Is Decreased Hip Flexibility a Risk Factor of Arm Injuries in Young Baseball Players? Systematic Review and Meta-Analysis.

Objectives: Although various kinematic parameters have been investigated as factors associated with shoulder and elbow injuries during pitching, the relationship between lower extremity flexibility and such injuries remains unclear. The objective of this meta-analysis was to examine the association between pitching injuries to the shoulder and elbow and lower extremity flexibility.

Designs: A systematic review and meta-analysis.

Date sources: A comprehensive meta-analysis was conducted using data extracted from five databases (MEDLINE, Web of Science, CENTRAL, Scopus, and PEDro) following the method of Minds. The inclusion criteria were studies focusing on throwing injuries in the shoulder and elbow, specifically related to baseball, and the investigation of motion in the lower extremities. Owing to the presence of cross-sectional and cohort studies, meta-analyses were conducted for each study type.

Main results: Meta-analyses were performed using data from 11 reports. The results revealed a significant difference in lead-side hip internal rotation for both cross-sectional (P = 0.04) and cohort studies (P = 0.02), indicating a reduced range of motion (ROM) in athletes with shoulder and elbow injuries. In addition, a significant difference was observed in the hip internal rotation of the trail leg in the cross-sectional study (P = 0.04), similar to that of the lead leg. However, no significant differences were found in hip external rotation or straight leg raising (SLR) between players with and without shoulder or elbow injuries.

Conclusions: This meta-analysis highlights the common occurrence of limited internal hip rotation ROM in baseball players with shoulder or elbow injuries. However, these injuries were not found to be associated with hip external rotation or SLR.