The single leg squat in clinical testing : aspects of reliability, validity, and associated factors

Background: The Single Leg Squat (SLS) test is a functional test widely used in clinical settings to examine and evaluate rehabilitation goals. Research indicates that the SLS is reliable when the knee relative to the foot is dichotomously assessed. However, the assessment of functional movements often comprises more complex analyses of the whole kinetic chain with several body segments which highlights the need to develop and test a standardised multi-segmental SLS. Movement quality is an important aspect when using prevention programs in the clinical context, and the SLS can be used for this purpose. As knee injuries are common among athletes and especially among female soccer players, further investigation of the SLS in this population is warranted. Overall, the development of both quantitative and qualitative measurements needs to be studied to improve clinical testing. Clinically, portable marker-less motion capture (MMC) systems are suggested to be an adequate substitute for a three-dimensional analysis system, and one such novel MMC system is the QinematicTM. Before a test such as the SLS, or any other new measurement instrument, can be used in clinical settings, it is important to explore its measurement properties. Aim: The overall aim of this thesis was to develop and assess aspects of reliability and validity of the SLS among physically active people, and from a biopsychosocial perspective investigate factors associated with the SLS in a sample of female soccer players. Methods: Study I was a systematic review and meta-analysis that investigated the current literature regarding the intra- and inter-rater reliability of visually assessed SLS, including the Forward Step-Down (FSD) and Lateral Step-Down (LSD) tests. Study II was a laboratory-based test-retest reliability and validity study of a three-dimensional MMC system, the QinematicTM. Study III was an intra- and inter-rater reliability study of a standardised multi-segmental SLS developed from the findings in Study I. Study IV was a cross-sectional observational study using linear regression models to explore if demographic and biopsychosocial factors associated with the outcome of the SLS, assessed as a total score for all segments and as a separate knee segment in a sample of elite and sub-elite female soccer players. An additional analysis investigated the possibility of the SLS to discriminate injured soccer players from non-injured players. Results: In Study I, the pooled results of ICC/kappa showed a “moderate” agreement for inter-rater reliability and a “substantial” agreement for intra-rater reliability of the SLS, including the FSD and LSD. In Study II, the QinematicTM showed “substantial relative reliability” but “poor absolute reliability”. Regarding validity, a “moderate” agreement between the visual assessment and Qinematic™ data for various knee angles was shown and the best discriminative ability of the SLS was found at a knee angle of 6°. In Study III the proposed multi-segmental SLS showed a “moderate” inter-rater reliability and an “almost perfect” intra-rater reliability. In Study IV, the outcome of the SLS was associated with previous injuries and various demographic-, biomechanical- and psychosocial factors depending on the tested leg. The total score associated with hip strength for both the dominant and the non-dominant leg, and the knee segment associated with division inherency for both the dominant and non-dominant leg. The additional analysis showed that the SLS was not able to discriminate between players with and without previous or present injuries. Conclusion: The SLS seems to be a reliable and clinically useful multi-segmental test of movement quality in contrast to the QinematicTM system. The SLS was, in a sample of female elite and sub-elite soccer players, associated with a variety of biopsychosocial factors when assessed as a total score or as a separate knee segment. The results imply that several factors need to be considered when assessing the SLS among female soccer players such as leg dominance, division inherency, hip strength, and psychosocial factors

Visual assessment of movement quality in the single leg squat test: a review and meta-analysis of inter-rater and intrarater reliability

ObjectivesTo conduct a review and meta-analysis on the inter-rater and intrarater reliability of the SLS, including the lateral step-down (LSD) and forward step-down (FSD) tests.DesignReview with meta-analysis.Data sourcesCINAHL, Cochrane Library, Embase, Medline (OVID) and Web of Science was searched up until December 2018.Eligibility criteriaStudies were eligible for inclusion if they were methodological studies which assessed the inter-rater and/or intrarater reliability of the SLS, FSD and LSD through observation of movement quality.ResultsThirty-one studies were included. The reliability varied largely between studies (inter-rater: kappa/intraclass correlation coefficients (ICC) = 0.00–0.95; intrarater: kappa/ICC = 0.13–1.00), but most of the studies reached ‘moderate’ measures of agreement. The pooled results of ICC/kappa showed a ‘moderate’ agreement for inter-rater reliability, 0.58 (95% CI 0.50 to 0.65), and a ‘substantial’ agreement for intrarater reliability, 0.68 (95% CI 0.60 to 0.74). Subgroup analyses showed a higher pooled agreement for inter-rater reliability of ≤3-point rating scales while no difference was found for different numbers of segmental assessments.ConclusionOur findings indicate that the SLS test including the FSD and LSD tests can be suitable for clinical use regardless of number of observed segments and particularly with a ≤3-point rating scale. Since most of the included studies were affected with some form of methodological bias, our findings must be interpreted with caution.PROSPERO registration numberCRD42018077822

