This month the journal Psychosomatic Medicine published a very interesting paper on the effects of stopping exercise on mood.
Their study involved taking 40 regular exercisers (>30mins per time, >3times/week) who were not taking or receiving any psychological or psychiatric treatment, and simply asking 20 of them to stop exercising for two weeks. They then compared symptoms and mood between those who continued exercising versus those who stopped.
Within one week of stopping exercise, compared with folks still exercising the study subjects reported more fatigue and depressive symptoms which then worsened in week number two.
While we probably didn't need a study to prove this (anyone who exercises regularly and has to stop knows this to be true already), here is now proof of yet another reason not to stop exercising!