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Editorial Commentary: Changing Times in Sports Biomechanics: Baseball Pitching Injuries and Emerging Wearable Technology

      Abstract

      Research has shown relations between amount of baseball pitching and overuse injuries, as well as between poor mechanics and high loads on the elbow and shoulder. However, overuse injuries continue to be a problem from youth to professional sports. Emerging wearable technology may enable players, parents, coaches, leagues, and clinicians to monitor biomechanics during competition and training, reducing the risk of serious injury.
      Once upon a time, we lived in a country where most boys and girls participated in multiple athletic activities, from pick-up basketball to Little League Baseball. But now, the most kids receive little physical activity (unless you consider rapid finger movement on cell phones). Those who are involved in sports are usually the better athletes and they tend to specialize in one sport. This paradigm shift has many social and cultural implications, including the rise in overuse injuries.
      • DiFiori J.P.
      • Benjamin H.J.
      • Brenner J.
      • et al.
      Overuse injuries and burnout in youth sports: A position statement from the American Medical Society for Sports Medicine.
      This is perhaps most evident in the epidemic of ulnar collateral ligament injuries in baseball pitchers. Pitching injuries in the youth and high school level have been strongly correlated with amount of pitching,
      • Fleisig G.S.
      • Andrews J.R.
      • Cutter G.R.
      • et al.
      Risk of serious injury for young baseball pitchers: A 10-year prospective study.
      and as a result, many baseball organizations are now regulating pitch counts and required rest. A partnership between Major League Baseball and USA Baseball has created the Pitch Smart program (www.pitchsmart.org) to educate parents, athletes, and coaches, as well as set a framework for pitch limits. I am pleased to see the growing list of baseball organizations enacting these safety guidelines.
      Poor pitching mechanics and throwing curveballs have also been suggested as injury risk factors. Several studies have shown associations between pitching mechanics and elbow and shoulder kinetics (forces and torques),
      • Fortenbaugh D.
      • Fleisig G.S.
      • Andrews J.R.
      Baseball pitching biomechanics in relation to injury risk and performance.
      • Chalmers P.N.
      • Wimmer M.A.
      • Verma N.N.
      • et al.
      The relationship between pitching mechanics and injury: A review of current concepts.
      supporting the value of proper pitching mechanics. However, the theory that curveballs increase joint kinetics and injury risk remains controversial. In this issue of Arthroscopy, Makhni, Lizzio, Meta, Stephens, Okoroha, and Moutzouros shared their article “Assessment of Elbow Torque During the Pitching Motion: Which Has Higher Torque, the Fastball or Curveball?”
      • Makhni E.C.
      • Lizzio V.A.
      • Meta F.
      • Stephens J.P.
      • Okoroha K.R.
      • Moutzouros V.
      Assessment of elbow torque during the pitching motion: Which has higher torque, the fastball or curveball?.
      Thirty-seven healthy high school and collegiate baseball pitchers were tested throwing fastballs, curveballs, and change-ups. Among the results was the finding that elbow varus torque was significantly greater in fastballs than in curveballs.
      • Makhni E.C.
      • Lizzio V.A.
      • Meta F.
      • Stephens J.P.
      • Okoroha K.R.
      • Moutzouros V.
      Assessment of elbow torque during the pitching motion: Which has higher torque, the fastball or curveball?.
      Similarly, all previous studies on this topic reported greater varus torque with fastballs than curveballs; in some publications, the fastball torque was significantly greater,
      • Nissen C.W.
      • Westwell M.
      • Ounpuu S.
      • Patel M.
      • Solomito M.J.
      • Tate J.P.
      A biomechanical comparison of the fastball and curveball in adolescent baseball pitchers.
      • Dun S.
      • Loftice J.W.
      • Fleisig G.S.
      • Kingsley D.S.
      • Andrews J.R.
      A biomechanical comparison of youth baseball pitches: Is the curveball potentially harmful?.
      • Nissen C.W.
      • Solomito M.J.
      • Garibay E.J.
      • Ounpuu S.
      • Westwell M.
      A biomechanical comparison of pitching from a mound versus flat ground in adolescent baseball pitchers.
      whereas in others, the difference was not statistically significant.
      • Fleisig G.S.
      • Laughlin W.A.
      • Aune K.T.
      • Cain E.L.
      • Dugas J.R.
      • Andrews J.R.
      Differences among fastball, curveball, and change-up pitching biomechanics across various levels of baseball.
      • Nakamura Y.
      • Hayashi T.
      Comparison of kinetic parameters of upper extremity between fastball and curveball pithes.

