Many people mistakenly try to generate more power by swinging their racket arm faster. The real source of power for a tennis stroke should come from the back. If the arm stays passive and the back stays back then an untapped hidden source of power can come from the back to the arm into the racket head into the ball.
Let there be an opposition between the back staying back and the arm moving forward. This opposition will generate all the power you need.
April 2nd, 2010