The Impact of Core and Leg Muscle Fatigue on Baseball Throwing Mechanics

As we move into Spring we begin to see our youth athletes return to the baseball diamond often with a sudden increase in practice volume.  The sudden increase in throwing volume, either in the field or on the mound, places the athlete's shoulder and elbow at greater risk of baseball injuries. The greatest risk factors for injury include throwing more than 80 pitches/game, playing baseball greater than 8 months/year, and pitching with arm fatigue. As discussed in our prior posts, an athlete's throwing velocity is driven by their legs strength and power. Athletes with leg weakness are more likely to suffer from progressive changes in performance and increased injury risks.

A recent study in the Orthopedic Journal of Sports Medicine authors analyzed the impact of fatigue on throwing velocity, accuracy, and throwing mechanics (Chalmers et al. 2016). Authors studied 28 elite adolescent (13-16 year old) pitchers as they pitched a simulated game (90 pitches). Each pitch was analyzed for velocity and accuracy while every 15th pitch was analyzed for pitching mechanics. As expected the velocity, accuracy, and mechanics suffered with increased pitch counts. Importantly, the authors showed the loss of velocity, accuracy, and biomechanics were preceded first by core and leg muscle fatigue.

This study adds to the importance of controlling pitch counts and treating the lower extremities in order to improve throwing performance and reduce injury risk.