See link below, improper meditation posture can have serious consequences: http://www.laserspineinstitute.com/back_problems/spinal_bone_spurs/
I don't think Maharishi had foreseen this! Although I remember him saying once that a meditator should have a pillow for his neck or he could have serious neck pain at a lecture I heard, though why it's apparently not in the checking notes is beyond me!! More sloppy TM management, leadership!
