At midday I went to the track - hot and very humid. I ran 8 x 800 meters from 3:37 to 3:24. I used my heart rate monitor and kept my heart rate below 150 bpm at 7 minute pace. I ran the last 800 with a fast initial 200 meters in 40 seconds and then eased up to finish in 3:24. I think I will start doing that more, running around 5:20 pace for the first 100 or 200 and then easing up. When I did that my heart rate stayed up in the mid 150s even though I was very comfortable. Also starting out fast gets my heart rate up to 145 bpm in under 30 seconds so I spend more time in the optimum training zone. It will be interesting to see what my heart rate does when it is cooler and the humidity is lower. This was a very comfortable workout.