Humeral Retroversion and Participation Age in Professional Baseball Pitchers by Geographic Region.

Abstract

Baseball is played around the world, including in North America and Latin America. The repetitive and stressful act of throwing can lead to adaptations such as increased humeral retroversion (HR) in the throwing arm. This adaptation is often considered beneficial as it allows more glenohumeral external rotation during the cocking phase of pitching without soft tissue stretching. Therefore, it is speculated that throwing should be started at a young age to capitalize on this adaptation. Interestingly, athletes in different geographic regions of the world often begin organized baseball at different ages. However, range of motion (ROM), HR, and the starting age of baseball have never been examined based on geographic region. To determine if ROM, HR, and the starting age of baseball players differed between professional baseball pitchers from North America and Latin America. Cross-sectional study. Clinical setting. Thirty professional pitchers (North American = 19, Latin American = 11) with no current injury or surgery in the previous 6 months. Both ROM and HR were measured in the dominant and nondominant shoulder of each participant. The starting age for baseball was self-reported. The Latin American group had more dominant-arm HR (8.7°; P = .034), more nondominant-arm external rotation (5.3°; P = .049), and a trend toward more nondominant-arm HR (6.5°; P = .058), yet they started playing baseball at a later age (by 3.7 years; P = .021) compared with the North American group. Latin American players had greater HR but started playing baseball at an older age. These findings contradict current thinking that HR would be more pronounced if baseball was started at a younger age. Additional research is required to better understand HR and the genetic, environmental, and nutritional factors that contribute to its development.