I went out at 7:30 am and it is COLD! I usually feel quite warm and peel off a layer after warming up, but today my buff stayed on my head and my jacket stayed on too. Almost unheard of!
That was hard, and I'm sure that my fast running (at least according to my Garmin) was not much faster than my slow. I did the 152bpm bit very slowly, a proper light jog, and sprinted (in a fashion) during the fast bits, burning out at about 45 secs, and slowing toward the minute. I'd like to be able to stretch the x axis on my Garmin graphs to see what was actually going on.
I caught a Twitter link from the Asics store today, and it looks like they do threshold testing. I might do a session.