VO2Connection

Coffee, glorious coffee, Coke, tasty Coke, tasty tea and Oh! the delightful Red Bull; these are just a few of the ways that we caffeinate ourselves.  With performance in mind or not, many athletes consume caffeinated beverages or foods on a regular basis.  So what exactly are the benefits and/or detriments of caffeine?  Should it be avoided or rejoiced?

Caffeine is the most widely used drug in sport and the world. Athletes often use it for ergogenic purposes but science has yet to conclusively figure out how it actually enhances endurance performance.  But we know that it does; almost every study that has tested the effects of caffeine and prolonged strenuous exercise has been positive.  However, caffeine has very little effect on muscular strength or events less than 1 minute in length.

Possible mechanisms for caffeine’s ability enhance endurance performance in everyone from runners to swimmers to cyclists may be due to increased carbohydrate oxidation, or decreased rating of perceived exertion via blocking adenosine receptors (fatigue triggers). It was previously thought that caffeine enhanced fatty acid mobilization but recent studies have shown that it actually increases carbohydrate oxidation when consumed with a carbohydrate containing beverage.  This is a good thing because this enhanced oxidation is a result of increased carbohydrate absorption from the intestines.  The more carbohydrate available for use, the less likely you are to “bonk”.  Habitual consumption of caffeine doesn’t seem to negate the ergogenic effects but can cause dependence and a certain level of tolerance.         

What about GI upset?  The good news is that a caffeine plus carbohydrate containing beverage causes no greater incidence of GI upset than just a carbohydrate beverage.  The bad news is that GI upset with either is still significantly higher than water alone.  So if your race is less than 70 minutes just drink water to avoid GI distress. 

What about dehydration?  There are lots of nasty rumors about caffeine being the dehydration monster but recent research has not found this to be the case.  Rehydrating with caffeine containing beverages verses non-caffeine containing beverages after exercise results in no difference in urinary output or electrolyte balance; additionally this study was conducted over several days of exercise in moderate heat (23 C). 

How much is enough?  Most studies have used 3-10 mg/kg/ body weight of caffeine.  In “real terms” this is 1 ½ – 5 cups of coffee for a 110 # person or 3 – 10 cups of coffee for a 220 # person.  I don’t recommend anyone drinking 10 cups of coffee and most studies show diminishing returns beyond 200 mg of caffeine (about 2-3 cups of coffee).  Caffeine consumption related to performance enhancement was generally 1-2 hours before exercise or immediately after exercise for research pertaining to rehydration.  Some studies have looked into the effects of consuming caffeine containing beverages during exercise.  These studies show increased rate of carbohydrate uptake and oxidation, increased time to exhaustion, and lower rating of perceived exertion.  One of the main shortcomings of these particular studies is that they are conducted in a controlled environment where caffeine beverages are consumed at regular intervals throughout the exercise testing period.  In real life race situations it is difficult to consume enough caffeine to have an ergogenic effect (how much defizzed Coke can you really get down at 40 k). 

Caffeine is relatively safe and has no known negative performance effects when consumed at a level of 5 mg/kg/body weight or less.  It can increase gastric motility, cause headache, increase blood pressure and heart rate when consumed by people who have a very low tolerance so it’s not advisable for the non-caffeine drinker to consume three cups of strong black coffee the morning of the biggest race of the year.

Personally, I love coffee.  I drink it everyday.  I try to cut back on my consumption a few days before I race.  This makes me feel like I get a little better “buzz” from my usual amount on race morning (non-caffeine drinkers show a greater response to the substance).  If I drink too much I get “gut rot” and if I try to drink Coke during a race I usually throw-up.  That’s all non-scientific data but I’ve learned what works for me and that’s something that the research can’t tell you, so experiment on yourself, just not on race morning.