Let me make it simple. All cameras have at least 4 shooting modes: Shutter Priority (Tv or S), Aperture Priority (Av), Manual, and Auto or Automatic. If you are looking for videos or courses online, most of them will point you to use Manual Mode to have full control of your camera. But, to freeze movement, the most important mode is Shutter Priority. Movement can cause blur in your photos, and karate is all around movement.
If the most important setting is shutter speed, why do you want to shoot manual? Set the camera to Tv or S and pick the lowest speed that you can to freeze movement, in most sports the starting point is around 1/1000.
Aperture must be always the lowest you can to keep ISO low or the lowest you can maintaining your photo sharp (depth of field).
Set your ISO to auto. You could choose a fixed number, but if light conditions change, you would have to adjust it manually, which is less efficient than auto mode. Keep in mind that since the event room is not well illuminated, the ISO will run high, producing "noise" in your pictures.
Good photographs rarely come straight out of the camera ready to be shared; they often require post-editing. Be prepared for long hours spent reviewing and editing every single picture, with one of your primary tasks being the reduction of image noise.
This configuration will free your time to think about other settings and composition.
This is the way it works for me. It's not the right way or the only way. Keep it simple. Manual is most of the time and overkill when you are talking about Sport Photography or Wildlife.





