Coffee Before Running: Science-Backed Benefits and Risks

Many runners rely on coffee as their go-to pre-run fuel, while others worry about jitters or digestive issues.

So, is caffeine helpful or harmful when it comes to running?

Research suggests that caffeine can enhance endurance, but individual responses vary.

Here’s what science says about drinking coffee before a run and how to use caffeine effectively.

Does Caffeine Improve Running Performance?

Caffeine has been widely studied for its impact on endurance sports, and the results are promising.

A 2022 review published in Nutrients analyzed 21 studies and found that caffeine improved both time-to-exhaustion and time-trial performance. The data showed a 16.97% improvement in endurance and a 0.71% faster time-trial performance.

Other studies report an average boost of 2-4%, though some individuals experience no benefits or even a decline in performance.

Caffeine works by blocking adenosine receptors in the brain, which reduces fatigue and lowers the perception of effort.

t also helps mobilize calcium ions in muscles and enhance carbohydrate oxidation, both of which improve performance.

However, individual response to caffeine varies due to genetics.

‍This 2018 study found that genetic differences in the CYP1A2 enzyme influence how athletes respond to caffeine:

• AA genotype: Strong performance improvement.
• AC genotype: Little to no effect.
• CC genotype: Performance decline at higher doses.

Since most people don’t know their genotype, trial and error is the best way to determine if caffeine enhances your running.

Best Sources of Caffeine for Runners

If you’re looking to incorporate caffeine before running, you have several options, each with different caffeine concentrations.

Coffee

Many runners prefer coffee as their caffeine source due to its convenience and effectiveness. A standard 8-ounce cup of brewed coffee contains around 95 mg of caffeine, while espresso has approximately 63 mg per shot.

The caffeine content varies depending on the coffee bean type, roast level, and brewing method. If you’re aiming for 3-6 mg of caffeine per kilogram of body weight, a 12-ounce mug may be enough to hit your target dose.

One downside is that coffee’s acidity may cause stomach discomfort. To reduce this, pair coffee with bland carbohydrates before running.

Tea

Tea provides caffeine in lower doses than coffee. Black tea contains about 40-45 mg per 8 ounces, while matcha has 19-44 mg per gram, depending on preparation.

This makes tea a good option for those who want a milder caffeine boost before running.

Energy Drinks

Some runners use energy drinks, but they often contain excessive caffeine along with other stimulants, artificial ingredients, and unregulated supplements.

A 2023 review in Nutrients highlighted potential risks, including heart palpitations, gastrointestinal distress, and negative effects on hydration.

Many energy drinks contain 200-300 mg of caffeine per serving, which can be excessive for endurance athletes.

Caffeine Supplements

Gels, chews, and sports drinks with caffeine provide an easy way to get a boost during long runs or races. Most caffeinated gels contain 25-50 mg per serving, while some have up to 100 mg.

These are particularly useful for sustaining energy levels during endurance events.

Pre-workout supplements also contain caffeine, but they are not well regulated. If using one, choose a third-party tested brand to ensure accurate labeling.

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How Much Caffeine Should You Take?

The International Society of Sports Nutrition recommends 3-6 mg of caffeine per kilogram of body weight for performance benefits. Some individuals respond to as little as 2 mg/kg, while doses over 9 mg/kg are more likely to cause negative side effects.

For a 143-pound (65 kg) runner, the recommended caffeine intake is 195-390 mg over the course of race morning. This includes pre-run coffee and any caffeinated supplements taken during the race. For example, a 12-ounce coffee (120-150 mg) plus two caffeinated gels (50 mg each) would keep intake within this range.

To avoid negative effects, limit total caffeine intake to 400 mg per day and avoid consuming large single doses.

When Should You Drink Coffee Before Running?

Caffeine takes about 60 minutes to peak in your bloodstream. To maximize its benefits, drink coffee 45-60 minutes before a run.

For races, timing caffeinated gels correctly is also important. If you want a boost in the final 10K of a marathon, take a caffeinated gel at mile 15-17 to allow it to take full effect by mile 21-22.

Potential Risks and Side Effects of Caffeine

While caffeine benefits many runners, some may experience negative side effects, particularly with high doses. Common side effects include:

• Digestive issues (acid reflux, nausea, or urgent bathroom trips)
• Increased heart rate or palpitations
• Anxiety or jitteriness
• Headaches
• Disrupted sleep (especially for slow caffeine metabolizers)

Additionally, some research suggests caffeine might contribute to muscle cramping, although more studies are needed.

If you’re sensitive to caffeine, consider starting with a lower dose (e.g., 1-2 mg/kg) and increasing gradually.

Should You Drink Coffee Before a Marathon?

Since caffeine can delay fatigue and enhance endurance, it may be beneficial before a marathon. If you tolerate caffeine well, combining pre-race coffee with in-race caffeine supplements can help sustain energy through the final miles.

Sample Race Day Caffeine Plan

• 1-2 hours before race start: Eat breakfast, drink 12-16 oz of a sports drink, and consume 8-16 oz of coffee or tea.
• During the race: Take caffeinated gels (25-50 mg each) at mile 6 and mile 15 to maintain energy.

Final Thoughts: Is Coffee Before Running a Good Idea?

For many runners, coffee before running provides a natural performance boost by reducing fatigue and enhancing endurance. However, caffeine is highly individual—some runners thrive on it, while others experience side effects.

If caffeine helps you perform better without digestive issues or jitters, then it’s a useful tool. If not, skipping it before races might be the better choice.

While coffee and caffeine can give you an edge, hydration and proper fueling remain crucial for peak performance.