Correlational and Regression-Based Insights into Shoulder and Core Stability Tests in Amateur Athletes: Reference Values and Sex-Based Comparison

Objective: To investigate correlation of core and shoulder physical tests, prediction of interdependent relationship and to develop reference values. Methodology: The study was conducted at Jinnah Sindh Medical University (JSMU), on amateur athletes: (n=70), recruited from JSMU sport society. Data were analyzed using IBM-SPSS version 23.0. Side bridge test right and left (SBTR and SBTL), flexor endurance test (FET), closed kinetic chain upper extremity stability test male/female (CKCUEST-M/F) outcomes and scores of CKCUEST were analyzed with gender using independent sample t test, reference values were established. Simple and multiple linear regression of normalized CKCUEST score was analyzed with independent variables. Results: Male had significantly higher mean values on SBTR and SBTL (p<0.01*) while no significance for FET, and CKCUEST outcomes. Male had significantly higher Core Endurance Asymmetry (CEA) (p=0.024*). ER/IR strength did gives 25.1% negative correlation with CEA, whereas Normalize scores of CKC-T did give 27.9% positive correlation with CEA and 50.6% positive correlation with power scores of CKCUEST. Simple and multiple linear regression models revealed that a one unit increase in Power score of CKCUEST and CEA will give significant increase in Normalize score of CKCUEST for samples. R-square of multiple regression model showed 30% variation in Normalize score of CKCUEST was explained by the studied predictors. Conclusion: Gender alone may not determine stability and ER/IR strength ratios seems less predictive comparing core engagement and coordination for stability. CEA and power emerge as stronger predictors. CEA prevails in male.