Hi Ron,
this "Hades-machine" (Hades = Greek translation for Hell
) trains the bizeps muscles, and nothing else.
May be the ex-governator of Califonia, Mr. Arnold Schwarzenegger is able to push up the heavy weights at high speed, thus requiring full stroke of the push bar.
62.4Ω per meter of the suggested constantan wire can be used for a voltage divider and following amplifier with an output either connected to a microcontroller's ADC to digitally indicate stroke in meters or percent.
A cheaper solution would be an analog voltmeter at full range of the amplifier's output.
That's the solution I'd choose for that kind of toy.
Regards
Hans