Heart Rate Query

About 6 weeks before the Chicago Marathon, I ran a half marathon at my intended marathon pace (8 min/mile). I wore my HM and found that I needed to clock about 158-160 bpm to do it. It was remarkably regular and accurate.

When it came to Chicago, I found I was running nearer 168-170 most of the way, and I only did 8.15 min/mile. I seemed to be perfectly healthy (no temperature or anything) but it was exceptionally cold all the way round.

Does anyone have an explanation?


  • WombleWomble ✭✭✭
    My heart rate tends to be lower in the cold weather. When it's hot your blood is thicker so the heart needs to pump more/harder. On the other hand, I think it's fairly well established that your heart rate will be higher in a race - must be the adrenalin - and that you can sustain a higher HR.
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