Thomas Braunwarth (Karlsruhe; Basel / CH), David Koch (Basel / CH), Dr. Corina Nüesch (Basel / CH), Prof. Dr. Stefan Schären (Basel / CH), Prof. Annegret Mündermann (Basel / CH), Dr. Dominika Ignasiak (Zürich / CH), Prof. Stephen Ferguson (Zürich / CH), PD Dr. Cordula Netzer (Basel / CH)
Abstract-Text (inkl. Referenzen und Bildunterschriften)
Introduction
Diminished endurance capacity1 and excessive fatigue of paraspinal muscles2 have been reported in patients with low back pain. To date, it is unknown if similar changes occur in patients with symptomatic lumbar spinal stenosis (sLSS).
Aims
The purpose of this study was to determine associations between paraspinal muscle endurance and muscle fatigue and examine differences in muscle fatigue between paraspinal muscles and sides in patients with sLSS.
Methods
We included 37 patients with sLSS (25M/12F; age, 69±9.1 years; body mass index, 25.6±4.4 kg/m2) in this study. Electromyography (EMG) sensors were attached bilaterally to the longissimus, iliocostalis and multifidus muscles. Muscle endurance and fatigue were tested with a modified Biering-Sørensen (BS) test (Fig.1). Paraspinal muscle endurance was assessed as the duration of the BS test. The median frequency (MDF) was calculated from the EMG power spectrum using 1s analysis windows with 50% overlap. Paraspinal muscle fatigue was assessed as the slope of the regression line of the MDF time series during the BS. Spearman correlation was used to investigate correlations between endurance and fatigue parameters, and Wilcoxon signed-rank tests to detect differences in muscle fatigue between paraspinal muscles and sides.
Results
At 4 of 6 muscle sites, endurance time correlated with MDF slope (R=0.340 to 0.520; Fig.2). MDF slopes showed positive correlations between all paraspinal muscles (R=0.330 to 0.710). No differences between left and right side MDF slopes were observed (P>0.130).
Conclusion
The greater paraspinal muscle fatigue in patients with worse endurance performance suggests that muscle fatigue may limit performance. More research is needed to increase our understanding of factors that determine muscle fatigue in patients with sLSS.
Funding: SNF#204461
1Matheve T et al. J Clin Med 2023
2Steele J et al. Cur Med Res Op 2014