Isokinetic muscle testing for weak patients suffering from neuromuscular disorders: a reliability study

Area of Science:

• Neurology
• Rehabilitation Medicine
• Biomechanics

Background:

• Accurate muscle strength assessment is crucial for evaluating neuromuscular disorders (NMD).
• Existing methods may lack the sensitivity required for patients with varying degrees of muscle weakness.
• Isokinetic dynamometry offers a controlled environment for objective strength measurement.

Purpose of the Study:

• To introduce and validate a novel isokinetic knee flexor and extensor testing procedure for NMD patients.
• To assess the reliability of this method in individuals with mild to severe muscle weakness.
• To investigate the correlation between the proposed isokinetic testing and traditional manual muscle testing (MMT).

Main Methods:

• Utilized the Biodex 3 system in continuous passive motion (CPM) mode for isokinetic testing.
• Calculated muscle torque by subtracting passive motion torque from active, concentric effort torque.
• Evaluated reliability through repeated testing in 15 NMD patients and compared results with MMT using correlation coefficients.

Main Results:

• High reliability was demonstrated, with intraclass correlation coefficients (ICCs) ranging from 0.91 to 0.99 for peak torque, work, and power.
• Moderate to strong correlations (Spearman rho 0.67–0.74, p<0.01) were found between isokinetic dynamometry values and MMT.
• Reliability for the angle at peak torque ranged from 0.50 to 0.90.

Conclusions:

• The described isokinetic testing method is reliable and sensitive for evaluating knee muscle strength in NMD patients.
• This dynamic assessment provides valuable, objective data for NMD patient evaluation.
• The method shows significant correlation with MMT, supporting its clinical utility.