Heartrate monitor reading low..

[wafter]

Typically after extolling the reliability of my Polar H10 chest-strap HRM on here recently, it's started reading conspicuously low..

I think it's done this once or twice before but not so obviously or consistently. Has anyone else experienced similar?

I've not tried replacing the battery but I don't think it's done this before when the battery was getting low.. I'm riding it in pretty cold conditions but it's right next to my skin so doubt this is affecting it much. Positioning seems normal and I'm moistening it before use.. although my skin does tend to get pretty dry in this weather..

 

[Ajax Bay]

To illustrate this, and maybe increase engagement, you may wish to consider showing us an image of a graph of your HR when the HR display read lower than you think it actually was. An interval session perhaps? Or a climb where you were up in the 170s (or whatever) and then it dropped. Sometimes I've had the display show what I think is half (cf before and after) and sometimes twice (e.g. 280) but a hand on the chest strap sorts that out. The battery in the strap lasts a long time ime.
I have been a Polar HRM user off and on since the late 80s.
Also consider not cleaning the pads and using saliva rather than water for "moistening". I also smear saliva on that strip of my chest. In extremis you could get some of the gel the medics use: this: https://en.wikipedia.org/wiki/Skin_electrode_gel

 

[fossyant]

Battery change first, and check the 'contacts' are wet enough - if you aren't sweating when riding it probably won't be reading well.

 

[Sharky]

Do you have a secondary means of checking your heart rate? A blood pressure monitor or an oximeter (finger clip) would enable comparisons to be done at home and you could do some spot checks with an oximeter at points on your ride, after halting for a quick stop.

 

[wafter]

To illustrate this, and maybe increase engagement, you may wish to consider showing us an image of a graph of your HR when the HR display read lower than you think it actually was. An interval session perhaps? Or a climb where you were up in the 170s (or whatever) and then it dropped. Sometimes I've had the display show what I think is half (cf before and after) and sometimes twice (e.g. 280) but a hand on the chest strap sorts that out. The battery in the strap lasts a long time ime.
I have been a Polar HRM user off and on since the late 80s.
Also consider not cleaning the pads and using saliva rather than water for "moistening". I also smear saliva on that strip of my chest. In extremis you could get some of the gel the medics use: this: https://en.wikipedia.org/wiki/Skin_electrode_gel

Thanks - can't provide much more info currently as the only riding I'm getting in is the commute. It's definitely sporadically reading low - for example circa 40% of max when mooching along on the flat at c. 12mph, when I'd typically expect 50-60%. On Monday's ride it averaged low-40s nearly all the way, when the norm would be low-60s. It did pick up to mid-70s when I hit the hill near the end, which seemed about right. For the first couple of starts recently it's read zero (rather than no value at all, as it would if there was a connection problem).

That's very odd about yours; I can understand it reading low, but high is bizarre - sounds more like a processing error than a reading issue.

I did wash the strap a while ago, but don't recall any problems directly afterwards. I already moisten the strap with saliva (out of lazyness rather than any understanding of why it's better!) but I can appreciate your argument for doing so now you mention it. Maybe my electrolytes are low..?

I think it's had maybe 4-5 batteries in 5yrs / 1000ish hours so I guess I can't complain - usually it gives a battery warning when it's approaching expiration and I've not had any from this one..

Battery change first, and check the 'contacts' are wet enough - if you aren't sweating when riding it probably won't be reading well.

Thanks - as above I don't think it's the battery as it was replaced relatively recently and I've had no warnings, but I'll give it a go if I get no joy otherwise.

I'm thinking that poor contact (probably between the HRM and the skin) is most likely. My skin is typically dry anyway, the house is like a desert and I don't usually ride when it's this cold so as you suggest it may be down to a lack of sweat.

Do you have a secondary means of checking your heart rate? A blood pressure monitor or an oximeter (finger clip) would enable comparisons to be done at home and you could do some spot checks with an oximeter at points on your ride, after halting for a quick stop.

Thanks - unfortunately not and while I'd like to compare it to something else for verification, the numbers are off enough to be certain that there's a problem.

This morning we started off with an HR of zero; didn't have time to mess about with it so just kept going and it started giving more believable figures after a few minutes. For convenience I tend to put on the strap before I leave the house, then it's a 20-25 min drive where I'm obviously not exerting myself before I connect the device to the strap and begin the ride.. this hasn't been an issue previously however as above I've not really ridden in these conditions before.

I'll pay more attention to the strap / chest interface and take it from there. Thanks again for the thoughts

 

[wafter]

Further, went at the strap like a pony with a salt lick prior to leaving the office earlier; which seems to have made things a lot more realistic and reliable.

Arguably nice to get some confirmation I'm not medically-dead - thanks for all the thoughts

 

[Drago]

Could you possibly be deceased, or some such?

 

[wafter]

Could you possibly be deceased, or some such?

I did wonder if there was some Beetlejuice shiz going on and I was just slow on the uptake..

