Electromyographical study on muscle fatigue in repetitive forearm tasks

Area of Science:

• Occupational health
• Biomechanics
• Exercise physiology

Background:

• Repetitive muscle tasks are common in various occupations.
• Understanding forearm muscle fatigue is crucial for preventing work-related musculoskeletal disorders.
• Ergonomic factors influencing muscle fatigue require detailed investigation.

Purpose of the Study:

• To investigate the impact of repetitive low weight load tasks on forearm muscle fatigue.
• To identify specific ergonomic risk factors contributing to forearm muscle fatigue.

Main Methods:

• Sixteen healthy males performed repetitive wrist extension tasks under varying frequency, weight, and angle loads.
• Surface electromyography (sEMG) recorded muscle activity from forearm extensors and flexors.
• Analysis focused on changes in mean power frequency (MPF) and median frequency (MF) to assess muscle fatigue.

Main Results:

• Higher frequency loads significantly reduced MPF and MF in extensors digitorium (ED), flexor carpi radialis (FCR), and flexor carpi ulnaris (FCU).
• Increased frequency, angle, and weight loads collectively led to significantly lower MPF and MF in ED.
• Angle load was identified as the most significant risk factor for fatigue in extensor carpi ulnaris (ECU), ED, and FCR.

Conclusions:

• Muscle fatigue levels vary even within the same repetitive task.
• Ergonomic factors, particularly angle load, play a critical role in forearm muscle fatigue.
• Findings provide insights for designing safer work practices and reducing the risk of musculoskeletal injuries.