A speed distance-based classification system for injury prevention and research in international and domestic youth baseball players.

BACKGROUND: An objective classification system for studying youth baseball players in the U.S.A. was published in 1996. Professional baseball is composed of greater than 25% international players a majority of whom come from five countries. Many youth baseball players are injured in early years play, both in the U.S.A. and internationally. There is no international classification system to study youth baseball pitching injuries, biomechanics, or maturation, but one is needed in order to compare and combine pitchers in multi-center studies. Uniform domestic and international pre-injury normative data is optimum. Ideally, data collection should be practical requiring inexpensive equipment and limited time demands. HYPOTHESIS: The mathematical model, developed in 1996 on 853 boys and validated on 114 boys in the Mid-Atlantic Region, U.S.A., is internationally applicable, allowing easy classification of youth baseball pitchers and levels throughout the world.
METHODS: Seven-hundred-twenty-one international pitchers, ages 8-14, threw five full-speed pitches recorded with a calibrated radar gun and four maximum distance throws on a marked field. Demographics included age, height, weight, and years pitched. Collection sites included foreign national baseball clubs (Dominican Republic, Venezuela, Puerto Rico, Japan and the Philippines), the Mexican national youth tournament, and a multinational tournament (Brazil, Peru and Colombia). The mathematical model developed in 1996 was used to generate predicted distances for this sample for comparison with actual distances. In addition to the overall analysis, adequate sample sizes were available for comparing predicted and actual distances by country for four of the countries.
RESULTS: The correlation between predicted distance using the mathematical model and actual distance was 0.90. The mean of the international players was 1-2 standard deviations above the USA mean for speed and one standard deviation above the mean for distance. There was no systematic over or under prediction indicating that both relative and absolute fit for the model was excellent.
CONCLUSIONS: The mathematical model developed in 1996 on U.S.A. baseball players is robustly generalizable to international youth baseball pitchers. CLINICAL RELEVANCE: Pre-injury distance/speed data allows for classification of youth baseball player of multiple levels between the ages of 8-14. International and regional comparisons are now possible for multi-center studies in order to better define risk factors, compare studies, and combine data based upon pre-injury maximum long toss data. Data collection requires only a field, a few balls, and a tape measure.