Comparison of two heights for forward-placed trunk support with standing work

Area of Science:

• Ergonomics
• Biomechanics
• Human Motion Analysis

Background:

• Prolonged or repetitive forward trunk flexion can lead to musculoskeletal discomfort and injury.
• Workplace and daily tasks often require individuals to maintain forward-leaning postures.

Purpose of the Study:

• To investigate the biomechanical effects of using forward-placed supports of different heights during trunk flexion.
• To assess the impact of trunk supports on muscle activity and body kinematics.

Main Methods:

• Human motion capture and electromyography (EMG) were used to record data.
• Ten male participants performed trunk flexion (0-40 degrees) under three conditions: no support, leaning on a desk (pelvic height), and leaning on a prototype support (sternum height).

Main Results:

• The prototype support significantly reduced low back and hip extensor muscle activity by an average of 60% compared to no support.
• Leaning on the prototype resulted in a two-fold greater forward trunk displacement, indicating an increased reach distance.
• No adverse kinematic changes were observed, suggesting the supports did not negatively impact spinal or pelvic movement.

Conclusions:

• A higher-placed trunk support (at sternum height) effectively reduces muscle activity in the lower back and hips.
• This type of support facilitates greater forward trunk displacement, enhancing reach capabilities.
• Using higher trunk supports may be beneficial for tasks that necessitate prolonged or frequent forward-flexed postures.