In the 1989 documentary film "Always", our protagonist pulls out of a high-speed dive by reaching around the yoke and pulling with the back of her arms:
Is this unusual, for a large high-speed aircraft (a B-26 adapted for firefighting) without powered flight controls?
Technically, you could get a harder pull by removing your forearm muscles from the situation, having the weakest muscles, and pulling mostly with your shoulders and back alone.
I have a set of straps used for moving furniture that hook into your arms right at the elbows, and achieve the same effect by removing the load from your forearms as you lift (you brace your hands on the piece with your elbows at 90 degrees), putting all the load on your shoulders, back hips etc. You can lift heavier pieces than otherwise.
Problem is, you have the elevator trim system, and for the airplane to go into a dive, you have to have it trimmed to a very high speed (Nose Down), or the tab on the elevator has maybe fallen off, or maybe the autopilot trim system ran away Nose Down.
If it's just trimmed wrong, that is, trimmed for high speed (excessive Nose Down) which is making the airplane dive to achieve its trimmed speed, you would just wind the trim wheel to a lower speed setting (Nose Up) and let the tab do the work.
If the tab has fallen off, or the trim mechanism that moves it is jammed or broken with the setting at a high (Nose Down) speed, you could use that technique to pull the nose up and overpower the trim system, but the need to hold that force wouldn't go away once you are level - you'd have to maintain that pressure all the way until the landing, and you'd be pretty tired, and now you can't use the ailerons as well with your arms hooked like that, so you are in a bit of a pickle if you are by yourself.
So the main thing is, you can theoretically make an airplane with a trimmable elevator do that, with the need to apply high forces to pull the nose up, say because the trim system is broken, but once the nose is level, you are still stuck with that trim state and won't be able to let go. If the trim is still working, you would wind the trim wheel to take away the pressure, and if that was the case, you could've used that feature right at the start.
Your trim condition wouldn't magically return to normal just from the act of getting the nose back to level, without retrimming for your level flight trim speed. The movie presents an old movie cliché for drama purposes, of the "spontaneous high speed dive" which automatically resolves when you pull out, which isn't how airplanes really work.
A more likely scenario in the real world would be where the airplane departs into a stall/spin and finds itself in a dive as a result, but in that case it'll be trimmed for a low speed and it won't take that kind of pitch force to recover from the dive, as the airplane will be naturally trying to raise its nose on its own. You won't need all of your strength to pull, and the main challenge will be trying to respect the maximum speed limit of the aircraft while not exceeding G limits from the pull (you pull, but not too hard). When pilots doing aerobatics, fall out of maneuvers and end up in dives, the challenge is not finding the strength to pull, but modulating the force of the pull to stay within both G limits and speed limits.
