Apr 22, 2015
Burst of Energy
Dr. Penny Wilson

The following article appears in the April 2015 issue of Training & Conditioning.

Caffeine can provide the boost athletes need when it matters most. The key to making it work is a safe dosing regimen.

A college track athlete sees an advertisement in his favorite magazine touting a new caffeine supplement. The ad says, “Go Fast! Pure Energy!” Thinking of his next big meet, he makes a beeline to the local store and buys some. Right before the race, the athlete drinks the caffeinated supplement. He finishes first in his heat and advances to the finals. After drinking more of the supplement prior to the finals, he runs the best race of his life. He’s found the secret to running faster–right?

In the past, most nutrition experts would have said, “No.” Due to concerns that caffeine could cause a host of negative issues, athletes were discouraged from taking it to enhance performance.

However, research over the last decade has shifted views on caffeine. Studies have shown that, when taken in appropriate quantities, it can help athletes reap rewards without triggering side effects. With the release of these new findings, more and more athletes are turning to caffeine for a boost.

To ensure they are doing so safely, it’s important to stay up to date on the latest claims. If you are armed with the understanding of the most recent research, how caffeine works, and how to use it as an ergogenic correctly, you can be a valuable source of guidance for athletes giving caffeine a try.


The impetus for the shift in thought surrounding caffeine and athletic performance came from the lab. Once a few studies broke ground with new findings on the pros of caffeine use, other researchers quickly followed.

Recent studies have been particularly influential because they’ve attempted to meet an ideal set of criteria. While previous evaluations were conducted on sedentary individuals or recreational athletes, participants in the latest investigations were athletes. In addition, testing protocols included closed-loop tasks that applied to particular sports rather than time-to-exhaustion tests. Here is a summary of some of the more significant findings:

Hydration: In the past, dehydration was one of the main reasons athletes were counseled against using caffeine. However, research that showed caffeine causing dehydration often examined subjects at rest as opposed to athletes engaging in their sport or physical activity. Now, multiple studies have concluded that taking caffeine does not have a diuretic effect on those engaging in physical activity.

Endurance Sports: Studies on endurance sports–including road and track cycling, distance running, rowing, swimming, and cross-country skiing–have shown performance enhancement with the use of caffeine. This research, as explained in a 2008 article by sports nutritionist Louise Burke, PhD, FSMA, FACSM, in Applied Physiology and Nutrition Metabolism, has shed light on dosages and different types of products.

Team Sports: Burke also examined studies focusing on the use of caffeine in different team sports, which had mixed results. In one investigation, possible or likely performance enhancement in rugby players was seen for sprinting, power generation in the first of two consecutive drives, tackle speed, and passing accuracy. However, caffeine did not lead to increases for the second power drive.

Racquet Sports: Two studies on tennis players in Burke’s article also revealed mixed results. One investigation showed females won more games and had an improved hitting accuracy after taking caffeine, but males did not. Neither gender had enhancement in tennis-specific running speed. The second study showed that caffeine consumption led to improvements in forehand skill tests.


If an athlete wants to try caffeine supplementation, it’s important to educate them on how it will affect their body. Once it is consumed, caffeine is quickly absorbed and metabolized by the liver. It takes 15 to 45 minutes for caffeine levels to rise in the bloodstream, typically reaching peak concentrations within 60 minutes.

The specific mechanisms of how caffeine enhances athletic performance have yet to be uncovered. However, the available literature references three main targets in the body. The first is the central nervous system. Caffeine in the bloodstream crosses the membranes of nerve cells and acts as an adenosine-receptor antagonist. When adenosine binds to adenosine receptors on nerve cells, neural activity slows down. Caffeine interferes with this process by binding to the adenosine receptors first, blocking the adenosine. This prevents neural activity from slowing down and may, in fact, speed it up. As a result, athletes may perceive less fatigue during workouts.

The second target of caffeine is believed to be the pituitary gland. Caffeine may act on the pituitary gland when it activates neural circuits, causing an increase in the production of adrenaline. Adrenaline can provide a burst of energy and increase attention levels.

Finally, caffeine may increase the availability of fatty acids for use as fuel and reduce the body’s reliance on glycogen. By giving the body another energy source, athletic performance may be enhanced.


Once an athlete understands how caffeine will impact their body, the next step is to educate them on how to use it as an ergogenic. Beginning a caffeine regimen requires careful dosing and planning.

The dosing range for performance enhancement is 1 to 6 mg/kg of bodyweight, consumed 60 minutes before activity. This would mean that a 150-pound adult would need between 68 and 409 mg of caffeine. This is a wide range, so athletes should start out with a low dose and gradually work their way up to a higher amount in order to determine their optimal level. An athlete who has gone past the ideal dosage will no longer get a bump in performance and/or may start experiencing negative side effects.

When trying to pinpoint an athlete’s optimal caffeine amount, it’s important to remember that caffeine affects different athletes in different ways. The presence of two specific genetic single nucleotide polymorphisms determines the speed with which an individual processes caffeine and his or her sensitivity to it. In addition, female athletes who are on estrogen-containing birth control will process caffeine slower than women who are not.

