Intratester Reliability and Validity of Concentric Measurements Using a New Hand-Held Dynamometer
Abstract
Janssen JC, Le-Ngoc L. Intratester reliability and validity of concentric measurements using a new hand-held dynamometer.
Objective
To assess the reliability of a new hand-held dynamometer (HHD) to perform concentric measurements, and to determine the agreement between the HHD and the criterion standard isokinetic dynamometer.
Design
Elbow flexion concentric measurements were performed on a mechanical arm using the HHD and the isokinetic dynamometer.
Setting
Engineering laboratory and university strength-testing facility.
Participants
Three patient profiles, differing in range of motion (ROM) and strength, were simulated by a mechanical arm.
Interventions
Not applicable.
Main Outcome Measures
Peak torque and ROM obtained from concentric elbow flexion profiles.
Results
Intratester reliabilities, measured with the intraclass correlation coefficient (ICC1,1), of the peak torque and start and end ROM are excellent for both the HHD (.99, .98, and .99, respectively) and the isokinetic dynamometer (.99 for all 3 variables). The angle of peak torque was rated fair to good in intrareliability for both devices, at .64 (HHD) and .69 (isokinetic dynamometer). Validity, measured within the limits of agreement (LOA) between the 2 devices, was clinically acceptable for peak torque and start ROM, although not for end ROM and angle of peak torque.
Conclusions
It is possible to use the new HHD to obtain dynamic measurements of joint motion. Intratester reliability of the HHD is excellent and is in clinical acceptable agreement with the isokinetic dynamometer for peak torque and start ROM. End ROM was, however, not in agreement because of a systematic error in the isokinetic dynamometer measurement for 1 of the 3 tested profiles. Intratester reliabilities of the angle of peak torque were fair to good for both the HHD and isokinetic dynamometer, but the LOA were not clinically acceptable. Stability of the arm and speed of measurement might be confounding factors in this study.
Industrial Research Limited, Christchurch, New Zealand
Correspondence to Lan Le-Ngoc, PhD, PO Box 20 028, Christchurch, New Zealand
Supported by the Foundation for Research, Science and Technology of New Zealand (contract no. C08X040).
A commercial party having a direct financial interest in the results of the research supporting this article has not conferred or will not confer a financial benefit on the author or one or more of the authors. Janssen and Le-Ngoc are employees of Industrial Research Limited (IRL), which developed the hand-held dynamometer. IRL intends to commercialize the dynamometer through joint venture or licensing agreement with a commercial party, which has not yet been identified. The authors will not be involved in the commercialization process, and no financial benefit will be conferred on the authors.
ABSTRACT