There's this thing that's found in normal everyday martial arts places.  It's called BOB, or Body Opponent Bag. 
Instead of practicing your punching, kicking, elbowing, and kneeing on a bag (or a real person), you practice on a rubbery dummy that's about 6 feet tall.  It's good practice because most people, as it turns out, aren't cylindrical, so punching a bag isn't always very life-like. 

In martial arts places that also offer classes for kids, there's a similar thing called Bobby Bully. 
It stands about 4 feet tall and has a mean face like a bully.  It teaches kids to punch other kids who look mean. 

An interesting thing happens at the kickboxing place I go to.  Our class is full of grown men and women, mostly in their early- to mid-twenties.  At the beginning of each class, we run around the mat in a circle to get our blood flowing.  Certain guys, as they run past the Bobby Bully, throw a punch or an elbow just for fun.  Since Bobby Bully is rubbery and relatively life-like, his neck bends at an impossible angle when he's punched hard enough.  Watching grown men punch a child-sized dummy is hard to explain.  If it's done with a serious face, these guys would look like sadistic criminals.  Done with a chuckle, it's harmless.  Either way, it helps us get ready to punch kids in real life.  And that's a skill everyone should have. #sports