Throwing Injuries in Youth Baseball Players: Can a Prevention Program Help

Sakata J, Nakamura E, Suzuki T, Suzukawa M, Akeda M, Yamazaki T, Ellenbecker T, Hirose N. Am J Sports Med. 2019 [Epub ahead of print]

Take-Home Message

Youth baseball players who participated in a weekly 10-minute prevention program experienced fewer shoulder or elbow injuries and improved performance compared to those that performed traditional warm-ups.


Shoulder and elbow injuries are common in youth baseball athletes. These injuries can lead to structural changes at those joints or invasive surgical repairs. Therefore, there is an urgent need for prevention programs to reduce the risk of throwing-related injuries. The authors of this randomized controlled trial investigated the effects of a 52-week exercise program performed at least once per week during a warm-up on new injuries among 237 youth (9-11 years of age) baseball players. The authors randomized 16 teams into two groups. The first group performed the modified Yokohama Baseball-9 (prevention program; 5 stretches, 2 dynamic mobility exercises, 2 balance training programs; 117 players) for 10 minutes during warmup. The control group performed their usual stretching and training program (120 players). The prevention program aimed to improve risk factors for throwing injuries: limited range of motion for elbow extension, posterior shoulder tightness, decreased shoulder and hip rotation, rotator cuff weakness, scapular dysfunction, rounded posture, and poor single-leg balance. Two physical therapists trained the athletes and coaches to perform the program. The teams performed the prevention program at least one time per week. The authors visited the teams every 16 weeks for clinical (pain, morphological change) and performance evaluations (pitching speed, range of motion, dynamic balance). Shoulder and elbow injuries were defined as pain that lasted >2 weeks, inability to play in a game or practice, pain with throwing, or abnormal findings on clinical assessment or ultrasonography.

Only 8 players were lost to follow-up in the intervention group, and 10 were lost to follow-up in the control group because they retired from baseball or moved away from the league. There was good compliance with 73% of the players in the intervention group completing the prevention program at least once per week (typically ~1.6 times/week). There were no differences in the number of pitchers in each group, but the authors failed to control for the number of pitches thrown. Over the 52-weeks, 24 players (22%; 1.7 per 1000 athletic exposures) in the intervention group reported a shoulder or elbow injury of the throwing arm. In comparison, 42 players in the control group (38%; 3.1 per 1000 athletic exposures) reported a shoulder or elbow injury of the throwing arm. The players that performed the prevention program also had more improved ball speed (~6.4km/h versus ~4.1km/h), range of motion (shoulder horizontal adduction and hip internal rotation), and improved posture compared the control group.


The authors of this study found that a 10-minute throwing injury prevention program reduced throwing injuries and improved functional outcomes in youth baseball athletes. The risk of these injuries was almost 50% lower in the intervention group compared with the control group. This decrease in injuries is similar to what we observe with lower extremity injury prevention programs. Unlike those programs, the drop out was low and compliance was high, which suggests that this upper extremity program is easy to implement and maintain over a long time.  It is also motivating for coaches and athletes to use this short program because it improved ball speed velocity and shoulder range of motion. Medical professionals should be aware of injury prevention programs for each sport and educate coaches, athletes, and parents about these programs. It is time that we step up and begin implementing these types of programs that are among the most effective prevention strategies available to the sports medicine community.

Questions for Discussion

Does this prevention program look feasible for your athletes? How can we increase buy-in from coaches and players to utilize the warmup more effectively to reduce injuries and improve performance?

Written by: Jane McDevitt
Reviewed by: Jeffrey Driban

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