There are many exercises for training the core that should be avoided. Some are downright dangerous while others are sub-optimal.
List of dangerous or sub optimal exercises. (Note: This list will be expanded on and explanation on each exercise will be provided.)
– Situps
– Crunches
– Reverse Crunches
– Swiss Ball Crunches
– Situps or Crunches Machines (Lying or Seated)
– Side Bends (Dumbbell or Cable)
– Russian Twists
– Torso Rotation Machines
– Any core exercise performed incorrectly
If you are currently doing any of these you should change to better alternatives form the selection provided under core training.