Context: The repetitive demands of throwing affect glenohumeral (GH) range of motion (ROM) and strength. Less is known about hip alterations in skeletally immature athletes.Objective: To compare GH and hip ROM and strength between age, position, and side of youth baseball athletes.Design: Cross-sectional study. Main Outcome Measure(s): Bilateral GH and hip internaland external-rotation ROM were measured passively and summed for total arc of motion (TAM). Glenohumeral and hip rotation and gluteus medius strength were measured. Analyses included linear mixed models.Results: Glenohumeral internal rotation was less in throwing than in nonthrowing arms (P , .05) except in younger pitchers (P ¼ .86). Compared with older athletes, younger athletes had more GH external rotation (103.38 6 7.78 versus 97.58 6 9.48; P ¼ .002), TAM (156.48 6 8.78 versus 147.98 6 10.98; P ¼ .04), and external rotation in throwing compared with nonthrowing arms (101.98 6 1.28 versus 97.98 6 1.18; P , .001). Glenohumeral TAM was less in throwing than in nonthrowing arms (150.58 6 2.18 versus 154.98 6 1.38; P ¼ .01). Younger athletes had more hip internal rotation (38.98 6 6.88 versus 31.28 6 7.58; P , .001) and TAM (68.48 6 10.08 versus 60.78 6 9.88; P ¼ .001) than older athletes. Lead-leg hip internal-rotation ROM was greater than in the stance leg (34.88 6 8.98 versus 32.88 6 7.78; P ¼ .01). Overall, older players were stronger than younger players (P , .05), and the throwing arm was stronger in internal rotation than the nonthrowing arm (10.12 6 3.72 lb [4.59 6 1.69 kg] versus 9.43 6 3.18 lb [4.28 6 1.44 kg]; P ¼ .047).Conclusions: Youth baseball athletes had typical GH ROM adaptations of less internal rotation and more external rotation in the throwing versus the nonthrowing arm. Greater ROM in younger athletes may be explained by prepubertal characteristics. We obtained hip-strength values in youth baseball athletes, and as expected, older athletes were stronger.Key Words: shoulder, kinetic chain, adolescents, throwing athletes Key PointsYouth baseball athletes showed glenohumeral and hip adaptations between age groups. Glenohumeral range-of-motion adaptations typical in baseball athletes-less internal rotation and more external rotation-were present in participants as young as 8 years old.

Clinical Scenario: There are approximately 200,000 anterior cruciate ligament (ACL) tears reported annually in the United States. Patients who undergo ACL reconstruction followed by an aggressive rehabilitation protocol can often structurally and functionally progress to a preinjury level. Despite physical improvements with ACL-rehabilitation protocols, however, there are still a substantial number of individuals who do not return to preinjury level, particularly physically active individuals, of whom only 63% return to their full potential preinjury level. This may be due to continued pain, swelling, stiffness, and weakness in the knee. In addition, research concerning the topic of kinesiophobia (ie, fear of reinjury), which may prevent individuals from returning to their activities, has increased over the past several years. Kinesiophobia is defined as the irrational or debilitating movement of physical activity resulting in the feeling of vulnerability to painful injury or reinjury. Kinesiophobia may have a significant impact on physically active individuals, considering the proportion of patients who do not return to their sport. However, it is unknown whether kinesiophobia is associated with patients' perceived physical-impairment levels after ACL reconstruction. Focused Clinical Question: Is kinesiophobia associated with self-perceived levels of knee function after ACL reconstruction?

The significant relationships identified in this study suggest the need to further examine youth and adolescent cumulative and seasonal pitch guidelines.

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