Is my HRM correct?

snowbab

I have a polar f4 and it usually seems to be very accurate. It even matches with the calories shown on my zumba game.

I just did 20 mins of trampolining on my big trampoline outside. I looked online to compare and it says I would burn about 70 calories according to my weight (134 lb), but my HRM says 215! That's such a big difference it seems a bit unreliable... I know that my weight/ height/ zones etc.... are set correctly though.

Any opinions?

purpleipod

Was it positioned correctly? Do you have your up to date weight info set in the HRM? I'd trust a HRM before I trusted anything else.

snowbab

Yep it's where it usually is with a good chest strap. My info is definitely all correct too. I do trust it usually it's just the differene is particularly big

CoderGal

I've always wondered exactly how they work. I know a guy who figured out how to take your heart rate via webcam
http://medgadget.com/2010/10/mit_student_uses_webcam_to_measure_heart_rate_from_a_distance.html
It makes me wonder if the fluctuations in blood flow when you're moving such a distance vertically may change it?