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Caffeine for Performance

Caffeine for Performance


The basics:

Caffeine works by blocking adenosine from binding to its receptors in the brain. This prevents signaling to the brain that you need rest, stimulates adrenaline, and promotes the effects of dopamine. That’s the short story of how caffeine seems to give you a bit of extra energy to keep going. Which is great for giving yourself a morning boost, powering through an afternoon meeting, or crushing that extra rep in the gym.

Speaking of that last one… caffeine is pretty well known as being a performance enhancer due to blocking that feeling of fatigue. Research shows that 75-90% of athletes turn to caffeine to boost their energy and get through competition without fading.

Want the long story of how caffeine works? Check out this TED talk.

Using Caffeine for Performance:

First, let’s discuss dosing, as how much you take and how much you can handle make all the difference when we get to discussing performance benefits. There are three types of people when it comes to caffeine; hypersensitive, hyposensitive, and normal sensitivity. You likely know which group you fall into. If you have half a cup of coffee and feel jittery, then you’re hyper (very) sensitive and should limit, if not totally avoid, caffeine intake. If you can have a triple latte and go take a nap, well then, you are likely hypo (not very) sensitive to the substance and might have to consume higher than average amounts to see any effects. Don’t fit into one of those two categories? Then you’re like 80% of the population and have normal caffeine sensitivity.  Normal consumption is considered 300-400 mg of caffeine a day which is about 2-3 cups (8oz is a cup guys, this does not mean 2-3 venti Starbucks roasts) of coffee. Roughly half of Americans consume this amount daily with around 25% opting for a high dose of ~600mg/day.

Where to Get your Fix:

Caffeine content is not as straightforward as you might think. When it comes to coffee, type of beans and roasting method matter. A shot of espresso has less caffeine than a cup of black coffee, dark roast has less than the same amount of light roast and instant coffee contains even less than dark roast. It’s also important to remember that decaf coffee is not 100% caffeine free; each cup has roughly 4mg, which isn’t much but can add up if you’re consuming a pot a day. Energy drinks contain a huge range of caffeine from 80mg for the popular Red Bull to over 300mg from the powerful (and very dangerous) Redline. Energy drinks typically pair caffeine with other unregulated stimulants, so be sure to read labels and stick to a small size when consuming these products. Tea, soda and chocolate also contain caffeine at amounts similar to a cup of coffee or less. Other products that contain caffeine at extremely variable amounts are products where the substance has been added in for supplemental purposes included waters, sport gels, bars, gums, and pills.

Click here to see a full chart of caffeine amounts in coffee, soda, energy drinks and food.

Performance Gains:

The high usage of caffeine by athletes is due to the substance being readily available, easy to integrate into nutrition strategy, legal in competition where drug testing occurs, and high potential for increased performance. Like any nutrition topic, there are studies that show caffeine clearly creates benefits and studies that come up with zero findings to suggest performance enhancement. In this case however, most research points to caffeine being a clear performance aid, so we are taking that stance; yes, caffeine helps. Specifically, it seems to help with endurance events; in research these are any athletic effort lasting over 5 minutes with acknowledgment that the longer the event, the more caffeine assists performance. This performance enhancing ability is due to caffeine’s effect on the central nervous system, ability to blunt pain, increase mood, reduce fatigue and improve mental cognition.

A much higher % of studies done on caffeine & performance found benefits than did not.

A much higher % of studies done on caffeine & performance found benefits than did not.

As previously mentioned, caffeine increases the effects of dopamine, making you feel happier and potentially less phased by difficult efforts.  The substance also provides a pain reducing effect, meaning you may feel less soreness after heavy efforts. Studies testing caffeine on sleep deprived soldiers points to clear effects on increased mental focus and athletes know mental strength goes a long way in promoting physical strength. There is thought that caffeine ingestion’s stimulation of fat utilization provides performance enhancing benefits, but this has come under extremely mixed results when studied. Other’s believe caffeine boosts performance by enhancing the gut’s ability to absorb glucose from sources consumed during the effort. I have no doubt this topic will continue to be studied to provide a clearer mechanism of action, but for now, we know it works even if we don’t know exactly why.

