Effectiveness of a Preseason Prevention Program on Arm Injury Risk Factors: An Randomized Control Trial in Adolescent Pitchers


      Deficits in posterior shoulder flexibility and strength have been identified as risk factors for pitching injuries. This study assessed the effectiveness of a preseason prevention program to resolve these deficits in adolescent pitchers.


      Pitchers(n=143 age=15.7±1.2;height=165.0±43.8cm; weight=72.2±12.6kg) participating in team activities were block randomized by school to intervention(INV n=88) or control(CON n=76). INV received an ATC supervised program(3x/week for 8-weeks). The CON had their usual training. All pitchers participated in a 4-week interval-throwing program immediate to the start of practice. Pre-post supine bilateral ER, IR, and HA ROM and strength were assessed using a digital inclinometer with the scapula stabilized at 90° of abduction. Muscle testing was used for strength assessments via held dynamometer with arm at the side and in supine 90°/90° then normalized to body weight(BW). Injuries were recorded over the subsequent baseball season. Two trials were averaged to calculate deficits(non-dominant–dominant) and pre-post change to determine if the program to ameliorate baseline deficits. A one-way ANOVA compared change scores between groups and a 2-way ANOVA(group by injury) compared change scores influence on injury(α=0.05).


      The INV group displayed a greater reduction in IR deficit(INV=7.3°±11;CON=1.8°±9;F(1,106)=5.1,P=0.01) P=0.05) and HA deficit(INV=3.3°±13; CON= -2.4°±11;F(1,106)=6.7,P=0.01) compared to the CON group. The INV group also maintained their dominant ER-0:IR-90 ratio(INT=-1.6 ±5%BW;CON= -3.5 ±5%BW; F(1,106)=2.1,P=0.09) compared to the CON group. There were 19 arm injuries over the subsequent season(INV=11 ;CON=8 arm injuries). Control group pitchers with an injury did not decrease their HA deficit (Uninjured=3.0°±10;Injured=-9.5°±14;F(1,106)=3.3,P=0.03) or their IR deficit went on to suffer an injury(Uninjured=-1.7°±8;Injured 8.5°±13;F(1,106)=3.8,P=0.02). There were no other differences between or among groups(P>0.05).


      Adolescent pitchers displayed clinically meaningful improvements in posterior shoulder flexibility (HA and IR) and maintenance of their ER:IR ratio during an Athletic Trainer supervised preseason program. The improvements were associated with decreased injury risk over the course of the subsequent season.