Biomechanical analysis of different lifting speeds when using an active exoskeleton

Area of Science:

• Biomechanics
• Ergonomics
• Human-Computer Interaction

Background:

• Musculoskeletal disorders (MSDs), particularly lower back pain, are prevalent issues linked to repetitive mechanical stress in occupational settings.
• Exoskeletons are emerging technologies designed to mitigate physical strain during labor by providing wearer support.

Purpose of the Study:

• To evaluate the impact of an active exoskeleton (Apogee) on muscle activation and joint kinematics during load lifting.
• To analyze the effects of varying lifting speeds and exoskeleton support levels on biomechanical responses.

Main Methods:

• Sixteen healthy adults performed 15 kg box lifts at two speeds (9 and 12 cycles/min) under four conditions: no exoskeleton, passive mode, 50% support, and 100% support.
• Muscle activity of M. erector spinae (MES), M. biceps femoris (MBF), and M. vastus medialis (MVM) was measured via EMG.
• 3D motion capture analyzed joint range of motion (ROM) at the ankle, knee, and hip.

Main Results:

• Faster lifting increased MBF and MVM activity, while MES remained unaffected.
• The highest exoskeleton support level significantly reduced MES (22.3% MVC) and MBF (10.6% MVC) activity.
• A slight increase in hip ROM (6°) was observed with maximal support; no interaction between support level and lifting speed was found.

Conclusions:

• The active exoskeleton Apogee effectively reduces spinal load and muscle strain during lifting, with full support yielding the most significant benefits.
• Exoskeleton support mitigates the increase in leg muscle activity at higher lifting speeds.
• Findings suggest exoskeletons can help prevent MSDs in occupational environments, with adjustable support levels for user-specific needs.