Getting somewhere

My run tonight ended up being a pretty good double circumnavigation of the Imperial Palace. The legs were a bit stiff at first, but soon warmed up. The rapid drop in temperature (only 20 degrees tonight) has changed the whole pace-to-heart rate equation. At first I was getting along at what I thought was a fair clip, certainly sub 5:00 min/km pace, but the heart rate would not go above 71%. So when I came to the hill after Takebashi I worked it a little and got up to 78%. Finished that lap in 24:07 or 4:52/km. Then on the second lap I worked hard to keep the HR over 80%. It felt fast. Ended up being 4:23/km pace. Still a way to go, but very encouraging. The legs just have to cope with the extra effort needed to make the heart and lungs work the way they have been for cooling. I would expect to see my pace be at 4:15 for this heart rate in a couple of weeks if all goes well.