Q
: Many students, when serving, do not feel the pronation occur or they have limited acceleration. Do you have any advice or exercises to improve this?
A: This can be a big problem for any person, child or adult, who has never developed a physically mature throwing pattern. In a mature throwing pattern, the pronation will occur naturally. This problem is compounded by the feeling a novice player gets when he serves the ball; namely, that the racquet feels it is moving on the outside of the ball and should continue in that fashion. The "natural" pronation effect, where the hand and forearm turn outward, seems unnatural.
One exercise we have found that really helps develop the ability to get the upper limb involved properly is passing a football. If your player is a child, you can get small foam footballs that his hand can easily go around. When you put your fingers on the threads of the football, and then throw the football so that it is a perfect spiral, your fingers must roll off the ball and a natural pronation will occur. Again, I emphasize that this can be used for any beginner, adult or child.
I was in Europe several years ago, speaking for a couple of national coaching federations and asked the European coaches to throw a football with a perfect spiral. Understanding that American football is not a major sport in any country in Europe, most of the coaches had extreme difficulty in getting the ball to fly with a spiral. However, they all agreed that if they could develop a spiral motion on the football, the development of pronation to play tennis more effectively would be enhanced.
Q: Occasionally, a player may begin his service motion with the front foot parallel to the baseline. Does this cause stress on the knee?
A: There is little doubt that if an athlete maintained a front foot position parallel to the baseline and attempted to hit an aggressive, high-velocity serve, there would exist a potential for excessive knee stress. However, the operational word in my previous statement is maintaining the front foot parallel. Most players do not do this. For example, a player may begin his service motion with his front foot parallel to the baseline but, I can guarantee you, as he projects his body upward toward the serve and just as the hip rotation and trunk rotation begin their powerful motion, the front foot is either angled forward or the friction of the front foot to the court surface is minimized. This minimization of frictional force against the court surface would relieve the knee of any rotational stress.
I believe we should emphasize that a player should model the true actions of the service motion and not simply a starting position. Since the naked eye does not see the true serving motion, it would be easy for a student of the game to "perceive" that a player with that kind of serving stance keeps his front foot parallel to the baseline throughout the entire service motion. If he did this, it would increase the possibility over time that he would create seriously excessive stress on the knee. Therefore, do not get overly involved in starting positions but use slow-motion video to see what truly happens as a player develops power in his strokes.
