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  Last updated: 11/12/2015


Caffeine, a legal stimulant, is one of a methylxanthines (similar to the asthma medication theophylline) and is found in coffee beans, tea leaves, chocolate, cocoa beans, guarana, and cola (kola) nuts.

Caffeine is both a central nervous system and metabolic stimulant used to reduce fatigue and as an endurance aid for some activities. These effects, which can be quite variable from person to person, can be noticed within an hour of consumption and wear off after four or five hours. It has been suggested that habitual use (a daily cup of coffee) will induce tolerance to the stimulant effects, thus a period of abstinence is needed to gain maximal endurance benefits in an athletic event. However a recent article investigating the effect of a 4-day caffeine withdrawal period on endurance exercise performance (one hour of cycling at 75% peak sustainable power output) proved that a single dose of caffeine significantly improved exercise performance irrespective of a 4-day withdrawal period for habitual caffeine users.

What is the underlying physiology, that is how does caffeine affect us?

What are other benefits and potential risks of coffee as a source of caffeine? On the down side, caffeine can aggravate headaches, insomnia, acid reflux disease, nervous irritability, and an irregular heart beat. In addition as it is a diuretic (can cause an increase in urinary water loss), it can lead to dehydration if one is not careful to maintain their fluid intake during the day.

But aside from these negatives, which are generally variable from person to person, there have been several recent studies suggesting an overall positive health benefit. In the first, it was noted that a daily intake of 3-4 cups of coffee has convincing protective effects against the development of type 2 diabetes and Parkinson's disease, with suggestive evidence that moderate coffee intake reduces the risk of stroke, the overall risk of cancer, Alzheimer's disease, suicide and depression. The second demonstrated a decrease in overall mortality directly related to the amount of coffee consumption per day. This inverse association was observed for deaths due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections, but not for deaths due to cancer.

How much coffee (caffeine) is enough to give you a boost on your ride? As we work through some calculations, it is important to note that the amount of caffeine in a brewed cup of coffee varies. An average 6 ounce cup contains 100 - 150 mg of caffeine but a tall (12 ounces) cup of Starbuck's drip coffee is 240 milligrams (mg). The literature presents results in mg caffeine/kg body weight but I will convert answers for a 70 kg (that is a 154 pound) cyclist.

Keep in mind that the IOC (International Olympic Committee ) considers caffeine doping if an athlete has a urinary level of > 12 mg/liter. A caffeine dose in the range of 9 - 13 mg/kg approximately one hour prior to performance will get you in the range of this maximal allowable urinary concentration. (Note: individuals metabolize caffeine at very different rates and medications as well as certain diseases may significantly alter the rate in which caffeine is cleared from the body. A rare athlete have come close to flunking the drug test after ingesting only 350mg. It is wise to consider this before using caffeine as an ergogenic aid.) So if you are going to be competing, and want to be on the safe side, use the lower dose of 9 mg/kg which would be the equivalent of 2 tall Starbuck's coffees (9 mg caffeine/kg x 70 kg rider = 560 mgs caffeine).

In 1995, a study on endurance performance (85% VO2 performance to exhaustion) demonstrated that a dose of 9 mg/kg of caffeine was actually INFERIOR to 3 and 6 mg/kg. And then in 2012, more detail was provided in a study that indicated 3 mg/kg of caffeine was equivalent to the higher dosage of 6 mg/kg (a common dosage in many recent studies) in enhancing 60 minute time trial performance.

What performance benefits might you see with your cup of coffee? Based on published articles:

My conclusion is that most endurance athletes consider caffeine useful if used correctly, 210 mg of caffeine (3*70 or 210 mg) before your ride, which is basically equivalent to a single tall Starbuck's coffee, is more than enough to give you a definite boost with minimal side effects.

Note: This is a good reference article if you would like more details on caffeine.

Caffeine in Multi-Day Events

As we have seen, there is ample evidence that caffeine improves endurance performance. But it has been questioned whether the trade off for improved performance on day one (in multi-day events) would be a progressive increase in muscle injury and, as a result, less benefit on subsequent days. What are the facts?

In conclusion, daily caffeine appears to be just as effective in improving performance in multi-day events as for single day efforts.

Caffeine aids post ride glycogen repletion.

It may be that caffein is giving an additional boost in a multiday ride via its beneficial effect on muscle glycogen replacement.

This paper demonstrated rates of glycogen replenishment post exercise that were.... "to the best of our knowledge, the highest reported for human subjects under physiological conditions."

Is this going to be a significant factor in your next day performance if you are careful to maximize you intake of carbohydrates and glucose post ecercise, especially in the first hour? Hard to say. But this is another reason to grab a caffeine containing cola (coke, pepsi) when you get off the bike.

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