HRM interference

[SkallerupYards]

Hi - I'm delighted with my new Concept2 erg with PM5. I have a Garmin Forerunner235 that I use for all my activities -- my true love is running -- and the HRM works reasonably well. I know that chest straps are better and used to race bikes wearing a Polar set up 20 years ago.

I've searched forums but haven't found this particular issue:
I can successfully connect the Forerunner to PM5 and PM5 to my phone. All are synced and registering my HR correctly/accurately. What happens, though, is 15-60 seconds into rowing, the heart rate starts to drop. For example, starts at 50-60 resting HR, starts to climb with activity to ~80-100 bpm, then drops to 50s-60s and bounces around there. The PM5 display, the iPhone display via ErgData, and the Garmin all show the same inaccurate number.

I thought I solved this by turning bluetooth off on the Garmin and connecting the wrist HRM to the PM5 via ANT+. This didn't work.

If I do not connect my watch to the PM5, then the HR on the watch displays the correct/accurate values. It is almost as if there is some sort of interference from the PM5 that is compromising the watch's ability to even measure HR!

I really would like reliable HR data while rowing -- and have it integrated with the ErgData (and subsequently Strava).

Thanks all!

[gvcormac]

I have never been able to get an accurate HR reading from a wrist device while rowing. I find wrist devices fine for cycling or walking, marginal for running, and hopeless for rowing.

[Sakly]

My experience is very different from gvcormac, my watch records HR very well during rowing, as long as it is a steady state session without hard gripping and fast strokes. +-3 bpm average compared to my belt, but sometimes with glitches.
I tried a few times with Ant+ as described and it worked well, so no idea what the reason could be. Using a Garmin EPIX Gen2.

[Tsnor]

... is 15-60 seconds into rowing, the heart rate starts to drop. For example, starts at 50-60 resting HR, starts to climb with activity to ~80-100 bpm, then drops to 50s-60s and bounces around there. The PM5 display, the iPhone display via ErgData, and the Garmin all show the same inaccurate number.

You are not having bluetooth connection issues. That would cause HR to freeze then eventually goto zero. You don't have that. So no worries about bluetooth, interference, etc.

Instead your FR235 HRM is picking up an incorrect HR.

Classic fixes for a wrist based optical that is struggling.
1. Wear it higher on your arm. If the watch falls to your wrist it can't read as well
2. Keep the strap tight. Loose makes it harder to read.
3. Concede that some wrist based optical sensors struggle to get good data while rowing. It's why your watch will get data from a belt even though it's got its own sensor. Get an ant+ capable belt and connect it to both the pm5 and to your watch (instructions here: https://www8.garmin.com/manuals/webhelp ... ED564.html)

My garmin fr 265 does OK with steady state rowing, but not great. Intervals, especially short hard ones are bad. I wear a belt. Previously I used three generations of fitbit, their HR while rowing was totally random - maybe worse than your 235. Some people report great success with apple watches and a few others, but my 265 with its high end optical pickup has me wearing a belt. And belts are a PITA: need to clean them, replace batteries, etc. But Belts get much better data.

This is garmins hints for bad HR data, not very helpful IMO https://www8.garmin.com/manuals/webhelp ... %20workout.

[gvcormac]

I recommend Coospo H808S chest HRM. Doesn't cost much, has ANT+ and (single) Bluetooth.

[SkallerupYards]

Thanks all for your replies. The most baffling thing to me is that the watch's detection of HR seems to perform within expected limits when on the erg except when it is connected to the PM5. I can think of a few other combinations to minimize other BT signals to try -- although I don't know enough about ANT+ to understand any interference there.

[Tsnor]

except when it is connected to the PM5.

Your watch has to do a lot of extra processing when using network/bluetooth/ant+. The battery life goes down reflecting the extra processing. Maybe this extra processing is limiting the watch's resources available to process the HR signal.

Your watch will record HR during rowing sessions. It would be an interesting experiment to do the same workout 8 times, including some short/hard intervals where optical struggles, all recorded with garmin, every other one connected to pm5 and also recorded with pm5. That would confirm or reject the observation that HR is more eratic when your watch is connected to the pm5.

Aside: ant+ and bluetooth are both protocols that run on the same 2.4 ghz frequency as your older wifi. Other things that use this frequency are everywhere. There are also a lot of things that can strongly impact 2.4 like invertor microwaves. If you had a network issue (HR freezes, connection lost) they would be worth exploring. Not sure how any of these could give you bad HR data successfully delivered but stranger things have happened.

[Carl Watts]

Go chest strap. The older Garmin ones are the best, the ones that detach from the strap so you can bin the old strap every 2 years and get a cheap replacement from AliExpress. These will keep going for 10 years if you look after it and rinse in hot water before and after each time you use it. ANT+ is also better than Bluetooth if you can use it, totally rock solid connection.

[SkallerupYards]

Update:
I connected Garmin HRM to PM5 via ANT+ -- but did not connect PM5 to my phone. I started rowing and the same thing from before: at the outset, I had a reliable and plausible reading on the watch face and the PM5, but by approx 50 seconds, the HR started to drop on both PM5 and watch to an implausible number.

I stopped and turned off "broadcast HR" on the Garmin and disconnected it from PM5. I connected my phone to PM5 and proceeded to row 5500 m with my Garmin recording a new activity. That worked just fine - it's just too bad the HR data want show up as integrated in ErgData/log book or Strava.

There's some interference between the two devices. If I find a solution -- and could be empiric trial of a chest strap -- I'll post it.