How accurate are sport watches & their calorie counting?

liveyenna

Hi MFP friends

First of all, I am a new with heart rate systems and also have no clue how to calculate calorie burning.. I was just wondering what you guys think about this. (Also, English is not my native language so sorry for mistakes!)

So I recently bought a polar heart rate system (POLAR RS 300 X) and this watch has already have been an angel to me but today I had a lot of questionmarks when it comes to counting the calories.
I used it previous week just to follow my heart rate to keep safe while doing cardio excercises but today I got curious and put the burned calories on my display. I went outside for a big walk, it was very windy and raining, and after half an hour I got surprised when I checked the watch because it said I already burned +250 calories. Even with the circumstances of the weather I do find 250 calories burned a lot because when I go to fill excercises on the excercise page on MFP and MFP calculates the burned calories for me it says that after 60 minutes I should/could've burned 250 calories and now after already 30 minutes I had burned 250 calories according to my watch...
So on my destination, an hour later, I had burned 500 calories according to my polar. On my destination I took my bicycle and went home. When I got home (15 minutes later) it told me I had burned 670 calories... That's 170 calories for a 15 min bike trip. I know my heart rate went really high when I was on my bicycle because the wind was straight into my face and very very strong. But 170 seems to be way too high!

Now my question to you guys; How accurate are those monitors?
Because I don't trust this at all... I may be a noob but 670 calories in only 1h15 min? Noo.. that's impossible... right?

blankiefinder

If you left it on, it will continue to rack up calories. My assumption with my heart rate monitor is that I should subtract 80 calories per hour as the cost of living (as in, the base rate that I would burn just for existing)

vorgas

• HRMs only monitor your heart rate.
• They are a fantastic tool for monitoring your expenditure level during exercise.
• They use the volume load on your heart to calculate the calorie burn during steady state aerobic exercise.
• Without knowing your VO2 Max (amount of oxygen you can inhale and process), they will only be an estimate.
• They do not work for intermittent exercise (high intensity intervals), exercise below the aerobic threshhold (light walking, daily life), or anaerobic exercise (lifting weights).

spfldpam

I only use my at the gym for workouts and my Polar FT7 that is over a year old is very accurate I feel. I pause it between machines when doing cardio also. I don't usually "eat back" my exercise calories so for me it is more of tracking thing than anything. My Polar FT7 was also very accurate under water during water cardio classes when I was a member at a gym that offered them. Currently I am at a smaller gym with no pool or classes. I only wear the Polar FT7 at the gym and not for just walks like in my office halls during my lunch hour. I guess I could but I don't.
Good luck!

liveyenna

vorgas wrote: »

• HRMs only monitor your heart rate.
• They are a fantastic tool for monitoring your expenditure level during exercise.
• They use the volume load on your heart to calculate the calorie burn during steady state aerobic exercise.
• Without knowing your VO2 Max (amount of oxygen you can inhale and process), they will only be an estimate.
• They do not work for intermittent exercise (high intensity intervals), exercise below the aerobic threshhold (light walking, daily life), or anaerobic exercise (lifting weights).

This is actually very informative, thanks!