Does caffeine help running performance?
Yes, caffeine improves endurance performance by 2-4% through reduced perceived effort and enhanced fat oxidation. Take 3-6 mg per kg of body weight 45-60 minutes before running. A 70kg runner needs 200-400 mg — roughly 2-3 cups of coffee or a caffeinated gel. Test in training first.
Caffeine is one of the most studied and effective legal performance aids for endurance athletes. Well-controlled research consistently shows 2-4% improvements in endurance performance — which at the marathon level can be 4-8 minutes. How it works: caffeine blocks adenosine receptors in the brain, reducing perceived effort so the same pace feels easier. It also enhances fat oxidation and may preserve glycogen. The optimal dose: 3-6 mg per kg of body weight, taken 45-60 minutes before the race or hard session. For a 70kg runner, that's 210-420 mg. Reference points: an espresso shot is 60-80 mg, a regular cup of coffee is 80-120 mg, a SIS or GU caffeinated gel is 75 mg, a can of energy drink is 80-150 mg. More than 6 mg/kg doesn't improve performance and can cause jitters, GI distress, or elevated heart rate. During very long events (ultramarathons), some runners take 100 mg every 2-3 hours in the back half. Practice caffeine dosing during training sessions first — individual tolerance varies massively, and some runners get GI issues. If you drink coffee daily, you're somewhat adapted — consider skipping caffeine for 3-5 days before your race to restore sensitivity, though even habitual drinkers still get a performance benefit. Avoid caffeine after mid-afternoon on pre-race day to protect sleep.