Are Crunches and Back Extensions Breaking Your Spine? Traditional sit ups, crunches and back extensions do more harm to the lower back than most people realize. What is worse is they do very little to improve core stabil

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Date: 2012-07-19 07:13:14		Are Crunches and Back Extensions Breaking Your Spine? Traditional sit ups, crunches and back extensions do more harm to the lower back than most people realize. What is worse is they do very little to improve core stabil Add to Reading List Source URL: www.pt-nijmegen.nl Download Document from Source Website File Size: 64,08 KB Share Document on Facebook