Originally Posted by
squirtdad
I think there is confusion here over work and energy.
the work done, moving similar mass over equal distances during the same time period is the same.
the energy required to do that work can be different.
Say one bike had bad bearings, rusted chain and no lube and the other was perfectly lube and adjusted. The amount of energy input to get the work (mass, distance, time) done would be greater with bike with more internal resistance. so the guy on the junker would burn more calories to get the same amount of work done.
I can't vouch for the science, but when I am out of shape I sure feel like I work harder to get the same results than I do when i am in shape, so can see that making a differnces in calorie burn between two diferent cyclists.
You feel like you are working harder only because your cardiovascular system isn't efficient. When you are trained, you have a more extensive capillary network than the couch potato. Your ability to utilize glucose and fat is more efficient in the trained athlete. The couch potato with less muscle mass and a less efficient cardiovascular system is probably burning fewer calories than the more muscular fitter athlete. Oxygen consumption would be a more sensitive measurement than HR.