Caffeine has become a regular part of our daily diets, found in items such as chocolate, coffee, tea, and soda, even over-the-counter medications, supplements and cosmetics. It stimulates the central nervous system, heart, and musculoskeletal system (1).
Caffeine is everywhere, essentially.
If you are a nutrition specialist with a wide range of clients, this information is especially relevant to you.
The Health Consequences of Caffeine
Part of the appeal of caffeine is that it has minimal health consequences for generally healthy individuals when taken in low-to-moderate amounts. Typical side effects include sleep disturbances, headaches, tremors, or increased anxiety, but overall benefits include improved concentration, alertness and mood (2-4).
Many athletes turn to caffeine not only for this stimulating buzz, but also to enhance sports performance. Between 1984 and 2004, caffeine was on the World Anti-Doping Agency’s (WADA) list of banned substances as evidence implicated caffeine as an ergogenic aid (2). I
t was eventually removed from the list as violation threshold levels were well beyond doses giving athletes a competitive edge (2). Though not currently banned, it is still a substance being monitored by WADA (2). Along these same lines, the NCCA bans caffeine at urine concentration levels of 15 ug/mL or higher for student-athletes to test positive, so it is still important to monitor just how much caffeine could be ingested from different sources (which will be listed later)(3).
How Caffeine is absorbed in the body
Caffeine is absorbed in the gastrointestinal tract and quickly metabolized by the liver. It begins circulating in the blood stream within 15-45 minutes, with peak concentration appearing an hour after consumption (1).
Caffeine research, overall, finds that it effects both the central and peripheral systems (1). It easily crosses the membranes of nerve and muscle cells, and even the blood-brain barrier. Caffeine can also enhance fat oxidation and spare muscle glycogen (1).
When combined with a carbohydrate source during recovery, caffeine is also shown to improve glycogen repletion, but timing becomes a factor so that it does not negatively impact sleep patterns (1). (This is just a brief overview of caffeine in the body. For more information explaining the physiological processes view the studies in the reference list.)
Health Benefits and Cautions of Caffeine
Just about every week a new piece of research on caffeine and its health benefits makes the headlines. Caffeine consumption (especially coffee) has been correlated with a reduced risk of Parkinson’s and Alzheimer’s disease, various cancers, diabetes, and also improvements in cognitive functioning and asthma relief (5-6). If you are a regular caffeine consumer, you are probably aware of the dependence you may have on caffeine.
Withdrawal can make you cranky, cause headaches, drowsiness, and even nausea. Caffeine beyond small amounts is not recommended during pregnancy, and those with high blood pressure, anxiety, sleep problems, heart issues, and stomach concerns may want to avoid caffeine (4). Caffeine may interact with prescription or over-the-counter medications, so consulting with a health care provider is advised.
Benefits of Caffeine on Athletic Performance
Need to improve ball-passing accuracy in a field sport? Caffeine may be able to improve that by 10% (7).
Caffeine has been shown to improve performance by decreasing reaction time, sustaining maximal endurance and intermittent high-intensity long-duration exercise by extending the time to exhaustion (1-3). Caffeine may offer benefits for strength-power and sprint activities, and potentially reduce RPE, but research in these areas has been equivocal (1-3).
Recent research has also shown that caffeine ingestion an hour prior to resistance training increased total repetitions that could be performed, but more importantly, significantly decreased DOMS in the days following compared to placebo (8). These researchers left us with an interesting question to ponder- would caffeine allow for more training sessions to be completed because of decreased soreness (8)?
Caffeine Dosing and Sources
Optimal dosing for improving performance is between 3-6mg/kg body weight, where lower amounts do not offer a significant benefit and higher doses offer no additional benefits, and can even have negative performance consequences (1,3). As an example, for a 150 pound (68 kg) athlete this would equate to 204 to 408 mg caffeine. Some common caffeine sources include (9):
Cola (12 oz.): 30-47 mg
Green tea (8 oz.): 24-40 mg
Black tea (8 oz.): 14-61 mg
Chocolate (bittersweet 1 oz.): 25mg
Coffee (8 oz.): 95-200 mg
Espresso (1 oz.): 40-75 mg
Over-the-counter medications are another source of caffeine to be aware of. As you can see, caffeine concentrations can vary widely, especially in coffees and teas due to brewing or even bean roasting methods. For those seeking a more controlled dosing using caffeine anhydrous, a dry powder form, can provide that.
For the regular caffeine consumer, a cup or two of coffee an hour before training doesn’t seem that extreme, but what about for the caffeine naïve athlete? Would a vente from the corner coffee shop on the way to a competition put them over the edge? Probably not, but a competition wouldn’t be the best time to discover an athlete’s response to caffeine.
To evaluate how long the ergogenic effect of caffeine lasts and how it differed between regular caffeine users and nonusers, Bell and McLellan (2002) had study participants ingest either 5 mg/kg of caffeine or a placebo and complete one of six randomized submaximal (80%) exercise tests to exhaustion trials, at 1, 3, or 6 hours after ingestion, once per week (10).
