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Letters and Responses |
We read with interest the article by Daubney and Culham entitled "Lower-Extremity Muscle Force and Balance Performance in Adults Aged 65 Years and Older" in the December 1999 issue. We generally found the work of interest and quite commendable, with one exception. In the article, the authors indicate that they measured force via a dynamometer, reporting these values as being measured at a location "just proximal" to various bony landmarks or joints. As it is well known that the measured forces vary as a function of the distance of the force-measuring device from the axis joint rotation, the methodand meaningfulness for otherswould be more appropriate if the precise distance were recorded and the torque calculated. The fact that the height of the subjects varied from 153 to 192 cm ensures that the distances were different.
Thus, in works such as this and the normative data published by Andrews et al,1 clinicians and investigators should record the force and the perpendicular distance to the joint axis and calculate torque, preferably in units of newton-meters. Unless torque is measured, comparability across patients is not possible because the same joint torque is measured by dynamometry at different locations, yielding entirely different force values. Using something other than torque data does not meet the measurement standards we need in our practice.
Professor
Physical Therapy
Southwest Missouri State University
Springfield, MO 65804
(gls016f{at}mail.smsu.edu)
Assistant Professor
Physical Therapy
Southwest Missouri State University
(bsr916f{at}mail.smsu.edu)
References
Associate Professor
Physical Therapy Program
School of Rehabilitation Therapy
Queen's University
Kingston, Ontario, Canada K7L 3N6
(culhame{at}post.queensu.ca)
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