Well....I definately did a number on my back. It happened on Monday and today (Thursday) is the first day that I feel a slight improvement. I did my workout Tue night and substituted 15 squats for the 10 box jumps as the box jumps definately would have sent me over the edge. I finished the workout in 15:15. I woke up Wed morning in more pain than I was in on Tuesday. I don't blame it on the workout - I think it is just running its course.
I skipped both workouts yesterday as my back definately would not have tolerated rowing or running. Today is a day off and although I would love to do a workout to make up for missing yesterday, I think resting the back is more prudent. I will reassess tomorrow.