title: Reliability of EMG measurements for trunk muscles during maximal and sub-maximal voluntary isometric contractions in healthy controls and CLBP patients.
abstract: The purpose of this study was to compare the reliability of trunk muscle activity measured by means of surface electromyography (EMG) during maximal and sub-maximal voluntary isometric contractions (MVC/sub-MVC) over repeated trials within-day and between-days in healthy controls and patients with chronic low back pain (CLBP). Eleven volunteers (six controls and five CLBP patients) were assessed twice with a 1-week interval. Surface EMG signals were recorded bilaterally from six trunk muscles. Intra-class correlation coefficients (ICC) and standard error of measurement as a percentage of the grand mean (%SEM) were calculated. MVC and sub-MVC showed excellent within-day reliability in both healthy controls and CLBP patients (ICC mean 0.91; range 0.75-0.98; %SEM mean 4%; range 1-12%). Sub-MVC for both groups between-days showed excellent reliability (ICC mean 0.88; range 0.78-0.97; %SEM mean 7%; range 3-11%). The between-days MVC for both groups showed trends towards lower levels of reliability (ICC mean 0.70; range 0.19-0.99; %SEM mean 17%; range 4-36%) when compared to sub-MVC. Findings of the study provide evidence that sub-MVC are preferable for amplitude normalisation when assessing EMG signals of trunk muscles between-days.
authors.affiliation: School of Physiotherapy, Bld 408, Curtin University of Technology, GPO Box U1987, Perth, 6845, WA, Australia. dankaerw@ses.curtin.edu.au
authors.forename: Wim
authors.initials: W
authors.lastname: Dankaerts
authors.forename: Peter Bruce
authors.initials: PB
authors.lastname: O'Sullivan
authors.forename: Angus Firth
authors.initials: AF
authors.lastname: Burnett
authors.forename: Leon Melville
authors.initials: LM
authors.lastname: Straker
authors.forename: Lieven Andre
authors.initials: LA
authors.lastname: Danneels
mesh_terms: D000005:Abdomen / Q000503:physiopathology; D000328:Adult; D001415:Back / Q000503:physiopathology; D002908:Chronic Disease; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D017116:Low Back Pain / Q000175:diagnosis* / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D005082:Physical Exertion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014836:Volition / Q000502:physiology