Concurrent validity and reliability of clinical evaluation of the single leg squat

Physiother Theory Pract. 2011 Nov;27(8):586-94. doi: 10.3109/09593985.2011.552539. Epub 2011 Jul 31.


This study determined reliability and concurrent validity of measurements of the single leg squat made by novice examiners. Twelve video recordings of individuals performing a single leg squat were evaluated by six student physical therapists. Students assessed movement quality on an ordinal scale and manually measured frontal plane knee movement quantity on a video monitor. Inter- and intrarater reliability of ordinal scale ratings were determined via quadratically weighted kappa. Inter- and intrarater reliability of frontal plane knee measures were determined through intraclass correlation coefficient models 2,k and 3,k (k = 3 ratings), respectively. Concurrent validity of frontal plane knee measures was examined by comparison with Vicon-Peak motion-tracking system measures via Bland-Altman scatterplots. Ordinal scale measures displayed intrarater reliability ranging from 0.38 to 0.94 and interrater reliability of 0.68 (0.46-0.87). Intrarater reliability of frontal plane knee measures ranged from 0.88 to 0.98 and interrater reliability of 0.99 (0.97-1.00). Difference scores between student and computer-generated measures of frontal plane knee movement were significantly different as determined through Bland-Altman scatterplots and calculation of the upper and lower limits of agreement.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Arthrometry, Articular*
  • Humans
  • Knee Joint / physiology*
  • Muscle, Skeletal / physiology*
  • Reproducibility of Results
  • Students, Health Occupations
  • Video Recording