Tues AM aerobic

Run type: Lower aerobic, target HR 140-145
distance: 16.2 km
Time: 1:13:58
Average pace: 4:34 min/km
Cumulative weekly km: 23.8
Weather: 25 degrees and moderate humidity

This run provides a very clear contrast to that of last Friday morning over the same course and distance. The only environmental difference was that today the humidity was lower. Today was 10 sec/km faster overall. That's quite a difference. Yet the heart rates were quite similar. In fact, even as I worked the legs at a solid effort today, the heart rate wouldn't rise. Today, at a heart rate of 143-145, I was doing the same kind of pace and leg effort that was previously producing heart rates of 150+ along with pronounced cardiac drift.

On the way home I decided to push the last couple of km. The last km was close to 4 minutes flat. Yet my heart rate maxed at 158. However, the really instructive thing was that as heart rate came up to about 153, only then did my breathing begin to labor at all. Prior to that it was pretty comfortable, with only the legs having anything to complain about. Hadd/Lydiard training works. It is now a question of continuing the conditioning so that the labored breathing does not cut in until closer to 160, and also getting the legs more used to running at faster speeds.

So, the conditioning has been taking place and the weather does make a difference. Which of course we know, but it is fascininating seeing it so clearly like this.