cups (200–300 mg of caffeine) 30–60 minutes before training, and see how it feels. If you want creatine's benefits, take 3–5 g a day, every day, separately — mixed into water, a shake, or food, at any time of day. If you still want a pre-workout tub, read the label for doses, not ingredients: caffeine at 3–6 mg/kg for your body weight, no proprietary blends, no synephrine or yohimbine, and no more than one serving. Never combine a pre-workout with other stimulants (energy drinks, fat burners, extra coffee), never take it late in the day if it affects your sleep, and stop using it if you feel a racing heart, chest discomfort, dizziness or severe anxiety. And remember that the biggest performance gains come from sleep, food and training — a pre-workout adds a few percent on top of a good programme, and nothing on top of a bad one.
What this guide does NOT tell you
Pre-workout supplements are not medicines, and this guide does not diagnose or prescribe anything. The caffeine doses (3–6 mg/kg) are from the published position stand (Guest et al., 2021) for healthy adults — they do not apply to people with heart conditions, high blood pressure, anxiety disorders, pregnancy, or caffeine sensitivity, who should avoid high-dose stimulants and discuss any supplement use with a clinician. Children and teenagers should not use pre-workout supplements. Supplement quality varies and products are not regulated as strictly as medicines in many countries, so choose products from reputable brands with third-party testing where available — and be aware that some products have been found to contain undeclared stimulants. This guide does not cover performance-enhancing drugs, which are a separate and serious matter. And the safety floors apply to the whole diet: never go below 1,200 kcal/day for women or 1,500 kcal/day for men without medical supervision, whatever supplements you take.
Frequently asked questions
What is in pre-workout?
Mostly caffeine, plus creatine, beta-alanine, citrulline malate, BCAAs and various herbal extracts — usually at doses below the evidence-based level. The ingredient that most users feel is caffeine. Many products use 'proprietary blends' that hide the individual doses, which is a reason to avoid them: if a company will not disclose the dose, assume it is too small.
Does pre-workout actually work?
Modestly. Caffeine improves strength, power, endurance and focus by a few percent at 3–6 mg/kg, and creatine and beta-alanine work when taken daily at full doses over weeks. But most pre-workouts under-dose every ingredient except caffeine, so the effect you feel is almost entirely the caffeine — which a cup of coffee provides at a fraction of the price.
Is pre-workout safe?
For healthy adults at the recommended dose, usually — but the risks are real: high stimulant loads can cause a racing heart, high blood pressure, anxiety and nausea, and rarely serious cardiac events, especially combined with heavy exercise, dehydration and heat. People with heart conditions, high blood pressure, anxiety or caffeine sensitivity should avoid them. Never take more than one serving or combine them with other stimulants.
Can I just drink coffee instead?
Yes — and for most people it is the better choice. Two to three cups of coffee (200–300 mg of caffeine) 30–60 minutes before training gives you the same caffeine dose as a pre-workout, at about 10p instead of £1.60 a serving. Add separate creatine (3–5 g a day, every day) if you want its benefits, and you have a cheaper, better-dosed, fully transparent alternative.
What is the beta-alanine tingle?
Paraesthesia — a tingling, itching sensation, usually in the face and hands — caused by beta-alanine. It is harmless but unpleasant, and it is not a sign the supplement is working: beta-alanine works by buffering acid in the muscles over weeks of daily use, not from a single dose. The tingle is a side effect, not a performance signal.
Should teenagers use pre-workout?
No. Pre-workout supplements are not recommended for children and teenagers — the high stimulant doses are inappropriate for developing bodies, and the products are marketed far more aggressively than the evidence supports. Teenagers who train should focus on sleep, food and coaching, not stimulants.
Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.