Intra-day, short- and long-term reliability of surface electromyographic measurements during a standardized measurement protocol for lower back pain patients.

BackgroundThe identification of back muscle dysfunction is a prerequisite for successful rehabilitation. Therefore, surface electromyography can be used for diagnostic and evaluative purposes. However, data quality highly depends on a) variance and inaccuracies in methodological procedures and b) on time-dependent changes, particularly in complex conditions such as chronic low back pain.ObjectiveTo assess intra-day, short-term and long-term reliability of a protocol designed for electromyographic measurements of the paraspinal muscles.MethodsThree everyday tasks were selected for measurement in two healthy populations (mean age (years): 26.25/30.49 (SD: 7.05/11.03), sex-balanced). The procedure follows a detailed protocol (e.g., including ultrasound, electrode placement, movement commands). Intraclass correlation coefficient (ICC), standard error of measurement (SEM) and minimum detectable change (MDC) were calculated.ResultsProne extension task demonstrated excellent test-retest agreement in all timespans (ICC = 0.92-0.96, SEM = 6.08-8.11, MDC = 16.85-22.49). Forward bending reliability ranged from moderate in long-term (ICC = 0.68-0.71, SEM = 1.98-2.52, MDC = 5.48-6.99) to good in intra-day (ICC = 0.76-0.89, SEM = 1.73-2.15, MDC = 4.79-5.95) to excellent in short-term assessment (ICC = 0.97, SEM = 1.07-1.21, MDC = 2.96-3.34). Sitting task showed the lowest test-retest agreement ranging between good to moderate in intra-day (ICC = 0.60-0.77, SEM = 1.22-1.26, MDC = 1.61-3.48)) and short-term reliability (ICC = 0.50-0.75, SEM = 1.24-2.06, MDC = 0.62-4.04) and moderate in long-term reliability (ICC = 0.65-0.71, SEM = 1.43-1.85, MDC = 3.95-5.12).ConclusionUsing standardized procedures, surface electromyography can provide reliable data for practitioners in low back pain rehabilitation. Timespan had a limited influence on reliability compared to the type of task performed.