about this; pushing can (re-)introduce slack into the body. you can 'biggify' and/ use windings (&(stacking)/breath) to (re-)remove the slack and swallow/absorb that (delta) back into the body. then use that bone-stacking fajin thing you wrote, to get it out. 'generate harmony'. just some ideas.
you wrote: Q:how do we efficiently generate and focus a force? A:straight muscle
pulse muscle?. maybe deltas are more important than absolute offsets. the changes.
can't push. our muscle is either in contraction (pull) state or non-contraction. a push to your chest is the same as a pull to your back. essentially, our body is a large and complex pulley system. adding to the complication, some muscles are fast twitch and some, slow, i.e. they don't contract at the same speed.
to generate force, can't just use muscle alone, although a large percentage of it. one thing about human body, because of the construct, we have springiness built-in as shock absorber. so what-if, we can use the shock absorber as part of the power generation equation to augment the muscle? what-if we can take the incoming force, be it from external or internal, and store it in the shock absorber to be released along with our muscle? our biggest shock absorber? our middle. how to build a good absorber? breathing techniques.
there are various standing meditation techniques that are shared between Chinese and Japanese. it really comes down to how to control your body muscle to use the least to up hold the body, and creating opposing force, and build shock absorber. so if you stand in meditation and imagine someone pushes against you chest, then you can increase the shock absorbing capability through certain type of breathing, then you mind direct you body to relax certain muscle and activate other muscle to counter the push.
if you twisted your body parts certain way, you feel you have a more connected body, i.e. winding/twisting/binding. you see similarity in various arts in the way they move, for example, corkscrew punch. the corkscrew motion wind/twist/bind your whole arm into one unit instead of a bundle of loose sticks. you will also see breathing techniques accompany such practice, because of the shock absorber affect in order to augment the muscle power and to handle the recoil force (every action has an equal and opposite reaction).
Force = mass times acceleration. acceleration is delta velocity (delta v) over time. yup, delta.