Seated Lumbar extensor strength in adults: a study of repeatability and reliability

Abstract Background: In this study, we examined the use of a static dynamometer chair to measure lumbar spine extensors strength in a sample of 79 healthy adults.Methods: In this study we examined 79 healthy subjects (33 males and 46 females), 25-63 years of age. Subjects were placed in a seated position on the novel chair, secured tightly with a lap belt. In each session, the subjects were asked to extend their back against the force transducer at maximum capacity, maintaining the extension for 5 seconds. The maximal force delivered over that period was recorded. Subjects had a practice trial followed by 3 forceful extensions with pausing intervals of 30 seconds. The average force of all 3 trials were recorded. A follow up session was carried out within 14 days later.Results: Initial session was 69.474 LBS (67.047 and 71.901). Intraclass Correlation Coefficient for single measure was 0.853 (0.765 and 0.908 with 95% CI) and for average measures, 0.921(0.867 to 0.952 with CI 95%).Follow up session mean noted was 71.661 LBS (71.615 and 71.706). Intraclass Correlation Coefficient for single measure was 0.798 (is 0.683 and 0.874 with 95% CI) and for average measures, 0.888 (0.812 and 0.933 with CI 95%).Relationship (average measure) between initial session and follow up session set of measurements (r=0.80; p<0.001; R2=0.62).Conclusion:The use of the static dynamometer chair is reliable. It is a non-invasive, cost-effective test that facilitates the assessment of lumbar spine extensors strength in adult patients.