Attack Angle of the Serve

If you are not well enough aware that the serve is a sidearm shot not an overhead shot, you are probably hurting yourself, and most likely your serve is not all it could be. The serve, like the pitch of a baseball, is delivered with the body at a 20-30 degree angle off vertical perpendicular to the baseline which lets the hitting arm meet the ball at full vertical extension and still be 20-30 degrees off axis from the spine (see excellent analysis by Clay Ballard of Top Speed Tennis) . The "sidearm" throw is a far more comfortable and powerful position for the shoulder, but to achieve it and still maximize your vertical reach on the serve you have to get your body out of the way. You establish this position during the trophy pose by bending the knees and aligning spine with the upper legs. In this position, a line drawn through the upper legs, hips, and body will be the requisite 20-30 degrees off vertical when viewed from the front or back. The actual feeling is one of "crouching and arching the back", but there is little to no bend in the spine itself. One should never, ever, intentionally bend the spine or use the spinal muscles in tennis. The spinal muscles are designed to straighten the spine, not bend it.

When you explode into the ball, and your shoulders rotate into the stroke, the angled body becomes the center of rotation of the serve thereby maintaining the 20-30 degree angle and allowing the hitting arm to come through freely.

If you don't bend your knees in the trophy pose you cannot achieve this orientation. If you are not in excellent dynamic balance as you approach the trophy position, you will not be able to lean back at all because this changes the location of your center of gravity. In static balance, your balance is dependent on the location of your center of gravity. You control dynamic balance by varying the tension in your thighs. Moving your center of gravity will generally not throw you off balance (a convenient feature in sports!).