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HRM Issues - multiple brands
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Several months ago, my Garmin HRM failed (again) and rather than go for a warranty replacement, I decided to try the 4iiii HRM, and just go for simplicity - all I ever really needed was HR. Don't really care about running metrics.

After a period of time, I realized that the new 4iiii HRM I had bought was giving me really flaky behaviour (it would sometimes shoot up to near max HR even though my effort didn't warrant it). The really odd thing is that it would only happen on the run - indoor cycling sessions never displayed the behaviour. Got a warranty replacement and had the same issue. Ultimately got a refund and bought a Wahoo HRM.

I now have a warranty replacement for the Wahoo HRM, which is also displaying flaky behaviour (but different from 4iiii). Behaviour I see now is that on the run, everything looks good for the first few minutes of a walking warmup, but as soon as I start to run, the HR shoots straight up like a square wave. Sometime it holds at near maximum HR, and sometimes it bounces up and down a bit (but always "square"). After a few minutes it settles down and the HR for the rest of the run is as expected.

I've got one more thing I want to try with the Wahoo HRM, but I suspect I'm going to go for the refund as well.

Of note - with the Wahoo in particular, I've worn the HRM for a good 20 minutes prior to starting the run, including some muscle activation. There doesn't seem to be any issue with skin connectivity since I'm picking up HR from the start of the walking warmup. I deliberately did not wet my skin because my past experience with Garmin is that 20 minutes is more than long enough to get a good connection.

Has anyone ever seen issues like this before? I'm going to try Polar next unless someone can tell me what I'm doing wrong, if anything.

I really don't want to go back to Garmin HRMs. They only seem to work until you change the battery, then they're broken.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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Does it happen in the same general location on the run? They can be susceptible to RF interference. I have a couple of places near power lines on my runs where things go a little nuts sometimes.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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I'm not a Polar fan in general, but the Polar H10 has been drop-dead reliable for me.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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I've posted several times about this in the past, but Scosche Rhythm+ has been by FAR the best.

I just looked up when I bought my Scosche in my gmail - it was Aug 12 2016 via amazon that I ordered it, received it 2 days later and have been using it nearly everyday, almost continuously since then.

For real, it is as good and as reliable now, 4 years later, compared to the very first day I got it. In comparison, I have killed literally every Garmin (6ish straps) and Polar straps I've tried- they aren't sudden deaths,but the data starts getting worse and worse after about 6-12 months, and then shortly becomes really bad afterwards, but usually only after 3-4 months of 'kinda crappy' data where there are questionable stretches in most workouts.

The Scosche isn't completely cost-free though - I have replaced the strap ($15 on AMazon) every year and had to buy one replacement charger ($12 on amazon knockoff brand) when the pins on the main charger got stuck due to sweat/corrosion. But otherwise, that's it - I'd def recommend it but keep in mind you do have to find the best spot to use it which does take some experimentation. (For me it's the forearm - doesn't work well anywhere else, but is rock solid there.)
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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Try some electrode gel. That might help out as when you aren't sweating in the beginning of a run as there ilcaj be contact issues and also potentially static interference with your shirt moving to and fro. Had issues with my Garmin HRM soft strap (removable unit/replaceable strap version) on runs in the beginning shooting up to max within the first 10 minutes of a run (and randomly when it the strap was way too worn). Once I started to use electrode gel issues went away. But did notice it came back once the original Garmin soft strap started to fail. Once I replaced it with a different brand it's been fine so far.

I also clean my strap now after every workout when I shower unlike in the past where I'd randomly clean it. In the washing machine.

But these days I only use my strap for rides. Haven't run very much in a while due to life. But I do have a newer Garmin watch with an optical HRM built in. Seems to work fine the very few times I did run with it.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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The underlying issue is normally that static electricity from your running top is finding an alternate pathway through the belt, and masking the genuine electrical signals from your heart. There are a number of ways of dealing with this:

