The rules of this backyard volleyball variation are simple: Each player must remain seated on the ground at all times. And if you're like most players, you'll spend most of your time sitting -- unless you're diving after the ball, of course. In that case, you can leave the ground briefly, but must quickly make contact again with your rear end, torso or shoulders. It's challenging to reach for and hit the ball, and playing volleyball in a seated position requires a healthy measure of strength and stamina.
The game was invented in the 1950s, when Danish athletes combined volleyball and sitzbal, a German ball game played while sitting. Seated volleyball is now an official Olympic sport and is played around the globe [source: London 2012].