The product an athlete chooses should have a label that clearly states its caffeine quantity. Because the levels in coffee and tea can vary depending on the origin of the beans or leaves, these beverages are not ideal choices for performance enhancement. Instead, athletes should look for commercial products that list the caffeine content and are easy to use and digest. With my clients, I often recommend Clif Bloks or caffeine-containing gels.

I don’t recommend energy drinks and caffeine-containing powders and pills. Because these products are typically categorized as dietary supplements, they are not monitored for safety by the U.S. Food and Drug Administration. Therefore, their contents can vary widely. (See “Latest Buzz” below for more information on energy drinks.)

It is critical for athletes to test their reaction to caffeine in training before using it in competition. This will help them understand how the drug will impact performance and whether or not negative side effects will occur. The athlete should document the quantity of caffeine used, type of product consumed, how they felt, and any changes in performance. Athletes can progress to using caffeine before competitions once they know how their body reacts.

Depending on the length of the athletic event, consuming multiple doses of caffeine may be ideal for maximum performance enhancement. However, there are many variables that play into how long athletes should wait between doses, and it varies from person to person and sport to sport. My rule of thumb when advising my athletes is to try another dose of caffeine right before fatigue typically sets in.

As with many drugs, the body can develop a tolerance to caffeine. Research is equivocal about habituation, so it is something athletes will need to monitor. Once they stop getting the boost from their optimal dose of caffeine, they may need to stop using it for a while and restart at a later date. Developing a tolerance is not a reason to increase caffeine intake, though, as this may trigger negative side effects.


I’ve had positive results using caffeine as a performance enhancer with a number of my clients. Sam, a triathlete, decided to introduce caffeine into his regimen while training for his second Ironman. He started taking Clif Bloks during the running leg of the race because that’s when he felt a decline in mental focus and most fatigued.

Sam and I worked together to develop a protocol for him to follow. He would take two to three Clif Bloks–50 mg of caffeine per three Bloks–starting at mile 10 and every 15 minutes after that until he completed the run. Sam practiced this protocol in his training and found that the Bloks provided him with improved energy levels and mental clarity.

On race day, Sam posted improved times in both the swim and the bike. However, at around mile 10 of the run, his energy and concentration levels plummeted. He forgot to take his Bloks before the onset of fatigue and ended up walking the next six miles in a mental fog. Eventually, Sam realized his error and got back on his Bloks schedule. Soon after, he felt a burst of energy and mental clarity and was able to finish the remaining 10 miles of the run at his anticipated pace.

Sam’s overall time was 12:56:17, which was 21 seconds better than his first Ironman finish. He is confident that if he had used the Bloks as planned, his run would have been much faster, and he would have had a lower overall time.


Although views on caffeine are changing, it is important to keep an eye out for potential issues. For example, since caffeine is classified as an ergogenic, overconsumption can cause compliance issues.

The NCAA lists caffeine as a banned substance, and any amount greater that 15 mcg/ml in urine constitutes a positive test. This is equivalent to consuming 500 mg or more of caffeine within a few hours of the test.

Ultimately, it is the athlete’s responsibility to understand what substances are banned in their sport and by their governing organization. However, you should be aware of how caffeine violations could affect your athletes, as well.

When starting to use caffeine, the athlete should also be monitored for side effects. For example, if they complain of sleep disturbances, their last dose of caffeine should be taken earlier and earlier until they are sleeping normally again. Other common side effects include nervousness, nausea, gastrointestinal disturbances, increased heart rate, increased respiration, headache, and ringing in the ears.

Caffeine can be an appropriate ergogenic for athletes, as long as it is consumed safely. That’s why it’s crucial for us to provide guidance in helping athletes implement an appropriate regimen. When performance is maximized and side effects minimized, they can get the most out of caffeine.


Energy drinks may seem like an easy way to add caffeine to a pre-competition routine, but I do not recommended them. Despite the boost athletes might get from the caffeine, a host of regulatory issues cancel out any potential positive results.

For instance, energy drink companies are not required to list the amount of caffeine on their product labels, so athletes might be consuming more or less than they realize. In 2012, Consumer Reports analyzed the caffeine content of 27 energy drinks, and what they found was alarming. Of the 16 products that listed the amount of caffeine, five contained 20 percent more than what was indicated on the label.

In addition, athletes can never be 100 percent sure of what’s inside each can. When ingredients are listed, many times they fall under the header of “a proprietary blend,” which means the manufacturer does not have to list the name or quantity of each one. These unknown substances can cause compliance problems for athletes or may threaten their health.

Penny Wilson, PhD, RDN, CSSD, LD, is the owner of Eating for Performance, where she provides nutrition coaching for a variety of athletes–from weekend warriors to Olympic and professional competitors. She has served as the dietitian for the Houston Rockets and can be reached at: [email protected].

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