Lumbar muscles biomechanical characteristics in young people with chronic spinal pain

Abstract Background The prevalence of low back pain is rising among the young adult population. Altered lumbar muscle tone was suggested to be associated with underlying pathologies and symptoms. To date, there is minimum information available on the repeatability of lumbar spine muscle mechanical properties in the young adults who experienced low back pain. This study aimed to assess the reproducibility of mechanical properties of lumbar spinal muscle in young adults with spinal pain by myotonometer and explored the difference in reproducibility when different number of indentations was used. Methods Participants who aged between 18 to 25 and reported chronic LBP were recruited. Lumbar muscle tone (Hz) and stiffness (N/m) were assessed by myotonometer on one occasion by two assessors. Parameters were recorded by triple scans and 5-scans mode. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), smallest real difference (SRD), Bland and Altman analysis were used to assess agreement between two measurements. The relationship between muscle mechanical properties and pain score and disability level were assessed by Spearman’s rank correlation coefficient. Results The results of ICCs indicated excellent repeatability in triple scans and 5-scans mode for each lumbar level bilaterally (ICC > 0.75). SEM and SRD were smaller in triple scans than 5-scans mode for most levels. Bland and Altman analysis revealed no systematic bias. Spearman’s rank correlation analysis indicated significant high correlations between muscle tone and disability level (r = 0.80, p