VO2max And Calories Burned

Garmin's calorie burn figures seem to be way too dependent on HR when running. Weight and distance are by far the most important factor. HR and pace only have a small influence.

Here's an example where I supposedly burned 555 calories while running 8.37: https://connect.garmin.com/modern/activity/1586317578

Same run at a faster clip, still just 707: https://connect.garmin.com/modern/activity/1637992146.

Garmin's calorie burn figures seem to be way too dependent on HR when running. Weight and distance are by far the most important factor. HR and pace only have a small influence.

Here's an example where I supposedly burned 555 calories while running 8.37: https://connect.garmin.com/modern/activity/1586317578

Same run at a faster clip, still just 707: https://connect.garmin.com/modern/activity/1637992146.

Man, you have a crazy low HR, not sure I have seen anyone with that low of an HR at those paces.

Agree that caloric burn is simply the amount of energy it takes to move a mass a certain distance (vertical as well as horizontal), but including inefficiency. This is where HR plays a role generally, but would be better to use actual running power to derive caloric burn (plus BMR during the run of course). Without a way to measure running power they fall back on using HR to help, particularly when you also cannot measure the impact of running efficiency, surfaces and terrain (i.e. small rolling hills) where you could be working harder for the same pace / distance because you are moving your mass up and you do not recover that energy on the downhills, or you lose energy through surface frictional loss (i.e running on ice) or you have poor form (see Phoebe running from Friends ;) ).

Here is my take on heart rate.

Heart rate and breathing are a direct result of O2 uptake. There is no fitness device (at least that I know of) that has the ability to measure O2 uptake directly, so the next best thing (IMO) is to measure HR. I also learned (back when I was a fitness instructor in the Army back in the 1980's) that 80% of a persons cardio endurance is hereditary, and that means we can only develop 20%. I know times have changed since then, but I think the basics of HR training still hold true.

The basic rule of thumb that I learned is... if you keep your HR in the cardio zone for a minimum of 20 minutes non stop, and do that a minimum of 3 times per week, you will get a minimum training effect (increase cardio fitness level). A longer session more times per week will yield a better training effect. Also Higher HR zones will yield a higher training effect. I like to stay in zone 4/5 for my intense workouts and zone 2/3 for my recovery workouts.

So to me, pace is not a big factor. Sure it makes a person feel good if they can run faster, but some people inherently run faster than other people (that 80% I mentioned) in the same HR zone(s), and I think it's more important to focus on HR rather than pace.

A little over 2 years ago I was obese and so out of shape that I had to lay down after walking only 1 mile at a slow pace. I had a stress test done that did not come back good. They had to do a catheterization which showed a small part of the bottom of my heart was slightly enlarged, and that I could have had a mini heart attack at some point. They also tested my lungs and told me I had COPD. They told me that if I did not start exercising and lose weight that I would not be around too much longer. They recommended walking.

I started walking my butt off. 2, 3, sometimes 4 times a day. I kept my HR in the cardio zone for as long as I could each time and my pace and distance increased over time (that 20% I mentioned). At first I could walk a mile at about a 3 mph pace. After a year I could walk 10 miles at a 4.5+ mph pace. About 8 months ago I started having trouble keeping my HR up enough just from walking so I started adding run intervals into my power walks. I could only run for 30 seconds at first, but now I worked my way up to being able to run 5 miles non stop and can keep my HR in zone 4/5 for an hour.

Sure it's nice to get faster, but my point is that I was able to do this by keeping my heart rate in a cardio zone longer and putting a load on my lungs.

That's why my motto is... if you ain't huffing and puffing and sweating, you ain't doing it right...:)

A great deal has been learned about cardiovascular and aerobic fitness since the 1980's. Again, I suggest you take a look at "Fast after 50," by Joe Friel, published in 2015.

Here is my take on heart rate.

Heart rate and breathing are a direct result of O2 uptake. There is no fitness device (at least that I know of) that has the ability to measure O2 uptake directly, so the next best thing (IMO) is to measure HR. I also learned (back when I was a fitness instructor in the Army back in the 1980's) that 80% of a persons cardio endurance is hereditary, and that means we can only develop 20%. I know times have changed since then, but I think the basics of HR training still hold true.

The basic rule of thumb that I learned is... if you keep your HR in the cardio zone for a minimum of 20 minutes non stop, and do that a minimum of 3 times per week, you will get a minimum training effect (increase cardio fitness level). A longer session more times per week will yield a better training effect. Also Higher HR zones will yield a higher training effect. I like to stay in zone 4/5 for my intense workouts and zone 2/3 for my recovery workouts.

So to me, pace is not a big factor. Sure it makes a person feel good if they can run faster, but some people inherently run faster than other people (that 80% I mentioned) in the same HR zone(s), and I think it's more important to focus on HR rather than pace.

A great deal has been learned about cardiovascular and aerobic fitness since the 1980's. Again, I suggest you take a look at "Fast after 50," by Joe Friel, published in 2015.

Are you implying that if one person runs at a slower pace but at a higher percentage of MHR, and another person runs at a faster pace but at a lower percentage of MHR, that the person who runs faster is getting a better training effect than the slower person?

Speed is not the result of O2 uptake. Heart rate is.

Or maybe I'm just not understanding you correctly.

I may be over simplifying, but I would think that if your heart rate is higher than the person beside, if all other factors are equal, you are probably burning more calories than the person beside you. My simple take would be that the person running with a lower heart rate is running more efficiently (ie. their body is trained to a higher level and requires less exertion to complete the same task) and therefore you require more energy to achieve the same output.

