Transient pain developers show increased abdominal muscle activity during prolonged sitting.

Area of Science:

• Ergonomics
• Biomechanics
• Occupational Health

Background:

• Prolonged sitting is prevalent in work environments and may lead to adverse health effects.
• Limited research exists on thoracic spine motion and multi-axial movements during extended sitting.
• This study investigated 3D trunk motion and muscle activity during a 2-hour sitting period.

Purpose of the Study:

• To examine three-dimensional trunk kinematics and muscle activity during prolonged, uninterrupted sitting.
• To identify differences in motion and muscle activation between individuals who develop pain and those who do not.
• To explore correlations between pain perception and trunk muscle activation patterns.

Main Methods:

• Ten healthy males participated in a simulated office task for two hours.
• Six spinal segments (Neck, Upper-, Mid-, Lower-thoracic, Lumbar, Pelvis) were analyzed for 3D kinematics.
• Electromyography (EMG) was recorded from eight bilateral trunk muscles.

Main Results:

• Four participants reported transient pain, exhibiting higher abdominal muscle activation.
• The pain-free group demonstrated less lateral bending in the mid-thoracic region compared to upper and lower regions.
• Positive correlations were observed between pain ratings and low back muscle activation.

Conclusions:

• Reduced thoracic spine movement and altered muscle activation patterns are associated with pain development during prolonged sitting.
• Sustained low-level static muscle contractions may increase injury risk.
• Elevated abdominal muscle activity in pain developers might predispose or contribute to transient pain.