Calorie Accuracy: TR vs Garmin Forerunner 935

Hey everyone I am a new TR user (don’t know why I waited so long) and I am using virtual power. I have a garmin forerunner 935 I am using to track HR but it is not connected to TR as I have not yet purchased a dongle.

I am getting a large (over 300 calories for Mt Field) calorie difference from TR and my Garmin. Would the Garmin be more accurate because it also takes HR into account?

Also I am trying to shed some weight at the same time. Would it be beneficial to keep the lower TR calorie number in My Fitness Pal and eat fewer calories or am I setting myself up for burnout and fitness loses?


Your Garmin uses Firstbeat to calculate calories burned so should be the closest to being accurate (outside of lab tests)

Awesome, thank you. Would it be best to consume the full amount of calories? I have MFP set up to be at a deficit as well.

I would differ. A trainer with power measurement precisely measures how much energy has been expended - power x time. Estimates based on HR are just that - estimates.


It is worth noting that your HR will generally be higher for indoor cycling because of the heat, than it would be for riding the same power outside. This will cause the 935 to overestimate the calorie burn using the HR method.

Of course, there could be some issues with the accuracy of virtual power, but it could be high or low, whereas HR data is likely to be systematically higher with indoor cycling.

Its ALL estimates. TR is based on 25% of joules/watts burnt based on average body efficiency figures, which of course can still widely vary person to person. Its just a guide really, in all cases, which is good enough.

He’s using virtual power, so HR is likely more accurate than a kJ to calories conversion. You’re correct that if you have accurate power measurement via a smart trainer or a power meter that would trump any HR calculation, but since he’s on virtual power the HR data is going to be better

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