I hear that in baseball there is a lot of concern about arm injury. Is that the same in softball or is the pitching motion a little more natural and therefore, easier on the arm?
The pitching motion in baseball is much more dangerous for the arm. In softball, there are definitely arm injuries but not to the same degree as in baseball. My brother was a pitcher in college and he has had shoulder surgery twice. It really hindered his career. It's important for pitchers, in softball and baseball, to get adequate rest for their arm.
Katty is right on.
The pitching motion in softball is much more natural and it changes the game completely. A girl doesn't have to wait several days in between starts, she can throw a double header... so any kind of rotation doesn't have to be in place. The pitcher I played with in high school started every single game in our season--somewhere around 50 games in a little less than two months. The concern for arm injury is not nearly the same level it is in baseball.
I actually know a pitcher who had to have her bones re-knitted in her forearm (including a metal plate) because of constantly hitting her hand on her thigh when she was releasing a pitch. It ended her pitching career in college, though she moved to an offensive role and did well (after a red-shirt).
Yes, arm throwing ia very commong thing. There was actually a discussion on that topic that I just read:
Hope that helps.
Softball Peak Performance Coach