HIIT workout tracking - calorie burn and heartrate tracking

[Steveparadox]

Hi all.

I received my Fitbit Sense yesterday after debating getting a fitness tracker for some time. 

My first impressions of the Sense aren't great for many reasons. That aside, my biggest concern is the ability of the Sense to track workouts including calories burned and heart rate. 

I workout 10 hours a week (that's the actual active time I do). I mainly do HIIT workouts, but also do resistance bands, weights and suspension bands too. 

I have used my Sense to track workouts yesterday and today and the tracking seems way off to me. 

I've used the "Workout" exercise on the Sense. 

The HIIT workouts I do are very intense advanced workouts. However the calories burned tracking is very low. As an example, a 40 minute HIIT was tracked at around  240 calories, which equates to 360 calories in an hour. I know for a fact that this is very low and not accurate. 

I have read many articles and reviews that criticise Fitbit for their heart rate tracking. Could this be the issue? I'm surprised when I look at the Sense and see my heart rate is "below zone" when I'm hitting it hard doing burpees, mountain climbers, jumping jacks etc.

Any help would be greatly appreciated. I'm hoping I haven't just wasted my money buying the "flagship" Fitbit Sense. 

Thanks

[Steveparadox]

[RebeccaElizabet]

It could well be heart rate tracking - I have similar problems with HIIT workouts. I use a chest strap as well (which connects to the app I use for my workouts) and also use my FitBit to sync to Vitality. My chest strap is often a lot higher than my Sense, with Sense often showing I'm "Below Zone" when actually my chest strap is showing I'm close to max HR. Judging by how I'm feeling, and how much I'm sweating and panting I would definitely say the chest strap is more likely to be correct!!!

I've had this issue with previous Fitbits and naively thought that if I bought the top end one it would be better. It's not. I am getting incredibly frustrated now, and also cross with myself that I keep falling for the marketing and buying progressively more expensive Fitbits in the hope that they might actually function in any way adequately. 

Some things to try in case you haven't already (because these are the first thing support will tell you to do) are to make sure you're wearing it slightly higher than you would usually do - about two fingers width away from your wrist bone, and also slightly tighter than usual (snug, but not constricting the blood supply!). I have to caveat this with the fact that this absolutely has not worked for me and my Sense is still basically a random number generator as far as HR is concerned. They will also tell you to restart (the stage I'm at now), and see if that helps. 

On the calorie tracking side, other than the impact that inaccurate HR will have on this, I do find Fitbit calorie tracking to be somewhat lower than other estimates. I did read an article at some point where they explained that, and it did seem plausible (I think it mentioned that other estimates don't take into account as much of your personal data such as height, weight, age, etc, but annoyingly I can't find the article now). Accurate calorie tracking is very difficult and so I tend to take it with a pinch of salt, regardless of which method / device / etc I'm looking at. 

Hope some of this helps. If you have access to a chest strap it might be useful to compare and contrast, and then contact support if you do find your HR to be way off. 

[Steveparadox]

@RebeccaElizabet many thanks for your reply. Having tested the Sense out over the last 3 days, heart rate monitoring is definitely the issue. It is so far off it's a joke. I've noticed it recording under 100 bpm when I have been doing very intense HIIT workouts, I'll check my wrist when doing Burpees, jumping jacks, mountain climbers, etc and see it saying something like 98bpm which is laughable at just how far off it is! The average recordings I'm getting across my sessions is around 110bpm! During the sessions I'm active for 30 or 40 seconds and with 10 seconds rest and I do around 1 hour 45 mins a day. 

I'm

I have spoken with Fitbit and they said there are known issues with the device and have proposed sending a replacement. I suspect I will have the same issue with the replacement in which case I'll have to look at getting a refund. I had high hopes for the device and this is my first fitness tracker. I hoped it works encourage me in my workouts with it being able to track my stats, however it simply cannot track any of the stats and is completely useless to me, other than tracking my sleep. 😤

[RebeccaElizabet]

I'm in a very similar situation, as I do mostly HIIT workouts, weights, and a bit of yoga/pilates for mobility. I actually got my Sense a couple of months ago but haven't been able to do much exercise due to an injury. Now I'm getting back into it again and am discovering all the issues.

I have Vitality life insurance so bought the Fitbit because it's easy to link up to that. But I'm not getting the Vitality points for my workouts (which then reduce my premiums) because my Fitbit is just consistently saying I'm "below zone" when I can see from my chest strap that I'm working at my max (or as close to my max as I can at the moment). It'll spend about 10 minutes saying I'm below zone, then go up to a vaguely sensible HR, but then at any point might dip down again to below zone and stay there for another 5 minutes or so before jumping back up. I suspect it has some kind of algorithm that over-compensates for rapid changes in detected HR by smoothing it out, but goes too far. I'm going through support but also think returning it is on the cards. 

If the main thing you want is to track workouts, and you're mostly doing HIIT workouts, I'd recommend a chest strap for the best accuracy. Wrist heart rate monitors are never quite as accurate for HIIT, weights, and anything that involves wrist movements (although they should be at least in the rough ballpark!!!), but are good if you want to track general health as well as workouts. 

Anyway, I hope the replacement works better - who knows, maybe we both have duds! And otherwise hope you manage to find a device that works for you 🙂

[Steveparadox]

@RebeccaElizabet  thanks for the further info. I hope we both have duds so there might be hope of getting it resolved rather than getting a refund. I wouldn't mind if the heart rate was a bit out, but when it isn't recording having any active zone minutes when I'm going all out, it is clearly beyond the realms of what would be tolerable with a device that is meant to track heart rate. I hope you are recovering from your injury. 

[Honulii]

Same issue here with the HR during HIIT workouts.  I find that the Fitbit is slow to register increases in my HR and quick to register the decrease in HR, which really sucks when you're doing HIIT.  I wear a chest strap monitor and I'll be out of breath and it will say I'm in the 90%+ range and my Fitbit will tell me I'm in the "Below Zone" (100BPM).  If I stand still during the rest period, sometimes the Fitbit will register the correct HR.  It used to really annoy me during workouts to finish a set and then see my HR was still in the low 100's.  So I've basically started to ignore the Fitbit and only activate the workout mode so I can keep track of the days I'm working out.   To give you an idea of the discrepancy, my last several workouts, Fitbit will show an average HR of 130's and my chest strap 150's.  That's a pretty decent discrepancy.  

Previous to the Sense, I had the original Versa and I felt that was way better in tracking the changes in my HR, although I think maybe it overestimated my HR at times (perhaps it was slower to register decreases).  IMO I think the Sense's technology sucks and there is room for improvement.  I kind of expected some bugs since this is the first version of it's kind, but its disappointing for the price I paid and how much I'm not liking it.  If I had to do it all over again, I would have gone with the Versa 3.  I honestly don't find the additional functions of the Sense useful for how much more I paid vs if I had gotten the Versa 3. 

I've never really paid much attention to the calories burned - I feel it's not accurate anyways and so I never really paid much attention to it at any point owning Fitbits.

Been a long time user of Fitbits - This is probably the 5th version I've owned.  With the exception of one that just died on me, I just like upgrading to the newest option every couple of years.