Taught martial arts for many years, yes shouting does boost energy in specific circumstances. There's a whole art to it, and really it amounts to raising adrenaline levels in yourself (shouting startles yourself) and oxygen. The inhaling before the shout charges your muscles.

In fact, you can get a fantastic demonstration of this without the shouting or cursing. Next time you have a jar lid or anything that you need to manually move that's just slightly more difficult than your muscle power can comfortably move, take three very deep breaths, then on the last breath inhale as hard as you can and hold it for a moment as you try to open the jar or turn the thing, you will have a very noticeable burst of muscle power.

Lmao I didn't get through the first sentence without picturing Ondra.

He even has a screaming coach: https://youtu.be/Ugvw3pBbYqY