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How Much Caffeine is Too Much?

By Katie Rhodes | Feb. 23, 2016, 1:26 p.m. (ET)

Grabbing for that daily morning cup of joe may not be the route for endurance athletes. Now don’t get me wrong, I enjoy the benefits of a caffeine rush just as much as most of you. But, when it comes to those wanting to use caffeine to create a competitive edge during an event, being a habitual consumer decreases the likelihood of such an effect. Caffeine enhances performance. The research can’t be ignored that caffeine is a proven ergogenic aid in endurance exercise through its effects on alertness, concentration, pain tolerance and perception of fatigue. But, in order to get the most out of your caffeine consumption is to not consume it on a regular basis and limit it to your endurance exercise and events. So, as you are sadly putting down your usual afternoon pick-me-up let’s start with understanding the basics about caffeine and then how you can use it as a competitive advantage.


(MYTH BUSTER: Caffeine is not a diuretic. Despite your bathroom urgency, continuous research consistently debunks this hypothesis.)

Caffeine is the most widely consumed drug in the world with over 50 percent of the population consuming caffeine on a daily basis in various forms, the most common being coffee. Once consumed it is easily absorbed into the bloodstream through the stomach and intestines causing physical and psychological responses within the body. Benjamin Stone, Ph.D. and founder of Sigma Human Performance, shared that he uses caffeine because of its sparing effect on muscle glycogen. He explains that caffeine causes a higher dependency on exogenous forms of carbohydrate, prolonging endurance activity. Psychologically, researchers agree in addition to increasing alertness, caffeine reduces pain levels and alters your perception of fatigue, allowing endurance athletes to work at a higher level of intensity for a longer period of time resulting in an increase in work performed. Less research is available on caffeine’s effect on strength training and shorter events, but what is available has shown caffeine consumption increases the dynamic and isometric muscular force, power and endurance strength, all of which positively impact endurance performance. After averaging out findings from various studies, caffeine consumption before an endurance event can improve performance by 3-3.5 percent. That may sound small, but think about it; in a one-hour time trial that is almost 1.8-2.1 minutes and in a 10-hour race that is 18-21 minutes. That is huge, folks. Recent research has concluded that caffeine has a significant impact on recovery as well, reducing perceived muscle soreness. Worth a try, right?

How much caffeine do you consume to improve performance and when? Research concludes the amount of caffeine consumed to have an ergogenic effect is 3-6mg/kg or 1.14-1.7mg/lb. So, for example, for a 75kg or 165lb male the amount of caffeine to consume would be 225mg-450mg.  Once consumed, peak blood plasma levels are reached between 60 and 100 minutes from intake. Caffeine consumed in amounts exceeding this range does not enhance the effects on performance; if anything it can increase the chances of you experiencing side effects such as nausea, gastrointestinal upset, and shaking. To put this range in perspective:

8 ounces brewed coffee: 80-100mg
8 ounces brewed tea: 50mg
2 ounces espresso: 65-100mg
12-ounce soft drink: 35-55mg
8-ounce energy drink: 80mg
2 capsules Excedrin: 130mg
1 Tablet NoDoz: 200mg
1 serving gu (1.8 tablespoon): 36mg 

Deciding the amount of caffeine to consume, when, and in what form you tolerate best can be intimidating and is very individualized. Therefore, I recommend you start early and trial different amounts using different forms during your long workouts. Consult with a sports nutritionist or doctor before making big changes to your caffeine intake. Journal what you consume, when you consumed it, and how you felt during and after your workout. Caffeine isn’t for everyone. If the side effects outweigh the benefit, for example having GI issues throughout your race, recognize that and move on to the plethora of other strategies to enhance performance, like nutrition planning before, during and after an event.

*Note: The World Anti-Doping Agency lists caffeine under the substances to monitor during a competitive event. It is not prohibited.

Katie Rhodes, owner of OWN-Nutrition, is a registered and licensed dietitian in Little Rock, Arkansas, with a Master of Science in clinical nutrition. Through her experiences training elite athletes and working in the clinical setting at Arkansas Children's Hospital and the Central Arkansas Veterans Association, Rhodes understands that what we are putting in our bodies directly affects our performance, quality of life and longevity. She's worked with triathletes for six years on their nutrition year round as well as focusing on race day nutrition. Rhodes primarily works with clients remotely, through phone calls and Skype for communication, to supplement unique, personalized nutrition plans.

The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.