Caffeine significantly improved (increased) time to exhaustion, and was greater for nonusers who had a longer lasting ergogenic effect that was still evident at the 6 hour post ingestion trial (10). For those who are caffeine experienced, caffeine clears from the blood stream between 3 and 6 hours after ingestion, whereas for our caffeine naïve consumers it takes a bit longer (1, 10).
What do Athletes Know?
During the 2005 Hawaiian Ironman Triathlon World Championship, participants were asked to complete a questionnaire to discover what their knowledge about caffeine and exercise was, along with the sources they received their information from.
73% of the respondents perceived that caffeine had a positive or strongly positive effect on performance, with the most common sources of caffeine information being fellow athletes, magazines, journal articles, and coaches, in addition to self-research and experimentation (11). 53% of these athletes planning on using caffeine indicated they did not know how much caffeine would improve their triathlon performance (11)!
This research highlights the need for more athlete education on the topic of how to correctly use caffeine to enhance performance—if its use is being considered.
Though we are not promoting the use of caffeine, this article shares some of the benefits and dosing strategies for improving performance. The ergogenic effects of caffeine can vary depending on dosing, timing, exercise intensity, duration, and habitual or naïve caffeine use.
Athletes should use caution if considering using caffeine if they have medical conditions or prone to sleep disturbances, and consult with their healthcare provider.
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- Goldstein, E. R., Ziegenfuss, T., Kalman, D., Kreider, R., Campbell, B., Wilborn, C., & ... Antonio, J. (2010). International society of sports nutrition position stand: caffeine and performance. Journal of the International Society of Sports Nutrition, 71-15. doi:10.1186/1550-2783-7-5
- Del Coso, J., Muñoz, G., & Muñoz-Guerra, J. (2011). Prevalence of caffeine use in elite athletes following its removal from the World Anti-Doping Agency list of banned substances. Applied Physiology, Nutrition & Metabolism, 36(4), 555-561. doi:10.1139/H11-052
- Clark, M.A., Lucett, S.C. NASM Essentials of Sports Performance. Baltimore, MD: Lippincott Williams & Wilkins;2010.
- Evert, A. "Caffeine in the Diet: MedlinePlus Medical Encyclopedia." U.S National Library of Medicine. U.S. National Library of Medicine, 5 May 2011. Web. 13 Dec. 2013. www.nlm.nih.gov/medlineplus/ency/article/002445.htm.
- Butt, M.S., Sultan, M.T. (2011)Coffee and its consumption: benefits and risks. Critical Reviews in Food Science and Nutrition 51(4):363-73. doi:10.1080/10408390903586412.
- Welsh E.J., Bara A., Barley E., Cates C.J. (2010) Caffeine for asthma. Cochrane Database of Systematic Reviews Issue 1. Art. No.: CD001112. doi: 10.1002/14651858.CD001112.pub2.
- Stuart, G.R., Hopkins, W.G., Cook, C., Cairns, S.P. (2005) Multiple effects of caffeine on simulated high-intensity team-sport performance. Medicine and Science in Sports & Exercise 37:1998-05.
- Hurley, C.F., Hatfield, D.L., Riebe, D.A. (2013) The effect of caffeine ingestion on delayed onset muscle soreness. Journal of Strength and Conditioning Research. 27(11)3101-3109. doi:10.1519/JSC.0b013e3182a99477
- Staff, Mayo Clinic. "Caffeine Content for Coffee, Tea, Soda and More." Mayo Clinic. Mayo Foundation for Medical Education and Research, 01 Oct. 2011. Web. 10 Dec. 2013. http://www.mayoclinic.com/health/caffeine/AN01211.
- Bell, D.G., & McLellan, T. M. (2002) Exercise endurance 1, 3, and 6 h after caffeine ingestion in caffeine users and nonusers. Journal of Applied Physiology. 93(4): 1227-34. doi:10.1152/japplphysiol.00187.2002
- Desbrow, B., & Leveritt, M. (2007). Well-trained endurance athletes' knowledge, insight, and experience of caffeine use. International Journal of Sport Nutrition & Exercise Metabolism, 17(4), 328-339.
Stacey Penney, Contributing Content Strategist with the National Academy of Sports Medicine (NASM), holds a master’s degree in exercise science and health promotion from California University of Pennsylvania, a degree in Athletic Training from San Diego State University, along with credentials in Health Promotion Management and Consulting (UCSD), and Instructional Technology (SDSU). She holds certifications from NASM and ACE in personal training, corrective exercise, sports performance, group exercise, fitness nutrition, and health coaching. Previous San Diego Fall Prevention Task Force Chair, she develops continuing education curriculum for many fitness organizations in addition to personal training, writing, and helping coach youth soccer.