ISOKINETIC PERFORMANCE CAPACITY OF TRUNK MUSCLES .1. THE EFFECT OF REPETITION ON MEASUREMENT OF ISOKINETIC PERFORMANCE CAPACITY OF TRUNK-MUSCLES AMONG HEALTHY CONTROLS AND 2 DIFFERENT GROUPS OF LOW-BACK-PAIN PATIENTS

The aim of this investigation was to assess the reproducibility of the isokinetic trunk muscle performance measurement among patients with d ifferent degrees of low-back pain. Twenty-two healthy volunteers, 20 p atients with mild and 18 patients with severe low-back pain participat ed in isokinetic measurements, Lidoback(R) isokinetic dynamometer was used, The measurements mere performed with the subjects standing, usin g velocities of 60, 90 and 120 degrees/second. Five repetitions were p erformed at each velocity, All subjects were tested three times with a 1-week interval between the tests, Peak torque, average peak torque, coefficient of variation, total work done and peak torque to body weig ht ratio were calculated for each velocity for both flexion and extens ion, The results showed that in every measurement peak torque, average peak torque, peak torque to body weight ratio and total work done cor related with each other very strongly both in flexion and extension (r greater than or equal to 0.9). The average peak torques increased in further measurements, The change had a strong correlation with the sev erity of the back problem, which was evaluated by means of the Oswestr y disability index. The critical value was found to be 20% in the Oswe stry index: values above this meant big changes between measurements a nd values below this meant small changes between measurements.