Ulnar collateral ligament (UCL) injuries are common in baseball pitching. The elbow external valgus torque is assumed to be indicative for the applied load on the UCL. This study investigated the maximum external valgus and extension torque and their corresponding load variabilit
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Ulnar collateral ligament (UCL) injuries are common in baseball pitching. The elbow external valgus torque is assumed to be indicative for the applied load on the UCL. This study investigated the maximum external valgus and extension torque and their corresponding load variability during a baseball pitch and the relationship between the magnitude and the within-pitcher load variability of these elbow torques. Furthermore, this study investigated to what extend the elbow torques and the ball speed are related. Eleven Dutch AAA pitchers each threw 25 fastballs. The motion was captured with an optical motion capture system. The ball speed was measured with a radar gun. The data of the upper body, in particular the elbow torques, were analysed using a custom-made 3D inverse dynamics model. The results show that the within-pitcher load variability differs among pitchers. A higher applied elbow torque compared to other pitchers indicates a higher within-pitcher variability. From these results, both a higher valgus torque and a higher within-pitcher load variability are expected to lead to higher injury risk. It is advised not to take one pitch per pitcher into account since it cannot represent all the pitches, especially if only the fastest is selected. Among the pitchers, ball speed is found not to be a good indicator for the elbow torques. Within a pitcher, the ball speed serves better as an indicator. This study emphasises the importance of analysing each pitcher’s results individually instead of comparing them to the whole group.