Fitbit is not "HIIT-friendly"

[Dominique]

My experience with the Fitbit Surge is it’s not very good at detecting frequent and sharp changes in HR, such as the ones you would observe during a HIIT workout.

Yesterday, I did a 39 min. workout that consisted of a 7’30" warm-up, followed by 14 successions of 45" sprinting bouts and 90" walking bouts, ended by a 1 min. cool-down.

This is the activity as recorded by Runtastic, using the Mio Alpha heart rate monitor (wrist-based, like the Surge). The 14 sprints are visible as HR peaks (peaking at about 155-160 bpm): 

 

This is the same activity, as recorded by Fitbit with the Surge as HRM:

It only detected a peak at 144 bpm, and most of the session was between 80 and 110, definitely not reflecting the perceived rate of exhaustion.

Average HR during the session was 98 bpm with Fitbit, 132 bpm with Runtastic.

This is not an isolated case, I see this almost every time. For me, the value of the Surge (as far as HR is concerned) is more in the 24/7 monitoring, and less in very intense effort.

[au7772]

I appreciate the thought, but in a word, no. My manual checks only take 15 to 20 secs (multiply by 4 or 3). It’s a **ahem** close approximation, and confirms that I’m at or above the 90-100% of max heart rate I’m shooting for. I take this measure only a couple of times per workout during the short “coasting” phase of a HIIT segment, and I do 9-10 segments in each HIIT workout. BTW, max heart rate per conventional means as you probably know is 220 minus your age, for me 68, for 152. But because I’ve been doing this at such a high degree for so long I’ve arbitrarily set a max for myself of 173, which drives much more realistic for me and my conditioning numbers of 86+ bpm for fat burn and 121+ bpm for cardio. Plus, my workouts carry such a physical movement aspect the chest strap would be hard to maintain in the proper position, especially in my rowing with high degree of movement in my torso, chest, back and arms.
But thanks for the thoughts.

Sent from my iPhone

[SunsetRunner]

Fitbit is still a poor device to attempt any heart rate tracking over 120 BPM.  I've used it for HIIT training, circuit training, crossfit, weight lifting, running, rowing, etc. - its awful.  I no longer use it for any workout heart rate tracking and use chest band instead.

I enjoy the software however so I am forced to use Endomondo with a chest band and push it to my fitbit ap.  Sad they haven't fixed this in the past 4 years...

[WavyDavey]

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@SunsetRunner wrote:

Fitbit is still a poor device to attempt any heart rate tracking over 120 BPM.  I've used it for HIIT training, circuit training, crossfit, weight lifting, running, rowing, etc. - its awful.  I no longer use it for any workout heart rate tracking and use chest band instead.

I enjoy the software however so I am forced to use Endomondo with a chest band and push it to my fitbit ap.  Sad they haven't fixed this in the past 4 years...

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I'm not sure the problem is exclusive to Fitbit. Almost every wrist-based tracker I've heard, read about and tried has issues with HIIT and the dynamic heart rate readings that go along with it. Really the chest strap is the only reliable tracking for HIIT, because it doesn't use LEDs. I'm hoping one day Fitbit will directly support using a chest strap with their smartwatches/trackers.

[SunsetRunner]

I totally agree.  If they allowed us to link to a chest band during workouts it would be epic.

I bet they are planning to release their own chest band and do it that way

[t.parker]

I'm not so sure Fitbit will introduce branded chest strap. If so, that would probably happen some time ago and this clearly isn't the company main focus. It would be probably easier to allow third parties to pair with Fitbit devices but here we have another Fitbit limitation - restricted support for third-party hardware (which means pretty much no support whatsoever). The competitors realized the need for supporting external sensors a long time ago and nowadays you can easily pair Wahoo or Polar strap with any watch that supports BT sensors (with certain brand-specific limitations like not being able to use cached HR if you mix brands - for me, very little inconvenience and mostly related to swimming). Lack of external sensors support doesn't really come down to HR only. There are additional sensors for cycling, running (foot pods especially useful on the treadmill, make great support outdoors, too). For me, when I buy a new watch, the ability to use external sensors (multiple sensors during a single session) is a must. After Fitbit, I switched to such a watch and since then I know I will never pick a device without such support. Hence, some smartwatches like Apple Watch, Samsung Gear, or even recent, really good in my opinion, Suunto 7 doesn't work for me - even despite they may support external sensors but it's so overcomplicated and not out-of-box that I don't see myself using them for serious training. These are just fancy toys, not sports tracking and training equipment.

[Heybales]

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@SunsetRunner wrote:

Fitbit is still a poor device to attempt any heart rate tracking over 120 BPM.  I've used it for HIIT training, circuit training, crossfit, weight lifting, running, rowing, etc. - its awful.  I no longer use it for any workout heart rate tracking and use chest band instead.

I enjoy the software however so I am forced to use Endomondo with a chest band and push it to my fitbit ap.  Sad they haven't fixed this in the past 4 years...

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Well - poor device for your arm and your workouts.

There are others that report it reads very well on them up to 160 no issues. I've seen 180 a few times - but many don't workout that way.

Others I've seen, it seems to stop at 130 and is inaccurate above that.

There are limits to the tech, nothing to do with Fitbit. Everything to do with a person's wrist area and genetics.

Good solution you've found.

[t.parker]

@Heybales true and untrue. If you consider that the tech itself (as optical HR) is limited then try PolarOH1. Here's an example of my 1hr bike ride (quite vigorous):

The blue line is tracked with PolarOH1 (optical) worn on the elbow (inner side) and tracked with the connected sports watch. The yellow line is PolarH10 chest strap and HR is tracked with PolarBeat mobile app. It's not going to be a lie saying that let's say 95% of the time both devices are accurate (and OH1 has no problems with higher HR). I believe PolarH10 is still slightly more accurate but such results made me retire the chest strap and switch to optical PolarOH1. It is easier to wear, it's great for swimming (can be attached to swimming goggles) and is just smaller (easy to carry with you). Why is this sensor so accurate? The answer is simple - it isn't worn on the wrist. The wrist is the worst possible place to wear the HR monitor. It may work well when the activity doesn't involve lots of wrists bending and isn't too shaky. Otherwise, most of the wrist-based HR trackers will fail. Even for running it may pick up the cadence for the heart rate (for me, this was very often the case, just with Fitbit you can't tell because no Fitbit device supports cadence as a metric). Optical OH1 sits very stably and the location (even elbow but can be worn on a bicep, too) isn't too bad. When I do push-ups, pull-ups, dead-hang it still has no issues with reading my HR (although I place the sensor on my bicep if I bend the elbow a lot). My late Ionic and Charge 2 never ever gave me correct readings (and with other watches, it was hit and miss, too so it's not just Fitbit's problem). So it's not really the technology is flawed but rather the way it's being used. If only Fitbit made possible to use external sensors...

[Heybales]

There is actually advice on Fitbit pages to move it up closer to the elbow if you have accuracy problems.

I'm just curious how many have a strap that would allow it.

And I agree couple recent comments are correct that Fitbit is not after the serious athlete market, but the average consumer market.

As such devices usually do fine for average consumer.

The gripping hand locked wrist scenarios failing to see impacts being a notable exception.

And some people just can't find good spot to put HR-based devices to get good HR readings - but the % appears to be pretty low - or vast majority aren't working out at a level to notice an issue - that's my bet.