Since we released this program in 2009, we’ve updated the program based on our observations with our training clients and also from the feedback from those who have run through the program.Based on this feedback, we’ve found that the following skills tend to be the most challenging ones, so we’ve created detailed articles to help you break these movements down even further if you need to.L-SitSkin the CatMuscle-UpFront and Back Levers