HR monitor (chest strap) showing low values?

Is it actually working? Check the battery. When you turn your watch on you should get a notification that the 'HR monitor connected' along with a Heart symbol (assuming you're using a Garmin). If that doesn't happen then the watch/HR strap aren't connected and so probably the battery is dead. 3-4 is a long time for it to last!

Yes, it definitely connects each time. I wet the electrodes, too. The connection is never lost. On Strava, I can see my HR data, and it's steady on each run. There was one time recently when I decided to look at my resting HR (standing), and it was suspiciously low, hovering around 38, which would normally be my HR while lying down, so that was a red flag.

I'd prefer not to spend money on a new one, but I suppose it's time.

My Garmin HRM-Run consistently measures HR anywhere from 5-10 BPM *lower* than the optical sensor when in Zone 1 / 2. They are much better aligned at higher pace / BPM.

Presuming you have been using the same monitor this whole time, maybe your base fitness has just improved? ?

zdf wrote:

My Garmin HRM-Run consistently measures HR anywhere from 5-10 BPM *lower* than the optical sensor when in Zone 1 / 2.

But which one is accurate in Zone1/2? To check against a manual pulse measurement, take pulse for 6 seconds and multiply by 10.

HR monitor? wrote:

zdf wrote:

My Garmin HRM-Run consistently measures HR anywhere from 5-10 BPM *lower* than the optical sensor when in Zone 1 / 2.

But which one is accurate in Zone1/2? To check against a manual pulse measurement, take pulse for 6 seconds and multiply by 10.

Another thing to check is whether the strap is averaging over the same period as the watch sensor; if they have different averaging periods, their different averaging time lag will produce different measurement values in cases where the heart rate is changing faster than that time lag.

HR monitor? wrote:

HR monitor? wrote:

But which one is accurate in Zone1/2? To check against a manual pulse measurement, take pulse for 6 seconds and multiply by 10.

Another thing to check is whether the strap is averaging over the same period as the watch sensor; if they have different averaging periods, their different averaging time lag will produce different measurement values in cases where the heart rate is changing faster than that time lag.

I can't reliably self-measure pulse during even light exercise, so I simplified quite a bit by just using an additional chest strap (from my NordicTrack). It was pretty much dead even with the Garmin chest strap. So unless there's some global strap conspiracy that I don't know about, I'm inclined to favor the strap (whick we've all been told many time before is more accurate than an optical sensor).

zdf wrote:

I can't reliably self-measure pulse during even light exercise...

A lot of readers may not have a second strap.

The old-school way is to stop during the exercise and quickly take the 6sec measurement. Being in Zone 1/2, the HR won't drop too rapidly, at least enough to assess differences between 5-10bpm between devices.

zdf wrote:

I'm inclined to favor the strap (whick we've all been told many time before is more accurate than an optical sensor).

My Garmin 245 optical sensor checks out quite well with manual pulse measurements.