Importance of specifying physical activity?

[DataNerdella]

Hi, I'm relatively new to Fitbit and very happy with it so far!

How important is it for accuracy of calorie expenditure through physical activity (CE) to correctly specify the activity? I have the Fitbit Versa, and from what I know it calculates CE only by HR tracking (correct me if I'm wrong).

However, let's take for example weight lifting: During compound movements (e.g. squats, deadlifts), true CE is likely higher than when training smaller muscles, even though HR may be similar. When enganging in "risky" sports, HR may be higher just from the psychological side effects (even though true CE isn't higher).

Main question: Should I be more careful for selecting exercise type to get more correct CE details, how can I maximize its correctness?

Additional question: Does Fitbit take into account that someone with a high fitness level will have lower HR during physical exercising than an untrained individual (is this even important for CE)?

Thanks so much in advance

[Dominique]

Here is my take: it’s not very important. There are 24 hours in a day, and the few minutes spent doing the heavy lifting (even if your total session lasts for one hour, maximum effort only occurs during a fraction of that time, when you substract rest between sets) won’t have a major impact on total calories. Fitbit may underestimate energy expended during that kind of activity, but OTOH may overestimate your activity at other times of the day, so in the end, it likely evens out.

Better fitness will result in lower perceived effort by your Fitbit. Some Fitbit do rank your fitness (Cardio Fitness Score), but I’m not aware Fitbit uses the score calculated by it when gauging the calories you burn. 

[Bill_k]

Never mind...ignore.

[Baltoscott · Accepted solution]

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@DataNerdella wrote:

Hi, I'm relatively new to Fitbit and very happy with it so far!

How important is it for accuracy of calorie expenditure through physical activity (CE) to correctly specify the activity? I have the Fitbit Versa, and from what I know it calculates CE only by HR tracking (correct me if I'm wrong).

...

Thanks so much in advance

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It probably takes HR into account somewhat, as well as the movement of your tracker through space.  For that reason, if you don't specify an exercise at all, it will tend to credit more CE for walking fast for an hour than it will for weightlifting the same hour.  On the other hand, if you do specify weight lifting, fitbit will take that info into account, and may give you a bit of a CE 'boost' even though your average HR an hour of weight lifting may be less than the same hour walking fast. 

That said, @Dominique is right.  An hour of exercise in 24 hour day is really a very small part of the calories you burn throughout day.  Most of your calorie burn comes from simply being alive ... breathing, pumping blood, breaking down your food into nutrients, and everything else it takes to keep you up and running day after day.  Fitbit estimates much of that primarily by your current body weight, age, and sex. The movement the tracker records through space is another part and the HR is probably a small part as well.  (I don't think HR is relied on too much for reasons you've suggested ... changing HR is not always or only due to increased activity and is an imperfect proxy for CE)

Whatever the actual number, the best way to find out how your average daily CE matches the calories you eat, is to record everything for a few weeks and see what affect changes have on your weight.  

[DataNerdella]

Thanks for your answer! I agree that it probably evens out over time. Yes, the Versa calculates the cardio-fitness score. That would of course be awesome if it were able to take it into account, maybe in a future version. Thanks for the thoughts

[DataNerdella]

@BaltoscottThanks for your answer. This makes sense. I actually keep track of my food intake; I'll use the data to compare if it matches the calorie balance suggested by my Fitbit once there's more data.

@DominiqueAlso Dominique thanks for your answer, I unintentionally didn't mention you in my answer (above) and haven't figured how to edit it.