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935's OHR vs Mio Link

I've been running with my new 935 since mid-October and love the features compared with my old 910. One thing I don't love is the 935's OHR... it's awful. I would notice on runs that my heart rate would not track with my effort and often appear stuck before jumping/falling to what it should be (at least according to my perceived effort). I had used a Mio Link (I believe the same or similar OHR in FR 225) with my old 910 for approximately three years so I knew the tricks to get the most accurate numbers from an OHR, namely to turn it on 5-10 minutes before running, wear it tight and position it farther up the arm. I never had any real complaints with the Mio Link. The battery life was short and there was some lag compared to a traditional chest heart rate strap but it at least tracked my effort.

Wanting to compare the difference between the 935 OHR and my old Mio Link I went to the track yesterday to run a series of 400m intervals. The workout was a 10 minute warm-up, 12 400m with rest intervals of 90 seconds (30 second walk with a 60 second jog), and 10 minute cool-down.

https://connect.garmin.com/modern/activity/2379049042

*Mio Link is the Auxiliary Heart Rate

Yup, the 935's OHR is awful. The Mio Link tracks my effort very well and the 935... well, it's all over the place. I mean it's laughable that some of my rest intervals have higher average heart rates than the interval I just completed.

Any ideas on what's happening? I'm running the latest firmware (7.0.0.0). Do I have a faulty device? I find it ridiculous that I'm at the point where I have to use a Mio Link in place of the 935's OHR.

0 Former Member over 7 years ago

I have noticed the same with my scosche rhythm+. I have made a lot of comparisions with the auxiliary heart rate and yes, I do use my scosche all the time as an additional heart rate device since that time. I don't rely on the ohr.

But nevertheless I like the OHR very much because it gives me results of the day-to-day rest heart rate, stress score etc...

For high intense running it is of no use. But that's nothing new and already well discussed...

0 2goBeyond over 7 years ago

I have noticed the same with my scosche rhythm+. I have made a lot of comparisions with the auxiliary heart rate and yes, I do use my scosche all the time as an additional heart rate device since that time. I don't rely on the ohr.

But nevertheless I like the OHR very much because it gives me results of the day-to-day rest heart rate, stress score etc...

For high intense running it is of no use. But that's nothing new and already well discussed...

When these posts come up, I try to jump in and second them because they are right on the nose (and there are a TON of these posts)

OHRM are great at only one thing-24/7 activity tracking and light load things like a recorded walk. There are a few exceptions but normally they are bunk beyond this. Even the MIO and Rhythm+ are poor compared to a chest strap (also cannot get HRV with OHRM).

In the case of Garmin's OHRM, they are wishy-washy even in 24/7 mode, but i'll chalked that up to poor algorithms with a poor sensor and poor software support for the sensor. 24/7 mode tracking can be done well, Apple's OHRM is apparently really good at this. And Garmin has no excuse; this is the 3rd generation of these sensors, they should be one of the leaders in the market with such a big market share.

If you want accurate always use a chest strap. If you want close to accurate for workouts, use anything but the built-in OHRM from Garmin.

0 Dr Phil over 7 years ago

If you want close to accurate for workouts, use anything but the built-in OHRM

on any device with built in OHRM

There, fixed it up for you.

0 Former Member over 7 years ago

Too bad Garmin didn't fix it up for everyone in the Forerunner 935 specification.

0 Former Member over 7 years ago

For high intense running it is of no use. But that's nothing new and already well discussed...

well discussed? There is a number of people unhappy with it and complaining about it here. That’s not the same as generally “of no use”.
I had posted in another related threat one of my high intense intervall workouts with perfectly right/shaped OHR readings (I’m too lazy to dig that out, I rather go out training).
And that goes with 935 users I have met. So, I don’t know what you guys doing with your device ....

0 Former Member over 7 years ago

And that goes with 935 users I have met. So, I don’t know what you guys doing with your device ....

We are running with two devices at the same time (e.g. auxiliary heart rate field) and are comparing afterwards and judging the OHR to "of no use"... ;)
After much data work I decided to keep on running with external HR devices and stop comparing. The time is better spent with training.

If you are happy with your OHR everything is fine. For me it is not accurate. Maybe due to type of skin, hair on wrist or other... I don't like the chest belts either.

0 Dr Phil over 7 years ago

^^^^^Yep, this^^^^^^
On occasion I'll get something reasonable from the WHR, but not often enough. I knew that when I bought it. I was not surprised.

There is a number of people unhappy with it and complaining about it here. That’s not the same as generally “of no use”

Ordinarily I'd agree with a statement like this however, there are more than enough discussions in a multitude of threads, on all of the Garmin WHR devices to clearly demonstrate the overall unreliability of this method of heart rate tracking. And similar is reported on other devices.

Generally speaking, WHR works for low intensity activity, but more often than not fails once the activity gets more 'volatile'. Period.

As for using auxiliary devices such as the Mio or the Scotsche, why would I? I can just use the HR strap.

0 Former Member over 7 years ago

Period.

Objection your honor. Generally speaking: optical heart rate measurement method appreciates a high degree of accurracy in sports science. There is a number of studies out there, you may want to torture google yourself. I acknowledge that from my own, personal experience as well from the runners around me with various devices, from all different brands.

I don’t consider the handful of people on Garmin Forums and the voice of Internet as reference for general bad PPG perception opposed to overall Garmin Product Lines sales numbers and thus people who have not been complaining (yet; or maybe given up of frustration, who knows).

Maybe that was Garmin’s motivation to get rid of those complainers for placing their omnipresent disclaimer on GC for the usage of WHR during Training.

On occasion I'll get something reasonable from the WHR, but not often enough

Ok, poor/bad Garmin implementation to make it work for some but not for others, but for sure not generally speaking.

0 Dr Phil over 7 years ago

optical heart rate measurement method appreciates a high degree of accurracy in sports science

for static measurements, but not when active.

poor/bad Garmin implementation to make it work for some but not for others,

That's not Garmin's (or indeed any other manufacturer's) fault. That's down to individual physical characteristics.

0 autoxer7 over 7 years ago

I appreciate everyone's responses! As a follow-up, today I did a tempo run and the results are much better with there being little difference between the 935 and Mio.

https://connect.garmin.com/modern/activity/2381555473

This at least gives me some confidence that I can use just the 935 to pace my races.

Thanks,
Steve