Did you miss this in the FAQ?
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Do I log all my exercise in MFP per instructions MFP gave?
Don't need to at all. That is merely so you use MFP more, and more usage is more ad dollars.

Fact is for the non-HR devices any step based exercise (walking, running, gym classes, ect) will have a pretty good estimate for calorie burn from Fitbit (if stride length is correct), unless the walking/running is at good incline for good amount of time, because it assumes flat. You would need to log non-step based workouts though (swimming, rowing, biking, elliptical, stair climber, resistance training with weights or machines), because the steps seen are not related to the calorie burn at all.

For the HR devices any cardio is going to be decent enough estimate. Though here again, lifting should be manually logged as it's not aerobic steady-state, and calorie burn will be inflated using HRM formula. Manually logged in database as - Weights on Fitbit, Strength Training on MFP.

So for what should be manually logged, it can be logged in MFP or Fitbit. Fitbit's database uses a better method of calculating calorie burn, and for some non-step based exercises has more intensity options, more about that below. It also prevents the need for an extra sync from MFP to Fitbit, before updated daily burn is synced back to MFP.
If you want friends to see your workout, just make a wall post about it, with more details than you'd normally get. The Fitbit Activity diary has better view and options anyway compared to MFP.
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Fitbit site specifically states that the Charge HR is not accurate for biking and other non step based activity. The new Surges have an update now that is more accurate.

I have just started to ride a bike again, I am using the MapMyRide calorie info to manually log my biking.

mbhomishak wrote: »

Do you find that your Charge HR is accurate in calories burn/steps while using an elliptical or bike?

I love my Charge HR.

Log the biking either in Fitbit (that's what I do) or in MFP. (Exercise logged in MFP overwrites your Fitbit burn during that time.) You probably don't need to log the elliptical at all—it'll take trial & error to find what works for you.

The formula for calorie burn based on HR doesn't change depending on activity unless major difference between upper and lower body engagement - and there have been no good studies giving better formula for the required stats that are used.

It is accepted (but bad study design for 1 study used) that biking has a different HRmax and VO2max than running.
Therefore the calorie burn at the same HR will be different.
But that was only from pro triathletes that came from running background. Another study with them coming from biking background showed no difference.
So you average recreational person really has no difference.

Swimming will also be different, thought to be because it's horizontal, rather than fact it's primarily upper body smaller muscle engagement.

And again, studies have not shown any clear difference that can be expressed per formula.
Just that it's lower calorie burn per same HR.

I really doubt that Fitbit is the first on the block attempting to do different burns for different activities when no studies support a good formula for doing so.

So to that end, the activity selection merely gives the activity a name, rather than prior devices where the button press just created an unnamed activity you had to correct later if you ever wanted to review and find them later.

I'd be curious if someone could do a bike and elliptical at exact same avgHR and see how different the calorie burns are. Must be within the same week though, because I'm sure Fitbit is using restingHR and weekly exercise amount in a known formula to estimate VO2max.

I'm surprised Fitbit says the ChargeHR is no good at biking until the upgrade, unless they are applying that mistaken lower calorie burn.