Good thing I moved squats from yesterday to today. I tweaked my back memorably this morning. I didn't realize that the "POP" that I heard on my 2nd single was that big of a deal at first. That happens not all that infrequently and generally means nothing much. But an hour or so later, whoa! I can't imagine trying to have taught Jujitsu with my back like this. Already got an appointment with the bone cracker tomorrow.