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.

[WendyB]

Interesting. I will test mine as well next time I wear my Surge

[OCDOC]

@Dominique

I've switched to HIIT and vigorous resistance training the last couple of weeks. The Surge is terrible at tracking HR (eg after a set of lunges my p is 135..Surge either doesn't sense at all or reads 90-ish).

I loved it when steps was my goal (it may be again in a different cycle), but right now it's basically useless.

[Dominique]

@OCDOC: I wouldn’t say your Surge is useless just because it fails to fully capture activities you are doing 2-3 times a week, 15 minutes each time. It’s still tracking all of your other activities. And there is more than steps and HIIT in a fitness-oriented lifestyle. So for me, my Fitbit is still most useful.

[OCDOC]

@Dominique

Yes, 'useless' is probably the wrong adjective. It is still excellent for telling time and tracking sleep.

It's also great at counting steps and flights (which I currently don't care about..I did before and I will again), but is very inaccurate at HR monitoring during HIIT and resistance (which is currently relevant).

It's a lovely tool and motivator, but like most things on earth it has its strengths and weaknesses. 

[vlaura]

Here's how one of my HIIT I did a while ago (Max Interval Circuit, approx 1 hour) looked like recorded by Charge HR:

I'd say it's one of the best results I've seen recorded by my Charge HR. I've also discovered that I get better results when I'm wearing my tracker during the exercise the same way I do during my daily activites (not tighter) - this helps a little with accuracy. 🙂

Though I'd say after this workout, I felt like I burned a 1000 cals not around 400.

[Dominique]

Following up on HIIT with Runtastic vs. Fitbit: I was now able to do exactly the same HIIT workout again, but with a Fitbit Blaze. The Blaze appears to be much better than the Surge when capturing HR during HIIT. This is what the HR graph looks like with the Blaze:

It’s not as "sinusoidal" as with the corresponding HR graph recorded by Runtastic with the Mio Alpha HRM, but the Blaze definitely captured highs (at about 160-165) and lows (around 125). The average HR during the session was 141 bpm with the Blaze and 134 bpm with Runtastic/Mio Alpha, so close enough. I’ll repeat the experiment in a few days, to see whether the better performance of the Blaze is confirmed.

[Mukluk4]

Is there an exercise tracker that is HIIT friendly (ie. calorie burned counts)?

Since I've upped my non-competition cardio activity, there is no way that 40ish minutes of interval jogging burns as many calories as 90+ minutes of full court basketball.  (Granted I only have a Charge and not a Charge HR)

[vrDrew]

I've being Sprint 8 HIIT workouts on a recumbent stationary bike (with handgrip HR monitoring) for a year or so now. And I have to say my Fitbit Charge HR doesn't seem to do a very good job of recording my HR.

I usually am hitting my peak zone of 150+ BPM pretty hard towards the end of the last couple of intervals. But the Charge HR is barely showing any activity at all over 120 BPM. I've speculated that the bent position of my wrist as I grasp the grips might be preventing me from getting an accurate reading.

I don't really worry too much about this. I *know* I've done the workout.

The one thing I can say is this: The Fitbit Charge HR has made me very aware of the risks of overtraining, and especially not allowing enough recovery time between HIIT workouts. I notice my resting HR is usually up a few beats the next couple of days after an intense HIIT session. I usually make a point of scheduling only very low intensity exercse - usually nothing more than a brisk walk in the days immediately after HIIT.

HIIT is a very powerful workout tool. But it is very important not to overuse it; and to pay close attention to your resting HR as a guide to when you are on the verge of over-training.

[emili]

any tracker with an HR function will be more accurate (of course) than one that basis on statistical data. I have the charge HR and I love it. I am thinking about the blaze next, particularly as noted in Dominique's post, results are even better. If you are thinking of a gift for yourself- that's what I would suggest. 

[sirmattylad]

Hi Dominique,

Do you have any further updates on how the Blaze holds up to HIIT? Just i'm thinking of buying one and HIIT is a big part of my fitness regime.

