Obviously anytime you're moving your body, whether it's walking or doing a martial art, you run the risk of injury. My BJJ instructor who also teaches real Muay Thai at his school sort of pushes Muay Thai on everyone. Not in a bad way, but I get the feeling he thinks it's a better overall art and less hard on your body. He's in his 50's. Oddly enough, all of his major injuries were from BJJ so we laughed when he said that. I asked him in a real street fight which art he would prefer and he said BJJ FWIW. Started doing the MT clinch last night. Love it. If you're striking with a big guy, striking alone may not be enough and I still think you run the risk of breaking your hands/wrists. A nice takedown and choke does seem to be the less harmful way. A MT instructor recently left and he's back teaching MT so I'm wondering if that's the motivating reason for making it a strictly BJJ school.