Most people in healthcare that work in/on/around the spine have heard of Dr. Stuart McGill, a PhD from Canada that is the leading authority on spine biomechanics. He’s not necessarily the go-to guy in terms of how to fix or address back problems, but has has done ALOT of research into what NOT to do if you want to prevent or lessen your chances of developing back pain.
What Stuart McGill’s research tells us is that exercises that require high repetitions of lumbar spine (low back) flexion and extension (low back rounding to fully extended) have the greatest potential to tear your discs, cause disc herniations, and potentially cause damage to spinal ligaments.
These are the exercises he recommends NOT to do:
*Toes to bar
*Knees to elbow
*traditional sit up
Notice that all of these involve excessive amounts of low back flexion, or violent transitions between flexion and extension.
Based on my experience and the biomechanics of the body, I also recommend people avoid the following:
*Pigeon Pose- a yoga move that stretches the ligaments surrounding the sacro-iliac (SI) joint.
*A stretch where you lay on your back and bring one leg across your body- same reasons as above.
*Squats where your knees bend more than 90 degrees- this creates low back flexion with the fulcrum being L5/S1, which happens to be the most common area of disc herniation. (wearing weight lifting shoes helps maintain low back extension).
*Kettle bell swings and dead lifts- both of these are amazing exercises, but problems arise when people either use too much weight, or sacrifice form for increased repetitions.
Here are two research articles from Dr. McGill (here and here), though more can be found directly on his website.