Noon run on dirt path. I dusted off my heart rate monitor and decided to see how fast I could run 10 miles if I ran at 145 bpm. I didn't start looking at it until mile 2. I ran the 1st 5 miles in 38:00 and the next 5 miles at 39:45. I was getting tired of speeding up and slowing down to try to stay near 145. I don't think I'll try that again soon.