If both persons are the same weight, running at the same speed etc and yet one is running with a higher heart rate, then surely there must be at least a moderate increase un energy use for the less efficient runner to maintain the same pace? Weight would probably still be the largest contributor to the calorie calculation, because there is a huge amount of merit in the minimum energy requirement to move mass. However, efficiency would then mess with those figures a little, making the less efficient runner use more calories. If you have two cars driving at the same speed, but one of them has flat tyres, it will use more power (fuel) to drive the same distance. If you have two runners and one has less aerobic capacity than the other, that person will work harder to achieve the same target. While the big measurement (dragging the mass over a distance) won't change much, letting the air out of the tyres will further impact on the energy requirement.

Maybe too simple? I am not an expert, but it would explain why we all get such different calorie calculations. Happy to be corrected, as I would really like to understand this myself. I am actually studying a health and technology course at the moment, so all this information is excellent!

Are you implying that if one person runs at a slower pace but at a higher percentage of MHR, and another person runs at a faster pace but at a lower percentage of MHR, that the person who runs faster is getting a better training effect than the slower person?

Speed is not the result of O2 uptake. Heart rate is.

Or maybe I'm just not understanding you correctly.

Dude, training with heart rate is so 1970's! It's like jogging wearing a sweatband and listening to John Denver's Rocky Mountain High on your walkman. It's so wheat germ and granola!

Seriously though, we were talking about increasing (maximizing) your VO2 max. There's no better way to do that than running intervals, and you want to run them fast enough so that you're at least at your VO2 max pace, the pace at which you consume the most O2. As I mentioned earlier, when doing aerobic capacity intervals, heart rate lags effort. By the time your heart rate gets into the "proper zone," your interval is over and your walking already.

Although plenty of people train using heart rate, heart rate isn't a very good gauge of when you're at your VO2 max. Heart rate is a proxy for effort, and often not a very precise one. Heat, hydration, stress, all affect heart rate. For any given effort, heart rate can be all over the place. If you've been training too much lately your heart will let you know by only sluggishly increasing. On the other hand, when your body is ready and rearing to go, heart rate often responds very quickly to running effort.

If your interested in digging into the details, as I said, I recommend Friel's "Fast After Fifty." Key in on the aerobic capacity intervals. Another book I'd recommend is "The One Minute Workout," by Martin Gabala. Gabala is the researcher who sort of discovered what intervals can do you for you fitness and VO2 max. The book's title is to peak interests, but the book explains interval training and gives a number of examples of interval routines. Buy Friel's first.

I may be over simplifying, but I would think that if your heart rate is higher than the person beside, if all other factors are equal, you are probably burning more calories than the person beside you. My simple take would be that the person running with a lower heart rate is running more efficiently (ie. their body is trained to a higher level and requires less exertion to complete the same task) and therefore you require more energy to achieve the same output.

If both persons are the same weight, running at the same speed etc and yet one is running with a higher heart rate, then surely there must be at least a moderate increase un energy use for the less efficient runner to maintain the same pace? Weight would probably still be the largest contributor to the calorie calculation, because there is a huge amount of merit in the minimum energy requirement to move mass. However, efficiency would then mess with those figures a little, making the less efficient runner use more calories. If you have two cars driving at the same speed, but one of them has flat tyres, it will use more power (fuel) to drive the same distance. If you have two runners and one has less aerobic capacity than the other, that person will work harder to achieve the same target. While the big measurement (dragging the mass over a distance) won't change much, letting the air out of the tyres will further impact on the energy requirement.

Maybe too simple? I am not an expert, but it would explain why we all get such different calorie calculations. Happy to be corrected, as I would really like to understand this myself. I am actually studying a health and technology course at the moment, so all this information is excellent!

I don't think you're over simplifying things at all. It is pretty simple.

I could even simplify it even more by saying that it really comes down to heart rate and time.

If you keep your heart rate at a xxx BPM for xxx time, you will get xxx training effect. And if you get a good training effect you will increase your fitness level.

It doesn't matter how much you weigh, how old you are, or any of that.

One thing I will say is that you should know what your real max heart rate is so you can set your zones up correctly. I just had a stress test done a couple weeks ago and my MHR is 161 (which just happens to be the same as the 220 - age calculation).

Also, most marathon runners will tell you that they train at very long distances at very slow paces because it is more affective. They also recommend not increasing speed too fast because it can cause injury if your bones/joints are not developed enough.

I don't think you're over simplifying things at all. It is pretty simple.

I could even simplify it even more by saying that it really comes down to heart rate and time.

If you keep your heart rate at a xxx BPM for xxx time, you will get xxx training effect. And if you get a good training effect you will increase your fitness level.

Here's some additional info from Training Peaks that explains their method of calculating a "training effect" as you say. They call their metric TSS, training stress score. The heart rate method is the least accurate, as heart rate is simply a rough-ish proxy for effort. Power is the most accurate because it's a measure of exactly how much work you're doing, literally, work/time. Pace, grade adjusted pace is somewhere in between, as it's a function of power.

It's mentioned that heart rate can be useful in steady state efforts. Even then, it's quite dependent on heat, stress, hydration. Heart rate is pretty much useless in VO2 max intervals.

https://help.trainingpeaks.com/hc/en-us/articles/204071944-Training-Stress-Scores-Explained