Evaluation of the cushion setting on performance of a Biodex II dynamometer

Objectives: To compare the effects of the soft cushion setting with those of the hard cushion setting of a Biodex II isokinetic dynamometer on peak velocity and peak torque with six loads at 23 preset speeds. Design: Mixed within- and between-groups, repeated-measures design. Setting: Research laboratory of a physical therapy education program. Interventions: Each load was strapped onto the right knee attachment of the dynamometer and was dropped through a 100°arc of motion five times at each preset speed using the soft and hard cushion settings. Main Outcome Measures: Peak velocity, peak torque, time to peak velocity, time to peak torque. Results: Peak velocity was significantly influenced by the cushion setting, the weight dropped, and the preset speed. Maximal peak velocity achieved was 400°/sec. Peak torque was influenced significantly by the cushion setting, the load, and the preset speed. Maximal peak torque measured was 34.99kg-m. Conclusion: The rotating shaft of Biodex II dynamometer moved at a slower speed through the entire arc of motion at the soft cushion setting and often failed to achieve a constant, preset speed. Peak torque measured using the soft cushion setting was more variable and therefore questionable.