Converting unit of "work" (1 bench press rep) to calories burned?

[UncleFred]

@Tim_R.Mortiss

Uncle Fred - that is exactly what I was talking about: the difference between “energy expended” and “work performed.” Both can be measured in calories (or joules or ergs or watts or anything else), but the amount consumed (input) can be much more than the amount achieved (output). And output/input = efficiency. In your example, work performed is zero, so efficiency is zero. Still good exercise, though.

But let me ask again - do we know for certain that my arm is burning any more calories than the normal at-rest metabolism would? Your response (thank you) implies it is without explicitly stating so, and that would certainly be my expectation - but do we have a for sure ‘yes’?