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

Introduction The measurement of quadriceps strength is crucial for various clinical applications. However, tra-ditional isokinetic dynamometers are expensive and bulky. Handheld dynamometers represent accessible alternatives, but the agreement between compression and traction dynamometers in evaluating knee exten-sor torque requires investigation. Objective To evalua-te 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 sam-ple. Participants were recruited by researchers in the physiotherapy outpatient clinic of the Federal Univer-sity of Juiz de Fora – University Hospital, between June 2021 and June 2022. Two dynamometers were used: the MMT manual dynamometer from Lafayette Instru-ment Company, and the E-lastic® 200 kg traction dy-namometer. 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 equiva-lence. The Bland-Altman plots also showed good agree-ment, and Student´s t-tests did not detect significant differences between examiners. Conclusion The hand-held 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.