Isokinetic strength testing in patients with chronic heart failure - A reliability study

Measurement of skeletal muscle strength gains increasing importance as outc ome parameter in patients with chronic heart failure. This study aimed at e stablishing short-term reliability of isokinetic strength measurements of k nee extensor and flexor muscles in 38 patients with chronic heart failure. Strength tests were performed on the Cybex 6000 dynamometer. Trunk fixation was restricted to pelvic fixation. Two bouts of strength testing were perf ormed on day 1 and one on day 5. Each isokinetic bout consisted of 3 recipr ocal knee extension and flexion movements with an angular speed of 60 degre es per second. Isometric strength was measured at 30 degree knee angulation . Intraclass correlations ranged between 0.96 and 0.99 for isokinetic and i sometric peak torque of knee extensor muscles and 0.82-0.96 for flexor musc les. Analysis of repeated measurements showed significant differences among the values of flexor peak torque in the isokinetic mode and between all me asurements in the isometric mode (p<0.05). Pearson's correlation coefficien ts for isokinetic and isometric extensor peak torques ranged between 0.95 a nd 0.99, for flexor peak torques between 0.81 and 0.85 tall p<0.0001). Meas urement of isokinetic knee extensor and flexor peak torque is a reliable me thod to assess muscle strength in patients with chronic heart failure even with altered trunk fixation.