Reliability of Absolute and Ratio Data In Assessment of Knee Extensor and Flexor Strength

Article type: Research Article

Authors: Kramer, John F.^{a; *; **} | Ingham-Tupper, Susan^{a; ***} | Walters-Stansbury, Karen^{a; ****} | Stratford, Paul^{a; *****} | MacDermid, Joy^{a; ******}

Affiliations: [a] Departments of Physical Therapy, University of Western Ontario, St. Joseph's Hospital, London, and McMaster University, Hamilton, Ontario, Canada

Note: [*] Department of Physical Therapy, University of Western Ontario, London, Ontario, Canada.

Note: [**] Address reprint requests to Dr. J. F. Kramer, Department of Physical Therapy, Faculty of Applied Health Sciences, University of Western Ontario, London, Ontario, Canada N6G IHI.

Note: [***] Department of Physical Therapy, University of Western Ontario, London, Ontario, Canada.

Note: [****] Department of Physical Therapy, University of Western Ontario, London, Ontario, Canada.

Note: [*****] Department of Physical Therapy, McMaster University, Hamilton, Ontario, Canada.

Note: [******] Department of Physical Therapy, St. Joseph's Hospital, London, Ontario, Canada.

Abstract: The purpose of this investigation was to compare reliability coefficients and standard errors of measurement (SEM) for absolute (peak torque in newtonmeters) and ratio (concentric/eccentric (C/E)) and knee flexion/extension (KF/KE) ratios—as percentages) data. Forty healthy volunteers (20 men and 20 women) completed knee extension and flexion tests on two occasions within a 2-week period. On each occasion, two concentric and two eccentric muscle actions, with a 5-second rest between muscle actions, were completed from 90° to 5° flexion at 60 deg/sec angular velocity. For each gender, absolute scores were characterized by higher interrepetition, interoccasion, and overall intraclass correlation coefficients and lower relative measurement error (SEM/SD) than were either C/E or KF/KE ratios. These results do not discount the utility of ratio data, but suggest that to maximize reliability, ratio data should be acquired using more repetitions and/or occasions than is the case when using absolute data.

Keywords: Reliability, muscle performance, tests and measurements

DOI: 10.3233/IES-1994-4201

Journal: Isokinetics and Exercise Science, vol. 4, no. 2, pp. 51-57, 1994