Calorie count on Polar HRM

samsemtex

Hi,

I've been using my HRM which is a polar cs300 for the past while and i have always noticed it tells me i am burning a very high number of calories. I went out for a 110km spin with a friend recently and he has a hrm hooked up to a garmin and it told him he burned 1500calories less than me. I was burning about 1050-1100calories an hour and hrm avg was around 82% while his was around 77% (I'm not sure how accurate my %s are because i seem to be able to spin away all day at 82-85 average so maybe the fact it says i was at 82% doesnt mean much). I was definitely pushing to keep up with him but i did it.

Anyway doesnt a calorie difference of 1500 seem like an awful lot? Every time I go out, even when its at a slower comfortable pace it tells me i am burning about 950-1000 calories an hour. Isnt that very high?

shockedsoshocked

If you have the proper data ie been lab tested, the algorithm the polars use is relatively accurate (if you've got the version that lets you put in weight/max HR/Lactate HR/VO2 Max).

flywheel88

Well do you weight a lot more than him? You burn more if you are bigger. I have a Polar HRM and have foind it to be very accurate. The other thing is you might want to check and see if you have your weight inputted correctly. (If that model lets you do that- mine does).

cougie

Theres no way youve burnt 1000 calories in an hour on the bike.

Running is an easy way to work out calory burn - and its roughly 100 calories per mile.

http://www.runnersworld.co.uk/weight-lo ... /3166.html

So ask yourself does it feel like you've done 10 6 minute miles ?

ric/rstsport

i work with riders who, on long rides, expend between ~400 Kcal/hr and 1260 Kcal/hr (sometimes higher).

Energy expenditure is related to the power output you're riding at, as mechanical work done (Kj) is equal to power x time. Actual energy expenditure (Kcal) can be estimated from mechanical work done.

In general cyclists are about 20 to 25% efficient and 1 Kj is 4.1868 Kcal (so efficiency and Kj > Kcal roughly cancel). In other words whatever work done you do (e.g. 1000 Kj) is approx the Kcal your expended (1000 Kcal).

If the Polar HRM energy calculation was useful, you wouldn't need a power meter as you could back calculate power from energy expenditure. It's way off (under and over estimating for people)

Ric

Dave_P1

Ric/RSTSport wrote:

i work with riders who, on long rides, expend between ~400 Kcal/hr and 1260 Kcal/hr (sometimes higher).

Energy expenditure is related to the power output you're riding at, as mechanical work done (Kj) is equal to power x time. Actual energy expenditure (Kcal) can be estimated from mechanical work done.

In general cyclists are about 20 to 25% efficient and 1 Kj is 4.1868 Kcal (so efficiency and Kj > Kcal roughly cancel). In other words whatever work done you do (e.g. 1000 Kj) is approx the Kcal your expended (1000 Kcal).

If the Polar HRM energy calculation was useful, you wouldn't need a power meter as you could back calculate power from energy expenditure. It's way off (under and over estimating for people)

Ric

That's interesting as I always try to put back in what I've burned but after reading this I don't think I've been eating enough as my power meter (just bought) is reading much higher than my Garmin, which is what I've been using in the past.

samsemtex

flywheel88 wrote:

Well do you weight a lot more than him? You burn more if you are bigger. I have a Polar HRM and have foind it to be very accurate. The other thing is you might want to check and see if you have your weight inputted correctly. (If that model lets you do that- mine does).

Nope I weight about 10kg less than him. I weigh 74kg at 5'11 and have around 10% body fat. Weight is input correctly but I dont have an option for lactate threshold and I dont actually no what my lactate threshold is.

Ric/RSTSport wrote:

i work with riders who, on long rides, expend between ~400 Kcal/hr and 1260 Kcal/hr (sometimes higher).

Energy expenditure is related to the power output you're riding at, as mechanical work done (Kj) is equal to power x time. Actual energy expenditure (Kcal) can be estimated from mechanical work done.

In general cyclists are about 20 to 25% efficient and 1 Kj is 4.1868 Kcal (so efficiency and Kj > Kcal roughly cancel). In other words whatever work done you do (e.g. 1000 Kj) is approx the Kcal your expended (1000 Kcal).

If the Polar HRM energy calculation was useful, you wouldn't need a power meter as you could back calculate power from energy expenditure. It's way off (under and over estimating for people)

Ric

So I should just ignore the calorie count and use it to estimate HR zones? Or is that is even useful really? Is perceived effort the way to go?

smoggysteve

on my last turbo session my garmin told me I burned 800 cals in an hour work out average spped of around 37kph. I weigh 69kg so I would say this was closer to the truth. even so I would always take it as an over estimate than under. that way if I lost more than it says I have still achieved my goal.