Axe Michael J, Strube Michael, Osinski David, Andrews James R, Snyder-Mackler Lynn
Washington University, St. Louis, MO, USA.
American Baseball Foundation, Birmingham, AL, USA.
Int J Sports Phys Ther. 2014 May;9(3):346-55.
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.
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.
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.
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.
The mathematical model developed in 1996 on U.S.A. baseball players is robustly generalizable to international youth baseball pitchers.
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.
1996年发布了一个用于研究美国青少年棒球运动员的客观分类系统。职业棒球联盟中有超过25%的国际球员，其中大多数来自五个国家。在美国和国际上，许多青少年棒球运动员在早年的比赛中受伤。目前尚无用于研究青少年棒球投球损伤、生物力学或成熟度的国际分类系统，但为了在多中心研究中比较和整合投手，需要这样一个系统。统一的国内和国际伤前规范数据是最佳的。理想情况下，数据收集应切实可行，所需设备价格低廉且时间要求有限。
1996年基于853名男孩开发并在美国中大西洋地区的114名男孩身上验证的数学模型在国际上适用，能够轻松对世界各地的青少年棒球投手及其水平进行分类。
721名年龄在8至14岁的国际投手投出五记用校准雷达枪记录的全速投球，并在有标记的场地进行四次最大距离投球。人口统计学数据包括年龄、身高、体重和投球年限。收集地点包括外国国家棒球俱乐部（多米尼加共和国、委内瑞拉、波多黎各、日本和菲律宾）、墨西哥国家青少年锦标赛以及一项多国锦标赛（巴西、秘鲁和哥伦比亚）。使用1996年开发的数学模型为该样本生成预测距离，以便与实际距离进行比较。除了总体分析外，对于四个国家，有足够的样本量来按国家比较预测距离和实际距离。
使用数学模型得出的预测距离与实际距离之间的相关性为0.90。国际球员的平均速度比美国球员的平均速度高出1至2个标准差，平均距离比美国球员的平均距离高出1个标准差。没有系统性的高估或低估，这表明该模型的相对拟合度和绝对拟合度都非常好。
1996年基于美国棒球运动员开发的数学模型可有力地推广到国际青少年棒球投手。
伤前距离/速度数据有助于对8至14岁的多个水平的青少年棒球运动员进行分类。现在可以在多中心研究中进行国际和地区比较，以便更好地确定风险因素、比较研究并根据伤前最大长传数据整合数据。数据收集仅需一块场地、几个球和一个卷尺。
