For players who are not total tennis beginners, the comprehension of biomechanics related tennis stroke is as important as everyday practices. Practice repeatedly for certain elements of stroke without achieving higher comprehension of related biomechanics, the benefits won't speed up to a higher playing level. On the other hand, some awakening of understanding of biomechanics can speed up training and the skill improvement.
In my case, I realized the importance of hitting the forehand with an open wrist. Then applied it to my open tennis serve before the summer last year. That was time I wrote the article "Open Tennis Serve Techniques" - An Introduction to Wrist Extension Tennis Serve (WETS) -
Open Tennis Serve Techniques (WETS)
Here, I won't repeat what were said in that paper; instead, I like to explore this topic from a different angle.
The kinetic chain of every tennis stroke involves muscle groups from big toes to little fingers of our body. So the division of labor and delegation of tasks make sense. I'm not a boi-mechanical major graduate, nor an expert to explain how each muscle group works. I'm just use a layman's experiences to say what I understand.
An often used term "hitting" comes to my mind. In hitting the tennis, almost every muscle groups of body are involved, even the eyes, to say the obvious. But not everything is created equal. For example, which muscle group does the hitting most, or should do the hitting most? A beginner may just use the arm as his/her main hitting tool, with no or very little involvement of lower body muscle groups (beside using the legs to support the whole body). On the other hand, advanced players let the arm just holding the racket in a right grip and right position for meeting the ball with an evolving racket face. Federer's forehand is the best example. If one watches his ideal forehand in a slow motion, the arm looks pretty much stationary relative to the main body after the Pat the Dog point. His wrist is kept at extension state throughout before and immediately after the contact point. Put this into the context of a beginner forehand, the arm is not the one that does the hitting. Understanding of this is crucial to comprehend and to know how the division of labor and delegation of tasks work for modern forehand.
Instead using the term hitting, I'd like to use the term "absorbing the ball" in the context of division of labor and delegation of tasks for the hitting arm. In short, the hitting arm should not do the hitting. Its main task is to absorbing the ball so it can stay longer on the string bed. The best way to do this is keeping the wrist at extension state, letting the whole arm loose, letting the whole arm passive, not active. This is the model of Federer's forehand.
In this model or style, there is almost no isolated forward and cross body swing by the arm before the contact point. The perceived swings are all done by the lower body muscle groups, ie, they are the ones that does the hitting, not the arm. A video of Federer's forehand can clearly show this -
Roger Federer - Forehands in Slow Motion
So delegating and maximizing the body to hit the ball, and delegating and maximizing the arm to absorb the ball (minimizing the arm to hit the ball) are the utmost things to comprehend mentally and practicing physically to achieve high level forehand performance. Doing otherwise will cut short the ball stay and wasting big muscle groups' hitting potential. These are the fundamental reasonings behind my published articles "Forehand Serve" and "Open Tennis Serve Techniques".
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