Originally Posted by chasm54

There is a direct relationship between power output and calories burned. That is an objective relationship unaffected by perceived effort. A watt doesn't care how strong or weak the person doing the lifting is, or how hard they think they are trying.

The only argument here is whether the fit athlete has acquired a more efficient metabolism so they are more efficient at turning energy into power. The usual estimate is that we are around 25% efficient. It's possible, I guess, that training changes this marginally but we await an expert.