I’ve noticed that when I run first thing in the morning my HR at a given pace is much higher than my HR at the same pace running after work.
For example, I’ve been running on the treadmill for 45min in the morning for the past few weeks, trying to maintain an easy pace with my HR at 70%max. I’ve found that this paceturns out to be ~6 mph in the AM, whereas it’s ~7 mph in the PM for the same HR.
Does anyone else experience this? Any idea what the cause would be?
Originally, I thought it may just be that I needed to give my body time to adjust to the early morning runs (I had been running only after work), but it doesn’t seem to be changing.
Dehydration is what causes it for me. I remember once I ran a 1/2 marathon, it was my first one actually, and I had a REALLY unusually high HR that morning. I finally narrowed it down to the fact I was really dehydrated going into that race.
Mark
That was my thought, too. I notice HR elevation the most when I have a couple drinks the night before. No alcohol the night before my long runs anymore. It gets too frustrating to have to run 11-12 minute miles.
After years of running, I noticed for the same same PE, my running time would usually be around 30s to 1min/mile slower in the morning then when running at lunch time or in the evening. I always attributed it to lower body efficiency in the mornings.