So caffeine works, got it… but how well? A well-documented study on 5k runners found that caffeine at a dose of 5mg/kg provided a 1% increase in race times. While 1% may not seem like much, it equates to 12 seconds shaved off a 20 minutes effort and that’s not a bad improvement for such a short race. That same increase for a marathon would be almost 2 minutes off a 3-hour race and any athlete I know would take a 2:58 over a 3:00, especially if all they had to do was drink some coffee. In two studies, one with women cyclists competing an 8.2km time trail and another using mixed gender completing a 10km time trial, caffeinated times were roughly half a minute faster than non-caffeinated times. Again, that might not seem like much, but races have been won and lost by far less than 30 seconds.

There is a gender gap when it comes to caffeine. Studies specifically done on women and caffeine (and there are some!) show that women do see performance gains, but they might come without realizing it; power and time were improved in cycling time trials with caffeine usage but no reduction in perceived effort was reported. Caffeine is also metabolized more slowly in females, meaning women need to ingest caffeine earlier in the workout then men and may experience a slightly higher diuretic (although still not significant) effect.

Oftentimes when we see nutritional studies involving athletes, the trained athletes see less of a benefit from whatever the variable is as compared to untrained, recreational athletes. Beet juice is a great example of this. It is widely agreed that elite athletes are so well trained that little can provide an edge. Not so in the case of caffeine consumption. Studies have indicated that caffeine benefits well trained athletes significantly more than a beginner. If you are at the elite or professional level, you might want to play with a higher dose of caffeine as your body has increased physiological adaptions to the substance. Recreational or beginner athletes might want to start with a lower dose until their bodies are better able to tolerate it.

Besides your body’s trained ability to utilize caffeine, athletes at every stage of training should pay attention to how well they can take in caffeine while performing a serious effort. Caffeine is known to stimulate the gastric system, leading to impromptu bathroom break. This is why we practice and train with nutrition strategy to ensure what is taking in is not going to lead to any negative outcomes. Tolerance of caffeine also depends on how much caffeine you take in daily.

To reap the benefits, you do need a certain dose of caffeine. Most of the studies I reviewed used intakes of 3-6mg/kg or 6-9mg/kg. Doses of less than 3mg (just over a cup of coffee for a 130-pound person) seem to not produce performance benefits. Moderate doses of 5-7mg/kg (~300 – 400ml for a 130-pound person) seem to be the sweet spot. Additional benefits were not seen when athletes were given amounts > 9mg/kg, so moderate is more folks.

Anhydrous caffeine is more effective than coffee, dosing of 3-6mg /kg of caffeine capsules has shown to provide a 24% improvement compared to no caffeine. In reality, few races give the opportunity to consume actual coffee during the effort, so attention should be put the tolerance and effectiveness of pill and supplement caffeine forms.  This is a good time to stop thinking about how many cups of coffee you drink but also take a look at your stash of sports nutrition and check for added caffeine to see how much you’re really getting in a day. This should also make you realize that associating cups of coffee with caffeine intake for sport is a silly thing to do. A 170-pound athlete would need roughly 4 cups of coffee or 6 Red Bulls to get the suggested performance dose. Consuming that prior to or throughout a race is very unrealistic. This is why we turn to sport specific supplements enhanced with small doses of caffeine. See below ‘Strategic Caffeine Plan’ for more on this.

