1 RELIABILITY AND VALIDITY OF HIP STABILITY ISOMETRIC TEST ( HipSIT ) : A 1 NEW METHOD TO ASSESS HIP POSTEROLATERAL MUSCLE STRENGTH 2 3

26 STUDY DESIGN: Cross-sectional study. 27 BACKGROUND: The HipSIT evaluates the strength of the hip posterolateral 28 stabilizers in a position that favors greater activation of the gluteus maximus and 29 gluteus medius and lower activation of the tensor fascia lata. 30 OBJECTIVES: To check the validity and reliability of the Hip Stability Isometric Test 31 (HipSIT) and to evaluate the HipSIT in women with patellofemoral pain (PFP). 32 METHODS: The HipSIT was evaluated with a hand-held dynamometer. During 33 testing the participants were side-lying, with the legs positioned at 45° of hip flexion 34 and 90° of knee flexion. Participants were instructed to raise the knee of the upper 35 leg while keeping the heels in contact. To establish reliability and validity, 49 women 36 were tested, with the HipSIT, by 2 different evaluators on day one, and then again 7 37 days later. The strength of the hip extensors, abductors, and external rotators were 38 also evaluated. Twenty women with unilateral PFP were also evaluated. 39 RESULTS: The HipSIT has excellent intraand inter-rater reliability. The standard 40 error of measurement was .01kgf/kg, and the minimal detectable change was .027 41 kgf/kg. The HipSIT showed good validity in the isolated hip abduction, external 42 rotation and extension (P < .01). Women with PFP showed a 10% deficit in the 43 HipSIT results for the symptomatic limb (P = .01). 44 CONCLUSION: The HipSIT showed excellent interand intra-rater reliability, 45 moderate-to-good validity in women, and was able to identify strength deficits in 46 women with patellofemoral pain. 47