I woke up with sore core and tight back, probably from the punching series from yesterday Kenpo. I turned my hips and body when doing the jabs and all the punches. That did the trick. It didn't tire me out but still made me sore the next day. X Stretch was a good choice to loosen up this tight muscles. I know I usually just take a whole day off during rest day instead of doing X Stretch. What can I say, I do want to get extra Zs.