Investigators from multiple Japanese institutions conducted a nonrandomized controlled trial to assess the impact of a stretching and strengthening program on the incidence of medical elbow injuries among youth baseball players without a history of previous elbow or shoulder pain. Youth 8–11 years old were allocated to either a control group, in which they received usual training, or the intervention group, in which they were instructed to perform 9 stretching and 9 strengthening exercises involving the elbow, shoulder, and hip at least once per week for 1 year.
Data regarding age, baseball position, number of throws per day, and number of hours of baseball played per day were collected from participants at baseline. Intervention participants received training on the exercise program at baseline and at 1 and 3 months after the start of the study. At baseline and every 3 months, all participants underwent clinical assessment of the elbow and shoulder for pain and received ultrasonography of their elbow. Measurement of physical functioning (such as shoulder and hip range of motion as well as the thoracic kyphosis angle, a measurement of posture) was done at baseline and at the 1-year follow-up. Participants logged episodes of pain, number of exercise programs completed (with compliance defined as at least once per week), and number of practices or games.
The primary outcome was medial elbow injury, defined as medial elbow pain that was associated with abnormal ultrasonography findings (eg, partial or complete bone fragmentation of the medial epicondyle). The incidence of medial elbow injury was calculated using athlete-exposure (AE), defined as 1 athlete participating in 1 practice or game where the athlete was at risk of sustaining an elbow injury. Regression models were used to determine the association of the exercise program on incidence of medial elbow injury as well as risk factors for medial elbow injury.
There were 493 participants enrolled and 305 included in analysis. There were 136 intervention participants and 169 control participants. There were no differences in baseline characteristics among intervention and control participants.
Among intervention participants, 57% were compliant with the program. The incidence of medial elbow injury was significantly lower among intervention (vs control) participants (0.8 per 1,000 AEs vs 1.7 per 1,000 AEs; hazard rate ratio, 50.8%; P = .016). Factors protective against medial elbow injury were improved total rotation of the shoulder on the non-dominant side, improved hip internal rotation on the non-dominant side, and a decreased thoracic kyphosis angle.
The authors conclude that a stretching and strengthening program can prevent medial elbow injury in youth baseball players.
Dr Hennrikus has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.
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