Now to L‘s last question :-
I do have a question for you in regards to waist swallow/spit. I noticed soon after I started applying it into motion (hits, kicks..) past year, I have had lower back pain associated with exercise. Have you experienced anything similar?
The motion of swallow and spitting is a physical movement that requires the use of the waist in conjunction with the lower back. So if you already have problems with your lower back I would urge you not to practice this.
However, if you must still do it then you need to modify the way you do it. You need to pay attention to the following :-
i) Emphasize the motion of your waist around the lower stomach area instead of the lower back
ii) Work on extending the lower stomach instead of bending the lower back
iii) Reduce the forcefulness of your strikes as the added force will impact your lower back
iv) Use a wooden dummy to work on a slightly shorter long range to reduce the need to have to move your lower back to strike further
v) If the above does not work as well then you need to focus on developing your footwork and shifting of body weight to compensate for the shortened arm striking range
vi) Substitute the body angling from the knives for the body square-on facing