Abstract
We report 14 separate studies of the mechanical and/or physiological performance reliabilities of selected isokinetic dynamometers, including the Biodex, Cybex 340, Cybex Liftask, Cybex TORSO, Cybex TEF, and Merac systems. A total of 171 volunteer subjects (85 females, 86 males; age range 16–34 years) were randomly assigned to a dynamometer for physiological reliability testing. Testing consisted of five maximal performance efforts across a velocity spectrum. Each session was preceded by an isokinetic and cardiovascular warm-up, through a controlled range of knee, spine, or lifting motion in a test/retest design separated by 48 hours. Mechanical reliability testing consisted of five repetitions of dropping a certified load through a controlled motion arc across a velocity spectrum, also under the test/retest paradigm. Intraclass correlation statistical procedures showed significant levels of mechanical and physiological test/retest reliability for each of the tested dynamometer systems. Within the limitations of the study, the selected isokinetic devices demonstrated reliability for performance measurement during concentric isokinetic, eccentric isokinetic, or concentric isotonic functions, depending on the specific device.