Biomechanical differences in lower limb movements during lifting tasks before and after fatigue

Area of Science:

• Biomechanics
• Occupational Health
• Ergonomics

Background:

• Manual lifting is a common occupational activity.
• Fatigue can impair motor control and increase injury risk.
• Understanding fatigue effects on lower limb biomechanics is crucial for workplace safety.

Purpose of the Study:

• To investigate the effects of fatigue on lower limb kinematics and kinetics during manual lifting.
• To quantitatively analyze these effects for safe work practice guidance.

Main Methods:

• Twenty healthy males performed 15kg (low) and 25kg (high) load lifts before and after fatigue.
• 3D motion capture and force plates collected kinematic and kinetic data.
• Inverse dynamics analysis quantified joint parameters.

Main Results:

• Low-load lifts showed no significant changes post-fatigue.
• High-load lifts exhibited decreased movement duration and increased joint range of motion, angular velocities, power, and energy expenditure post-fatigue.

Conclusions:

• Lower limb joints are fatigue-resistant under low loads.
• High loads combined with fatigue alter movement patterns, increasing musculoskeletal burden and potential injury risk.