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Does America run better on Dunkin’®? Caffeine and Exercise Performance

Updated: Nov 9, 2020

Nicole Farnsworth, MS, RD, LDN


Caffeine is the most commonly consumed stimulant in the world. Perhaps you are reading this post with your morning coffee or your afternoon pick-me-up and wondering how caffeine affects your body. In the athlete population, caffeine is regularly consumed and is permitted for use in sport with specific maximum concentration limits. So, with its widespread consumption and potential applicability for performance, it’s worthwhile to discuss what caffeine is, where is it found, and what the research says about its potential as an ergogenic aid. 

What is Caffeine?

Caffeine is a bitter-tasting chemical that is present naturally in plants such as coffee beans and tea leaves and is synthesized as well. Caffeine stimulates the body via the central nervous system, which can lead to a more heightened, alert state. It can take effect in under an hour and the effects can last for four to six hours. Caffeine can be found in a variety of food and supplement sources, a few of which are described below. 

Sources of caffeine

Coffee, tea, soda – Coffee is the most common form of caffeine consumption in the world and the research available suggests that it can be as effective as other forms of caffeine. Coffee’s caffeine content varies based on the coffee bean, it’s preparation, and numerous other factors. Tea and soda similarly have variability in their caffeine content. Therefore, it can be difficult to accurately dose caffeine intake for performance using these beverages.

Anhydrous caffeine – Dehydrated caffeine is a highly concentrated powder that can be easily measured making it useful for clinical research and for inclusion in consumer products. Due to its potency – 1 teaspoon of anhydrous caffeine is the equivalent of 28 cups of coffee – great care should be taken to ensure one does not consume toxic amounts of this product.

Caffeine-containing supplements – There are a number of products on the market today containing caffeine (for example, energy drinks, caffeine gum, and gels). These products may use caffeine or other botanicals and stimulants, such as guarana and ginseng. Energy drinks in particular are marketed to young adults and in the United States 30%-50% of adolescents and young adults consume energy drinks. Caffeine-containing gels are often marketed to endurance athletes in a product that also delivers carbohydrates and electrolytes for sustaining performance. Caffeine-containing gum has been studied in cyclists and shown to improve performance when chewed immediately before cycling.

Caffeine and athletic performance

Research suggests that caffeine will likely have a benefit on athletic performance in adults who regularly consume it. The optimal amount of caffeine for an individual may vary based on their caffeine tolerance, the athletic endeavor, and the caffeine source. One should be cautious of exceeding moderate caffeine consumption due to possible negative consequences, including jitteriness, anxiety, irritability, and gastrointestinal distress. Young athletes should be cautious of high levels of caffeine consumption due to caffeine’s potential interaction on sleep and appetite regulation. Furthermore, the American Academy of Pediatrics discourages caffeine consumption in children and does not recommend energy drink consumption in children or adolescents. Athletes should meet with a sports dietitian if interested in discussing caffeine dosage and sources, especially if the source being considered is a dietary supplement. While the current literature suggests that caffeine is most likely an ergogenic aid, a personalized and tailored approach is the best way to determine if it will benefit performance for the individual athlete.


1.         Hodgson AB, Randell RK, Jeukendrup AE. The Metabolic and Performance Effects of Caffeine Compared to Coffee during Endurance Exercise. PLOS ONE. 2013;8(4):e59561. doi:10.1371/journal.pone.0059561

2.         Caffeine content for coffee, tea, soda and more. Mayo Clinic. Accessed September 27, 2019.

3.         Nutrition C for FS and A. Guidance for Industry: Highly Concentrated Caffeine in Dietary Supplements. U.S. Food and Drug Administration. Published April 22, 2019. Accessed September 27, 2019.

4.         Landsverk G. A 21-year-old died after drinking a protein shake with a caffeine supplement so powerful it knocked him unconscious. Insider. Published July 9, 2019. Accessed October 1, 2019.

5.         Seifert SM, Schaechter JL, Hershorin ER, Lipshultz SE. Health Effects of Energy Drinks on Children, Adolescents, and Young Adults. Pediatrics. 2011;127(3):511-528. doi:10.1542/peds.2009-3592

6.         Ryan EJ, Kim C-H, Fickes EJ, et al. Caffeine Gum and Cycling Performance: A Timing Study. The Journal of Strength & Conditioning Research. 2013;27(1):259. doi:10.1519/JSC.0b013e3182541d03

7.         Grgic J, Grgic I, Pickering C, Schoenfeld BJ, Bishop DJ, Pedisic Z. Wake up and smell the coffee: caffeine supplementation and exercise performance—an umbrella review of 21 published meta-analyses. Br J Sports Med. March 2019:bjsports-2018-100278. doi:10.1136/bjsports-2018-100278

8.         Heather Mangieri. Fueling Young Athletes. Champaign, IL: Human Kinetics; 2017.

9.         Temple JL. Caffeine Use in Children: What we know, what we have left to learn, and why we should worry. Neurosci Biobehav Rev. 2009;33(6):793-806. doi:10.1016/j.neubiorev.2009.01.001

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