First some background (as I mentioned in my introduction), I have no MA training except for Marine Corps MA Training. I'm 27 yrs old, 5'11" about 160lbs, so I may be a little old to start MA. My buddy is a MuayThai/grappler and he thinks I would be ok at this and wants to train me. However besides being too old, I had broke my tibia in Jan of 2003 and was wondering if I should train in Muay Thai and grappling or would I risk the chance of breaking my shin again? Thanks, Cat.