This post is directly from the LA Times. This article was written in 2010 in regards to Jillan Micheals Kettlebell DVD and other DVD's she has starred on (some claiming 5lbs of weight loss per week!). Please read the article below. I feel that Jillian has done a great service in the fitness industry through her motivation. She has enabled thousands to find that inspiration to get off the couch and to start moving more. However, like many who have preceeded her some of these videos are more concerned about making money than teaching and coaching correct exercise technique. An old rule of thumb is to move better in order to move more. Unfortunately videos like this can do more harm than good. Personally I have watched these videos and if you have a disc issue you WILL make it worse, it's just a matter of time. Enjoy the article and feel free to comment on your past experiences, either good or bad, with exercise dvd's. Yes, videos from Richard Simmons and Jane Fonda count!

http://articles.latimes.com/2010/oct/11/health/la-he-fitness-jillian-michaels-20101011