Swimming calorie count inaccurate

[PapaLuxe]

This is a screenshot of one of my front crawl moderate speed swimming sessions. The 271 calorie count for this session is inaccurate, as it is for all of my sessions, if you use the 2024 compendium of physical activities as the standard in which case it has a met value of 8.0 which translates to 512 calories. Could someone explain to me why the discrepancy?

[JohnnyRow]

My point of view is to disregard whether is was swimming or whatever activity, but look at the heart rate chart, which is what calorie burn is based on.  Compare another activity such as walking or running or anything else for 53 minutes at a similar heart rate and see what the calorie burn is there; or for a shorter time and just the calorie burn rate per minute.

As for the "compendium of physical activities", that is a good starting point when you have nothing else to go on, but when you have actual heart rate readings, I think they override any generalized values.

Another point about swimming: I used to swim a lot and studied and tried to learn as much as I could to improve, though I never got very good, but I did learn that the amount of energy output varies greatly with technique; a top swimmer with excellent form burns a fraction of the calories of an average recreational swimmer, so I expect coming up with a met value for swimming requires quite a bit of equivocation, more so than with other dry land activities.

[PapaLuxe]

Thanks Johnny, your suggestion is a very good alternative to relying on the Luxe. However, I have paid for an smartwatch and premium service for the convenience of not having to do additional calculations. I have also consulted other sources for MET values for my age and weight and they all fall within the range of 500 to 700 calories. So, the Luxe calorie estimates for swimming are on the very low side.

 

 

[JohnnyRow]

I guess I didn't explain myself well.  I did not mean to suggest an alternative to the Luxe;  I meant to support the Luxe and its calorie estimate based on its heart rate measurement.  I only meant to compare the swimming to any other activity measured on Luxe with corresponding heart rate, though I realize that wouldn't work if swimming might be your primary activity.
But, in my mind, my same argument would hold for swimming, using any other source.  Swimming, by its very nature, is going to vary greatly in calorie burn by individual, depending primarily on stroke efficiency, and any source is going to have to be just a rough generalization based on general population, without the added benefit of having heart rate measurements.  Having heart rate data means you don't have to go by these generalizations.
But that's just my viewpoint; I expect you see it differently, and I am willing to agree to respectfully disagree.

If you want to change the calorie burn count, I believe you can manually log the workout for the same time period and enter whatever calorie burn count you want.

[PapaLuxe]

Thanks Johnny for the clarification. So I went back into my Luxe records to find a comparable activity for the same length of time (see pic).

So walking 8 mins more at a 70% moderate rate with a lower BPM results in 160+ more calories. I have checked my calorie counts for walking against the compendium of physical activities and other sources and they are within the same ranges. So why are the swimming calorie counts not? Do you burn more calories at a moderate intensity and lower BPM then add a vigorous intensity and higher BPM?

[Gr4ndp4]

Hi, @PapaLuxe welcome, how did you record your swim? did you use the exercise>swim function on your Luxe or did you manually enter the activity? I ask because normally Fitbits disable HR recording when swimming. 

This is my swim this morning on a PW2 for comparison -

Let us know by posting here again.

Cheers

[PapaLuxe]

Nice swim, I wish! To answer your question the Fitbit Luxe recognizes that I am swimming without me having to do anything. I haven't figured out yet how to input the length of the pool in order to count laps and don't even know if that's a Luxe  function? 

[Gr4ndp4]

Hi, @PapaLuxe you can set up your swim lengths by swiping left from the clock face screen to exercise>swipe up to swim (if you do not see it check the manual to set shortcuts)On the swim start screen you'll see a little chevron at the bottom, swipe up to units toggle between yards or metres>swipe down to pool length & select the length (in metres or yards) by sliding your finger up or down the screen>swipe right to get back to the clock screen & you are set.

I hope this helps, let us now how you get on.

Cheers

[PapaLuxe]

Thx @Gr4ndp4 , that was very helpful. As luck would have it, my Luxe was already set at 25 metres which explains why the distance was so accurate. You have been very helpful, much appreciated.

[PapaLuxe]

Hi Again @Gr4ndp4 , just one last observation. Based on your swim data your PW2 calculated +/-  383 calories in half the time (50 mins) which is still 100 + calories more than my Luxe. While my age (70) and weight (69 k) may not be the same as yours, thus affecting calorie count calculations, it still speaks to my contention that the Luxe appears to under-estimate my swim calories. I am assuming 🤔 that you are not doing the butterfly for 150 lengths of the pool  😆.

[Gr4ndp4]

Hi, @PapaLuxe, I swim freestyle, I have a similar profile to yours but have been swimming like this for 40 years. In addition to my PW2 I also wear a device from another manufacturer, this morning the calorie difference was 20, a typical discrepancy in my experience of numerous Fitbit devices. The real test of calorie accuracy is whether I am losing or gaining weight as anticipated (I weigh myself daily). The answer is a very clear "YES". I appreciate there are a number of variables to achieve this but I've not changed the way I record my meals or the calorie database I use.

You might find this article of interest How does my Fitbit device calculate my daily activity? - Fitbit Help Center (I apologise if you've already seen this). Additionally, you may find there is a slight difference in your calorie count if you start the "Excercise" from the Luxe on your wrist rather than rely on the auto-recognize feature. I recognise it's a pain trying to set up without glasses on at the poolside but you might like to try it to see if it makes any difference. 

Let us know how you get on, remember swimming is much safer than running or cycling, hips & knees remain damage-free and there's no risk of falling off your bike or being hit by a car.

Cheers

[PapaLuxe]

Hi @Gr4ndp4 , so I followed through on your suggestion and started my first swim from the Luxe "Exercise" module on my wrist.

Then a little while after I started a second swim allowing the Luxe to recognise the activity, which again, was a leisurely breastroke.

As you can see: the time, distance (intensity) and calorie counts were near identical. So, I am still wondering why my swim calorie counts appear to be lower than standard estimates for my profile and swim intensity, even though those for walking and biking are within the normal ranges? Btw, I started calorie counting which turns out to be quite effortless. Cheers

 

[Gr4ndp4]

Hi, @PapaLuxe, thanks for the feedback, if you look at my stats, a 25-minute swim (1/5th of 99 minutes) would consume  1/5th of 765 calories (153 calories) not too far from your stats bearing in mind I'm quicker. You will find calorie counting very helpful in managing your weight, be aware that portion control is critical (I weigh out portions on a digital countertop scale) it is quite easy once you populate the app - we are creatures of habit and do not vary what we eat over a week or so.

Good luck.

Cheers