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Caffeine is thought to be the world’s most consumed stimulant. For many people, this might mean a morning cup of coffee from Starbucks or Dunkin’ Donuts, a can of Coke with lunch, or an indulgent chocolate treat afterwards.

Your average gym junkie’s caffeine intake, on the other hand, might come from a very different product. That’s because caffeine is also one of the most common ingredients in pre-workout supplements.

Studies have indicated that caffeine can boost athletic performance by between 1 and 3%. To be more specific, it can enhance athletic endurance.

The Caffeine Kick

Plenty of research has been done certifying caffeine’s strong showing as a performance enhancer. A study of tennis players found that caffeine gave them extra energy towards the end of long matches. Cyclists, runners, and rowers, meanwhile, have all been documented as recording better performance times.

As a stimulant, caffeine quickens the pulse and temporarily heightens blood pressure. It might seem to follow that increased blood flow to the muscles is what gives caffeine its kick. Chemically, though, something else is at play.

Caffeine reduces our sensitivity to a substance called adenosine, a chemical found in all human cells. Adenosine plays a role regulating the sensation of tiredness and fatigue – the less receptive we are to it, the longer it will take us to feel tiredness and pain.

Caffeine also has an effect on the body’s fat stores, allowing them to be used as energy. This results in a phenomena known as glycogen sparing.

Glycogen can be thought of as the body’s reserve fuel source, stored in the muscles and liver. By delaying the exhaustion of glycogen reserves at the point of the muscle, caffeine can further enhance athletic stamina.

Allowing us to keep going for longer in various ways, caffeine comes into its own in cardio training and endurance sports. This is doubly underlined by the fact that the effects of caffeine are at peak levels between forty-five and sixty minutes after it’s been taken.

In fact, when it comes to muscle glycogen depletion, peak results occur even later, after three or more hours.

Too much of a Good Thing?

This all sounds great, but how much caffeine should we be taking, and how often?

Sports Nutritionist Dr. Nancy Clark recommends no more than around 1.5 milligrams per pound (or 3mg/kg) of body weight, around an hour before exertion.

To put this in context, for an athlete weighing 160 pounds, that is less caffeine than is generally found in a small black coffee.

The performance enhancing effects of caffeine actually max out at around the 200-250 mg mark anyway. That’s a lot less than the amount previously recommended, and in many cases will even be below what’s found in that same small cup of black.

Caffeine, of course, can be found in a variety of products and formats, from sports and energy drinks to gels and gum. The problem with many such products, though, is that they don’t state exactly how much caffeine they contain, which makes determining the right dosage difficult.


The general consensus is that in caffeine terms, more doesn’t equal better. Each athlete, in any case, will respond slightly differently to its effects. As much as it can produce positive results in some, it can work the other way as well.

Overindulged in, caffeine can affect stomach acidity, which might contribute to the notorious ‘coffee belly.’ Others report jitteriness, disturbed sleep, headaches and anxiety.

As if all of that wasn’t fatiguing enough, there’s also the danger that too strong a reliance over long periods could actually be detrimental to performance. If a large dose enhances one workout, for example, could it fry you for the next?

Special care should also be taken when considering exactly what activity you plan to use caffeine with. Although the World Anti-Doping Agency (WADA) reversed a long-standing caffeine ban for athletes in 2004, the governing body for college sports in the U.S., the NCAA, still prohibits it above 15 mg/ml of urine.

As with any other element of your diet or workout regimen, then, the best advice is to carefully assess what levels work best for your own situation, on the off chance you end up doing more harm than good.

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