Back in February, I posed the question of whether stopping exercise triggers depression in a regular exerciser.

Comes a blog commenter two months later with a citation:

· Mondin, G,. Morgan, W., Piering, P. Stegner, A, Stotesbery, C., Trine, M. Wu, M. (1996), Medicine & Science in Sports & Exercise, Williams & Wilkins, 28, 1199-1203

The consequences of exercise deprivation for regular exercisers was studied over a 3 days, with ten volunteers. Regular was defined as at least 45 minutes 6 or 7 times a week. State and Trait Anxiety (STAI) was assessed, plus tension, depression, mood, anger, vigor, fatigue and confusion. Increases in state anxiety, mood disturbance, tension confusion and depression were reported at significant levels.