I've found Vox's new website to be great for news. Ezra Klein, Matthew Yglesias, and many other contributors have made it an excellent source of information. Full disclosure: Vox is owned by the same parent company as SB Nation and Badlefthook.
Across all these activities, the gains from caffeine are modest but consistent: on average, a dose before an eventleads to a three percent improvement, whether in race times or other measures. This obviously isn't a ton, but for people bent on shaving every second possible from their times, it makes a difference.
1) Caffeine improves endurance;
2) Caffeine may make muscles more powerful; and,
3) Caffeine may dull the body's sensitivity to pain and exhaustion.
The gains from caffeine are modest but consistent.
I thought this was an interesting article about caffeine. I know from personal experience that I always feel better during a sparring session after drinking a large iced coffee. I hope some of you check out the article and Vox in general. So far it's been an excellent news source.