It’s totally true from a physics standpoint. A longer lever arm between the load and fulcrum requires more force to move the same weight, all else being equal. Edit: thinking on this more, I think a type 3 lever is more applicable to my chest flye example, but the same concept applies; as you lengthen the load arm relative to the effort arm, more input force is required to move a given load.

“Harder to exercise” is poorly defined, especially when you go on to discuss endurance, speed, and force, all of which are very different terms.

I totally get what you’re saying, but I specifically narrowed it down to force for a reason. My shorter friends kick my ass in lifting due to the mechanical advantage their shorter limbs have, but I smoke them in a distance run because my longer limbs allow me to traverse a greater distance in a single step. This is complicated though because larger lungs are a factor here too.