Diaphragmatic breathing is something I’ve covered in detail before, but it seemed a good time to revisit it with a lot of people self isolating and training from home at the moment. Correct breathing is very central to keeping you relaxed (hence fast) and generating high levels of impact. Some of this video may go against conventional wisdom, but give it a try and you’ll see it really works.
https://bunkaijutsu.com
Bunkai Jutsu