Vivosmart HR bad readings on hills

philkeeble

I bought a Vivosmart HR as a more comfortable replacement for a chest strap HRM. It ticked all the boxes as it links to my Garmin Edge, my GPSMap 62S hand-held, and my Forerunner watch. I bought it in full knowledge that wrist monitors are not as accurate as chest straps, so my expectations were managed accordingly. The trouble is that as soon as I hit a hill where I have to put some serious effort into my pedalling, the heart rate figure drops from say,120, to around 60-70 (sometimes zero!!) instead of the 155-160 or so that would be expected. This is totally consistent and happens every time. I have calibrated it against a chest strap worn simultaneously (Polar - so that the transmissions won't interfere), I've worn the Vivosmart on left hand, right hand, above wrist, beneath wrist and on upper arm, covered and uncovered, and the results are the same every time. I have awaited the several (3, I think) firmware updates but nothing has changed. In fact, that's not quite true: before the last firmware update the device returned a credible measurement of minutes of high intensity exercise, but since the last update even a fast, 47 mile, hilly cycle ride registered precisely zero!
When at rest, or at moderate steady exercise, the heart rate display is pretty accurate, but vigorous cycling is unreliable. The only explanation I can think of is that the pulsing of grip on the bars when pushing hard interferes with the pulsing blood flow in the wrist that the LEDs are supposed to illuminate and detect. As soon as I back off at the top the HR reading returns to a higher more credible reading (but not as high as that registered by the chest strap).
Anyone else found this, or have any other explanation?

grenw

MIne's not too bad if a little sluggish to react. I woiuldn't trust the exact numbers, more the shape of the curve

Weird thing is that it's okay out on the road but appalling on the turbo where it gets several dropouts every few minutes - where luckily I don't mind wearing a chest strap. I can only think it's the sweat

Man Of Lard

One immediate thought is that photoplethysmography is crap compared to ECG for monitoring heart rate - especially in an exercise scenario.

http://www.wareable.com/sport/optical-h ... speak-9763

amaferanga

Optical HR works well IME until you move. I've had a Tomtom and now have a FR235. Both are utterly unreliable for running and cycling. I just turn the Forerunner off now when I'm cycling (don't care much about HR on the bike) and use a HR strap for running. The HR strap may be less comfortable, but it is totally reliable.

wongataa

philkeeble wrote:

Anyone else found this, or have any other explanation?

It is quite well known that these optical HRMs are often a bit rubbish in accuracy terms and even more so when exercising, especially cycling. See DC Rainmaker reviews.

niblue

My Vivosmart HR appears to map pretty well to the readings I get when using a 220 and a chest strap (or my 810 and a chest strap). Wrist HR's can be quite dependent on how tight you have them though.

Websta24

As others have said, optical HR isn't too bad...until you move!

I use a forerunner 235 and in general its fine for tracking "24hr heart rate" but once you get into exercise a strap is a much better option. To be fair, ive compared to a polar strap etc whilst jogging and the difference isnt really that bad....but, When you do a hard effort or interval it really lags behind and never really catches up. I imagine once you hit the hills your heart rate rises and you may rock, get out of the saddle etc so the optical sensor cant keep up. It wont be the firmware that's causing the issue, its the technology! Fact is, optical heart rate sensors are not up to scratch and their are far too many variables (positioning, tightness etc)

meanredspider

A friend of mine was involved in the research for the Philips sensor and he said that it simply doesn't work for some people. That might just be the answer.