* wet the contact pads on the strap before your run to ensure better electrical contact between strap and skin - especially in cool/low humidity conditions. The issue normally goes away a few minutes into your run once you start sweating (salty sweat is an excellent conductor). I usually just run wet fingers over the contact pads, but some people use electrode gel.
* wash the strap regularly - over time salts from sweat can accumulate in the fabric of the belt, making alternate pathways for static easier. Best practice is to give them a quick rinse under the tap after each run, and wash them once a week or so.
* replace the strap when washing no longer resolves the problem - the fabric strap should be regarded as a consumable to be replaced every 12-18 months (swap the sensor unit). Unfortunately Garmin's HRM-RUN and HRM-TRI are not removable.
* consider what running shirt you are using - the technical fabrics in some tops can be a static nightmare. I have a couple that I avoid on cool/low humidity days (I'm too cheap to throw out a perfectly functional running top). I have also used anti-static spray on these shirts which is effective, but a hassle.
Last edited by: mcalista: Sep 1, 20 18:49
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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I would re-iterate the previous comments about static electricity. In the dry technical fabrics can really build up charges when rubbing against the strap and cause erratic behavior. Optical HRM solve this issue but you have to remember to charge them. Given I am 0-3 in terms of successfully changing a battery in a Garmin HRM and having it work again I am not sure what is more cost effective in the long term. I remain baffled why you don't seem to be able to just change a battery in a Garmin unit but I am not sure the optical units will actually have a longer shelf life.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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Thanks for all the quick replies. My general responses:

1) No overhead power lines nearby. Can't speak to anything underground though. Interesting thought though.

2) Problem is occurring with brand new HRM, so it hasn't had a chance to degrade yet due to my not rinsing it post-run. That being said, I do rinse.

3) Problem does not occur on the bike, where I would expect more static issues.

4) I use a different running shirt for each run. Same problem every time.

5) Electrode gel - absolute last resort. I don't think I should have to use it after wearing the strap for 20-30 minutes before starting the run. Note that I get good heart rate for the first few minutes while I'm walking - it's only when I start to run that things go crazy, and then only for the first few minutes (which, I agree, might be when I start to sweat in earnest).

6) Changing Garmin battery - issue I had with the HRM-TRI (and the subsequent two warranty replacements) was that following the battery change, the battery would drain in about a week. I would really hate to have to go back to Garmin.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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MEW wrote:
Thanks for all the quick replies. My general responses:

5) Electrode gel - absolute last resort. I don't think I should have to use it after wearing the strap for 20-30 minutes before starting the run. Note that I get good heart rate for the first few minutes while I'm walking - it's only when I start to run that things go crazy, and then only for the first few minutes (which, I agree, might be when I start to sweat in earnest).

Static is usually only a problem in cool dry conditions, like the arid western US early morning or winter most everywhere. I get a similar behavior to what you described above...about 5 minutes into every winter run, if I forget to wet the contacts. In the Texas summer that's not a problem because I'm sweating before I even start moving...and the dew point is 75+.

Saliva works just fine vs. Gel. I put my strap on, flip the contacts inside out, lick my fingers and rub the contacts and repeat a couple of times. Then flip it back into place.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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What is important to remember is that you are experiencing failures at the exact point where HRM struggle the most and in the very circumstance they are expected to fail.

Run cadence causes noise that HRM have to filter out. Cadence is basically a very regular repetitive signal at a frequency which overlaps heatr rate (160-180 bpm) and needs to be filtered out. This is generally worse for optical sensors but it effects all straps in all locations. On the bike you don't have this so its not an issue. When you are walking the cadence signal is weak relative to the HR as you are not bouncing around so again no issue. When you start running though your HR will be low and a relatively weak signal due to you not sweating much. The noise of run cadence then screws with the reading, and probably locks onto the cadence, until the strap is wet enough to get a really strong HR signal. Wetting the strap or using electrode gel is a way to avoid this brief signal to noise issue. Static is a bit similar. Its only causes issues when you have a very high noise to signal ratio which is the window you are describing.

Its more information than you need but the problem with wrist based optical HRM is that they struggle to recover once they lock-on to cadence. No amount of sweating increases the strength of the correct signal on an optical unit so cadence or bouncing around on the bike send the units to the land of random number generators. It takes careful unit placement and a very good algorithm for optical units to get around this problem. My Garmin 735XT is completely useless as a run HRM as it only seems to be able to detect run cadence.

The solution here really is to wet the strap. Or ignore a few minutes of questionable HR data.
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Re: HRM Issues - multiple brands [MEW] [ In reply to ]
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I have had a number of Polar watches over the years and been very happy with the ownership experience. The product is fantastic, and support is responsive. Highly recommend the current generation.
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Re: HRM Issues - multiple brands [scott8888] [ In reply to ]
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This is interesting. But how is a physical vibration from running affecting the reception of the electrical signal? Shifting of the strap against the skin?

As it turns out, my last run had a HR around 162, more or less matching my run cadence. My HR was much lower though, around 125.
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