Beware of Pronation!

The information you are about to read is currently the subject of an interesting debate among some of the world's leading tennis biomechanists and physiologists, including some not cited in this article. Individual interpretation of this information is still ongoing, and the USHSTCA does not present this article as a final answer to the question However, Dr. Groppel's concerns about the cause of shoulder injuries in junior players should be seriously considered.

One of the greatest breakthroughs in tennis teaching in the last 20 years was the discovery of pronation, the outward turn of the forearm, wrist and palm at the end of the service motion that happened so quickly, most observers could not see it.

For many years, tennis teachers told their students to "snap your wrist", which was misconstrued to mean the snapping down and inward of the hand instead of the upward and outward turn. Today, many teachers now say, "high-five" the ball.

The discovery and teaching of pronation and the power it contributes to the serve because of its place at the end of the kinetic chain has not been all positive, however, according to noted biomechanist, Dr. Jack Groppel.

Dr. Groppel believes that an over-emphasis on pronation by teachers and coaches who are accenting this part of the kinetic chain out of proportion to its importance is leading to a dramatic number of shoulder and arm problems, and a scientific study may bear his theory out.

Dr. Bruce Elliot of the University of Western Australia is highly-regarded worldwide for his work on tennis biomechanics and has been a pioneer in the effort to determine what each link in the kinetic chain contributes to overall power.

According to Dr. Elliot and his associates on upper limb segments only, forearm pronation contributed only 5.2% of overall speed on a serve! In essence, there is little or no wrist movement on the serve, forearm pronation causes the hand to turn outward, which means all the hand can do is flex at the finish of the serve.

This article continues with surprising information on how little pronation actually contributes to racquet head speed, where most power on the serve actually comes from, and why emphasizing pronation may lead to injury.