Quantifying Throw Counts and Intensities Throughout a Season in Youth Baseball Players: A Pilot Study

Abstract

Overuse injuries in youth baseball players due to throwing are at an all-time high. Traditional methods of tracking player throwing load only count in-game pitches and therefore leave many throws unaccounted for. Miniature wearable inertial sensors can be used to capture motion data outside of the lab in a field setting. The objective of this study was to develop a protocol and algorithms to detect throws and classify throw intensity in youth baseball athletes using a single, upper arm-mounted inertial sensor. Eleven participants from a youth baseball team were recruited to participate in the study. Each participant was given an inertial measurement unit and was instructed to wear the sensor during any baseball activity for the duration of a summer season of baseball. A throw identification algorithm was developed using data from a controlled data collection trial. In this report, we present the throw identification algorithm used to identify over 17,000 throws during the 2-month duration of the study. Data from a second controlled experiment was used to build a support vector machine model to classify throw intensity. Using this classification algorithm, throws from all participants were classified as being "low," "medium," or "high" intensity. The results demonstrate that there is value in using sensors to count every throw an athlete makes when assessing throwing load, not just in-game pitches.

Quantifying throwing load in handball: a method for measuring the number of throws

“…In the development study, we found a median best per-player sensitivity of 100% and a median best per-subject PPV of 96%. This is higher or equal to what other methods have found in studies of baseball and cricket [13][14][15] where the sensitivity was between 94 and 98%, and the PPV was between 81 and 95%. However, in the validation study the sensitivity was lower with a median sensitivity of 79% for overhead throws.…”

“…An alternative approach, which is both relatively cheap and easy to scale, could be using wearable devices to identify throws. In baseball 13,14 and cricket 15 , wearable devices have shown excellent ability to identify throws, but these devices do not seem immediately transferable to handball. For instance, the baseball studies 13,14 placed the device on the upper arm, which may be problematic in handball due to large amounts of physical contact 16 , and the cricket study 15 relied on GPS measurements, which are difficult to obtain indoor.…”

“…In baseball 13,14 and cricket 15 , wearable devices have shown excellent ability to identify throws, but these devices do not seem immediately transferable to handball. For instance, the baseball studies 13,14 placed the device on the upper arm, which may be problematic in handball due to large amounts of physical contact 16 , and the cricket study 15 relied on GPS measurements, which are difficult to obtain indoor. Additionally, handball players throw with more varied arm positions than in baseball and cricket.…”

Quantifying throwing load in handball: a method for measuring the number of throws

“…An alternative approach, which is both relatively cheap and easy to scale, could be using wearable devices to identify throws. In baseball 13,14 and cricket 15 , wearable devices have shown excellent ability to identify throws, but these devices do not seem immediately transferable to handball. For instance, the baseball studies 13,14 placed the device on the upper arm, which may be problematic in handball due to large amounts of physical contact 16 , and the cricket study 15 relied on GPS measurements, which are difficult to obtain indoor.…”

“…In baseball 13,14 and cricket 15 , wearable devices have shown excellent ability to identify throws, but these devices do not seem immediately transferable to handball. For instance, the baseball studies 13,14 placed the device on the upper arm, which may be problematic in handball due to large amounts of physical contact 16 , and the cricket study 15 relied on GPS measurements, which are difficult to obtain indoor. Additionally, handball players throw with more varied arm positions than in baseball and cricket.…”