Why no separate activities for hiking vs backpacking?

2572376 said:

I doubt you will see a difference between walk and hiking

I disagree with that statement. You will notice a difference. Both activity profiles use different algorithms.

Ok, well if thats true, I guess you will.

where do you get info about the different algos ?.

Quick test:

- 6 minutes walking with no additional weight

- 6 minutes walking carrying 10kg weight plate

- 6 minutes walking carrying 20kg weight plate

- 6 minutes walking with no additional weight.

You can see the difference in the HR on the graph. I guess impact on HR is even bigger when hiking compared to only walking around house.

*Recorded with H10 chest strap

So more weight -> more HR -> more calories;

No need to input weight of the backpack.

If you performed the same experiment but changed your pace for each weight (in order to maintain the same heart rate) does the estimated calorie expenditure change?

Here is another study "Prediction of energy expenditure from heart rate monitoring during submaximal exercise".  

http://www.braydenwm.com/cal_vs_hr_ref_paper.pdf

They derived this equation for predicting energy expenditure:

EE = -59.3954 + gender x (-36.3781 + 0.271 x age + 0.394 x weight + 0.404 V[O.sub.2max] + 0.634x heart rate) + (1 - gender) x (0.274 x age + 0.103x weight + 0.380x V[O.sub.2max] + 0.450 x heart rate)

The factors include gender, age, weight, VO2max, and heart rate. They were able to show that all of these factors do affect energy expenditure, it is not heart rate alone. Their model predicts that if an individual of a given gender and age, with a known VO2max (based on their level of fitness), were to perform an exercise maintaining the same heart rate but with different weights, the energy expenditure would also change.  

Interesting but a more appropriate test would be:

1. Walk for 10 minutes carrying a 20 kg backpack.

2. Do the same but change weight by +20 kg in Garmin Connect.

Then compare the calorie count between the two. HR indicates your body having to work harder, but I doubt the algorithm would accurately account for calories burned that way.

The hypothesis that heart rate alone counts for the extra calories cannot be true. If I change my weight to 5 kg, I would surely see the calculated calories drop for each of my activities. Weight has to be accounted for in the calculation or it's just not going to be accurate. a 50 kg man will not burn the same amount of calories (even with the same heart rate) as a 150 kg man.

Exactly!  I haven't tested in the field yet but I will.  I'll test on a couple of my hiking and mountain biking hot laps that generally result in the same fitness outcomes.

LoganWest said:

a 50 kg man will not burn the same amount of calories (even with the same heart rate) as a 150 kg man.

When you entered your age, sex, height, weight and activity level when you got your watch you were calculated a BMR by Garmin. So, in your example the calories burned by the two with the same HR would be different, but only because of the BMR and not weight carried.  Let's say the two of us are the same age, height, weight, etc. and have the same BMR. We're both carrying 50 lb packs walking side by side, the same pace and distance. Our hike was nothing for you, but it kicked my rear because I was becoming ill, or hungover, whatever the case, and my HR was elevated much higher than yours.  Because my heart, lungs and muscles worked harder for me, I will show a higher calorie burn than you. 

singletrackmind said:

If you performed the same experiment but changed your pace for each weight (in order to maintain the same heart rate) does the estimated calorie expenditure change?

I would guess that calorie consumption would remain the same as long as HR is same.

singletrackmind said:

Their model predicts that if an individual of a given gender and age, with a known VO2max (based on their level of fitness), were to perform an exercise maintaining the same heart rate but with different weights, the energy expenditure would also change.  

"Their model", do not forget that we are talking about Garmin model here

Considering that even strength training profile/app does not take into consideration weight of the weights lifted (relies solely on HR) i would be very surprised that other profiles/apps are any different (maybe profiles with external sensor inputs like power/cadence/pace) .

You can easily test this by starting strength training app, doing 20 air squats, pressing lap button, correct the rep count if needed, leave weight at 0 (body weight), stop and save activity.

Wait a bit so HR settles, then do the same, but edit weight to be 200kg. Calories consumed will be the same (if you managed to keep the same HR).

I understand. HR will be higher, calorie count will be higher. But I contest the belief that it will accurately reflect the additional calories burned. I don't see how that follows at all. Weight must also be accounted for, and adjusting the BMR (temporarily) accomplishes that.

The most basic form of energy expended, or work performed, is work = mass x distance. Heart rate is a nice little trick Garmin uses to more accurately measure the complex system of energy expenditure in the body, but mass should be the primary factor.

Changing (body) weight in the GConnect will screw up calculation even more. You will get additional calories from increased HR + additional calories from increased BMR. Don't do it.

Carrying weight will increase your HR -> increasing calorie consumption. Is this accurate? I don't know. But by adding the weight of the backpack to your body weight - only thing you are accomplishing is additionally screwing up the calculation.