Standing toe touches, military presses, standing quadricep stretch, double leg raises, and full sit-ups are all contraindicated exercises. Some instructors and trainers do not feel this way. Do you still teach them? Why?
The answers are great. Contraindicated is an ambiguous term. Teach your class to the least fit. The most fit will modify as they can. Working one on one, you will know your client and what he or she can best be challenged by.