Arde:
The way Raspy is describing it, it would have to be a side kick. The way Susan described it, I can't tell, but only a side kick from an inexperienced individual could do sufficient damage. Remember the figure skater that got a direct unexpected pipe to her knees and how little effect it had on her.
The reason I suggested "the spider monkey" manuver is that untrained, and even trained but not regularly practicing individuals will not be able to manuver and use such a kick against the average mugger because the mugger is usually watching for defensive moves.
Avoidance first, capitulation never, especially if they want you to go to a secondary crime scene by promising not to hurt you if you cooperate.
Bountyhunter