A very interesting article (well, to me anyway):
http://www.theatlantic.com/health/archive/2014/09/how-exercise-could-erode-teeth/380851/
From the article:
The IOC suggested that the high rates of tooth decay and gingivitis among elite athletes could be linked to sugary sports drinks. A reasonable proposal, especially since you can often find Olympians gracing the bottles and advertisements of those sports drinks. But a small new study published in the Scandinavian Journal of Medicine and Science in Sports found that there might be a less intuitive reason for the hot bods/bad teeth connection.
and
Everybody’s spit had pretty neutral pHs when they were just sitting around the lab, jawing on some wax. But, and this is where it gets interesting, athletes saliva had a significantly higher pH (meaning it was more basic, or alkaline) during the workout. They also produced less saliva overall.

