Knee Injury

Dear coach,

I am back. I had a burning problem now. I had already learned the 2 wing attacker strokes. Now I am learning how to use forehand winning/power loop on the whole table once into the rally. However, yesterday during a friendly match with a left handed where I was trying out this new technique into my style of play, I realized I need even faster footwork. Bascially my opponent placed a ball down into my middle, I moved and use my forehand, however because he is left handed, the ball curved left upon bouncing off the table and I did not anticipate it. I use a minor adjustment and lean my weight towards my left and simultaneously bend lower. This resulted in a pain in my left knee.

I wonder if it is normal for table tennis athlete to have such conditions. 

Yours sincerely,

Mark