Back muscle activation patterns in chronic low back pain during walking: a "guarding" hypothesis

Area of Science:

• Biomedical Engineering
• Rehabilitation Science
• Clinical Biomechanics

Background:

• Chronic low back pain (CLBP) affects a significant portion of the population.
• Understanding movement patterns in CLBP is crucial for developing effective interventions.
• Guarded movement strategies may contribute to persistent pain and disability.

Purpose of the Study:

• To determine if patients with CLBP display "guarded" movements during walking.
• To investigate the relationship between lumbar muscle activity, fear of movement, and disability in CLBP.
• To test the hypothesis of increased muscle activity and reduced relaxation during specific gait phases.

Main Methods:

• A cross-sectional study involving 63 CLBP patients and 33 healthy controls.
• Surface electromyography (sEMG) measured erector spinae muscle activity during treadmill walking.
• Calculated smoothed rectified sEMG (SRE) values and SRE ratios to quantify muscle activity and relative relaxation.

Main Results:

• CLBP patients demonstrated significantly higher mean SRE values compared to controls during both double support and swing phases.
• No significant difference in SRE ratios was observed between CLBP patients and controls.
• Disability and fear of movement did not correlate with SRE values or ratios in CLBP patients.

Conclusions:

• Patients with CLBP exhibit increased lumbar muscle activity throughout the stride cycle, suggesting impaired muscle relaxation.
• The findings support the conclusion that CLBP patients employ a guarding mechanism during walking.
• Perceived fear and disability were not found to be associated with the observed muscle activity patterns.