Polar FT4 calories burned vs treadmill calories

[Spacikasi]

Not exactly fitbit related (i do have one!) so hope its okay to ask... My stats are: Weight: 178 Height: 5'8" Gender: Female While on the treadmill yesterday (Life Fitness brand), it estimated that i burned 355 calories in 39 minutes (3 miles). my Polar FT4 says 560 calories during that time, with my average heart rate being 171. My resting heart rate is around 92. I was doing interval training, so I was going back and forth between 3.8 miles and 5.5 miles every couple minutes or so. I've read to trust the HRM over the machines, but that still seemed like a big difference in calories. Is the Polar [approximately] accurate?

[WendyB]

I have a Polar FT7 and I find mine very accurate. Way better than a machine.

Yours does seem high. Do you have your weight Age etc set correctly in the watch?

560 sounds high for 39 minutes

[Heybales]

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@Spacikasi wrote:
Not exactly fitbit related (i do have one!) so hope its okay to ask... My stats are: Weight: 178 Height: 5'8" Gender: Female While on the treadmill yesterday (Life Fitness brand), it estimated that i burned 355 calories in 39 minutes (3 miles). my Polar FT4 says 560 calories during that time, with my average heart rate being 171. My resting heart rate is around 92. I was doing interval training, so I was going back and forth between 3.8 miles and 5.5 miles every couple minutes or so. I've read to trust the HRM over the machines, but that still seemed like a big difference in calories. Is the Polar [approximately] accurate?

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HRM's use a calorie burn formula that is very specific to the ONLY conditions where HR can translate to calories burned.

Steady-state aerobic exercise, same HR for 2-4 minutes.

If you were doing the intervals correctly, you may have even been anaerobic for the high end, at the least you were on the edge where accuracy falls off.

But more important - you were no where near steady-state - just the opposite.

So your avgHR 171 was badly inflated for the level of effort actually being done.

You can prove this to yourself next time. I'm guessing you start out at the 3.8 mph walking first?

What's the HR then, when you do the walking first as warmup?

That is the HR that is needed to support that level of calorie burn.

Now do your hard interval, HR gets up to say 190 or above or whatever. You then start walking again.

How long does it take for the HR to drop back to what you now know is required for that speed of walking?

Does it ever drop that low again, or do you start the hard part before it's even reached the low HR?

See - elevated that whole time walking probably - inflated calorie burn.

In this case, if the treadmill has your weight, it's more accurate.

Even when used in correct exercise type, the cheaper Polars make some big assumptions because they don't have the values really needed or test for them.

They assume that if BMI (weight/height) is bad for your stats (age/gender), then your fitness level is bad too (VO2max).

But that is bad assumption. Especially when really out of shape, or really in shape.

Because you can have bad BMI and good fitness level, you can have good BMI and terrible fitness level.

The other thing that could be easily throwing this off - your resting HR is really 92, like waking up first thing in the morning? That just seems high - any meds that would cause that?

http://www.exrx.net/Calculators/WalkRunMETs.html

Using Gross option, since that's what treadmill and HRM report - 178 lbs at 4.62 mph = 446.

But since some of that was actually walking not jogging, tad less. 357 in that case.

So treadmill right on - not surprising, since the formula for treadmill calorie burn is one of the most accurate as it's most tested in studies and well known and used.

If Fitbit is decently correct for distance, it'll probably match the treadmill, since it uses the same formula also.

[Spacikasi]

Thank you both for the replies!

Heybales: I was meaning my resting heart rate as in my normal heart rate. I am on medication temporarily. My blood pressure has been a little high the last couple months as well, but I know it's because of the medication as its been the same amount of time I've been on it.

I am fairly new to using a HRM so this is all a learning experience, I want to make sure I am doing it right from the beginning!

According to my polar, I was only "in the zone" for about 6.5 minutes out of that 39. The polar says my "zone" is between 125-165.

So basically, if I'm jogging and it's above my zone, I should then slow down again to stay in the zone? This will give me the best workout? My goal is to lose another 20 lbs, so I'm not working out for toning up or anything yet.

[Spacikasi]

Also to add: yes I start out walking at the 3.8. This had my heart rate usually in the 150s.

[Heybales]

Best workout?

Depends on your goal.

Endurance and you want to train the fat-burning side of the aerobic range for 1 plus hours?

Calorie burn and you want to burn the most calories for limited time available?

Body improvement from given exercise making the most changes?

Heart benefit?

Yep, they can all be different.

So best workout is highly dependent on your reason for doing it, and your goals.

You comment on 20 more pounds, so I'm betting you'll say calorie burn. But let me know.

[Spacikasi]

yes, you are right, calorie burn : )

[Heybales]

For purely calorie burn to increase what you burn daily - thus allowing you to eat more but still lose fat....

As hard as you can make it each day that still allows a hard workout the next day.

Hard as measured by some objective value - speed, pace, HR, ect. Not how it feels.

You can be dead tired and feel like you are pushing as hard as you can - and probably are - but that doesn't mean your body is doing a lot of hard work compared to what it could do if you were not tired.

So if you find a certain pace makes it impossible to hit the same pace the next day - it's too high a pace, at least for now. As fitness improves, so will that ability.

The more days you have in a row, the more important recovery is for the next day to be just as hard.

So good sleep, not a bigger deficit than is reasonable, ect.

This type of workout will be a high calorie burn with high % of carbs, and as much fat as can be burned.

Which means with muscle glucose that used up, your next meal or two will be sending carbs to the muscles, insulin will drop that much faster, and your body will be back in normal fat-burning mode sooner than if you didn't do the workouts.