Cheers.

[Dominique]

@sirmattylad: the Blaze has been consistently better than the Surge at detecting sudden changes in HR. However, keep in mind an HR-enabled Fitbit is not a sportwatch like Polar, Suunto or Garmin: it focuses more on the 24/7 monitoring. Even if your Fitbit fails to fully detect the intensity of your activity 30 minutes each day, that still leaves 23.5 hours during which you will get relatively accurate data. And HIIT sessions usually aren’t performed each day, and they may be shorter than 30 minutes.  

[silentium]

How do you wear your Blaze during this exercise? Thight or loose and where on the arm?

When I do weightlifting, the Blaze always drops low into the 70 - 80 bpm range and then slowly adjusts up to 110-130 bmp after about a minute post the exercise. 

[Dominique]

@silentium: I’m aware of the "official" recommendations regarding where and how tight to wear your HR-enabled Fitbit during intense effort, but they don’t really work for me. If I try to wear it higher up on my arm (eg. three fingers away from my wristbones), it will slip down at some point, especially when sprinting and sweating. Anyway, the main point of exercising for me are the benefits I get from it, not the HR data I’m collecting.

[tntfal]

I hope you're still responding to this thread...  because I am having the exact same issue...I'm almost ready to return my fist that.... My wife teaches Zumba and I do hits on the treadmill.... And were noticing that the Wahoo chest monitor picks up heart rates perfectly during 1minute HIITS however the fitbit is useless................... my question is have you found another device on your wrist that picks HIITS up better..... Do you think the apple watch would be better?

[vlaura]

I am not sure apple watch would be better as it's not meant for vigorous exercise - personally haven't used it. I've heard Garmins in general are pretty good so I'd probably do my research on them.

[DreamertK]

I'm not sure about how to link my data in here, but I get some very beautiful graphs when I do HIIT. Though I use a machine that tracks my heart rate too and the numbers are different. Like fitbit will say 150 and the machine says 161 at peak cardio. Not too sure which I should believe....

[WavyDavey]

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@tntfal wrote:

I hope you're still responding to this thread...  because I am having the exact same issue...I'm almost ready to return my fist that.... My wife teaches Zumba and I do hits on the treadmill.... And were noticing that the Wahoo chest monitor picks up heart rates perfectly during 1minute HIITS however the fitbit is useless................... my question is have you found another device on your wrist that picks HIITS up better..... Do you think the apple watch would be better?

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My experience has been that all wrist-based trackers can have trouble with the big HR swings we get in HIIT. The chest strap is the way to go, I have one just for HIIT, and use the Fitbit for everything else.

The kind of HIIT you do can come into play. If I'm using a prowler sled, my wrist is cocked back, which makes the readings more difficult. Sprints are a little better, but I've yet to find something that's better than a chest strap.

[au7772]

I’m in complete agreement. My experience with fitbit and the high bpms I reach in my HIIT workouts mirrors yours exactly. I’ve also had the same experience with the Apple Watch. I do HIIT on two different platforms, a recumbent bicycle and a rowing machine, two separate workouts on alternating days. I regularly reach bpms in the 150s/160s, my target heart rate. No wrist heart rate device even comes close. I’ve been doing HIIT workouts for almost 7 years on the bike, and added the rowing machine about 6 months ago, before any of you go off about my high heart bpms. Because of the discrepancies between the fitbit and my target heart rates, I periodically check my bpms manually to confirm I’m in my target areas. I’ve read several articles where testing has borne out that when attaining the high bpm goals of 85-90% of max heart rate for HIIT, wrist based apparatuses fail miserably. So I rely on my manual checks during my HIIT workouts to verify I’m within my bpm windows. And BTW, I’m almost 69 and my V02 is 49. Yeah, that might be bragging, or just pride. So be it. 

[t.parker]

@au7772 wouldn't be easier to get a chest strap rather than measure HR manually?