Just Relax Xioali
…relaxing in emergency situations like holding the hand of a child while all muscles are engaged. This is Xiaoli (a relaxation technique that allows the user to absorb powerful attacks and not take damage)
…We train to change our response to instinct opening the possibility of choice
As parmesanmadness said, it doesn't exist as portrayed in the manga but you can do something that matches the description of Xiao Li. Did you know drunk drivers are more likely to survive the accidents they cause then the people they hit? Relaxation at point of impact DOES distribute force more evenly and reduce likelihood of severe injury but it only works in certain cases.
Does Xiao-Lee theoretically exist? : Grapplerbaki