My lower back's felt a little stiff for a couple of days, which I've attributed to crazily jumping around barefoot on a concrete garage floor with minimal padding. Today, I finally heeded M's advice to pull out our super-thick, padded gymnastics mat to help cushion my landings during Max Interval Circuit. It certainly helped -- my back's a lot happier today, and I was able to get through the entire workout without taking any unscheduled breaks.
Still, I can't help but feel a little guilty for allowing myself that much extra support. Plus, my ankles are less likely to roll on a more stable surface. Today was a nice respite from the usual pounding, but I'll likely be mothballing the gymnastics mat again, and going back to my Manduka.