Every body is goin to react differently depending on the natural state of the body. I found that with my body, I get more intense pumps after I do about 20-30 minutes of treadmill or eliptical. I guess it gets the blood flowing. This also gets your heart rate up quicker and it will stay up longer if you go directly to the weights. And as we all know the longer your HR is up the more fat you're burning. HTH, Rig