Exercise settings and calories burned

[Freesia01]

Hi,

I’ve never used an activity tracker before, using my phone for steps and the numbers on the gym machines for calories - but they’ve told me it’s not all that accurate and a heart rate monitor is better, so I’ve bought myself an Inspire 3.

Sorry if this has been covered before, I couldn’t find it answered exactly though.

I am wanting to know about how to best set my Fitbit in the gym when my focus is on calories burned.

So general questions are:

If I am looking at calories does actually telling it I’m on a treadmill or exercise bike make any difference if its looking at heart rate for this or I just leave it on its automatic setting?

Same for if I tell it I’m on a treadmill and am on an incline, will it still get calories right?

For the weight machine is it best to set it to something?

I did find for the sort of arm bike type machine I need to change that cos it thinks I’m doing steps!

I did find in bed last night it said my HR was well over 100, I counted it and it was nowhere near! So not sure what was going on there!

I’m also rather insulted it counts my normal walking pace as strolling very slowly!

Thanks all!

[JohnnyRow · Accepted solution]

A lot there.  Yes, calories are just based on heart rate, so exercise choice does not affect that.

However, you mentioned just going with automatic setting.  I suppose you mean relying on Fitbit auto-detecting that you are exercising and assigning a category to it, versus the alternative of using the Exercise App on your wrist to select the exercise type and manually starting and stopping the exercise session.  Both options should give the same result for daily calorie burn, but relying on auto-detection might miss detecting some exercise sessions so you would not get the calorie burn broken out for the exercise session but would still get the calories for the day.  But any time you use the on-wrist Exercise App, it is guaranteed to be counted as an exercise session and to give the calorie count for that session.  And if you don't see a description that fits what you are doing exactly, "Workout" is a good general descriptor.

If you are at the gym doing several activities, you could just set "Workout" for the whole time if you didn't want to bother trying to reset for each activity.

Your mention of steps for the arm bike brings up a whole other issue.  First, steps do not affect calories,  Again calories are just from heart rate.  And generally your choice of activity is not going to prevent steps detection.  Fitbit, and any tracker worn on wrist, cannot directly tell what legs are doing, so just infers steps from arm movement, assuming regular rhythmic arm movement like swinging arms as in walking is steps.  It tries to tell the difference but makes some mistakes,  In most cases over course of full day, comes out fairly close.  Arm bike might be one case that throws it off.  Others are knitting, playing drums;  other cases where steps are not detected are where arms are not moving such as on treadmill holding hand rails so arms do not move.  But none of these affect calories as long as heart rate is still detected.

Lot of info there.  Hope I didn't just confuse you.

[Freesia01]

That’s really great, yes thank you.

[JohnnyRow]

Here's the official Fitbit Help page bit about calories, going into BMR (Basal Metabolic Rate) calorie burn also, from How does my Fitbit device calculate my daily activity? 

[YachatsMike]

The Fitbit measures time, heart rate, and arm motion (it has a magic algorithm that turns that to steps).  The exercise apps pick parts of what the Fitbit measures and turns them into other measures like distance or calories using their own calculations.

As far as I'm concerned, the only valid measure is Active Zone Minutes.  It is derived directly from what the Fitbit measures and corresponds very closely to the exercise recommendations of the HHS Physical Activity Guidelines.  (150 minutes per week of Moderate activity or 75 minutes per week of Vigorous Activity or a combination of the two)  All the other stuff;m steps, miles,calories; are just arbitrary measures that can be interesting and motivating but not the main game.

A limitation of deriving everything from heart rate is that calorie calculations from the first 10 - 15 minutes of exercise is that it takes a while for your heart to catch up with what you're doing.  It will under-report the number of calories used.  The machine knows how much force I'm applying (Watts) and, if it knows my weight, can do a pretty good job of calculating calories.  I take their counts at face value.

[MrBosco]

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@JohnnyRow wrote:

A lot there.  Yes, calories are just based on heart rate, so exercise choice does not affect that.

Very many thanks.  This explains why the Fitbit calorie count is so inaccurate for me.

To give an example - I have a Charge 6 and a couple of weeks ago the Fitbit app reported that I had burned 4,507 calories in a single day.  The only exercise I had done that day was a 35 minute walk and 25 minutes of sweeping leaves, preceded and followed by about an hour of light activity as prepared food and packed for a trip.  I am fat and very unfit, and as I did these activities in relatively quick succession I somehow managed to keep my heart rate up enough to get 369 zone minutes that day.

Interestingly, the 'Cardio Fitness' feature in the app rates my fitness as 'Good to very good'.  I am not fit enough to go for a run to calibrate this feature properly.  I'd probably die of a heart attack if I tried to run for 10 minutes straight.

The bottom line seems to be - you have to be close to the average cardio fitness level in order for the calorie count feature to be close to accurate.  Very good to know!