How does caffeine intake impact exercise?

By Monica Kinney

How does caffeine intake impact exercise? - black woman in a red cap and natural hair sips a coffee cup with a light yellow wrapSociety runs on caffeine: coffee, energy drinks, tea, soda, you name it. But have you thought about how it impacts your exercise performance? Let’s go over caffeine, the body’s overall response to it, and its relationship to exercise.

Caffeine and the body

Caffeine is a chemical compound found in seeds, nuts, or leaves in certain plants and can now be synthetically manufactured as well. It is a natural stimulant for your nervous system. This can make you feel more awake and energized. Caffeine blocks the neurotransmitters that signal the brain to suppress arousal and causes sleepiness. In addition, this stimulating effect increases heart rate and blood pressure, creating more blood for the renal system to filter. The renal system in turn requires a higher waste output which is why caffeine is considered a diuretic.

Caffeine and exercise

Naturally, because of its known benefits for energy, people often consume caffeine for sports performance, or before exercise. It is common for marathon runners to take some form of caffeine during their races and also some individuals who lift weights at the gym to take some type of pre-workout. But does it really improve performance? Or is it a placebo effect? And what about the average person? One who isn’t looking to PR in races or lift record amounts in weightlifting.

Is it worth it to have some caffeine intake before exercise?

The answer, is, it depends. For untrained individuals, studies have shown mixed results on caffeine and exercise performance. There was a small improvement among some of the studies done on resistance training (2). Those done on aerobic exercise show it yields more positive results on aerobic long slow distance training vs anaerobic sprint training (2).

Now if you do not normally consume caffeine, you should not run to the shelves and buy all the coffee and tea in sight. It may aid your exercise, but the results of the research are varied and not convincing enough to make a major difference. A few factors to keep in mind when using caffeine with exercise. Most studies show that coffee should be consumed between 30-60 minutes before exercise. Generally, the amount that needs to be consumed is 5 to 6 mg/kg of body weight (1). For some people, it may cause an upset stomach or insomnia. And, if you do have high blood pressure, exercise increases that without caffeine intake. So, take that into consideration. We do know what effect caffeine generally has on the body. And like any sort of food, drink, supplement, etc., it varies per person. Take inventory of yourself and if you enjoy the way you feel after having your pre-workout coffee or tea. If it makes you feel energized and ready to seize the day, then have some before you exercise.

Monica Kinney is the program manager of the College of Health and Human Science’s Adult Fitness Program at Colorado State University.  Adult Fitness offers exercise opportunities for employees of CSU as well as community members, while providing hands-on learning experiences for health promotion students. To learn more, see the Adult Fitness Program website



  1. Guest, N.S., VanDusseldorp, T.A., Nelson, M.T. et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr 18, 1 (2021).
  2. Kruskall, Laura J. Ph.D., R.D., CSSD, FACSM; Miracle, Amy M.A., M.S., R.D., CSSD. CAFFEINE AND EXERCISE PERFORMANCE: What’s All the Buzz About?. ACSM’s Health & Fitness Journal 13(6):p 17-23, November 2009. | DOI: 10.1249/FIT.0b013e3181bcd865