FitBit calories burned

jnomadica

My FitBit estimate of calories burned overall seems fairly accurate, since when I lost some weight through calorie restriction I lost as expected based on those numbers.
However, I’m recently surprised by my exercise calories burned. For example, it says I burned 180 calories on Friday with a 33 minute walk (I’m 41F, 5’5’’, 132 pounds). It says I burned only 227 calories the next day for an hour long Krav Maga class (it only counted 45 minutes for some reason, I’m guessing since there are brief rest times). The difference in intensity between these two “workouts” is huge. The walk was a stroll with my dogs, brisk, but I could still easily carry on a conversation. The Krav class is punching, kicking, burpees, push-ups, hill sprints, etc.- completely exhausting, at times it’s hard to catch my breath, and I’m an absolute puddle of sweat. So a 50 calorie difference seems off.
Do those calorie estimates seem right? I’m just asking out of curiosity, as I’m just maintaining now and am not counting calories. Thx!

heybales

Your Fitbit says the workouts burned that many calories?

Or on MFP in Exercise Diary your Fitbit Adjustment had that many calories?

The latter is not a figure for the workouts - but the total difference between what Fitbit sees you burning so far, and what MFP thought you'd burn at stated activity level and no exercise.

If indeed the latter, the harder workout may have wiped you out for rest of the day worse, and you moved less in general.

If this is all straight on Fitbit Activity Records - look at the HR graph - look correct?
Or did Fitbit lose a correct HR, thereby underestimating your calorie burn.

jnomadica

It’s the Fitbit estimate of calories burned through specific exercise. It’s hard to tell about the HR graph- lots of ups and downs for the Krav class, as we will go hard for some time, then have a short rest, then go hard again.

heybales

Because many people do find that even if the HR is accurate for daily and low-intensity things - it'll lose it when the HR goes up.

Either totally missing the jump up (as interval stuff would do), or it raises but won't show past a certain HR even though it's really higher.

Next time you get done with hard interval, take HR for 10-15 sec immediately and confirm Fitbit is right.

Now, interval type stuff does cause a HR-based calorie burn to be inflated, but I'm betting here the issue is missed HR readings at higher levels.

Interesting tidbit - in studies for weight lifting, it's equivalent in burn to walking 2 mph during that chunk of time.

Of course the hope is a good workout requires some repair later and you'll burn a tad more then.
Similar to the hope of interval type sessions if body is pushed hard enough damage is done that needs repair.
Or perhaps just below that level and EPOC adds a tad more calorie burn later.
But in either case it's not major.

And that's why those types of workouts aren't about the calorie burn - but the body transformation.
So 227 for 45 min still sounds tad low for higher intensity workout.

jnomadica

Thanks, I’ll try that. Luckily I don’t do it for the calories, just for fun and fitness. But it does seem weird!