The assessment of quadriceps muscle strength in patients with COPD: The reliability and difference of adjustable, straight-backed chair and computerized dynamometer results

Background: The measure of choice for appropriate assessment of muscle strength must be reliable, accurate, sensitive and feasible in terms of time, cost and technical skill of the tester. Aims and objectives: The aims of this study were to assess the reliability of adjustable, straight-backed chair (CHAIR) and Biodex dynamometer (BD) and to investigate the differences between them for measuring quadriceps muscle strength. Methods: Forty-one patients with COPD (mean FEV1 66.2±21.4%pred) participated in the study. Patients performed maximal voluntary contraction tests on the CHAIR and BD in a random order with one week interval. The highest values of the BD and CHAIR results were used for the analysis. Results: The mean peak BD and CHAIR results were 131.8±39.5 Nm and 130.8±42.9 Nm, respectively. The CHAIR results were highly correlated with those of the BD in each visit (r1= 0.87, p Conclusions: The CHAIR is an alternative assesment tool to BD and allows quick and reliable assessment of quadriceps muscle strength. Validity and reproducibility of the adjustable chair is good.