Caffeine is said to be the world’s most popular drug. The stimulant’s cognitive and physically uplifting effects are widely appreciated, and at least 85% of US adults drink one or more caffeinated beverages a day. Coffee is also closely associated with cycling culture, with good reason; aside from being a social lubricant, caffeine has well-documented and potentially significant performance-enhancing effects. Should you be incorporating caffeine into your cycling in a more deliberate way?

For more information on caffeine and cycling check out Ask a Cycling Coach Ep 271.



How Caffeine Works in The Body

Under normal circumstances, metabolism of ATP causes adenosine to gradually accumulate in receptors in the brain, eventually resulting in drowsiness. Caffeine acts as an adenosine antagonist, binding to and temporarily blocking these receptors from activating. It also stimulates some secondary effects such as elevated heart rate and mild euphoria. 

Caffeine commonly triggers tolerance with regular use. Likewise, suddenly ceasing consumption has noticeable effects. Drowsiness, headaches, irritability, and lack of focus are common results of caffeine withdrawal, familiar to any regular coffee drinker who stops cold turkey.

Caffeine’s impact and the pace at which the body metabolizes it are highly dependent on genetics. Half-lives of 2 to 12 hours have been recorded, meaning some individuals may take up to 6x longer to clear caffeine from their systems than others! 6 hours seems about average, meaning most people still have 1/2 their coffee’s caffeine circulating in their blood 6 hours after drinking it, and ¼ still present after 12 hours.

How Caffeine Can Enhance Athletic Performance

Caffeine’s effects on athletic performance are well-acknowledged. The World Anti Doping Agency even banned high levels of caffeine from competition between 1984- 2004. Although it’s no longer banned, caffeine consumption is still monitored by WADA.

Exactly how much caffeine improves athletic performance varies. Some studies show no improvement in maximal efforts, but most show at least some measurable impact on endurance, averaging around 3%. However, like caffeine’s effects generally, this is also genetically-determined. A study of cyclists riding 10k time trials found that depending on the rider’s gene variation, some athletes improved their time with caffeine by as much as 6.8%, some experienced no effects, and others experienced a 13.7% decrease in performance!

Despite WADA’s former ban on high doses, most athletes experience the strongest ergogenic effect with about 3 – 6 mg of caffeine/kg of body weight. This is actually a relatively “normal” dose, equivalent to a cup or two of Starbucks coffee for most people. There’s a good chance you consume a performance-enhancing amount of caffeine every morning without even realizing it.

Caffeine Content of Common Products

Beverage/Product TypeServing SizeCaffeine (mg)
Starbucks Coffee, Blonde Roast16 oz.360
Dunkin’ Donuts Coffee14 oz.210
Keurig K-Cup (Most Varieties)1 K-Cup75 – 150
Starbucks Espresso0.8 oz.75
Green Tea, Brewed8 oz.28-38
Diet Coke12 oz. 46
5 hour energy2 oz.200
Monster Energy16 oz.160
Red Bull8.4 oz.80
Clif Shot Energy Gel Mocha1.2 oz.50
NoDoz or Vivarin1 tablet200
Source: Center for Science in the Public Interest

Caffeine Side Effects and Misconceptions

Like any psychoactive substance, caffeine does some undesirable things too. According to the Mayo Clinic, over 400 mg a day can cause headaches, insomnia, upset stomach, and anxiety, and 14% of Americans drink this much caffeine regularly. Large doses can be fatal, and while this is unlikely with beverages it’s possible with tablets or powdered caffeine. 

Caffeine can hinder uptake of certain nutrients. Most notably for athletes, it can temporarily reduce Iron absorption by up to 90%. It also affects the body’s metabolism of calcium, Vitamin D, B-vitamins, and Manganese, among others. Luckily, impacts are short-term and reduced at lower doses. Use moderation in how much caffeine you consume, and take vitamins and supplements at least an hour apart from caffeine to reduce unwanted interactions.   

Interestingly, the common perception of caffeine as a diuretic seems mostly incorrect. Caffeine can have diuretic-like effects if you are not used to it, but among people who consume it regularly it does not seem to hinder hydration. The method of consumption can have impacts, though: coffee, for instance, is a well-known gastrointestinal irritant. 

The most important and common side-effect of caffeine is sleep disruption. This varies dramatically from person to person, but caffeine’s long half-life means that late-day doses can easily persist into the night and affect the quality of your sleep.

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Tips For Training With Caffeine

As we’ve already discovered, caffeine’s effects are extremely variable. Therefore, the number-one piece of advice is to experiment and find what works for you. No single regimen will benefit everyone, and depending on your genetics there’s a chance caffeine wont even help you at all. 

Consider how much caffeine you already consume. 3-6 mg/kg body weight (about 300 mg for a 150 lb athlete) is the optimal range for performance enhancement, with a daily ceiling of around 400 mg a good guideline. Tolerance has a strong impact on effect, so if you already drink a lot of coffee and want to achieve a noticeable benefit it might be a good idea to reduce your overall daily caffeine consumption. However, sudden reductions can seriously and negatively affect your training, and consistency is more important than one supercharged race day. Weigh any expected performance improvements against the potential downsides of withdrawl. Most of us are habituated to caffeine already and need to work around this fact.

Timing Is Key

Caffeine peaks in your blood 30 to 60 minutes after consumption, and exercise may slightly increase your receptivity to it. Postponing caffeine intake until your race or training ride can make the effects more noticeable. For long events or triathlons, this means you should strategically pace your caffeine ingestion to be most beneficial. A massive dose at the start of your race might not help you much by the end, but smaller and more carefully-timed intakes could be just what you need. 

Minimal Effective Dose

With its long half-life, even repeated small doses of caffeine can add up quickly and lead to sleep disruptions. Always be aware of your total intake, and remember to include your morning coffee in this calculation. Approach every workout with your next workout in mind, as ruining your sleep can hinder recovery and impede your consistency. This is especially important in a stage race, but even a hard 1-day event followed by a poor night’s sleep could lead to illness or a disruption in training. Experiment to find your sensitivity and always aim for the minimal effective dose, as larger intakes are not shown to trigger any additional improvement.

One final important note concerns the method of administration. Most studies looking at caffeine involve athletes taking it in capsule form, and some studies suggest that ingesting it in the form of normal coffee may actually weaken the ergogenic benefit. While this would seem to argue in favor of caffeinated supplements, be extremely careful with pills and powders. Caffeine powders are particularly prone to overdose, and we generally recommend against them because of this danger. Choose a form (such as gels) that allows your intake to be carefully controlled, and take the lowest dose you can to achieve a performance benefit.


For more cycling training knowledge, listen to Ask a Cycling Coach — the only podcast dedicated to making you a faster cyclist. New episodes are released weekly.


Header photo credit: Unsplash
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Sean Hurley

Sean Hurley is a bike racer, baker of sourdough bread, and former art professor. He is a connoisseur of cycling socks, and a deep believer in the power of periodized, science-based training. Rumor has it he also runs a famous cycling instagram account, but don't tell anyone about that.