Reliability of measuring isometric and isokinetic peak torque, rate of torque development, integrated electromyography, and tibial nerve conduction velocity

Abstract

To determine the reliability of measures used in neuromuscular diagnosis and rehabilitation, 23 adults underwent identical testing on two occasions. Intraclass correlation coefficients (ICC) showed the reliability of peak torque measurement to depend both on the movement tested and velocity of contraction (leg extension ICC = 0.64-0.94, plantar flexion ICC = 0.55-0.76, leg press ICC = 0.72-0.91). Peak rate of torque development (RTD) and the percentage of peak torque at peak RTD were not reliable for any movement (ICC = 0.02-0.28). Mean RTD between 30% and 60% of peak torque was unreliable for leg press (ICC = 0.46), yet fairly reliable for both knee extension (ICC = 0.61) and plantar flexion (ICC = 0.63). Mean integrated electromyography (IEMG) showed fair to good reliability for isometric and 1.05 rad.s-1 leg press (ICC = 0.66, 0.90, respectively), and plantar flexion and leg extension (ICC = 0.75-0.89). Tibial nerve conduction velocity was highly reliable (ICC = 0.89). A range of reliabilities can be expected when measuring these variables, and must be considered when interpreting neuromuscular data.