Reliability of an upper limb isokinetic evaluation in healthy individuals
Heloísa C B Nardim1, Raquel M M Sugano2, Thaís M Fifolato2
1Department of Health Sciences, Rehabilitation and Functional Performance Program. Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil; Rehabilitation Center of Clinical Hospital of Ribeirão Preto Medical School, University of São Paulo. Ribeirão Preto, SP, Brazil.
Background:
Muscle strength is a key functionality indicator and can be objectively assessed using isokinetic dynamometry (IKD). However, IKD evaluation of the upper limb remains clinically challenging as in research settings.
Objective:
To evaluate the test-retest reliability of IKD measurements for the shoulder, elbow, forearm, and wrist at different speeds, as well as for isometric handgrip strength.
Methods:
Isokinetic strength and isometric handgrip assessments were performed using the Biodex System 4 Pro™ and the Jamar™ dynamometer. Participants were tested twice with a 7-day interval. The speeds tested were 60°/s and 120°/s in concentric mode. Reliability analysis was performed using the Intraclass Correlation Index. Spearman's Correlation Coefficient (p ≤ 0.05) analyzed the correlation between handgrip devices.
Results:
Thirty-three healthy participants were tested. Peak torque and isometric handgrip strength demonstrated excellent reliability (ICC: 0.87-0.98) at both speeds. The standard error of measurement ranged from 0.56 to 8.6, and the minimum detectable change from 1.5 to 23.8. Significant laterality differences were observed at 120°/s for shoulder adduction, internal and external rotation, elbow flexion and extension, and wrist extension. Significant speed-related differences were found in some movements, with higher mean peak torque at 60°/s. The Spearman coefficient indicated a strong correlation between Jamar™ and Biodex™ handgrip measurements for both sides.
Conclusion:
Isokinetic and isometric assessments using the Biodex System 4 Pro™ are highly reproducible for the tested positions and speeds. Additionally, the Jamar™ and Biodex™ handgrip devices can be used interchangeably when measurement units are standardized.
