Right, I had a head cold on Tuesday evening after my run (well before/during actually, but I had thought it was just sniffles), so I took it easy and didn't run again until after work on Friday.
I did the same route & distance (roughly) as Tuesday, keeping myself as much as possible under 143bpm. I did the same distance in 2mins less! My reasoning says that when I had the cold I had to exert myself more, so my HR would have been a tad higher anyway, which meant I had to run slower or walk to keep it under 143.
Hopefully as the weeks/months go by I'll see my aerobic fitness increase, and I'll be able to run faster but be exerting myself less and still keeping my HR low.
I'm meant to be doing a LR today, but there's a storm overhead at the moment, so I'm chilling out and catching up on emails etc. If it improves, I'll do the run after lunch. Otherwise I'll do it in the morning, forecast for tomorrow is a lot better!
Just yesterday I found a split in one of my NB 1225's between two of the layers on the sole...not good: