Do you need strong muscles as far as applying the yoke is concerned, in order to be able to deal with some emergencies?
For the Airbus it is not actually require any strength, all the technology is fly by wire, this means that the actual control (Side stick) is not directly connected to any cable, so been this said, there is no actual force to fly any airbus plane. For the Boeing plane, at least for the 737, that's the one I know, when it loses all the hydraulic systems, the aircraft will become on a manual reversion mode and it will need strength from the pilot to move the aircraft controls that are linked to the surfaces by cables, but this is a remote possibility to happen, and if it is the case both pilots can apply force to the control column