Article Text
Abstract
Objectives Characteristics of muscle activity, represented by surface electromyography (EMG), have revealed differences between patients with low back pain (LBP) and healthy adults; how they relate to functional and clinical parameters remains unclear. The purpose of the current study was to examine the correlation between frequency characteristics of EMG (analysed using continuous wavelet transform (CWT) analysis) and patients’ self-rated score of disability.
Design and setting This is a case-control study with 15 patients with mechanical LBP without radicular symptoms. Patients were recruited from the orthopaedic clinic at Charing Cross Hospital. Ten healthy adults were recruited from the staff working in the hospital and associated university. Patients completed the Roland-Morris Disability Questionnaire (RMDQ) and bilateral EMG activity was obtained from erector spinae at vertebral levels L4 and T12. Subjects performed three brief maximal voluntary isometric contractions (MVICs) of the back extensors and the torque was measured using a dynamometer. CWT was applied to the EMG signals of each muscle in a 200 ms window centred around the peak torque obtained during the MVICs. The ratio (low/high frequencies) of the energy, the peak power and the frequency of the peak power were calculated for each recording site, averaged and correlated with the individual’s RMDQ score.
Results Patients had lower peak power (T12 and L4) and lower frequency of the peak power (at T12) than the healthy adults. Additionally, RMDQ positively correlated to the average ratio of energy at T12 (r=0.63; p=0.012), that is, greater self-rated disability corresponded to a dominant distribution of energy in the lower frequencies.
Conclusion The current findings reveal alterations in EMG profile and its association with self-related back pain disability, suggesting that spectral characteristics of EMG reflect muscle function.
- trunk muscles
- isometric
- electromyography
- wavelet transform
- back pain
This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Statistics from Altmetric.com
Footnotes
Contributors S-YC and PHS conceived and designed the study. S-YC and PHS conducted the experiment. S-Y C, EK and PHS analysed the data and interpreted the data. PG provided guidance on the data analysis. All authors drafted the manuscript and read, edited and approved the final version of the manuscript. All authors had full access to all of the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Obtained.
Ethics approval NHS NRES Committee London–Harrow.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.