BACKGROUND: The kinetic chain principle considers the body as a system of rigid links that allows for force distribution and energy transfer between segments. However, breaks within the kinetic chain caused by movement contraindications like dynamic knee valgus, can disrupt force transfers and increase injury susceptibility. Movement assessments such as the single-leg squat can assess the entire kinetic chain including knee motion. Knee valgus observed during the single-leg squat has been linked to knee valgus in the baseball pitching motion. Previous literature has determined that weakness in the kinetic chain during the baseball pitching motion increases injury susceptibility among baseball pitchers. This kinetic chain disruption caused by knee valgus during the fastball pitch could affect energy transfer from the proximal segments of the kinetic chain to the more distal segments in the upper extremity. Therefore, the purpose of this study is to use the single-leg squat to investigate the relationship between knee valgus in the single-leg squat and maximum shoulder internal rotation torque and maximal elbow varus occurring during the baseball pitching motion. METHODS: Data is currently being collected on a group of Division II baseball pitchers. Once consent is signed, participant will be hooked to an electromagnetic motion capture system and digitized. Participant will perform three single leg squats on their non-dominant leg. Peak values of knee valgus during all three trials will be collected between 45 degrees of knee flexion during the descent and 45 degrees during the ascent and averaged for analysis. Next participants will perform three overhand, fastball pitches with their dominant pitching arm. Peak shoulder internal rotation and peak elbow varus will be recorded during the pitching motion. Depending on normality of data, either a Pearson-product moment or Spearman-rank order correlation will be used to analyze data relationship using JASP 0.10.2. ANTICIPATED RESULTS: We expect that knee valgus seen in the single-leg squat will show moderate to strong correlation with peak shoulder internal rotation and peak elbow varus torque.

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