The first type of footwork is short distance footwork. This is when you are moving one step (or shuffle) to get a ball. You always move your outside foot first. The outside foot is the one that is farthest away from the ball. For example, if you’re moving to hit a wide backhand, you would need to move your right foot first. In order to do this you need to have a good spring in your legs. The only way to get a good spring to the ball is if you bend your knees and use the energy of your body going from down to up to move to the ball. Think of bending your knees like a spring. You push down on a spring and all that energy is waiting to explode. Then you release and all the energy makes a big impact. This is the effect of bending your knees.
Long distance footwork is almost the same as short distance, but in long distance you need to be more explosive and cover more ground. You need even more of a spring now which will require you to bend your knees.
The last common type of footwork is moving in and out of the table. If you are moving in to make a push or flip you need to have your right foot under the table. This will give you more reach. It is important to stay low (bending your knees) when flipping a short ball because you need to catch the ball at the top of the bounce. When you catch the ball at the top of the bounce you are catching it when it is highest, which means you will not have to lift the ball as much. If you don’t bend your knees you will not know when the ball has reached its highest point.
Bending your knees is very important in table tennis. Basically every single shot has something to do with bending your knees. If you do not bend your knees you are not going to improve very much and you will not reach the highest part of your game.