Test-retest reliability of EMG Beta-band intermuscular coherence of Non-specific chronic low back pain during Flexion-extension task

The aim of the study was to investigate the reliability and agreement of the Beta-band intermuscular coherence (Bb-IMC) as a clinical assessment tool for Non-Specific Chronic Low back pain (NS-CLBP) patients and healthy subjects by studying four phases of flexion-extension task; standing, flexion, relaxation and extension phases (F-ET).

Twenty-four men with NS-CLBP and 20 healthy subjects voluntarily participated in this study. All those subjects performed three trials of F-ET while the sEMG was recorded from the lumbar erector spinal, gluteus maximus and hamstring muscles of both sides. Beta-band intermuscular coherence analysis was used to calculate the pool coherence and the pairwise coherence for all mentioned muscles. Afterward, the intra-class correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) for four phases of F-ET were also used to analyze the intrarater reliability and agreement of the measurements.

The investigation of ICC, SEM and MDC showed that the reliability was moderate to a high level of reliability for pool and pairwise coherence of Bb-IMC in all mentioned muscles for four phases of flexion-extension task in NS-CLBP patients and healthy subjects. Yet, the agreement was low because the measurement error was relatively large.

Up until now, no studies have used the Bb-IMC method to study Low back pain which are carried out in our study to check the reliability of this new method. Our findings revealed that pool and pairwise coherence obtained during F-ET are moderate to a high level of reliability for using Bb-IMC and could be considered as a tool for the NS-CLBP patients’ assessment. Although the small sample size investigated, in clinical practice the using this measure to conclude the interaction of corticospinal in NS-CLBP and healthy subjects should help to improve the analysis. This requires including larger sample sizes in addition to studying other circumstances and functional movements such as lifting weight. Furthermore, more research appears to be warranted by the observed effectiveness of a particular intervention in modulation mechanisms of corticospinal tract function by Bb-IMC in NS-CLBP.