Trunk muscle function and its association with functional limitations in sedentary occupation workers with and without chronic nonspecific low back pain

BACKGROUND: The function of trunk muscles in chronic nonspecific low back pain (CNLBP) is controversially discussed, and trunk muscle function in sedentary occupation workers is poorly understood. OBJECTIVE: To investigate whether muscle function differs between sedentary occupation workers with and without CNLBP and to determine the association between functional limitations and muscle function. METHODS: This study included 32 sedentary occupation workers (16 workers with CNLBP and 16 age- and sex-matched workers without CNLBP). Group differences in isokinetic trunk flexion-extension strength, muscle cocontraction, endurance time (Biering-Sorensen test) and electromyographic muscle fatigue were assessed. The association of these parameters and Oswestry Disability Index (ODI) score were examined in the CNLBP group. RESULTS: Participants with CNLBP had lower trunk extensor (-20%) and flexor (-18%) strength and less cocontraction (-22%) than participants without CNLBP, but due to large variability in both groups these differences were not statistically significant. Trunk muscle endurance and fatigue were comparable between groups. Variance in endurance time explained 28% of variance in the ODI-score in the CNLBP group (R-2 = 0.277). CONCLUSIONS: In patients with CNLBP, greater functional disability was associated with lower endurance. Further evidence is necessary to elucidate whether specifically training endurance performance may be beneficial for sedentary occupation workers.