Predictors of throwing velocity in youth and adolescent pitchers

Abstract

Background: Shoulder and elbow injuries are a common cause of pain, dysfunction, and inability to play in overhead throwers. Pitch velocity plays an integral part in the etiology of these injuries; however, the demographic and biomechanical correlates with throwing velocity remain poorly understood. We hypothesized that pitchers with higher velocity would have shared demographic and kinematic characteristics.

Methods: Normal preseason youth and adolescent pitchers underwent dual-orthogonal high-speed video analysis while pitch velocity was collected with a radar gun. Demographic and pitching history data were also collected. Kinematic data and observational mechanics were recorded. Multivariate regression analysis was performed.

Results: A total of 420 pitchers were included, with a mean pitching velocity of 64 ± 10 mph. After multivariate logistic regression analysis, the most important correlates with pitch velocity were age (P < .001; R(2) = 0.658), height (P < .001; R(2) = 0.076), separation of the hips and shoulders (P < .001; R(2) = 0.027), and stride length (P < .001; R(2) = 0.016); in combination, these 4 variables explained 78% of the variance in pitch velocity. Each year of age was associated with a mean 1.5 mph increase in velocity; each inch in height, with 1.2 mph; separation of the hips and shoulders, with 2.6 mph; and a 10% increase in stride length, with 1.9 mph.

Conclusion: Pitch velocity is most strongly correlated with age, height, separation of the hips and shoulders, and stride length.

Keywords: Baseball; injury prevention; motion analysis; overhand throwing; pitching; superior labral anterior-posterior tear; ulnar collateral ligament tear.