Evaluation of the Load Reduction Performance Via a Suspended Backpack With Adjustable Stiffness

Area of Science:

• Biomechanics
• Ergonomics
• Sports Science

Background:

• Carrying loads in backpacks can lead to muscle fatigue and joint injuries.
• Suspended backpacks can reduce energy expenditure during load carriage.
• Optimizing suspended backpack performance may involve adjusting system stiffness.

Purpose of the Study:

• To investigate the effects of a stiffness-adjustable suspended backpack on carrying performance.
• To evaluate the impact of adaptive stiffness on metabolic cost and biomechanical responses.
• To compare the adjustable-stiffness suspended backpack with unadjustable and ordinary backpack conditions.

Main Methods:

• Developed a stiffness-adjustable suspended backpack with variable stiffness settings (690-1050 N/m) for different walking speeds (4.5-6.5 km/h).
• Six healthy participants carried a 5-kg load using three backpack conditions: adjustable-stiffness suspended (S_A), unadjustable-stiffness suspended (S_UA), and ordinary backpack (ORB).
• Measured peak accelerations, muscle activities, peak ground reaction forces, and metabolic cost.

Main Results:

• The adjustable-stiffness suspended backpack (S_A) effectively reduced peak accelerations, muscle activities, and peak ground reaction forces compared to ORB and S_UA.
• Metabolic cost was reduced by 4.21% (vs. ORB) and 2.68% (vs. S_UA) at 5.5 km/h.
• Metabolic cost was reduced by 4.27% (vs. ORB) and 3.38% (vs. S_UA) at 6.5 km/h.

Conclusions:

• Adjusting suspended backpack stiffness to match walking speed significantly enhances carrying efficiency.
• The stiffness-adjustable suspended backpack offers a promising solution for reducing physical strain and metabolic cost during load carriage.
• This technology has implications for improving comfort and performance in various load-carrying activities.