Do the rules say that shouting is necessary?
Why do we shout?
Why do we HAVE to shout? (not offensive, just really curious)Answer
: It is not the rule. Kendo comes with the shout. And it is probably normal to wonder why we shout. So it is OK.
We are trying to reach something we cannot see, which is called Ki energy. And by shouting we are trying to materialize it. So we know we actually trying ki as well as physical strength.
It also helps us to breathe. People tend to “stop” breathing when they focus but by shouting, it never happens. Needless to say, breathing is vital for us and if you don’t breathe properly, you will never develop physical endurance.
As we advanced, we need to shift from vocalized ki energy to unvocalized ki energy. So some sensei shouts less.
Of course, there are many martial arts that do not really shout. But they have their own methods to train the internal energy.
And also it is our historical background. In the battle fields in old days, apparently samurai warriors shouted during the battles. They shouted to encourage themselves, increase their potentials and also celebrate victory.
As you practice more and more, you will see how it works and you feel more energy inside you by shouting. Of course, you need to do it right.
Hope this helps.