Oh, did it hurt! Sixty minutes on a bicycle in the pretzel position and the next day I could hardly walk. My lower back was killing me, and I couldn't even turn my head. I immediately called my doctor—a good indication that I was hurting because I generally fend for myself. The doctor I called is a chiropractor. He asked all the right questions, carefully examined my aching back, and noted that my left leg was about one-half inch shorter than my right. X-rays (I do not submit to them routinely) showed a spine that had been beaten up by 30 years of running, but no fractures or collapsed disks. It was a spasm in the muscles of my left lower back that was pulling up my pelvis and making my left leg shorter. He went to work. Starting with my neck, he adjusted my entire spine, and relief was instant, almost magical.

— from Health & Healing by Julian Whitaker, MD