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  Last updated: 4/14/2019


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 about other benefits or negative effects from coffee (and caffeine)?

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 drawbacks, which do vary from person to person, there are at least two studies supporting a health benefit from that morning cup of coffee.

The first, 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 also reduces the risk of stroke, the overall risk of cancer, Alzheimer's disease, suicide and depression.

The second demonstrated a decrease in overall mortality which increased along with 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.

We know that that is individual variability in the rate of caffeine metabolism. Is it possible that those health benefits apply preferentially to a subgroup of riders, those that are rapid metabolizers of caffeine? That group would be protected from any negative effects of high caffeine levels. This blog entry weaves together the findings from several independent studies to raise that possibility.

But I find the results from this registry analysis from the United Kingdom more persuasive as it is direct evidence rather than a derived and thus more speculative conclusion.

Their finding: "Coffee drinking was inversely associated with mortality, including among those drinking 8 or more cups per day and those with genetic polymorphisms indicating slower or faster caffeine metabolism. These findings suggest the importance of non-caffeine constituents in the coffee-mortality association and provide further reassurance that coffee drinking can be a part of a healthy diet."

How much caffeine do you need to get a performance boost?

Keep in mind that the dose/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 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 one hour prior to your event (and urine screening) will keep you in the range of a maximal allowable urinary concentration. BUT, and this is an imporatnt but, individuals do metabolize caffeine at different rates, and medications may significantly alter the rate in which caffeine is cleared from the body. A rare athlete might flunk the urine test after ingesting only 350mg. So if you are going to be competing, and want to be on the safe side, use a 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) indicated that a dose of 9 mg/kg of caffeine was actually INFERIOR to 3 and 6 mg/kg. And in 2012 we find a study indicating 3 mg/kg of caffeine 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 from your cup of coffee? Based on published articles:

My conclusion was that 210 mg of caffeine (3*70 kg or 210 mg) before a ride, basically a single tall Starbuck's coffee, is more than enough to give a definite boost with minimal side effects. Further support for that recommendation is found in this meta-analysis published in 2019.

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 caffeine 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 exercise, 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.

Questions on content or suggestions to improve this page are appreciated.

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