Back and hip extensor fatigability in chronic low back pain patients and controls

Area of Science:

• Biomechanics
• Neuromuscular Physiology
• Rehabilitation Science

Background:

• Chronic low back pain (CLBP) is a prevalent condition associated with muscle dysfunction.
• Understanding muscle fatigability is crucial for developing effective rehabilitation strategies for CLBP.

Purpose of the Study:

• To compare the fatigability of lumbar paraspinal and gluteus maximus muscles between individuals with CLBP and healthy controls.
• To investigate the role of electromyography (EMG) spectral analysis in assessing muscle fatigue during isometric endurance tasks.

Main Methods:

• A cross-sectional study involving 20 women with CLBP and 15 healthy controls.
• Subjects performed a maximal voluntary isometric back extension task at 50% of their maximal voluntary contraction (MVC).
• Electromyography (EMG) was used to record muscle activity from lumbar paraspinal and gluteus maximus muscles, analyzing median frequency (MF) changes over time.

Main Results:

• CLBP patients reported higher pain intensity and functional disability, with lower MVC and endurance times.
• Lumbar paraspinal muscle fatigability was similar between groups.
• Gluteus maximus muscles showed significantly faster fatigue (greater MFslope) in the CLBP group compared to controls.

Conclusions:

• Individuals with CLBP demonstrate reduced muscle endurance and increased fatigability, particularly in the gluteus maximus.
• EMG spectral analysis reveals differential fatigability patterns in CLBP, highlighting the gluteus maximus as a key muscle group affected.