I've been attending a few Krav Maga classes at a MMA gym. Recently, I was told (by another student) that the proper way to punch would be with the thumb knuckle facing up for the the three basic punches - jab, cross, hook. (no rotation of the wrist)
Is this correct? What are the advantages of punching this way?
I've dabbled in a handful of martial arts, all of which emphasize rotation at the end of the punch except wing chun. It took a bit of adjusting on my part, but it made me wonder in what situations this type of punching would be useful.