      Escamilla RF, Fleisig GS, Groeschner D, Akizuki K. Biomechanical comparisons among fastball, slider, curveball, and changeup pitch types and between balls and strikes in professional baseball pitchers [published online September 1, 2017]. Am J Sports Med. doi:10.1177/0363546517730052.

      Although there was value in another study reaching a similar conclusion, the real contribution of Makhni et al. was in the technology they used. All of the previous fastball-curveball biomechanical comparisons used automated, 3-dimensional motion capture systems with reflective markers on bony landmarks tracked with high-speed cameras.
      • Nissen C.W.
      • Westwell M.
      • Ounpuu S.
      • Patel M.
      • Solomito M.J.
      • Tate J.P.
      A biomechanical comparison of the fastball and curveball in adolescent baseball pitchers.
      • Dun S.
      • Loftice J.W.
      • Fleisig G.S.
      • Kingsley D.S.
      • Andrews J.R.
      A biomechanical comparison of youth baseball pitches: Is the curveball potentially harmful?.
      • Nissen C.W.
      • Solomito M.J.
      • Garibay E.J.
      • Ounpuu S.
      • Westwell M.
      A biomechanical comparison of pitching from a mound versus flat ground in adolescent baseball pitchers.
      • Fleisig G.S.
      • Laughlin W.A.
      • Aune K.T.
      • Cain E.L.
      • Dugas J.R.
      • Andrews J.R.
      Differences among fastball, curveball, and change-up pitching biomechanics across various levels of baseball.
      • Nakamura Y.
      • Hayashi T.
      Comparison of kinetic parameters of upper extremity between fastball and curveball pithes.

      Escamilla RF, Fleisig GS, Groeschner D, Akizuki K. Biomechanical comparisons among fastball, slider, curveball, and changeup pitch types and between balls and strikes in professional baseball pitchers [published online September 1, 2017]. Am J Sports Med. doi:10.1177/0363546517730052.

      In contrast, Makhni et al.
      • Makhni E.C.
      • Lizzio V.A.
      • Meta F.
      • Stephens J.P.
      • Okoroha K.R.
      • Moutzouros V.
      Assessment of elbow torque during the pitching motion: Which has higher torque, the fastball or curveball?.
      used a sleeve containing an inertial measurement unit (IMU) positioned over the medial elbow (Motus Global, Rockville Centre, NY). This IMU contained a triaxial accelerometer and triaxial gyroscope recording data at 1,000 Hz. Data from the IMU were transmitted in real time to a tablet or cell phone app, where elbow varus torque, arm speed, arm slot, and shoulder rotation were calculated for each pitch. Makhni et al. realized the significance of using wearable technology, and stated that one purpose of their study was to test precision of the IMU system. They showed that the IMU system successfully measured elbow torque in 97% of the pitching trials.
      • Makhni E.C.
      • Lizzio V.A.
      • Meta F.
      • Stephens J.P.
      • Okoroha K.R.
      • Moutzouros V.
      Assessment of elbow torque during the pitching motion: Which has higher torque, the fastball or curveball?.
      A previous study by Camp et al.
      • Camp C.L.
      • Tubbs T.G.
      • Fleisig G.S.
      • et al.
      The relationship of throwing arm mechanics and elbow varus torque: Within-subject variation for professional baseball pitchers across 82,000 throws.
      validated measurements from the same IMU system against “the gold standard” of optical motion capture, showing a 0.93 correlation in elbow varus torque measured by the 2 systems.
      Makhni et al.
      • Makhni E.C.
      • Lizzio V.A.
      • Meta F.
      • Stephens J.P.
      • Okoroha K.R.
      • Moutzouros V.
      Assessment of elbow torque during the pitching motion: Which has higher torque, the fastball or curveball?.
      concluded that the wearable biomechanical sensor used in their study was a precise and practical tool for research, but it was limited because it could not be used during actual competition. The limitation of testing in lab settings is also an ongoing criticism of optical motion tracking. But times are changing. Markerless optical motion tracking is emerging as a potential technology for analyzing players during competition. Wearable technologies are also coming to the field, court, and ice, as sports leagues, associations, organizations, and governing bodies have implemented procedures to determine technologies permitted during competition. In fact, the elbow sensor used in the lab by Makhni et al. was recently approved by Major League Baseball for use in competition. Clinicians, athletes, analysts, and researchers want to understand the biomechanics that actually lead to injury or optimal performance. At Major League Baseball's 2016 Winter Meetings, I was invited to give a presentation on emerging technologies and was shocked to see a packed crowd for this special session. The physicians, trainers, and front office executives were certainly not there because of the speaker, but had come to learn about potential wearable technologies for their teams. Get ready, as collaboration between sports, science, and medicine is about to bring a wealth of in-game data to us.

      Supplementary Data

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