Mixed Martial Arts, or M.M.A., is a full contact combat sport that was once banned in much of the United States.  Today, it’s one of the fastest growing sports among men… and now women.  But why would any woman climb into a cage for all-out combat for what amounts to almost nothing?  CNN’s Amber Lyon steps into the Octagon to find out.

"Fighter Girls" is one of four riveting stories airing on CNN Presents hosted by CNN’s Soledad O’Brien and Dr. Sanjay Gupta this Sunday, October 23 at 8:00 pm ET, re-airing at 11:00 pm ET and 2:00 am ET.