Caffeine as a performance enhancer

I'm training for the bike portion of an ironman 70.3. Proper fueling during endurance events is always something that needs some practice. No one wants to discover on the day of their race that the new gu they are trying out is causing severe stomach cramping or unnecessary bathroom stops. Today, along with my medjool dates and a couple of chunks of chewy granola bar, I decided to test out the performance electrolyte tabs that nuun makes, containing caffeine. I haven't experimented with caffeine before - I normally head out the door straight after getting up in the morning, so an empty stomach is pretty much my norm. Although research suggests that caffeine is highly effective for most endurance athletes, there is variability, so you want to be sure that it is something you tolerate well before your event date.

My experience was pretty positive - I had noticeably more energy, and didn't feel as "whooped" at the end of my long ride as I normally have felt. It made me curious as to what it is about caffeine that makes it so effective. Here's what I learned:

Caffeine

1) may help make fat more available as a fuel source during exercise

2) as a result of #1, may help spare muscle glycogen, saving more fuel "in the bank" (muscle tissue) for when it is needed later - resulting in the ability to go longer

3) may lower heart rate during sub-max exercise (sub max = staying under 85% of your max heart rate during exercise)

4) may alter your perceived level of effort during exercise (always helpful!!)

5) may improve alertness and focus (definitely a benefit while riding in traffic)

6) may increase endorphins, resulting in feelings of wellness and possibly the athlete's "high" post workout

It's important to note that the performance benefits really seem to be limited to endurance training. Weight lifting, or shorter events such as sprinting, don't seem to show the same benefits. And of course, like anything - not everyone experiences the same benefits. Fueling is something that needs experimentation and practice!