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Taken my max heartrate to be 211 for a few years now, but today when putting a lot of effort in very early on in a ride I noticed it was holding steady around 225. As you can see for about a minute or so it was over 220, and at the time I didn't see anything that would be causing it to give an error or anything. Was absolutely fine for the rest of the ride, and the rides before that.
I know about the 220-age thing, so I was surprised to see it over 220.
Yes, possible.
I thought mine was 188 when I was 39ish, then got it up to 198 when getting spat out on a climb in a race in Majorca. Given that you are a wee bit younger than that, I'd say it's probably accurate.
Almost certainly a HRM glitch IMHO - used to get those regularly.
Riding close to powerlines can give you dodgy readings like that. Any of those on your route?
Were you close to throwing up/passing out etc? If so then maybe, otherwise a glitch.
I would regularly hit 207bpm...felt fine until it dropped to 190 then felt ill...lasted about a minute and could be repeated...220-age is some sort of guide for gums to save any accidents with unfit people overdoing it...so I've been told.