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The purpose of this study was to investigate how age-related factors may influence the capacity of the muscles to protect the ulnar collateral ligament during baseball pitching. Three-dimensional marker position data from 30 pitchers (across three age groups) were incorporated into a musculoskeletal modeling framework, using OpenSim software. The effect of pitcher size, strength, and mechanics were represented by independent implementations of scaling factors, isometric muscle force values, and joint angles, resulting in 27 model combinations. For each combination, the maximum isometric varus/valgus moments that could be produced by all of the muscles were calculated and evaluated. While we found minimal age-related changes in joint angles, varus/valgus moments were highly sensitive to muscular strength and pitcher size.