Intra-rater test-retest reliability of hip abduction, internal and external rotation strength measurements in a healthy cohort using a handheld dynamometer and a portable stabilisation device – A pilot study

Abstract Objective To investigate the within-day and between-day test-retest reliability of hip abduction, internal rotation, and external rotation strength measurements taken using a portable device externally stabilizing a handheld dynamometer in healthy participants. Design Observational study. Setting Institute of Technology Carlow, Ireland, a third-level education institute. Participants Healthy participants (N=18; 11 male, 7 female) who participate in a field sport for more than 2 hours per week were recruited via convenience sampling. Interventions Not applicable. Main Outcome Measures Hip abduction, internal rotation, and external rotation peak force during a maximal voluntary isometric contraction (N). The 3 best values recorded for each movement for each day were used to analyze within-day and between-day test-retest reliability. Intraclass correlation coefficients (ICCs), coefficients of variance, standard error of measurement, and minimal detectable change statistics were also calculated. Results External fixation of a handheld dynamometer produced excellent test-retest reliability for within-day (ICC>0.934) and between-day (ICC>0.802) contexts. Conclusions Clinical measurements of hip strength can be performed reliably, efficiently, and cost effectively using the methods described. Furthermore, the use of external fixation eliminates the influence of tester strength on the handheld dynamometry measurements.