The inter- and intrarater reliability and agreement for field-based assessment of scapular control,shoulder range of motion,and shoulder isometric strength in elite adolescent athletes

ObjectivesTo investigate the intra- and interrater reliability and agreement for field-based assessment of scapular control, shoulder range of motion (ROM), and shoulder isometric strength in elite youth athletes.DesignTest-retest reliability and agreement study.SettingEight blinded raters (two for each assessment) assessed players on field during two testing sessions separated by one week.Participants162 elite youth handball players with or without a history of previous shoulder pain within the preceding six months.Main outcome measuresKappa (κ) and prevalence-adjusted bias-adjusted kappa (PABAK) coefficients for scapular control reliability, and 95% limits of agreement (LOA) for ROM and strength agreement.ResultsScapular control demonstrated substantial to almost perfect reliability (κ 0.67 to 0.84, PABAK from 0.68 to 0.88). Mean strength values ranged from 0.9 N/kg to 1.6 N/kg, and LOAs ranged from −0.7 N/kg to 0.8 N/kg. Rotational strength revealed additionally systematic bias between and within rater. No or acceptable systematic bias were evident for ROM and abduction strength measures. Mean values and LOAs for ROM ranged between 39.9° to 52.3°, and from −12.6° to 9.9°, respectively.ConclusionsScapular control and ROM can be assessed on the field with acceptable reliability. The threshold for reliable measurements of isometric strength using handheld-dynamometers is high.