Adaptations to fatigue during a repetitive multiplanar lifting task

Area of Science:

• Occupational Health
• Biomechanics
• Ergonomics

Background:

• Repetitive lifting tasks in warehouses cause fatigue.
• Existing research often overlooks ecologically relevant, multiplanar lifting tasks.
• Understanding fatigue adaptations is crucial for preventing injuries.

Purpose of the Study:

• To investigate movement adaptations due to fatigue during a 60-minute multiplanar lifting task.
• To analyze changes in kinematics and muscle activity under sustained occupational load.
• To assess the implications of these adaptations on injury risk.

Main Methods:

• 28 participants performed continuous lifting, transferring, and lowering tasks for 60 minutes.
• Full body kinematics and muscle activity (lumbar erector spinae, rectus abdominis, external oblique, anterior deltoids) were continuously recorded.
• Analysis focused on changes in movement patterns and muscle activation over time.

Main Results:

• A 4% decrease in load moment arm and a 4% increase in movement speed were observed.
• Reduced variability (9%) in thorax-pelvis flexion deviation phase indicated altered coordination.
• Increased rectus abdominis activity (4% MVIC) and decreased anterior deltoid activity (2%) were noted.

Conclusions:

• Fatigue induces significant behavioral, coordination, and muscular adaptations during repetitive lifting.
• These adaptations, including altered movement speed and muscle recruitment, may increase the risk of musculoskeletal injuries.
• Further research into mitigating these fatigue-related risks is warranted.