Textbook

Biomechanics

We've talked in our web pages about "invasive" versus "non-invasive" methods. An "invasive" method sometimes used in biomechanics and medicine is electromyography (EMG - from "electro" meaning electricity, "myo" meaning muscle and "graphy" meaning to write). It is the study of the electrical activity in skeletal muscle. The electrical activity is detected by either electrodes on the skin or inserted into the muscle.

Duane told us that the word "muscle" actually comes from the Latin word "musculus" meaning "little mouse" For example, as you flex your biceps (muscles in your upper arm) the muscle under your skin resembles a mouse moving under a carpet. EMG actual records how the brain activates the muscles used in a movement. The USTA has conducted studies using EMG of the rotator cuff (the arrangement of the 4 muscles and their tendons that support the shoulder joint). Clearly a highly used and potential area for injury of tennis players, baseball pitchers and swimmers.

How is EMG invasive? To study deep muscles (like the rotator cuff), a fine wire or needle is actually inserted into the muscle of the subject and the electrical signal recorded. We thought that this would really restrict the movement of the athlete, but both Paul and Duane said that actually the subjects had a very good range of motion.

"The information that we learn from this research is then applied to coaching and training techniques", Paul said. "Swing patterns have changed, racquets have changed, so have the position or stance that the athletes use as they play. It's very common to find coaches that teach the way they were taught years ago and those older coaching and training techniques do not necessarily support the "modern game of tennis"." The USTA has summarized some of its research in biomechanics in a video tape production for coaches.

Duane continued, "We conduct these studies to determine: how to learn the skill, what works best and what's safest." He also pointed out that different sports have different types of injuries. For example, there are a lot of shoulder injuries in baseball. There is tennis elbow and carpal tunnel syndrome in wind surfing as well as tennis.

Where will the emphasis in biomechanics studies be in the near future. "Understanding how the equipment and court surfaces affect a players performance" was Paul's answer. "There's talk of increasing the size of the ball for Wimbledon. How will that effect player performance? Is there a greater risk of injury to the players with a larger ball?."

"Another area of interest is to understand the racquet strings and its effect on player performance. As the equipment changes or rules change we need to be asking: What are the ramifications to the game's techniques, the players' performance, training and potential for injury?"

Duane feels that as the computer technology, software and other tools used to study biomechanics improved greater contributions can be made. It will simply be easier to conduct the studies.

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