Real-Time Mobile Sensor Data Shows Pitchers’ Arm Fatigues Quickly

August 21, 2018 | Baseball, Sports Science, Sports Technology

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopedic Surgery, Stanford University

Key Points:

  • A recently published scientific study shows that pitching fatigue happens fairly quickly, and fatigue leads to loss of pitch velocity and changes in biomechanics
  • These biomechanical changes could lead to increased risk of injury to the elbow and shoulder
  • More data is needed to prove that the biomechanical changes actually cause injury
  • The use of wearable technology to capture real-time motion data is likely to become commonplace in professional and elite athletes to assist in injury risk reduction

Many people have a sense that injuries happen more often when you’re tired. We see this all the time in the orthopedic clinic:


someone tears an ACL on the last planned run of a long weekend of skiing; a volleyball player injures her ankle after the final game of a long series of tournament games. There is a common belief that fatigue plays a major role in increasing injury risk, but proving this can be difficult. A recent study on pitching mechanicsperformed at the Henry Ford Health System in Detroit, takes an interesting step in connecting the dots between fatigue, biomechanics, and possible injury risk.

The study authors’ basic question was to find out whether pitchers experienced increased arm fatigue throughout the progression of a game. The secondary goal was then to correlate arm fatigue with changes in biomechanics of pitching that could contribute to increases in injury risk.

11 high school or college age pitchers participated in their study. They threw a simulated 90-pitch game off of a mound at regulation distance. Pitch data was recorded with a wearable motion sensor on the pitcher’s throwing arm, and velocity was measured with a radar gun. The pitchers assessed fatigue and discomfort at the end of each simulated inning with a tool called a visual analog scale.

There were a number of interesting and relevant findings from the study. They found that fatigue increased inning by inning as assessed by each pitcher, and happened even from the first inning to the second inning. The study authors also found that pitch velocity decreased as the game wore on, and most importantly that torque on the inside portion of the elbow increased significantly after inning three.

This study is starting to connect the dots between fatigue, changes in biomechanics, and potential increased injury risk. The interesting parts of the study from my perspective is that the use of the wearable motion sensor device for the pitcher allowed the study to be performed in a real game setting, with data acquired in real-time.

Wearable devices are now commonplace for professional and elite athletes to help measure training load and other physiologic markers. I expect that we are now going to start seeing increased use of wearables to track specific athlete motions that may contribute to injury risk. We still need solid data to connect the changes in biomechanics to specific injury risk, but once we get that I expect that the wearables will be a real game changer in injury risk reduction.





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Categories: Baseball, Sports Science, Sports Technology

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