To clairify, I was talking about the force exerted by a asphalt plane slamming into you at X m/s, not the force exerted by your muscles. Although I was basing

To clairify, I was talking about the force exerted by a asphalt plane slamming into you at X m/s, not the force exerted by your muscles. Although I was basing that on force exerted by gravity (which is proportional to mass), whereas deceleration might be spread out proportional to length, so it might work out to L² anyway. It's too late to edit though.