Fenix 5 Plus HR very inconsistent

I've had my 5 Plus for a little over a week. I use it a lot as a HR strap in conjunction with my Edge 1030. The first week, the HR rates seemed consistent with what my strap had been reporting based on effort. The last 2 days, it's been all over the place, telling me my HR is 105 on an all out sprint. Even on a hill climb, I could not get it to read above 157 when I knew i was much higher.

When I got home, I threw on my HR strap and fed it into the Edge and left the Fenix broadcasting. I did about 5 mins of jumping jacks; enough to get my HR up. Strap read linear and based on effort; Fenix stayed about 30bpm below and not reactive.

I tried rebooting it; changing wrists, flipping it to my wrist. Nothing changed.

Do I have a bad unit or did the most recent update bork it?

0 carl.andersson over 6 years ago

Most yes. I find the Scosche Rhythm+ to be as accurate as the HRM-Run chest strap. I have no idea how or why as it seems to use the same method for reading as the Fenix. I used to wear the HRM-Run, but since getting a Stryd Footpod for power and running dynamics I wear the Scosche as I hate chest straps.

It's the same method sure but it's in a different location. It's much easier to get a stable clear reading from your upper arm than it is from your wrist. But people don't want to wear chest straps or arm bands all day yet they still want HR readings. So the watch is the compromise we currently have.

In my 5+ this is terrible. Today I had some interval Sprint runs, 10x150m and I almost couldn't breathe and this thing was showing 128 bmp. It has some big delay I reaction to pulse or it doesn't measure at all, showing only possible hr. Try swiths exercise from running to cardio and your hr will drop 20 bpms. This is stupid.

All wrist based optical HR monitors will struggle mightily with interval sprints. The sudden surge in heart rate is difficult any optical HRM to pick up, especially as the external noise from the rapid movement of your arms increases as well.
You can try and mitigate some of this (making sure the watch isn't sitting on your wrist bone, making sure the strap is tight and that the watch doesn't "bounce" while you sprint) but at the end of the day if this information is that important to you then you should use a chest strap as this is still by far the most reliable way to record this information.

The above also applies to any activity that sees you flexing your wrists a lot (Cycling, Weights at the gym, Crossfit etc).

Look - the technology isn't perfect, but it's rarely as bad as it's made out to be in some of these forum posts just as long as you understand the limitations of the technology.
I've been through multiple generations of optical HR devices now (from Fitbit, Tomtom and Garmin) and the Garmin has been best in class across both the 5 and now 5 plus. But best in class does not mean perfect, and the vast majority of the issues raised on these forums will probably never be solvable with this technology.

I get that it's a bit insulting to have spent so much on a watch only to be told "you need to buy a chest strap" or "yeah sorry but that's just the way OHRM works" but seriously it's not like you couldn't have discovered everything I've just mentioned before buying the watch. A simple google search about optical HR would've given you ample warning.
The people I do feel a bit sorry for are the ones who have "upgraded" from lighter Garmin watches. Nobody has really talked before about watch weight being a factor, but it really is when it comes to the "super heavy" Fenix watches.

0 esselite over 6 years ago

No, but don't get me wrong. When I run 5k and I stop, this thing is showing me good HR.
when I Sprint and I stop it is showing me nonsense.
why,I have just stopped and there is no any bouncing, but bpm is 128, while my real is around 170.

0 Former Member over 6 years ago

No, but don't get me wrong. When I run 5k and I stop, this thing is showing me good HR.
when I Sprint and I stop it is showing me nonsense.
why,I have just stopped and there is no any bouncing, but bpm is 128, while my real is around 170.

Simply because the heart rate measurements are fed through filters and depending on the relation of real-HR vs. false-HR samples, the size of the error will vary.

0 bluelavender over 6 years ago

Weight play very important part, and this is one of very important factor where titanium material play the part. I am now wearing titanium one and like some titanium users found, it is actually very accurate. In my usage, it is exactly same measurement as the chest hrm which I use too sometimes

0 Former Member over 6 years ago

I would not suggest at all to pay even more for the titan version bevause it‘s absolutely not solfing or significantly reducing the general problem (except i was a garmin marketing guy :) )

0 carl.andersson over 6 years ago

No, but don't get me wrong. When I run 5k and I stop, this thing is showing me good HR.
when I Sprint and I stop it is showing me bullshit.
why,I have just stopped and there is no any bouncing, but bpm is 128, while my real is around 170.

That's pretty much exactly what I was talking about though. Every single watch on the market will have the exact same issue when you sprint.

0 Baz 8755 over 6 years ago

The way I see it is that OHR is fine for general health monitoring but as soon as you do sport just wear a chest HR. That's the way I do it, no big deal as I have to change into my sports kit anyway so a chest strap is just another thing to put on. At least with Fenix you have the option, cheaper watches without ANT+ are stuck with OHR.

0 bfinary over 6 years ago

It's the same method sure but it's in a different location. It's much easier to get a stable clear reading from your upper arm than it is from your wrist. But people don't want to wear chest straps or arm bands all day yet they still want HR readings. So the watch is the compromise we currently have.
.

I wear my Scosche on my wrist. Right wrist exactly same place as my F5+ is on my left. Wildly different results though! No idea why Garmin cannot get this to work as others do.

0 carl.andersson over 6 years ago

I wear my Scosche on my wrist. Right wrist exactly same place as my F5+ is on my left. Wildly different results though! No idea why Garmin cannot get this to work as others do.

Curious that you put your scosche on your wrist when that's not where they tell you to put it. They even state on their website "greater precision than wrist based monitors"
Have you ever tried swapping sides - wearing your watch on the right and the band on the left? I'd be curious to see what your results would be then. Now I'm not saying the results would swap with the watch being better than the scosche if you swapped sides (I really doubt that would happen) but it would be worth testing all the same.

Regardless, I don't think it's fair to say Garmin cannot get this to work when others can. Because apart from a dedicated HR monitor from Scosche that isn't even meant to be worn on your wrist who else does wrist based optical HR well? No other watch I've used (and I've used a few) has ever been very good at tracking the sorts of things people on this thread are complaining about.

0 bfinary over 6 years ago

I hear what you're saying, but the others aren't charging the price tag Garmin is. I just expect a bit more from an HR sensor built into the premier fitness/triathlete device.