Visual assessment of movement quality: a study on intra- and interrater reliability of a multi-segmental single leg squat test

Abstract Background The Single Leg Squat test (SLS) is a common tool used in clinical examination to set and evaluate rehabilitation goals, but there is not one established SLS test used in the clinic. Based on previous scientific findings on the reliability of the SLS test and with a methodological rigorous setup, the aim of the present study was to investigate the intra- and interrater reliability of a standardised multi-segmental SLS test. Methods We performed a study of measurement properties to investigate the intra- and interrater reliability of a standardised multi-segmental SLS test including the assessment of the foot, knee, pelvis, and trunk. Novice and experienced physiotherapists rated 65 video recorded SLS tests from 34 test persons. We followed the Quality Appraisal for Reliability Studies checklist. Results Regardless of the raters experience, the interrater reliability varied between “moderate” for the knee variable (ĸ = 0.41, 95% CI 0.10–0.72) and “almost perfect” for the foot (ĸ = 1.00, 95% CI 1.00–1.00). The intrarater reliability varied between “slight” (pelvic variable; ĸ = 0.17, 95% CI -0.22-0.55) to “almost perfect” (foot variable; ĸ = 1.00, 95% CI 1.00–1.00; trunk variable; ĸ = 0.82, 95% CI 0.66–0.97). A generalised kappa coefficient including the values from all raters and segments reached “moderate” interrater reliability (ĸ = 0.52, 95% CI 0.43–0.61), the corresponding value for the intrarater reliability reached “almost perfect” (ĸ = 0.82, 95% CI 0.77–0.86). Conclusions The present study shows a “moderate” interrater reliability and an “almost perfect” intrarater reliability for the variable all segments regardless of the raters experience. Thus, we conclude that the proposed standardised multi-segmental SLS test is reliable enough to be used in an active population

Reliability and validity of a novel Kinect-based software program for measuring posture, balance and side-bending

Abstract Background Clinical examinations are subjective and often show a low validity and reliability. Objective and highly reliable quantitative assessments are available in laboratory settings using 3D motion analysis, but these systems are too expensive to use for simple clinical examinations. Qinematic™ is an interactive movement analyses system based on the Kinect camera and is an easy-to-use clinical measurement system for assessing posture, balance and side-bending. The aim of the study was to test the test-retest the reliability and construct validity of Qinematic™ in a healthy population, and to calculate the minimal clinical differences for the variables of interest. A further aim was to identify the discriminative validity of Qinematic™ in people with low-back pain (LBP). Methods We performed a test-retest reliability study (n = 37) with around 1 week between the occasions, a construct validity study (n = 30) in which Qinematic™ was tested against a 3D motion capture system, and a discriminative validity study, in which a group of people with LBP (n = 20) was compared to healthy controls (n = 17). We tested a large range of psychometric properties of 18 variables in three sections: posture (head and pelvic position, weight distribution), balance (sway area and velocity in single- and double-leg stance), and side-bending. Results The majority of the variables in the posture and balance sections, showed poor/fair reliability (ICC < 0.4) and poor/fair validity (Spearman <0.4), with significant differences between occasions, between Qinematic™ and the 3D–motion capture system. In the clinical study, Qinematic™ did not differ between people with LPB and healthy for these variables. For one variable, side-bending to the left, there was excellent reliability (ICC =0.898), excellent validity (r = 0.943), and Qinematic™ could differentiate between LPB and healthy individuals (p = 0.012). Conclusion This paper shows that a novel software program (Qinematic™) based on the Kinect camera for measuring balance, posture and side-bending has poor psychometric properties, indicating that the variables on balance and posture should not be used for monitoring individual changes over time or in research. Future research on the dynamic tasks of Qinematic™ is warranted