Many athletes who are habitual users of caffeine practice a pre-race withdrawal period in order to become sensitized to the effects. This seems to make common sense; however, the practice holds no scientific merit. Any study looking at the short term; 4-7 day, abstaining period found no difference in the gains achieved by consuming caffeine on race day compared to habitual users who did not abstain. This practice was actually contraindicated in research due to caffeine withdrawal effects (headaches, irritability, etc…) adding to excessive stress and disrupting normal patterns before an important race. As I sit here typing this, I am trying out my first pre-race caffeine withdrawal period of 5 days. I’m slightly grumpy after discovering this research and might actually have a cup of coffee immediately… however, as a high habitual consumer (~400mg/day, yea know…), I think I’ll stick with the potential placebo effect that my body will be more sensitive to the caffeine I give it on race day. At least it’s a good thing to try out and experiment with to know your own individual response. I could not locate any data on longer withdrawal periods. It is key to remember there is a high amount of individual variation in habitual caffeine consumption, effects, and tolerance. Knowing your own body is vital to a successful performance.

I have to say, as a sports dietitian, the more I think this practice through, the more it worries me. If someone is a high habitual user (Yes, I’m raising my hand) and is accustomed to the effects of caffeine pre-workout then abstains only to re-introduce a large dose pre-race race… this could cause a big gastric emptying effect and increase the risk of a mid-race catastrophe. I’m now changing my caffeine strategy; I will have a small dose before tomorrow’s (day before race day) shake out run to provide that initial reintroduction to caffeine.

Bottom line, if you are looking for that edge in your next race, it might be worth adhering to a strategic caffeine plan.

Strategic Caffeination:

Like anything athletes to do perform well, caffeine consumption should be a thoroughly thought out, well-practiced part of the training and nutrition plan. This includes assessing your normal daily caffeine intake, current training status, caffeine tolerance, preferred intake, and timing schedule.  

Your plan should consist of how much caffeine you are planning to take (‘x’mg/kg), what those sources will be (gels, bars, liquids, chews, pills), and when you will ingest these items throughout the race. This should be seamlessly integrated into your nutrition plan. For example, if you’re already consuming 2 gels / hour you do not need to change anything but whether or not you want those gels to contain caffeine. Figuring that step out brings us to timing. Just like everything in sports nutrition, timing is key and this is where many athletes go wrong. I constantly get athletes who take caffeine at the end of an ironman or marathon to get through those last miles of pain and suffering. Have you done this? If so, and it helped, it was likely placebo effect.

Caffeine takes 30-45 minutes to fully go into effect in the body. Taking caffeine at the start of a 5k or only in the final miles of ironman is likely going to give you very little benefit, if any. This is the strategic part; take your total planned dosage and diving it up throughout the race. I advise starting caffeine 2 hours prior for gastric effects to take place. Take another dose at the start line; ~10 minutes prior to the gun, and then space whatever caffeine mg you have left throughout the event.

Caffeine taken post-race along with carbohydrate and protein might increase the body’s recovery rate, however, this practice is generally ill advised as the adverse effects of this late dose of caffeine on sleep habits is seen to outweigh the potential benefit.  

Example Caffeine Plan*:

Race – Marathon

Total Caffeine – 6mg/ 59kg = 350mg

Forto Espresso Shot – 100mg – 2 hours prior

Red Bull – 80 mg – 1 hour prior

Gel – 35 mg – Start Line

Gel – 45 mg – Mile 10

Gel – 35 mg – Mile 16

Gel – 45 mg – Mile 22

Example Caffeine Plan*:

Race – 80 mile Road Race

Total caffeine 6mg/ 80kg @ 480mg

Double shot Cappuccino – 130mg – 2 hours prior

Picky Bar Smooth Caffeinator – 11mg – 2 hours before

1 No Doz Pill – 200mg - Start

GU Chomps ½ sleeve – 50 mg – 1.5 hour (read the nutrition carefully, each sleeve contains 2 servings with 50mg / serving)

GU Chomps ½ sleeve – 50 mg – 2.5 hour

1 Bottles Roctane GU hydration mix – 35mg - throughout ride

*These examples are highlighting caffeine intake only and are not necessarily representative of complete nutrition strategy for these events.

