When I excercise on a spin bike for 30 minutes with and average Heart rate of 152 and burn 344 calories why when I am on the eliptical for the same time and at the same average HR the % of FAT loss is different? Elipitical is 50% and Bike is 35% fat loss.
Is this your hrm giving you these figures or the machines???
Don't know why it would be different except maybe since you use more muscles on the elliptical if you use the arms too
mouse35, i have a polar f11 too. the lower the intensity of your workout, the higher the percentage of body fat burned. so walking will burn the highest percentage of fat in proportion to total calories burned. sprinting will burn the lowest percentage of fat in proportion to total calories burned. that's where ppl's ideas about exercising in the "right zone" or "weight loss zone" or "cardio zone" enter the picture.
my guess is that you're sweating A LOT more on the spin bike than on the elliptical; what i mean is, you're working much more intensely. your body can't convert fat to energy fast enough for the demands your spin routine puts on it. when you're on the elliptical, you're working hard (50% is still pretty intense), but less hard--so your body has more of a chance to burn fat for energy.
there are arguments either way for which one is better; some ppl say a combination. whatever works for you is just fine. i like to look at the percentages, though, myself. for example, my percentage of fat burned always decreases toward the end of my cardio, bec my body's working harder, even if i'm doing the same cardio exercise. you know? it's pretty fascinating stuff.