 

[presta]

I have a Polar M52, which came with a moulded plastic belt that you throw away when the battery's flat, and a Polar FT4 which has a transmitter with a replaceable battery that clips onto a fabric belt. As each have different functions I used both together off the same belt a lot of the time (that and the fact that the bleeper on the new FT4 was inaudible, even in a quiet living room).

The plastic belt was trouble free as long as you lick the electrodes before putting it on, even if they dry out whilst you're wearing it, and the battery lasted for several years. The fabric one, on the other hand, was never as reliable, and wore out to the point where it was useless within a year or less. I worked out that it was cheaper to throw out plastic belts when the battery died than keep replacing knackered fabric ones, which is what I did, but I think they obsolete now.

Erroneous readings I've had on mine are usually either nothing at all if the electrodes don't make contact, or ~230bpm if something like power lines, radio masts or the railway are interfering with them. I bought the FT4 because I thought the M52 was faulty, but it turned out that it was my heart, not the monitors. The M52 has been tested against paramedics monitors numerous times and never found wanting. Most of the heart related readings I had were high though, not low, except for the occasional tendency to switch up and down at random between two otherwise 'normal' looking readings.

 

[wafter]

I have a Polar M52, which came with a moulded plastic belt that you throw away when the battery's flat, and a Polar FT4 which has a transmitter with a replaceable battery that clips onto a fabric belt. As each have different functions I used both together off the same belt a lot of the time (that and the fact that the bleeper on the new FT4 was inaudible, even in a quiet living room).

The plastic belt was trouble free as long as you lick the electrodes before putting it on, even if they dry out whilst you're wearing it, and the battery lasted for several years. The fabric one, on the other hand, was never as reliable, and wore out to the point where it was useless within a year or less. I worked out that it was cheaper to throw out plastic belts when the battery died than keep replacing knackered fabric ones, which is what I did, but I think they obsolete now.

Erroneous readings I've had on mine are usually either nothing at all if the electrodes don't make contact, or ~230bpm if something like power lines, radio masts or the railway are interfering with them. I bought the FT4 because I thought the M52 was faulty, but it turned out that it was my heart, not the monitors. The M52 has been tested against paramedics monitors numerous times and never found wanting. Most of the heart related readings I had were high though, not low, except for the occasional tendency to switch up and down at random between two otherwise 'normal' looking readings.

Thanks - I hope the heart situation's under control now!

Sounds like a bit of a shonky setup with the disposible straps, although sadly Polar have form for this with their cadence and wheel speed sensors too; which are essentially disposible as they don't allow battery replacement.. utterly inexcusible IMO.

Not sure how familiar you are with current offerings, but mine is a separate elasticated strap with a plastic backing that runs along the chest area, and two stainless snap-fit connectors to attach the unit. This is quite convenient as you can just detach one to "turn it off" and conserve battery when out but not on the bike.

You make an interesting point about interferance and over-readings - my understanding of such things is tenuous at best so I'd not considered that as a possiblity, although mine's been consistently under-reading.

It seems that Polar have a good name for HRMs and mine's been really good (dropped pairing notwithstanding). I think this issue has been nailed down to poor conductivity between strap and skin; again today there was a lag between donning the HRM and actually starting out - initial reading was that I was - again - clinically dead, however removing, liberally licking and re-fitting the strap saw a much more usual reading in the low 40s, which obviously climbed once I started putting some effort in

While this has happened a little in the past this is the first time it's really become a consistant problem - hardly surprising considering it's the depths of winter, the air in the house is tinder-dry and there's often a delay between putting on the strap and actually starting to ride. I guess once you're going the sweat serves as an appropriate electrolyte

 

[presta]

I think it's a bigger problem with the fabric ones because the spit gets absorbed by the fabric and dries out quicker. Mine's like a PVC front and elastic back, with two electrodes made from a fabric that appears to have conductive fibres woven into it. The transmitter clips into pop fasteners like on clothing. It looks very worn and tatty compared to the plastic ones which are much older and more used.

I never had any problem with the plastic ones, even after they dried out they seemed to remain 'stuck' to my skin.

 

[wafter]

I think it's a bigger problem with the fabric ones because the spit gets absorbed by the fabric and dries out quicker. Mine's like a PVC front and elastic back, with two electrodes made from a fabric that appears to have conductive fibres woven into it. The transmitter clips into pop fasteners like on clothing. It looks very worn and tatty compared to the plastic ones which are much older and more used.

I never had any problem with the plastic ones, even after they dried out they seemed to remain 'stuck' to my skin.

Yes, that sounds plausible. Mine has a bit of plastic / rubber where the licking is required; which seems to work fairly well but evidently does dry out if not appeased with sweat after a while!

 

[figbat]

When this happened with my Wahoo TICKR I tried changing the battery, resetting the TICKR and ensuring the contacts were all good. In the end I replaced the strap and all was well.

 

[fossyant]

Arguably nice to get some confirmation I'm not medically-dead

Well if you are, can I have first dibs on your bikes.

 

[wafter]

Well if you are, can I have first dibs on your bikes.

All of them seems a tad greedy; one perhaps. I'll let you know if it turns out I'm dead 👍