Instead of using your body to apply pressure to the saw frame, try this method:
Loosen the wingnut on the side of the saw frame so it moves freely up and down.
Insert the blade into the top and bottom, then tighten both blade nuts.
Now rest the top bar of the frame on your bench pin.
With two fingers, press down on the bottom bar just above the handle.
While holding that tension, tighten the wingnut on the side of the frame.
You'll get excellent blade tension without any pain.