Studies have found that, when it comes to exercise, caffeine:
- Delays fatigue
- Slows the breakdown of muscle glycogen, which means your body has more fuel to keep going
- Enhances endurance
- Keeps you more alert
- Can reduce muscle pain during exercise
- May lower perceived exertion, making exercise feel more comfortable
While caffeine can have a positive effects on endurance exercise, you don't need it to have a good workout. If you're a competitive athlete thinking of using caffeine, keep in mind that it is a diuretic, so you may need more bathroom breaks. That could affect your workouts as well as your hydration levels.
How Much Caffeine Is Enough?
Studies have shown that 3 mg/kg to 6 mg/kg is enough to enhance endurance. The average cup of coffee has about 60 mg to 120 mg, so it doesn't take much caffeine to do the job.
Cautions
Caffeine is a stimulant, so it does have side effects that could cause problems for certain people:
- Increased urination
- Stomach upset
- Trembling or shaking
- Trouble sleeping
- Increased anxiety
- Headaches
- Nausea
If you're pregnant, you should avoid caffeine and you should also be cautious if you're on medication or taking other performance-enhancing supplements that contain other stimulants. Too much caffeine can increase the side effects and could be dangerous to your health if you have other illnesses or conditions.
Sources:
Graham TE, Rush JW, van Soeren MH. Caffeine and exercise: metabolism and performance. Can J Appl Physiol. 1994 Jun;19(2):111-38.
Motl RW, O'connor PJ, Tubandt L, Puetz T, Ely MR.
Effect of caffeine on leg muscle pain during cycling exercise among females. Med Sci Sports Exerc. 2006 Mar;38(3):598-604.
Demura S, Yamada T, Terasawa N. Effect of coffee ingestion on physiological responses and ratings of perceived exertion during submaximal endurance exercise. Percept Mot Skills. 2007 Dec;105(3 Pt 2):1109-16.
