Validation of Endurance Model for Manual Tasks

Area of Science:

• Occupational Health and Safety
• Biomechanics
• Ergonomics

Background:

• Physical fatigue in industrial settings can cause work-related musculoskeletal disorders (WMSDs).
• Repetitive tasks, especially in manufacturing, increase WMSD risk.
• Existing fatigue models require validation for specific occupational tasks.

Purpose of the Study:

• To validate an existing torque-based fatigue prediction model for shoulder flexion lifting tasks.
• To assess the model's accuracy considering anthropometrics and individual maximum torque.
• To evaluate the model's effectiveness for different lifting conditions (static, dynamic, one-handed, two-handed).

Main Methods:

• Twelve participants performed isometric and dynamic shoulder flexion lifting tasks.
• Inertial Measurement Units (IMUs) measured instantaneous torque and calculated endurance time.
• The Borg Rate of Perceived Exertion (RPE) scale assessed subjective physical exertion.

Main Results:

• The torque-based model demonstrated effectiveness for static and two-handed lifting tasks.
• Model errors ranged from 28.62% to 49.21% for the final task, indicating prior workload impacts perceived rest.
• The model was less effective for one-handed dynamic tasks, with observed gender differences.

Conclusions:

• An individualized, torque-based fatigue model can inform workload design and interventions to prevent WMSDs.
• This approach accounts for individual differences, promoting worker well-being and productivity.
• Further research is needed to refine the model for dynamic, one-handed tasks and address gender-specific responses.