Can a heart rate monitor read high?

TLDR; easyish ride, HR much higher than it felt.

I don’t have a PM on my winter bike so when I can be bothered I stick on a HRM. I haven’t used this particular one in a while (CooSpoo) but seem to remember it being OK. Had to put a new battery in as it was dead.

Anyway went for a solo Sunday ride. Kept it fairly easy but every time I looked at the HRM it was way higher than I expected. On a few mellow hills I was touching 170bpm - felt slightly uncomfortable, but this would usually have me grimacing big time.

The overall average for the ride was 155bpm, that’s what I’d expect for a full on effort for 50 miles. 130-140bpm is what I’d expect. Point is it felt fairly easy.

I don’t really get how a HRM could be wrong though - I mean it’s a pretty simple bit of kit. The graph doesn’t look obviously crazy either.

The short answer is yes.

A little over a year ago, FitBit showed random spikes in my sleep of up to 180rpm. That caused some anxiety which brought with it shortness of breath.

My GP referred me urgently to a cardiologist.

2 days before the appointment, I was standing in the kitchen making food. My fitbit showed my heartrate gradually rise to over 150bpm. I measured my heartrate manually by feeling for my pulse and using the second hand of the kitchen clock - 80bpm.

I reported this to the GP who got me to wear a holter for 3 days. HR during sleep was normal. On one of those nights, the fitbit showed a period of 140bpm.

The referral was cancelled and I returned the FitBit.

Long story short, see if another device gives similar numbers. If it does, I’d suggest that’s something perhaps actionable.

HR monitors are pulse counters; in that sense, they can’t be calibrated wrong - but they sure can count the wrong pulses. For a strap monitor like yours, the typical issue is the strap being dry; it then tends to pick up other pulses than your heart, such as cadence for runners, and sometimes upper body movements associated with pedaling for cyclists. A bad battery or battery contacts can cause the device to operate erratically, causing HR spikes up/down.

First thing I’d do would be to look at cadence in the areas where recorded HR appears off. If cadence is equal to HR (running) or half of HR (cycling), you have your answer. Make sure the contacts are well wetted before starting; if needed, try one of the gels sold for that purpose. Some synthetic materials behave worse with some straps than other combos, so that’s another solution to look at.

I’ve found a strap can spike high but overall will read correctly if its looked after. An optical sensor though can both spike and read wrong over a ride.

FWIW, We’re all different but 170bpm doesn’t sound absurd to me. I don’t think my CooSpo has ever recorded 200bpm plus, I would find that absurd and right it off a spike.

Even your own personal HR can be different from day to day. On Saturday I was strong and 170bpm would have felt easy but the next day (Sunday) 170bpm would have seen me grimace :+1:

In retrospect I think my heart rate was actually this high. Have been focusing on strength training for the last couple of months and seem to have lost a lot of cycling fitness.

Did an easy end of sweet spot workout yesterday and that was pushing me over 160bpm on the intervals on a different HRM - that’s after dropping 30 watts from my summer FTP…