Healing an Injured Hand

I have watched many movies dealing with shaolin masters or qigong students and I am fascinated by a certain part of it.
When a person punched a rock, for instance, he bruises his hand. Then the master looks at it, either breathe into it or apply heat with his hands, and then massages it. The pain goes away.

After learning qigong for years now, I can believe that something like that is possible.
My question is…how did they do it? And how does it work? Does it take enormous chi energy to do so?
Is there an experiment I can perform on myself?