As the temperature yesterday headed up to 100F, I was reminded of a post that I wrote about running by pace vs. heart rate…and how it applied to running in the heat.
Worth another look if you haven’t seen it in a while:
https://irondaughterirondad.com/running-pace-vs-heart-rate/
Here’s the ‘heat’ scenario:
- let’s say that on a cool day, I run at 10 minutes per mile with a Heart Rate of 120-125HR, and a RPE (Rate of Perceived Exertion) of 1, on a 1-5 scale…so for me all Zone 1
- on a hot day, I run at that same 10 minute per mile pace, but because of the heat, my heart rate is 140HR and my RPE is 3…so a Zone 1 pace, but a Zone 3 on the Heart Rate and RPE scales
What is my training ‘benefit’?…is it:
- Zone 1 based on the pace that I ran, or
- Zone 3 based on Heart Rate and RPE?
Turns out, that after a lot of reading on this, the conclusion is that both workouts are a Zone 1 workout…the extra effort that my heart is putting out is a mad attempt to keep me cool… particularly if I get dehydrated, and therefore even hotter…and the RPE is substantially higher in the heat than on a cool day at the same pace.
The reason that this is important, is that in the beautiful sultry summers of the South, every day can be a hot day…for months…and if I merrily run along, ‘feeling’ that I’m getting a workout because it ‘feels’ so hard, and my Heart Rate is through the roof…I may just be only getting a low Zone 1 training effect, when I ‘think’ that I’m in Zone 3 all the time.
…soooo, on days that I’m doing faster Intervals on the run, I either go out _very_ early, if it’s not too hot, or take it inside and run the intervals on the treadmill…if it’s an 8 minute per mile pace, that’s my target…no matter what my Heart Rate and RPE say.
If the day is really hot and/or humid, I just may not be able to get to and sustain an 8 minute per mile pace outdoors, as my body shuts down running muscles in a self-preservation frenzy…
I know that to run faster, I have to train faster…so pace becomes the determining factor…if my little legs are not moving faster, I’m not getting faster
…so even on long runs where I have faster intervals inserted…like just about all my long runs…instead of running over to the track to do the intervals, I’ll typically be running over to YMCA to get them in
…not as much joy being a hamster on a treadmill, but hopefully all worth it on race day
…outdoors yesterday for a 1 hour run…running back after a 25 minute bike ride to the bike shop to drop it (mountain bike) off…89F out the door, 95F coming in…just under a 10 minute per mile pace, Heart Rate in the low-mid 130’s, RPE 2 to 3 by the end….on a cool day with those Heart Rate and RPE numbers I would running a lot faster, like a 9:00/mile pace
…just a ‘recovery’ run, so used it to work on my tan, and scare people in stores when I came walking in…sweat pouring off me like I had just stepped out of a swimming pool…to refill my Gatorade and water bottles…too funny 🙂