Yes, Caffeine Will Improve Your Athletic Performance. But How Much Is Too Much?

Caffeine is a well-studied and effective ergogenic aid. That means it improves endurance and speed. But before you go pounding energy drinks before exercising, let’s look at how much you need. While caffeine can improve athletic performance, too much may leave you jittery and dehydrated—not exactly ideal during a work out. Like almost all things in life, there’s a balance to achieve. Just enough to aid performance but not so much that you feel like garbage.

What’s the sweet spot? How do you introduce caffeine without going overboard? Here are some expert opinions on adding caffeine to your fitness routine so you can crush your goals without crashing.

How caffeine improves athletic performance

Wondering if it’s worth it to use caffeine before your next workout? Sports dietitian, Mandy Tyler, RD, CSSD, LD, says athletes often consume caffeine prior to exercising to help increase alertness, reduce feelings of effort, or help with training at a higher intensity.

In fact, not only is caffeine one of the most widely used legal substances by athletes, says Roxana Ehsani, RD, CSSD, LDN, a registered dietitian nutritionist and board-certified sports dietitian, but it also has proven benefits. “A review found that male athletes were able to produce more power, were speedier, and were able to lift a greater amount of weight with caffeine,” she says.

What about females? Well, the menstrual cycle tends to throw a little wrench into study design and results, so there is much more supportive data for males. However, researchers have found that caffeine seems to be a more effective ergogenic aid in aerobic activities (i.e., sprints, weight-lifting) in males than in females.

Are you a runner or cyclist? Caffeine can help you push longer. Males and females alike. “Caffeine can help most types of athletes, from endurance to power athletes,” said Ehsani. She added, “I’d recommend caffeine before activity for athletes who are undergoing competition—before a game for team sport athletes such as soccer or basketball players or before a race for endurance-based athletes like marathoners or triathletes.”

How much caffeine do you need?

The amount of caffeine needed for your training session or competition varies based on your weight. “Generally it’s recommended to consume three to six milligrams of caffeine per kilogram of body weight in the hour before exercise,” Tyler says.

Find your weight in kilograms by dividing your weight in pounds by 2.2. For example, if you weigh 150 lbs, you’d be about 68 kg. So you’d shoot for ~200 mg caffeine. You can get this from most energy drinks, 10–12 ounces of cold brew, or a 14–16 oz. coffee or Americano. Take note: The amount of caffeine in coffee is dependent on how it’s brewed.

There are also caffeine additives for your water, like tablets or pre-workout powder. Besides caffeinated beverages, you could try caffeine supplements like energy gels, gums, capsules, or chews.

How much caffeine is too much?

When it comes to caffeine, Tyler cautions against assuming more is better. “High doses of caffeine—9 mg/kg of body weight or more—may cause negative side effects, such as jitters, nausea, or anxiety,” she says. She also warns to double-check the ingredient lists of energy drinks, energy shots, or pre-workout powders as they can include other stimulants besides caffeine like guarana.

Besides feeling jittery and anxious, you may hinder your workout if you take in too much caffeine beforehand. “Be mindful that caffeine is a diuretic, and excessive amounts can lead to excessive urination, potentially causing dehydration,” says registered dietitian, Celine Thompson, RDN. “To avoid overdoing it, limit your daily caffeine intake to 400 milligrams, and be on the lookout for signs [of overconsumption] like nervousness, rapid heartbeat, and difficulty sleeping.”

When should you consume caffeine?

Your early morning cup of joe won’t give you bonus strength or endurance if your workout is in the late afternoon. For caffeine to improve your athletic performance, consumption needs to be timed properly. Ehsani recommends consuming caffeine about 45 to 60 minutes prior to activity as it takes about that long for its effects to peak.

You may also find it beneficial to take caffeine while you’re exercising. It’s been reported that trained cyclists who consumed caffeine in the last third of their workout saw an improvement in performance. If you’re already fueling mid-workout with an energy gel or jelly beans, you could try products that have caffeine added.

Here’s how to start

It’s best to ease into caffeine supplementation, especially if you don’t normally consume caffeine. “If you’re new to caffeine supplements, start with 1–2 mgs per kilogram of body weight and try it in your training first to avoid side effects like jitters,” Thompson advises.

Have you kicked a caffeine addiction and you don’t want to start back up? It’s okay. You can still train hard and see results. “While caffeine can enhance performance, it’s not necessary for optimal results. Good nutrition and training are the primary factors,” Thompson says. Caffeine is just an option to give you the edge when you’re looking to take it up a notch.