Mechanisms of Shoulder and Elbow Injury in the Young Overhead Athlete


Baseball is one of the most popular sports in the United States. Unfortunately, a large number of injuries couple this participation, particularly in young developing pitchers where repetitive stresses applied at the shoulder and elbow can perpetuate significant joint debilitation. Equally disconcerting is that these injuries are often the catalyst for significant long-term joint degradation, career ending surgeries, and restriction in routine upper limb function. Information regarding the causal factors of shoulder and elbow injuries in young overhead athletes however is currently limited. We intend to address this void directly in our ongoing research within the laboratory, with the following representing our initial exploits:

Effect of Pitching Load and Between Bout Rest on Muscle Degradation and Pitching Mechanics: Implications for Shoulder Injury in Young Pitchers.

Shoulder injuries are a common and potentially traumatic injury in young baseball pitchers. With the mechanisms of such injuries still elusive, pitch counts and days rest between pitching bouts are currently viewed as the most effective preventative strategy. To date, there is a paucity of scientific data relating pitching load to muscle and/or joint degradation, particularly in young skeletally immature populations. It is thus plausible that current guidelines may in fact contribute to rather than reduce injury rates. It is also unclear whether muscle degradation is coupled with fatigue induced adaptations in the pitching action. The specific aims of this study therefore, are to 1. Compare exercise-induced changes in the rotator-cuff muscles across a variety of pitching loads, and 2. Determine whether the onset of muscle damage correlates with simultaneous alterations in pitching mechanics.

A total of 24 young pitchers (12-15 years) will be recruited to the study and randomly allocated to one of four groups, characterized by a predefined total pitch count (40, 50, 60, 70 pitches). T2 weighted magnetic resonance (MR) images of the rotator cuff muscles in the pitching arm will be obtained immediately prior to and after pitching, and once daily for five days post pitching. These data will be compared to determine the relative impact of pitch count on muscle damage, as evidenced by the amount of intramuscular water. Changes in upper limb joint motions and loads will also be quantified across the pitching bout, and correlated with MR data as a means of determining mechanical predictors of muscle damage onset. This study represents the first step in our long-term research goal of determining the causal factors of shoulder injuries in the young overhead athlete. Elucidating the link between pitching load and injury risk would immediately afford more effective and stringent guidelines pertaining to safe pitch counts. Understanding the relationship between pitching load, pitching mechanics and injury risk would also enable more effective injury screening and prevention strategies to be formulated. These combined actions would contribute directly to a significant reduction in shoulder injuries in the overhead athlete.

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