Too much of a good thing ... yeah, this saying applies to exercise, too. While it is very important to always push yourself hard during workouts, going TOO far (or too often, too long, too much, etc.) can lead to over-training.

When this happens, you actually start regressing. Muscle wasting occurs, body fat storage can increase, and immune suppression can lead to sickness and infection. One of the major reasons for these physiological responses to over-training is the release of excess amounts of the stress hormone cortisol. And while coritsol's body-busting affects have been known for quite some time, new research shows that it may also have a negative effect on your gums.

A study published in the Journal of Periodontology (a must for all summer reading lists) indicates that cortisol can worsen elements of gum disease. Bad bones, bad body, and now bad teeth? Man, that cortisol is some nasty stuff.