Agreement and reliability between two types of portable dynamometers: traction and compression

Abstract

Introduction: The measurement of quadriceps strength is crucial for various clinical applications. However, traditional isokinetic dynamometers are expensive and bulky. Handheld dynamometers represent accessible alternatives, but the agreement between compression and traction dynamometers in evaluating knee extensor torque requires investigation. Objective: To evaluate the agreement between handheld compression and traction dynamometers in knee extensor torque and to verify intra- and inter-examiner reliability. Methods: This is a methodological study with a convenience sample. Participants were recruited by researchers in the physiotherapy outpatient clinic of the Federal University of Juiz de Fora - University Hospital, between June 2021 and June 2022. Two dynamometers were used: the MMT manual dynamometer from Lafayette Instrument Company, and the E-lastic® 200 kg traction dynamometer. Results: The reliability of the dynamometers (compression and traction) was excellent, with high intra- and inter-examiner agreement (ICC(2,2) ranging from 0.94 to 0.99). No significant differences were observed between the dynamometers, indicating equivalence. The Bland-Altman plots also showed good agreement, and Student’s t-tests did not detect significant differences between examiners. Conclusion: The handheld compression and traction dynamometers used in this study demonstrated high reliability and equivalence in measurements, allowing flexibility in choosing these instruments in clinical practice. Future research may explore evaluators’ and patients’ perceptions of these measurements.