It's an interesting point ,I recently measured the force of (my) extensor action using a spring scale it was between 12&15lbs.This seems like i'm overdoing it because it tends to make me tense up a little.....but who knows-maybe that is the point and it is just MY feel.Hopefully there is a comment out there from a Yoda'Yodasluke, Manzella or any of you experts on quantifying extensor action.Yoda and Ted used a bungee cord to demo at the swamp...but these cords vary in strength.