I was taking a martial arts class and even though I was using the shield properly, I took a hard kick to my side. It literally moved me about five feet down the mat. It knocked the wind out of me, and the next day, I was so sore I could hardly move. I'm pretty sure I had bruised ribs. I had bruised skin, for sure.
I'm glad I didn't have a broken rib -- the bruised version hurt enough for two breaks. It was very uncomfortable. I couldn't even sleep on my right side for about a week or so. Serious owie.