As a biomechanist intersted in mountain climbing, I was intrigued by
Ian Stokes's posting. From my experience, there is no doubt that ascending
creates more body heat as the body burns more energy than in descending.
I believe what Ian has missed is the contribution of kinetic energy.
When descending, there is an optimum speed of traavel for minimum
energy consumption. If you go too slow, it takes more energy to slow
down. Conversely, to speed up also takes energy. I would therefore
revise equations 1b and 2 to the following:
Heat = metabolic work - P.E. gain - K.E. gain (1c)
Heat = metabolic work + P.E. gain - K.E. gain (2b)