Test-retest Reliability of EMG β-Band Intermuscular Coherence of Non-specific Chronic Low Back Pain During Flexion-extension Task

Abstract

Introduction: This study aimed 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 the Flexion-Extension Task (F-ET): standing, flexion, relaxation, and extension phases. Materials and Methods: Twenty-four men with NS-CLBP and 20 healthy subjects voluntarily participated in this study. All subjects performed three trials of F-ET while the surface electromyography 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 used to analyze the intra- rater reliability and agreement of the measurements. Results: The investigation of ICC, SEM, and MDC showed that the reliability was moderate to a high level for pool and pairwise coherence of Bb-IMC in all mentioned muscles for four phases of the flexion-extension task in NS-CLBP patients and healthy subjects. Yet, the agreement 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 is carried out in our research to check the reliability of this new method. Our findings revealed that pool and pairwise coherence obtained during F-ET have moderate to a high level of reliability for 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 measure can 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 and functional movements such as lifting weight. Further, 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.