How do you hit the ball harder on Topspin 3?

Question

I hold down the button for longer before I hit, but the ball still doesn't move that fast.. help?

Answer 1

For me the solution was in footwork.  I tend to play from the baseline, so the shots were weak as I was waiting for the ball to come to me.  Once I started to move up and down the court more and stepping into the shot, the shots increased in power.