Fenix 5S HR monitoring is grossly inaccurate?

I got my watch about a week ago, installed all the proper updates, and have been using it daily. I have noticed an issue with the HR monitoring across the board. I primarily do CrossFit, which means my activities vary from lifting to running to random cardio movements to strength. I can push myself to the brink and be lying on the floor breathless and the watch is reading my HR as something like 110 or even as low as something like 84. The only time I seem to get any semblance of accurate HR is if I am actually running or jogging, with my arms pumping. When I check, I will then be in the cardio zone with something like 140-150. Other than that, my watch does not seem to pick up changes in HR accurately. I have tried the strength setting, cardio setting, etc and was starting to think maybe I needed to update my software, but it is up-to-date. I have also tried re-positioning the watch on my wrist, as well as both tightening it and loosening it. Nothing I have done has seemed to improve the HR monitoring.

Note: I previously had the Forerunner 225 with HR monitor, so I am familiar with the wrist HR monitoring. I would have issues from time to time with that watch's HR monitoring, but not like this. I recognize that wrist HR monitoring is less accurate than a chest monitor, but I have upgraded my watch (at a hefty $$$) for what appears to be less accuracy.

Can anyone help? Is anyone else experiencing this?

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0 LiquidSquid over 5 years ago

My findings have been that the less expensive VivoActive 3 performed much better than the Fenix 5. This may be up to the fact that the VA3 is lighter, and perhaps stays in a fixed location on your wrist during vigorous activities, and therefore can track changes in heart-rate better. It may also have a brighter LED or any number of hardware differences allowing it to track differently. In general, the VA3 tracked heart rate amazingly well, and the F5 is a let-down for this. I find myself waiting for the next model to come out with improved performance.

There have been occasions where the F5 tracked my hockey better than others, and it seems to correlate with using the silicon strap rather than the leather one. I can snug the silicon strap better, the elasticity allowing more comfort with a tighter adjustment. If I were to guess that if the distance between the LED emitter and your skin changes at all during the workout, it is mis-interpreted as a change in translucency similar to blood flow and confuses the algorithm that determines heart rate. Similar with the compression of the sensor against your flesh, and why strength training is so hard to track. It is a technology limitation with the position of the sensor on your body. It would probably work much better behind your ear. It is not like that part of your body is doing much during a workout.

I just don't really want to purchase the far more accurate heart rate straps as I am not training for the Olympics, I am just a casual user who wants to be sure I am not over-doing myself during recreational activities.

0 JSRUNNER_ over 5 years ago

LiquidSquid you are coming up as many others have against the limitations of the technology and by picking the very heavy F5 you are stacking the odds against you. The lighter watches on the whole will move about less on your wrist and so will stand more chance of getting an accurate result. You would probably be better off with a 935 than a Fenix 5 (depending on exactly which features you need). When you say recreational user what do you mean - are you using HR zones to train to or are you simply wanting to see what your ave HR was and maximum during a traininhg session purely for "interest". If it is for training in HR zones then unless you are very luck you will not get accurate HR reading for many activities from any wrist-based HR monitor.

0 LiquidSquid over 5 years ago

When you say recreational user what do you mean - are you using HR zones to train to or are you simply wanting to see what your ave HR was and maximum during a training session purely for "interest". If it is for training in HR zones then unless you are very luck you will not get accurate HR reading for many activities from any wrist-based HR monitor.

Mostly I just want to be sure I am not pushing myself too hard, as I have a tendency to overdo myself. For example when I was biking this summer, my HR was sitting at 188 for 45 minutes as I whipped around my block not paying attention. I didn't realize until after the ride and I looked in Connect what I just did to myself. It was fine when I was 20... not so much when I am 50. I push myself just as hard and I need a reminder to tone it down a little. The hills in my area are a bit rough.

Same goes for hockey, trying to keep up with people 20 years younger than me.

If the watch can never report actual high heart rates, then for this purpose it is useless. Otherwise it is a really fun device to motivate me to do more.

0 Denodan over 5 years ago

Well I bike, and use a hr strap and my 5s is with 10bpm of the hr strap. Have even tried running with and without strap and still about up to 10 bpm of the hr strap, sometimes 2 or 3 bpm faster than the chest strap.

if you use these watches in the gym, it's a well known fact optical hr is useless in weight training, etc.

the watch is only good for ordinary actives, like running, walking or biking and everyday hr monitoring not the gym.

Had the vivomove hr before my fenix 5s and hr tracking biking was hopeless until you had be riding for around 20mins, then start recording properly

0 JSRUNNER_ over 5 years ago

miroman4o just because your 735 gave you correct readings and your 5 doesn't is not necessarily a problem with the watch software. The 5 is much heavier and thicker so is going to sit very differently on your wrist and be much more affected by arm movements than the 735. Wrist based is never with current technology going to be accurate for all people for all activities - just use a chest strap if you want accurate readings

0 JSRUNNER_ over 5 years ago

LiquidSquid why not just get a chest strap if you are concerned about overdoing it - once you get into the habit of wearing it you'll hardly notice its there

0 LiquidSquid over 5 years ago

Thinking about picking one up, but going to need some time to heal from getting nailed by a snowboarder this weekend. Took me a while to find my eyeballs and kidney. Sheesh. He nailed me from behind, and I was already going 35mph. Not something you expect! Spent a less than fun night in the ER, bruised but not broken.

0 AnhGiaRoi over 4 years ago

I just bought a Fenix 5X and am seeing the same with whatever activity I use it for. Can't find a suitable position on my wrist where the HRM works accurately. I note the other comments about wrist based HRms not working very, however, I also have a forerunner235 (have had for 3 years) and that is very accurate (wrist based HRM) for all the same activities. Seems like the 5 series HRMs are not up to scratch. The rest of the watch is great, but I am a bit dissappointed about the HRM as I would have expected it to at least have worked as well as my old forerunner 235.

0 8767265 over 4 years ago in reply to Dr Phil

Nice try. I’ve co-witnessed my fenix 5 Plus and Apple watch with both palpation and chest rig. The Fenix 5 almost seems to be making it up based on movement while the apple watch witnesses correctly the majority of the time. This needs a real fix, not an apologist.

0 8767265 over 4 years ago

I think I am starting to see the problem. I believe Garmin knows that the light sensor it used in this series is just, well, not very good, so they adjusted the software to be a little more sensitive and now the watch becomes inadvertently slaved to your movement when that is more consistent than the actual light feedback. This is why when doing HIIT you can palpate and feel a 140-160 pulse but because you are not in motion the watch is reading 86-110 or so. If this is the case then there is nothing they can do about it and they will most likely just ignore this or any other negative feedback unless it becomes a legal issue. They may put someone on it who can strike the balance between the crappy sensor and and the software, but it’s unlikely. My bet is this same sensor is in the 6 series as well. I hope I’m wrong and Garmin really does care about us, but what are the chances.