Heart Rate Variation with Temperature

I have huge differences in my heart rate based on external conditions, but I’ve seen an even larger gap this year as my fitness and volume has increased considerably. My heart rate is so much lower across the board in cool and non-humid conditions that you would almost think I’m 2 different people. I’ve seen a similar trend in running too, but it’s no where near as pronounced as in cycling.

As an example, below are my heart rates in different zones from doing outdoor workouts in hot/humid summer conditions.:

Z2: 130
SS: 160
FTP: 162
VO2: 168
Max: 174

Recently have done a couple workouts with temps in the 50s and low humidity- here’s about the HR splits that I saw. I almost give Lionel Sanders a run for the money with low HR:

Z2: 115
FTP: 140
VO2: 148
Max: 155 (I rarely crack 150)

I’ve also seen a similar split indoors as well performing workouts with no fan/cooling vs with the AC lowered and a big fan pointed right at me!

I know that it’s fairly common to have swings in heart rate based on external conditions, but I’m curious as to how others’ threshold and max heart rates vary based on temperature.

I’m in the same boat. Can’t decide whether my heart rate can’t go higher because it’s colder or just because I’m at the end of a hard training block

The HR will go up with temperature.
The body goes to work to try to cool down.

its perfectly normal…
There are tables out there that suggest your running pace (sorry not familiar if there are any for cycling) for temps higher than 60F

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Temperature has an affect on HR. In general, it is about 5-10 bpm increase when the temperature is 10 degrees above your normal training temp. I’m willing to bet Coach Chad has more accurate data on this subject. But, from experience, HR increases with temp.

Also, it is quite normal to see a decrease in max HR at the end of a training cycling. I’m interested to see what you hear rate variability(HRV) is compared to your baseline HRV.

Yeah no doubt HR is higher at higher temps and especially humidity due to less evaporative cooling. Riding at threshold at high Z2 heart rate feels strange, even though I should still be getting the same training affect from riding at threshold power.

One thing that I have wondered about is whether recovery is impacted by heart rate (and corresponding temps). I really only feel beat when I’m riding a low cadence (e.g. climbing), and that feels the same regardless of temperature. Certainly running in higher temps takes a lot more out of me, but I’ve never really felt that in cycling so long as I stay properly hydrated.

Yeah, the way your body cools itself is to increase blood flow to the skin where it’s cooler. The hotter you get, the more it does it, thus increasing your heart rate to move the blood.

I’ve had some pretty good experience on both ends of temp this week alone. Last week my basement was under 60 degrees and humidity in the 30-40% range. Sweet spot at 92% was glorious.

Yesterday my basement was near 80 and humidity at 70-75% and I had 95% intervals. It was a big nope. Trying to salvage the training day I did a 20min zwift race and ended up with an IF of 0.91 but my HR was what I’d expect for the 95% effort (I prob should have just reduced the intensity of the planned workout but I’m at the end of a block and I don’t care that much lol)

I believe the idea training temp inside is around 60 and below

In my experience the recovery is affected by lack of hydration.
The HR will let me know when i get to the point where the rest of the day will suck

HR is only one element of recovery. Heart Rate Variability is a better indicator of recovery along with sleep. Sleep has a massive affect on recovery.

I have a Withings sleep tracker mat and it consistently shows a higher average HR for the hotter nights. Usually 3-4 bpm higher.

So not just during training where you see the variation based on conditions.

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