The back is still a bit stiff, but much better than it was. I went for a bout of cross-training last night. I spent 12 minutes on a stationary bike, then 5k on the treadmill (does that count as cross training?) and 1 k of freestyle. Plus I did a few strength exercises, but I need to approach those in a more structured way.
This morning the alarm woke me from a deep sleep and I fumbled my way out the door and ran a lower aerobic 15.5 km in 1:14:35, average pace of 4:48, average heart rate of 141. The humidity made this a tough little run. I only aimed for it to be lower aerobic, but despite the conversation over at Ewen's place, I did find that my heart rate crept up past the upper figure (143) for lower aerobic. I slowed as necessary to stop it going too far out of range, but still the average HR after 30 min is above what it should be, and the gradual heart rate drift can be seen in the pace vs heart rate of the splits.
I was still definitely a lot happier with it as a run than last Friday's, which although doesn't look too bad on paper, practically did my back in.