Date of Award

12-2023

Document Type

Dissertation

Degree Name

Master of Science (MS)

Program

Biomedical Engineering

Track

Biomechanics

Research Advisor

Denis J. DiAngelo, PhD

Committee

Richard J. Kasser, PT, PhD; Douglas W. Powell, PhD

Keywords

backpack;ergonomic;load carriage

Abstract

Backpacks (BP) are one of the most common means for carrying loads but the loading mechanics that result from carrying heavy loads can have implications across the body. It has been suggested that loads in a BP should not excess 10-15% of the user’s body weight (BW) but that is not always feasible. The loads in a BP are transferred to the body via the shoulder strap which induce a shear and compressive force which act externally on the spine and transfer loads through it to the lumbar. Additionally, the weight of the bag induces an external moment that further stresses the spine structures. The ergonomic backpack (EBP) was designed as a possible solution to the problematic loading conditions that are induced by load carriage and therefore improving load carriage efficiency and ergonomic performance. The term ergonomic performance was characterized by an accumulation of variables that could be used to evaluate backpack technology, including decreased shoulder and spine loads, reduction in paraspinal muscle involvement, reduction in oxygen consumption, reduction in lower extremity muscle effort, and improved comfort. The EBP utilizes several design features that alleviates spine and shoulder loading by redirecting and counterbalancing the external load from the backpack.

The objective of study 1 was to validate the design of the EBP. This was done by determining the strap tension-bag load relationship in the EBP compared to a traditional backpack using modified luggage scales which were configured to measure the tension in each strap. Additionally, the shoulder pressure-bag load relationship in the EBP compared to a traditional backpack using pressure sensors. Ten measurements of shoulder load and strap tension were taken in each backpack condition with five weight increments (0 kg to 11 kg). Shoulder loads were significantly reduced with the EBP (50%) at all weight increments (p

The objective of study 2 was to evaluate ergonomic performance while wearing the EBP compared to a traditional backpack during a walking task. The first aim was to measure paraspinal muscle response and the second aim was to measure oxygen consumption and lower limb muscle response. Fifteen healthy participants walked on a split-belt instrumented treadmill at 1.3 m/s in two backpack conditions, the EBP and a traditional backpack, with two loads (7 kg and 11 kg). A 3D motion capture system recorded electromyography and kinematic data, while the force treadmill recorded ground reaction forces. Kinetic and kinematic variable calculations were used to determine trunk angle and muscle powers at each major joint. Electromyography signals were processed and used to determine the muscle activity over the gait cycle. A metabolic cart recorded the volume of oxygen consumed during the walking trial. Results revealed significantly decreased trunk angle (more vertical trunk position), decreased paraspinal muscle activity, and decreased hip muscle power in the EBP compared to the traditional backpack (p

This body of work provides evidence that the EBP could provide the basis for design improvements that should be considered in improving backpacks for safer load carriage.

Declaration of Authorship

Declaration of Authorship is included in the supplemental files.

ORCID

https://orcid.org/0009-0007-8452-3624

DOI

10.21007/etd.cghs.2023.0637

Additional Files
2023-025-Bouve-DOA.pdf (157 kB)
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