I did my tempo run this evening again with the Runner's Choice Marathon Training Group in London. Coach Brian suggested a 9 mile (14.4 km) tempo run -- just like last week -- with the second half of the run at better-than-race pace. We targeted an 8:15/mile (5:07/km) pace going out, and then we were looking for a 7:30/mile (4:40/km) pace coming back. Coach Brian would pace me and fellow runner Berne Leforte was going to join us for as long as he could. Well, that's how it started.
It was a warm night and it is well documented in text and video that I don't react well in the heat. The run out to the turnaround point was fine. But when we stated back, the internal temperature started to rise and with about 1.5 miles to go (i.e. only 3 miles into the fast part of the run), I had to walk. Bernie had lots of energy though, and kept on truckin'. Brian and I eventually picked up a jog, and then for the last mile back, we picked it back up to something resembling tempo pace.
About the only saving grace was that lots of other runners were having similar issues. And, as Brian said, if you hit all of your goal times, you probably didn't set the goal high enough. Well, clearly the 3:25 marathon goal time is high enough!
Here were my times going out (target 5:07/km) according to my GPS:
5:12 (400 m.)
And here are the times coming back (target 4:40/km):
4:29 (400 m., back running again)
The average time was 5:00 per km. -- the same pace as I did in Boston last year. This was just 1/3 the distance, but between the heat and the hills on the way back, I simply couldn't do it.