How do you measure your calories used exercising?

ukjude

I'm gutted!... my Heart Rate Monitor arrived yesterday so I was looking forward to doing my Zumba this morning and adding in my Level 1 session of 30 Day Shred to hopefully see around 483 cals gone (as I've been claiming from advice given with my Wii machine for the Zumba routine and various websites for the Jillian Michaels DVD till now)... how wrong could I be? Very it seems - 152 cals for 30DS and 200 for the Zumba my HRM says.. meaning I've been 131 cals worse off than I thought!! I'm logging my usual exercise for today and will see if these figures come out the same tomorrow, in which case I think I'll just have to believe the HRM and cut back on my calorie intake (sob, sob!). I put my age, weight, etc into the Wii machine so really believed that I was using the 303 cals it told me I used up on my Zumba routine... has anyone else found such a huge discrepancy in the figures? I'm using a Polar FT4 HRM having read good reviews for it and only wanting to basically measure the calories I use.

Any advice on this would be much appreciated, thanks.