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My personal marathon caffeine strategy practiced for the recent Milwaukee Lakefront Marathon went as follows:

  • Normal intake = roughly 400 mg /day (7mg/kg) a day.

  • 6 days out, only took in 130 mg. Felt good about taking this on!

  • Day 5,4,3,2 = NO caffeine at all.  Abstaining from caffeine helped me get extra naps during my taper, but it also made my GI system feel very sluggish. Also, I missed my lattes! But did replaced them with steamers.

  • One day out, reintroduced a pre run latte ~130 mg. I think this step was 100% necessary. It helped clear me out pre-run (TMI but you athletes get it) and also let me experience a run with my heart rate feeling the effects of a small dose before race day.

  • Race day =

    • 2 hours out Forto Espresso Shot 100mg

    • 1 hour out Red Bull 80mg

    • 15 minutes pre start caffeinated gel 35 mg

    • Mile 10 caffeinated gel 35 mg

    • Mile 15 caffeinated gel 45 mg

    • Mile 20 caffeinated gel 35 mg

  • So was this practice worth it? Yes, I would do it again… of course it is difficult to say based on one try if it actually helped or not.


Of course, those potential benefits come with potential downsides. Caffeine consumption can promote sleeping problems, restlessness, anxiety, high heart rate and urine production. Many of these issues are personal and vary highly from individual to individual, making specific guidelines difficult to advise. Most athletes are concerned about the diuretic effect which has been shown to be negatable and not an actual risk, just popular myth.  A real concern with caffeine intake at the amounts likely needed to see performance benefit is addiction. Caffeine’s stimulant properties can create the need for more and caffeine withdrawal is recognized as a medical condition. In my opinion the biggest risk in taking caffeine is the possibility to disrupt sleep. Caffeine stays active in the system for 6-7 hours, meaning anything taken late in the day (not all races happen at 7am) will likely result in a poor quality of sleep and it is no secret that athletes need a high amount of sleep to rest and recharge.

Another danger to consider is athletic doping control. Yes, it is legal to consume caffeine, but each overhead organization has individual rulings on how much is legal. Consuming roughly 500mg of caffeine 2 hours prior to a competition would likely result in a positive urine test with the NCAA. That might seem high, but considering the amount of caffeine supplements available, that limit can be easily (although maybe not safely) reached. WADA & IOC once had a stricter restriction placed on caffeine, however it has been moved completely off the banned list due to not meeting the agency’s standards of proven performance-enhancing effects, a significant health risk or a violation of the "spirit of sport," which includes illegal recreational drugs. Sorry NCAA athletes.


Caffeine can be an extremely effective way to boost your performance if taken at a dose your body can handle and it is provided at the right during your performance effort. Special attention should be paid to learning your individual caffeine habits in and out of training to develop a protocol that is right for you.

Studies reference:

·      Zhang, et al. Caffeine and diuresis during rest and exercise: A meta-analysis. J Sci Med Sport. 2015 Sep; 18(5): 569-574

·      O’Rourke et al. Caffeine has a small effect on 5-km running performance of well-trained and recreational runners. J Science and Med Sport. 2008 Apr;11(2):231-233.

·      Goldstein et al. Interational Society of Sports Nutrition Position Stand: Caffeine and Performance. J International Society of Sports Nutrition. 2010; 7(5)

·      Astorino et al. Increases in cycling performance in response to caffeine ingestion are repeatable. Nutr Research. 2012 Feb; 32(2): 78-84.

·      Pickering, et al. What Should We Do About Habitual Caffeine Use in Athletes? J Sports Med. 2018.

·      Astorino et al. Caffeine does not alter RPE or pain perception during intense exercise in active women. 2012 Oct; 59(2): 585-590.

·      Arazi et al. The effects of different doses of caffeine on performance, rating of pain perception in teenager’s female karate athletes. Brazilian J Pharm Sci. 2010; 52(4).

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