High HR reading in 5K

Last night I did a 5K race, which is part of a series, I also did one in June.

In June it was happened over an unusually warm period, Garmin reported 22C at 7:30PM. I clocked around 18:35 (pretty close to my PB) with an average HR of 172 and max of 182. Those HRs align with what I’m generally see.

Last night Garmin reported it at 26C and I did 19:09 with an average HR of 180 and max 188, so around 8 beats higher.

So, was that due to:
a) The heat?
b) The magnetic race number pins I used for the first time interfering with chest HRM?
c) COVID - I had a weekend away with the lads, one of feeling rough and has since tested positive. I’m currently feeling fine (well I thought I was) and testing -ve.
d) Something else

a) the heat


likely the heat but dont sweat the small stuff as you’re only looking at one race. if it becomes repetitive you then need to dig deeper as to why.

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I’m usually pretty good in the heat, but 20mins into an easy run in yesterday’s heat I was about 15bpm above what I would normally experience.

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Certainly a, possibly c and maybe d…

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Have you ever seen HR of 188 before?
Ever seen a HR between 182 and 188?

If you’ve never been over 182 then 188 seems slightly too much of a jump to be real to me? But if it’s only a couple beats higher than what you think your max is then I’d vote for heat +/- possible covid - my HR was 10 beats high throughout ironman.

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Last year I saw up to 186, but since I had covid in November I’ve not been past 182 since then.

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:fire: Not unreasonable then :fire:

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Chest strap or wrist?

Edit ignore me, you said chest

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I did 5k on the treadmill this morning (can’t run outside yet, recovering from a soleus tear).

Managed to hit a maximum of 194 bpm. And, judging by the state of me when I finished, I’d concur that was accurate.

Solely down to the heat, in my book!


Can you show us the individual records have no obvious anomalies, or the HR graph?

This is the graph from Coros:

Link to Strava activity: 5.0 km Run Activity on July 19, 2022 by Ben W. on Strava

All looks ‘normal’ to me, just high.

I guess I was thinking my max was my max and in the heat I’d have to effectively reduce physical exertion to balance the equation, which I did to a degree (slower time), but the equation didn’t balance (normal max was exceeded). But I guess I now realise my max is my max under normal conditions (e.g. weather, fitness, fatigue and illness).

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Then I’d say the recording is probably accurate. But I’d probably stick with 186. Maybe do a maxHR test if its important for you and verify?

Using an optical HRM?