test-retest reliability of emg β-band intermuscular coherence of non-specific chronic low back pain during flexion-extension task

Introduction: this study aimed to investigate the reliability and agreement of the beta-bandintermuscular coherence (bb-imc) as a clinical assessment tool for non-specific chroniclow back pain (ns-clbp) patients and healthy subjects by studying four phases of theflexion-extension task (f-et): standing, flexion, relaxation, and extension phases.materials and methods: twenty-four men with ns-clbp and 20 healthy subjectsvoluntarily participated in this study. all subjects performed three trials of f-et while thesurface electromyography was recorded from the lumbar erector spinal, gluteus maximus,and hamstring muscles of both sides. beta-band intermuscular coherence analysis was used tocalculate the pool coherence and the pairwise coherence for all mentioned muscles. afterward,the intra-class correlation coefficient (icc), standard error of measurement (sem), andminimal detectable change (mdc) for four phases of f-et were used to analyze the intraraterreliability and agreement of the measurements.results: the investigation of icc, sem, and mdc showed that the reliability was moderateto a high level for pool and pairwise coherence of bb-imc in all mentioned muscles forfour phases of the flexion-extension task in ns-clbp patients and healthy subjects. yet, theagreement was low because the measurement error was relatively large.conclusion: so far, no studies have used the bb-imc method to study low back pain, which iscarried out in our research to check the reliability of this new method. our findings revealed thatpool and pairwise coherence obtained during f-et have moderate to a high level of reliabilityfor using bb-imc and could be considered a tool for the ns-clbp patients’ assessment.despite the small sample size investigated, in clinical practice the using bb-imc measurecan help to study the interaction of corticospinal in ns-clbp and also in healthy subjects.this measure requires larger sample sizes in addition to studying other circumstances andfunctional movements such as lifting weight. further, more research appears to be warrantedby the observed effectiveness of a particular intervention in modulation mechanisms ofcorticospinal tract function by bb-imc in ns-clbp