GRADES 9-12
BIOMECHANICS OF JOINTS

BACKGROUND INFORMATION: Sport biomechanic studies are conducted to determine the best and safest athletic performance techniques as well as the relationship between equipment and athletic performance. For example, in tennis, over the years swing patterns, rules, racquet technology and player stances (position) have changed. With these changes biomechanists determine the ramifications to the game's techniques, the players' performance, training and potential for injury. 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. 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 United States Tennis Association has conducted research using EMG to study the rotator cuff (the arrangement of the four muscles and their tendons that support the shoulder joint). Clearly, this is a highly used and potential area of injury for 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. Information learned from this research is then applied to coaching and training techniques. As the computer technology, software and other tools used to study biomechanics improve greater contributions can be made. It will simply be easier to conduct the studies.