Here's a funny video of astronaut bloopers:
Try this at home...although, you'll need to counter-act the forces of gravity.
Here's How (it's easy, just two steps!):
1. While standing up, bend over and hold your toes with your hands, keeping your knees slightly bent.
2. Try to jump forward in this position without removing your hands from your toes while you are jumping.
Why This Happens!
In this position, you can jump backwards from one end of the room to the other, but you won't be able to jump forward even a single leap! When we jump, we first shift our center of gravity in the direction we want to jump, and then we move our support base in the same direction to regain our balance. When you are holding onto your toes, jumping backwards is not a problem because you can use your heels. But to jump forward, you would have to use your toes... and your fingers are in the way.