Caffeinated Workouts … the Truth in the Buzz

Some days a workout – whatever it involves, whatever your fitness level – seems to feel better than others, right? Many factors before exercise clearly affect this feeling, including sleep, what and when food was consumed, hydration status and your workout history. Trained athletes, who exercise more than most, definitely know this. And they are always looking for an edge, especially in competition.

Caffeine has been studied extensively in athletes for its ergogenic – or performance enhancing – properties, and there is evidence to support its benefits for both physical and mental performance. It naturally occurs in coffee, tea, cocoa beans and kola/cola nuts (a flavoring in food and beverages).

How it Works & Potential Benefits
Caffeine stimulates the central nervous system, heart and muscles. However, the exact mechanisms for how it enhances athletic performance are still being studied. Based on laboratory research with trained athletes, caffeine may affect performance in the following ways.
  • It may improve performance during prolonged endurance exercise as well as short-term (about 5 min.) high-intensity exercise.
  • Caffeine consumption may reduce pain and perception of fatigue by affecting receptors in the brain, encouraging training at higher intensities.
  • It may decrease perceived exertion (during resistance training), leading to extended strength training sessions.
  • Caffeine may also increase concentration and alertness, helping to sustain intensity in training.
When and How Much
Most studies indicate that about 1 hour before exercise is the best time to consume caffeine for enhancing performance. The effects likely last approximately 4 hours.

Also based on research, 2-6 milligrams of caffeine per kilogram of body weight (1kg = 2.2lbs) is recommended for performance improvement. That’s about 1 to 4 (8-oz.) cups of regular brewed coffee (at roughly 100 mg caffeine per cup) for someone weighing 150 pounds.

By the way, more isn’t necessarily better. Some studies have shown that lower amounts of the recommended caffeine range may be just as effective as higher amounts, so start with the low end of the range.

Important Tips
So how does the research – mostly performed on trained athletes in lab-based settings using caffeine tablets/powder – apply to the general population involved in a wide array of workout activities? Well, there are no guarantees, but these tips may be helpful:
  • Try sipping 1-2 (8 oz.) cups of regular brewed coffee 1 hour before your usual exercise. The generally-recommended level to supplement for performance is 2-3 mg of caffeine per kilogram of body weight, which translates to 100 mg caffeine for a 50 kg/110 pound individual (for 2mg caffeine/kg body weight).
  • The amount of caffeine in coffee can vary depending on how it’s made. Eight ounces of regular home-brewed drip coffee should have about 100 mg of caffeine. Other sources of caffeine include energy bars and drinks, gels and medications. However, be sure to know the level of caffeine you’re consuming, and make sure the source doesn’t contain other unwanted stimulants.
  • Keep in mind that individuals metabolize caffeine at different rates, so pay attention to how you are feeling during your workout. You should not feel “shaky” or “overstimulated” by the amount of caffeine you consume. This will not help your workout performance. Be sure to check with your doctor or a registered dietitian nutritionist if you have a reason to avoid caffeine.
  • Remember, caffeine does not replace the energy from food needed to properly fuel your body. Also, overall hydration plays a role in performance. Most health authorities recommend 9 to 13 cups (more for men) of fluid daily, including fluid from food, water and other beverages.
  • About 3 to 5 cups of coffee in a day is considered moderate coffee consumption and has been studied for potential links to decreased: mortality from all causes, risk of developing type II diabetes, risk factors for heart attack and stroke, dementia, liver and other cancers.

Bottom Line
There is not a body of research specifically studying the effect of caffeine on the workouts of “weekend warriors” or individuals who do not consider themselves well-trained athletes. However, a modest amount of caffeinated coffee consumed about an hour before exercise not only might be enjoyable but could help you feel more alert and encourage you to work a bit harder than usual … without necessarily feeling more tired than normal. That said, count me in!


The following studies are for supporting caffeine and better workouts:
Duncan, M.J. Journal of Strength and Conditioning Research, October 2012.
Hodgson A, Randell R, Jeukendrup A. The metabolic and performance effects of caffeine compared to coffee during endurance exercise. Plos One [Internet]. 2013 [cited 2014 June 5]. 2013;8(4):e59561. Available from: MEDLINE, Ipswich, MA.
Rosenbloom CA, Coleman EJ. Sports Nutrition: A Practice Manual for Professionals. 5th ed. Chicago, IL: Academy of Nutrition and Dietetics, 2012. Print.

Popkin B.M. et al. (2006) A new proposed guidance system for beverage consumption in the United States. Am. J. Clin. Nutr, 83:529-542.
Silva A.M. et al. (2013) Total body water and its compartments are not affected by ingesting a moderate dose of caffeine in healthy young adult males. Appl. Physiol. Nutr. Metab, 38:6.
Kolasa K.M. et al. (2009). Hydration and health promotion. Nutr Today, 44:190-203.
Ganio M.S. et al. (2007). Evidence-based approach to lingering hydration questions. Clin Sports Med 26, 12-16.
Goldstein E.R. et al. (2010) Caffeine enhances upper body strength in resistance trained athletes. J. Int Soc Sports Nut, 7:5.
Armstrong L.E. (2002). Caffeine, body fluid-electrolyte balance, and exercise performance. International Journal of Sport Nutrition and Exercise Metabolism 12, 205-222.
Killer S. C. et al (2014) No Evidence of Dehydration with Moderate Daily Coffee Intake: A Counterbalanced Cross-Over Study in a Free-Living Population. PLoS ONE, 9(1): e84154.
Ganio M.S. et al (2009). Effect of caffeine on sport-specific endurance performance: a systematic review. Journal of Strength and Conditioning Research. Volume 23; 315-324.

Beth Witherspoon, MPH, RDN, has a passion for communicating culinary and nutrition information. She is a registered dietitian/nutritionist who consults with Community Coffee Company to help communicate the flavor and health benefits of coffee.