Fitbit HR based calorie burn: What's the point of logging exercise?

DogBuddy69

What's the point of logging exercise if Fitbit is supposed to calculate my calories burned based on my heart rate?

When going for a run, do I just need to have my fitbit on or do I need to actually go into fitbit's menus and select a type of running?

I often use my punching bag to get an aerobic exercise without leaving the house. Since it's not step based, I need to log it separately? I thought fitbit was supposed to estimate my calories burned based on my heart rate, so why do I need to log this separately? Same with other things like biking.

Also, I'm confused as to why I need to log things like pushups/situps separately. If my heart rate goes up during these exercises, fitbit will estimate my calorie burn for that time period, yes? So, why log them manually?

From the FAQ:

lifting should be manually logged as it's not aerobic steady-state, and calorie burn will be inflated using HRM formula.

Do pushups/situps fall under this? Why would they be inflated?

I just don't understand why I should log any exercise if Fitbit claims to estimate my calories burned based on my HR.

Was up til 3:30 am last night trying to figure this thing out. I haven't even started using it and I'm already frustrated over the idea of over-eating because I don't understand how everything works.

Thanks for any help you can provide.

pineygirl

I don't log cardio (running, walking, elliptical) at all...since it just calculates it off my heart rate. I do log weightlifting though. Because fitbit might say I burned 300 calories in 30 minutes based on my heart rate, when in reality I've burned maybe 60 to 80 calories. So I log it so it adjusts the calories burned.

I probably would log push ups and sit ups and other body weight exercises, since they aren't steady state cardio....so the heart rate isn't accurately indicative of calores burned.

NancyN795

I'd recommend reading the FAQ found in the stickies for a comprehensive explanation of all things Fitbit/MFP.

The math that is used to compute calorie burn from heart rate is based on studies of people doing steady state cardio exercise (i.e. running, walking, etc.) where the heart rate doesn't vary a lot over time. So, exercise that doesn't produce that effect won't give accurate calorie burns. Plus, there are things that can elevate the heart rate that don't have any calorie burning effect (e.g. stress) so, your Fitbit needs more than just a high heart rate to decide to use the calorie burn formula. It also needs to see steps. So, when you do something like push-ups or sit-ups it won't see many steps and won't apply the calorie burn formula. I have no idea how it would handle hitting a punching bag.

heybales

Also depends on time spent.

If 5 min every morning doing some pushup/situps - no big whoop, get what you can from the estimate, don't worry about manually logging it.

Intense or longer workouts where the inaccuracy could add up over a week - that matters.

3 x 30 min weight lifting weekly - probably no big deal in the scheme of things.
6 x 90 min - now that is a big deal and the inflated calorie burn could cause problems based on HR, or under-reporting based on steps.