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Visual assessment of movement quality in the single leg squat test: a review and meta-analysis of inter-rater and intrarater reliability
  1. John Ressman1,
  2. Wilhelmus Johannes Andreas Grooten1,2,
  3. Eva Rasmussen Barr1
  1. 1Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
  2. 2Allied Health Professionals Function, Functional Area Occupational Therapy and Physiotherapy, Karolinska University Hospital, Stockholm, Sweden
  1. Correspondence to John Ressman; john.ressman{at}


Single leg squat (SLS) is a common tool used in clinical examination to set and evaluate rehabilitation goals, but also to assess lower extremity function in active people.

Objectives To 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.

Design Review with meta-analysis.

Data sources CINAHL, Cochrane Library, Embase, Medline (OVID) and Web of Science was searched up until December 2018.

Eligibility criteria Studies 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.

Results Thirty-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.

Conclusion Our 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 number


  • reliability
  • meta-analysis
  • sports medicine
  • lower extremity
  • methodological

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  • Contributors JR contributed to the design of the study, and was responsible for collecting, analysing and interpreting the data and for drafting the manuscript together with ERB. ERB contributed to the conception and design of the study, undertook analysis and interpretation of data, drafted the manuscript together with JR and provided feedback on drafts of the manuscript. WJAG contributed in analysis and interpretation of data and provided feedback on drafts of the manuscript. All three authors read and approved the final manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests Competing interest.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.