Nutrition: Caffeine and Triathlon Part 1- Pain Reduction

I decided to investigate the specific interaction between caffeine and the physiology of the endurance athlete. With supplements containing caffeine gaining an increasing foothold, I wanted to know specifically how and why caffeine may enhance or inhibit my performance. From GU including 35mg (about half to one-third the amount in a 7oz cup of brewed coffee), to Chris McCormack placing Red Bull in his special needs bag early in the run at Kona at the advice of Peter Reid, caffeine is starting to be a widely advocated supplement. The International Olympic Committee even recently removed it from its list of banned substances. But, beyond the benefits purported by advertisements or hearsay (be it from a world champion or not), I wanted to know the science behind the buzz caffeine provides. Though I'll refrain from referring to caffeine as 1,3,7-trimethylxanthine, I did reference primary sources from research journals and here is what I found:

Background:

From a past research project on caffeine, I knew that the compound is a competitive antagonist of adenosine. This means that caffeine binds to adenosine receptors in the brain, blocking the binding of adenosine. As adenosine is a neurotransmitter with an inhibitory effect (it promotes a calming response, such as promoting sleep and inhibiting excitement), the blocking of adenosine results in the excitatory response we so frequently associate with caffeine. For a visual representation of this phenomenon, please refer to the figure below:

More than allowing you to terrorize the Japanese, the ingestion of caffeine results in physiological changes that a triathlete would find beneficial. Journal articles repeatedly refer to caffeine as an 'ergogenic aid', which is the way individuals with PhDs say 'performance enhancing.' Motl et al hypothesized that, given Adenosine's role in nociception and pain processing, the inhibition of adenosine by caffeine could play a role in inhibiting the processing and perception of pain stimulus. In a study published in the Journal of Sport Nutrition and Exercise Metabolism, they found that quadricep pain induced by cycling was reduced with caffeine consumption in both habitual coffee drinkers and those who rarey consume caffeine. Though they did not elucidate the specific physiological mechanism, accroding to Motl, ""We've shown that caffeine reduces pain reliably, consistently during cycling, across different intensities, across different people, different characteristics. (1)"