This article is from the Fitness FAQ, by Jeff Gleixner (firstname.lastname@example.org) with numerous contributions by others.
Any exercise can cause an injury when done improperly. To
keep it safe go slow, don't bounce, and don't cheat. The
only exercise that are generally not advised are the following:
-Full sit-ups, do crunches instead.
-Upright Rows, may cause shoulder problems/pain.
-Deep pullovers, may cause shoulder problems/pain.
If you feel any pain during any exercise STOP!