What Are the Validity of the Single-Leg-Squat Test and Its Relationship to Hip-Abduction Strength?

Abstract

Context:The Trendelenburg and single-leg-squat (SLS) tests are purported measures of hip-abduction strength that have not been previously validated.Objective:To correlate isometric hip-abduction strength to frontal-plane hip motion during an SLS and determine the criterion validity of a clinical-observation-analysis method to grade an SLS against 2-dimensional kinematic analysis.Design:Single-measure, concurrent validity.Setting:Biodynamics research laboratory.Participants:50 uninjured participants.Main Outcome Measures:Hip-abduction strength and hip and knee kinematic data during a Trendelenburg test and an SLS.Results:A weak, positive correlation between hip-abduction strength and hip-adduction angle was found during both the Trendelenburg (r= .22,P= .13) and the SLS (r= .21,P= .14) tests. The observation-analysis method revealed a low sensitivity, .23, and a higher specificity, .86, when compared with the kinematic data.Conclusion:The usefulness of the Trendelenburg and SLS test in screening hip-abductor strength in a healthy physically active population is limited. The origin of observable deficits during SLS requires further objective assessment.