RELIABILITY OF CYBEX-II ISOKINETIC EVALUATIONS OF TORQUE IN POSTPOLIOMYELITIS SYNDROME

The aim of this study was to ascertain the reliability of isokinetic strength measurements in a population of post-poliomyelitis subjects (PPS). Eight subjects (four males and females, mean age of 47.5 ± 10 and 56.8 ± 16 years, respectively) were evaluated, on a weekly basis for three weeks at approximately the same time of day. During each test session the knee flexors and extensors (bilaterally, where possible) were evaluated. Subjects became familiar with the equipment prior to recording three maximal contractions at the four test velocities (1.05, 2.09, 3.14, 4.18rads · s-1). A two-minute rest period was allowed between sets of contractions. The variables of peak torque, angle of peak torque, torque at specific joint angles (0.79 and 1.05rads), total contractile work, maximum power, and average power were measured on-line with the Cybex II a system using a commercially available software package. In both muscle groups, all the variables were significantly weaker on the most affected, but testable limb (p < 0.01) in subjects where both limbs could be tested (n = 5). Peak torque and total work of the quadriceps were observed to decrease with increasing velocity of movement. The effects of velocity were less apparent in the hamstrings. Average and maximum power developed by the knee extensors and flexors increased with increasing velocity of movement. Reliability of performance over three test sessions was confirmed by the intraclass correlation coefficient (ICC) values derived from the univariate ANOVAs calculated for each of the above variables (>0.80). Angle of peak torque, however, was not found to be a reliable measurement across the three test sessions. Although subjects in the present study were tested on three separate occasions, reliability of peak torque over two test sessions was also observed. However, peak torque of flexion was more reliable on Days 2 and 3. This was especially true for knee flexion at 2.09 and 3.14rads · sec-1. In conclusion, this study demonstrated that a Cybex II isokinetic device is a reliable means to evaluate strength in persons with PPS. © 1993.