Influence of a Prevention Program on Arm Injury Risk: An RCT in Adolescent Pitchers

OBJECTIVES: High school pitchers are at three times greater risk of an upper extremity (UE) injury compared to position players, with most (69%) injuries occurring during the first month of the season. Therefore, a prevention program for pitchers targeting known risk factors may reduce their injury risk, particularly early in the season. The purpose of this study was to determine the effectiveness of a preseason training program in decreasing the injury rate and altering the pattern of UE injuries in a cohort of high school pitchers. METHODS: Healthy high school pitchers (n=196) who were participating in all team activities were block randomized by school to intervention (INV, n=103) or control (CON, n=93) groups. The INV group received a scapular stability, rotator cuff strength, and posterior shoulder flexibility program (3 times/week for 8 consecutive weeks) supervised by an Athletic Trainer. The CON group participated in the teams’ usual preseason training. Training activities for all teams were recorded. All players participated in a 4-week interval-throwing program. Athletic exposures (AEs), injury incidence (participation absence or limitation due to injury) were tracked from the first day of practice until the last day of competition. Incidence rates were calculated per 1,000 AEs and monthly trends for injury were examined for occurrence by group, injury history, and body location. As a secondary analysis, published injury rates from 2009 in the same high schools were compared to their 2012 data. Rate ratios (RR) and 95% confidence intervals (CIs) were used to compare injury rates by group, injury history, body location, and year. RESULTS: Overall, there were 27 UE injuries incurred among the pitchers; 15 in the INT group (10 shoulder & 5 elbow injuries) and 12 in the CON group (10 shoulder & 2 elbow injuries). The injury rate was similar in the INT and CON groups (RR=0.86; 95% CI: 0.43-2.2). The pattern of arm injuries throughout the season was evenly distributed in both groups. In 2012, 67% of CON teams were observed participating in a general “arm care” program as compared to 6% of CON teams in 2009. Previous arm injury did not increase the risk of an UE injury in the INV group (RR=1.0; 95% CI: 0.38-2.8) but did increase the risk of an UE injury almost 4-fold (RR= 3.7,95% CI: 1.3-10.7) in the CON group. The injury incidence rate for pitchers was 12 times higher in 2009 (29.3/1,000 AEs) than in 2012 (3.4/1,000 AEs) (RR=11.6, 95% CI: 7.1-16.1). The risks of shoulder (RR=11.0; 95% CI: 6.6-15.4) and elbow injury (RR=12.6; 95% CI: 8.0-17.3) were higher in 2009 compared to 2012. The pattern of upper extremity injuries was higher in the first quarter of the season compared to 2012 (See Figure 1). CONCLUSION: The main finding of this study is that INV and CON pitchers had a similar injury rate, however, the overall injury rates were significantly lower in 2012 than in 2009. Thus it appears that a general “arm care” and interval-throwing program may also be effective in reducing the injury rate in high school pitchers, perhaps in the early part of the season as injury rates based on the differences in rates between 2012 and 2009. Pitchers with a previous injury in the INV group were less likely to suffer an injury in 2012 than pitchers’ with a previous injury in the CON group. Thus, a targeted pre-season conditioning program may help reduce the injury risk in pitchers with a history of of previous arm injury. Further studies are warranted to confirm our results.