Rose-Dulcina K, et al. - This study was undertaken to determine if non-specific chronic low back pain (NSCLBP) patients presented with higher lumbar muscle fatigability and fatigability asymmetry than asymptomatic candidates. For this investigation, 30 NSCLBP patients and 23 asymptomatic candidates performed the Sorensen test. During the test, the median frequencies from the electromyographs of the right and left erector spinae longissimus (ESL) and lumbar multifidus (LMF) were measured. According to results, patients with NSCLBP showed significantly poorer back extensor muscle endurance than asymptomatic candidates. There were no differences in fatigability or fatigability asymmetry for either the ESL or LMF between NSCLBP individuals and asymptomatic participants. In both muscles, the initial median frequency was significantly lower in patients with NSCLBP. These findings may be explained by the heterogeneity of the NSCLBP population due to the absence of any specific etiology.