The following is a page from The Fault Tolerant Forehand, available in eBook and paperback formats on Amazon (click here).
The key to effective stroke production is efficient bio-mechanical alignment. For every shot, there are certain body alignments which produce racket head speed most efficiently and most consistently. The more often we can align our body properly before swinging, the higher quality, and the more fault tolerant, our shots will be.
On the forehand, our bio-mechanical advantage is our ability to whip the racket around the torso unimpinged.
The tricky part is routinely getting ourselves into these alignments while playing many different balls, at different heights, from many different positions on the court. We need to contact the ball in a myriad of different locations, and yet in doing so we need to use a remarkably consistent relative upper body position.
On the forehand, our bio-mechanical advantage is our ability to whip the racket around the torso unimpinged. In order to allow this, we need to maintain adequate space between our torso and arm – if the angle between the torso and the arm gets too narrow, the arm won’t naturally flick out and around as we rotate our trunk.
Therefore, we need to adjust our contact height without significantly changing our arm angle. This is accomplished by adjusting with the larger muscle groups. We always adjust with the largest muscle group we can. This means we have two primary methods of adjustment:
- Adjust with the legs, either by sitting down or widening them
- Adjust with the torso, by tilting it

The vast majority of our forehands will be played with an identical torso-arm angle, regardless of contact height, with adjustments made via the legs and torso. Legs and torso adjustments are the only two effective adjustments, as they are the adjustments that let us alter the contact height without impeding our torso-arm-racket alignment – the alignment which facilitates our rotational whip.
Suboptimal Adjustments
Adjustments of the arm and wrist are a last resort.
When sufficient adjustment can’t be made by using only the legs and torso – perhaps we’re on the dead run or the ball is coming so fast that we don’t have time to move – then we adjust with our arm (not the hand or wrist).
Only as a last resort do we adjust by straightening our wrist and violating the Fundamental Theorem of Tennis.
We either elongate it or bring it closer to the body, as called for by the situation, but we do not violate the fundamental theorem of tennis. Adjusting with the arm is not ideal, but since we maintain the right angle between the forearm and the racket, and since we contact the ball out in front of us, the shot will still go in. It won’t be great, but the rally will continue.
Only as a last last resort do we adjust by straightening our wrist and violating the fundamental theorem of tennis. A common case of this is when the ball is so far away that even on the dead run we are just barely are able to make contact – we simply need every inch of legs, arm, and racket fully straight in order to reach the ball. If you find yourself in this situation, try to hit it in front of you and pray it goes in. The shot is not going to be fault tolerant.
The Fundamental Theorem of Tennis as a Cure For Improper Adjustment
Focusing on the fundamental theorem of tennis helps many players break bad adjustment habits. All too often, I see players using their wrist to adjust to low balls. They elongate their racket-forearm angle (violating the theorem) in order to get the racket head low enough to hit a low ball, and in doing so lose all stability and control. To avoid this, ensure you’re always throwing a relaxed right angle racket-forearm system through the ball. For most players, thinking about this causes them to naturally adjust with the larger parts of the body, the legs and torso, rather than the wrist.
Arm adjustments do not violate the fundamental theorem of tennis, but they are not optimal. You can move your arm closer or farther from your body without interfering with the forearm-racket system, and thus these shots will still be relatively fault tolerant and frequently go in, but they’ll be lacking in power because they don’t harness the rotational kinetic chain nearly as well as shots where adjustment was made with the legs or torso.