Rucking

Those aps make no sense. Garmin calculates the Calories based on your heart rate. When you carry an additional weight, your HR is increased accordingly, and the additional Calories you burn by carrying the weight, are therefore added automatically. So having an app artificially increasing the amount of calories is a pure nonsense.

The point seems to be to allow saving of the ruck weight with the activity record, and also be able to prove whether or not Garmin's algorithm for calories agrees or or not with other validated calculation methods.  A lot of people have doubts as to whether or not Garmin's algorithm actually is correct with an added ruck weight.  Some people adjust their weight setting in the user profile settings.  Personally I don't think this is the correct approach.

No you can’t track calories from rucking by heart rate. If my heart rate is 100bpm but I am rucking with 60lbs on my back it is not the same as hiking or walking at that same heart rate. It’s adding an anaerobic component to a moderate intensity aerobic exercise. 

5569441 said:

No you can’t track calories from rucking by heart rate. If my heart rate is 100bpm but I am rucking with 60lbs on my back it is not the same as hiking or walking at that same heart rate. It’s adding an anaerobic component to a moderate intensity aerobic exercise. 

I am sorry, but no, you are mistaken. A muscle can work in anaerobic mode only couple of seconds (up to some 30s), producing lactate acid. And that needs to be burned in aerobic mode, leading hence to increase breathing rate and increased HR, which is of course detected by the watch, and all those Calories are properly accounted for.

That’s inaccurate. Calorie burn isn’t always equal to heart rate. 

3141635 said:

Calorie burn isn’t always equal to heart rate.

Of course, Calorie burn is not equal to the HR, but there is a direct relation. The metabolism is controlled by the HR, and by the respiration, and both of it can be detected or estimated with the help of the HR sensor. The body simply canot burn more energy than the metabolism can deliver, and the metabolism is directly dependent on the blood and oxygen volume. Hence, Bitti is right, Calories can be indeed always derived from the HR rather accurately. If you want to know more details, I recommend studying the following whitepaper from Firstbeat Analytics, the author of the algorithm Garmin uses in their devices: An Energy Expenditure Estimation Method Based on Heart Rate Measurement 

The EE formula described in the white paper takes into account weight. Rucking usually involves carrying a weight. Therefore, the formula would incorrectly calculate a result based on the additional weight carried that is unaccounted for by the formula because one cannot add a weight for rucking. 

see Figure 1. Model for deriving energy expenditure (EE) from heart beat data. 

I disagree. Strapping on 50lbs effectively changes one’s bodyweight. There is nothing in the paper that you shared stating the additional weight magically disappears or should not be counted. Please share a new study that confirms that or independent peer reviewed papers that are not sponsored by Firstbeat. A paper sponsored by the company selling the product is generally considered to be of low quality.

My athletes need greater recovery time after a ruck with 20% of their bodyweight than they do walking the same distance without weight even though Garmin calculates the same calorie burn with or without the load. Common sense would suggest that performing a more difficult activity would place a higher demand on the system and lead to an increased physiologic response that should be seen in the Garmin tracker results.

Do you work for Firstbeat?

Is that why you are so quick to jump on anyone who questions the accuracy?

Thank you for your thoughts. 

DPT-dad89 said:

My athletes need greater recovery time after a ruck with 20% of their bodyweight than they do walking the same distance without weight even though Garmin calculates the same calorie burn with or without the load.

I disagree with that. The extra weight has an effect on your heart rate. It increases. Accordingly, it is very unlikely that the same calories will be calculated as without a ruck.