3 star

[isshinryuronin]

I still don’t see how expanding chest aids a strike.

It's used in any spin back fist.

I would say expanding the chest adds torque to the arm moving sideways. I just tried it and found the chest expansion is accompanied by the scapula being pulled back. When I fully extend my arm to the side and then expand, the scapula being pulled back naturally causes the arm to move a bit further to the rear. Try it and see if you notice the same effect (maybe it's just me). If you try it, it's important not to have any bias whether it will go back or not, so your mind and body has to be relaxed and neutral.

In iaido I learned the nukitsuke - initial horizontal cut to the right immediately after the draw - with a chest expansion. At the same time, the left hand holding the saya - scabbard - pulls back on it in the opposite direction, magnifying the expansion (as both scapulae are being pulled back) as well as adding torque (power) in even this very quick and short cut.

This expansion increasing torque is also used in takedowns and arm breaks. I believe it's the same principle in all these examples.

 

[Kung Fu Wang]

When I fully extend my arm to the side and then expand, the scapula being pulled back naturally causes the arm to move a bit further to the rear.

When you swing your fist (such as a sideway back fist), the gravity will pull your fist away from your shoulder. That will cause your chest expanding.

The northern CMA uses a lot of "chest expanding" moves. The southern CMA and Karate may not use that much.

It's clear to see the "chest expanding" in this "三环套月 3 rings catch the moon - vertical down back fist, overhand, grab, sideway back fist" video.

 

[Same Trick]

I would say expanding the chest adds torque to the arm moving sideways. I just tried it and found the chest expansion is accompanied by the scapula being pulled back. When I fully extend my arm to the side and then expand, the scapula being pulled back naturally causes the arm to move a bit further to the rear. Try it and see if you notice the same effect (maybe it's just me). If you try it, it's important not to have any bias whether it will go back or not, so your mind and body has to be relaxed and neutral.

In iaido I learned the nukitsuke - initial horizontal cut to the right immediately after the draw - with a chest expansion. At the same time, the left hand holding the saya - scabbard - pulls back on it in the opposite direction, magnifying the expansion (as both scapulae are being pulled back) as well as adding torque (power) in even this very quick and short cut.

This expansion increasing torque is also used in takedowns and arm breaks. I believe it's the same principle in all these examples.

Maybe not expanding the chest but definitely not sunk it in, google “boxing jab” pictures show mostly a good stretch of the chest

Boxing jab - Bing

Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.

cn.bing.com