Predictors of throwing velocity in youth and adolescent pitchers

Abstract

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