[SECGolf]

When I wrote 'running in place' I only meant (trying to stay with the dog thing) that the pull was extreme and reckless.

A brand new rubber band is a circle- hold on part of it with two fingers (the left shoulder) and pull the other side (right arm) and it becomes two parallel lines- that is what extensor action is.

Any pull (of the dog) has nothing to do with extensor action - a pull that is extreme suggests an active left arm (over acceleration) - not extensor action.
If you are referring to the pull as the stretch produced by the right hand - how can the stretch be too extreme? The hinge will direct the force. If your trying to hit a ball with any part of a lever that is a rope, you'd certainly want to stretch the rope as much as possible to provide structure, prevent collapse.

As for the rubber band, if the the assembly was attached to a hinge, you'd want an intense stretch just so hinge action could take place. (difference of force - cetrifugal or muscular, acting on a limp vs taught rubber band). With no stretch, hinge action would go awry. But this has no bearing on whether the stretch can be too much.

If indeed too much stretch can mess up the hinge or joint structure, I'd say you could have to much. But for all purposes, I don't think this is possible.