George: lots of strong people seem to like it...
Garrett: I agree that the analogy is missing some elements. If nothing else, in one case you're moving your body (rather than an extremity) and are working the distal connection of the muscle to strengthen the proximal (rather than working the distal to strengthen the distal).
But I'm not sure why it should be that these differences make the exercise pointless. It may be less effective, but just speaking in terms of muscles, are those differences really so vast that the GHR is a great exercise and the leg extension, or something similar, is a useless one?
Because although there are other things going on, in the end the main thing happening in a GHR seems to be that a leg curl.