Quick answer: Coffee before a workout can help you perform a little better. Research shows caffeine improves strength, muscular endurance, power and especially endurance in many, but not all, studies. The usual research dose is 3 to 6 mg of caffeine per kilogram of body weight, taken about 60 minutes before training. Most people should start at the low end, around 3 mg per kg, and stay under 400 mg for the whole day.
This article is for you if you train in the morning, after work, or any time you reach for a coffee first. You’ll learn what the research says, how much to drink for your body weight, and when coffee before training is a bad idea.
Does coffee before a workout actually help?
Yes, for most people, though the effect is modest. Here’s what two major research summaries found:
- The International Society of Sports Nutrition (2021) concluded that caffeine improves performance in many but not all studies. Benefits include muscular endurance, movement speed, strength, sprinting, jumping and throwing. Endurance exercise showed the most consistent benefit. It also found caffeine helps both trained and untrained people (Guest et al., 2021).
- An umbrella review of 21 meta-analyses (2019) found caffeine improved endurance, muscle strength, muscle endurance, power, jumping and speed. The quality of evidence was mostly moderate. Most studies were done in young men, so we know less about women and older adults (Grgic et al., 2019).
Caffeine works by blocking adenosine, a chemical that builds up in your brain and makes you feel tired. That helps you feel more alert and can make hard effort feel a little easier.
How much coffee should you drink before training?
The ISSN says caffeine consistently improves performance at 3 to 6 mg per kilogram of body weight. The minimum effective dose may be as low as 2 mg per kg. Very high doses, around 9 mg per kg, cause more side effects and don’t seem to add any benefit (Guest et al., 2021).
Here’s what 3 mg per kg looks like for different body weights:
| Body weight | Caffeine at 3 mg/kg | Roughly equal to |
|---|---|---|
| 130 lb (59 kg) | About 175 mg | One 12-oz brewed coffee |
| 150 lb (68 kg) | About 205 mg | One 12-oz brewed coffee |
| 180 lb (82 kg) | About 245 mg | One large brewed coffee |
| 200 lb (91 kg) | About 270 mg | One large brewed coffee, or 4 espresso shots |
These are estimates. The FDA says a 12-oz brewed coffee can have anywhere from 113 to 247 mg of caffeine (FDA, 2024). According to USDA data, one shot of espresso has about 63 mg (National Coffee Association). So the same size cup can vary a lot between coffee shops.
Keep the whole day in mind. The FDA says up to 400 mg a day is not generally linked to negative effects in most healthy adults (FDA, 2024). If you already drink coffee in the morning, your pre-workout cup counts toward that total.
When should you drink it?
The most common timing in research is about 60 minutes before exercise (Guest et al., 2021). That gives your body time to absorb it.
If you train in the evening, think twice. In a sleep study, 400 mg of caffeine taken even 6 hours before bed disrupted sleep. The researchers recommend avoiding substantial caffeine for at least 6 hours before bedtime (Drake et al., 2013). Poor sleep will hurt your next session more than coffee will help this one.
Will coffee dehydrate you before training?
Not in moderate amounts. In a study of 50 men who regularly drank coffee, four cups a day hydrated them about as well as the same amount of water (Killer et al., 2014). You still need water during training, but your coffee doesn’t cancel it out.
Who should be careful
- If you’re pregnant, trying to conceive or breastfeeding, the FDA advises talking with your healthcare provider about caffeine.
- If caffeine makes you anxious or jittery, start at 2 mg per kg or skip it. The ISSN notes that people react differently because of genetics and how much caffeine they usually have.
- If you have a heart condition or high blood pressure, check with your doctor first.
- If you’re training late, try decaf or skip it to protect your sleep.
My advice: try coffee before an ordinary training day first, not before a big test or event. See how your body reacts, then decide if it works for you.
Summary
- Caffeine improves performance in many studies, especially endurance, with smaller gains for strength and power.
- Research doses are 3 to 6 mg per kg of body weight. Start around 3 mg per kg.
- Drink it about 60 minutes before you train.
- Stay under 400 mg for the whole day, and avoid caffeine within about 6 hours of bedtime.
- Moderate coffee doesn’t dehydrate you.
Get the most from your session
Coffee can give you a small edge. A good plan gives you a big one. 12REPS gives you trainer-built programs, two demo videos for every exercise and a gym log that shows what you lifted last time, so you know exactly what to beat. New users get a 7-day free trial.
Download 12REPS and see what you’ll get:
Sources
- Guest NS et al. International Society of Sports Nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr, 2021
- Grgic J et al. Wake up and smell the coffee: caffeine supplementation and exercise performance, an umbrella review of 21 published meta-analyses. Br J Sports Med, 2019
- Drake C et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med, 2013
- Killer SC et al. No evidence of dehydration with moderate daily coffee intake. PLoS One, 2014
- FDA. Spilling the beans: how much caffeine is too much? 2024
- National Coffee Association. Espresso (citing USDA nutrition data)
I’m Will Duru, a personal trainer and the founder of 12REPS. I hold a BSc (Hons) in Sport and Exercise Science and have more than a decade of experience coaching people in strength training.