pish posh bra. That's a load of hooey.
limbs are limbs, the body is a unit as a whole, it uses and converts and expels and evacuates and consumes etc etc.
you can increase mass, you can decrease mass, you can increase strength and power and you can increase force output with method and practice.
You have one body and it includes all the energies you use, the mind you use, it contains you as a person and your concious thought.
when your body is gone, that's it, you're done and all that's left is someone elses memories.
if we comprehend that, then there simply is no internal/external question and there never was.