Warm ups? What are those?

[Diarmuid gives Zack a confused look. Especially when he starts doing the squats. The confusion is soon replaced by a fit of giggles, though. The boy tries to hold them back by covering his mouth with his hands because it's not nice to laugh at someone, but the man looks so funny.]

What does moving funny have to do with fighting? How does it help you fight dragons? Does it make the dragons laugh?