How does moderate upper limb activity modify sitting forces for able-bodied persons and wheelchair users?

Area of Science:

• Biomechanics
• Rehabilitation Engineering
• Human Factors Engineering

Background:

• Pressure injuries (PrI) are a significant concern for individuals with spinal cord injuries.
• Understanding sitting forces is crucial due to the high healthcare costs associated with PrIs.
• Dynamic activities may alter force distributions compared to static sitting.

Purpose of the Study:

• To investigate sitting forces (normal, shear, and Peak Pressure Index) in able-bodied individuals and wheelchair users (WCUs).
• To compare these forces under static and dynamic (hand-cycling) conditions.
• To test the hypothesis that sitting forces differ significantly between able-bodied participants and WCUs.

Main Methods:

• Utilized an experimental seat and a pressure mapping system.
• Recruited 102 able-bodied participants and 15 WCUs.
• Analyzed forces during static sitting and synchronized hand-cycling, comparing populations and conditions.

Main Results:

• Significant differences in normal forces and Peak Pressure Index (PPI) were found between able-bodied individuals and WCUs.
• Shear forces showed non-significant differences between the two populations.
• Able-bodied participants exhibited significantly reduced average normal force, PPI, and shear forces during dynamic activity compared to static sitting.
• WCUs showed non-significant reductions in average normal force and PPI, but significant reductions in average shear forces during dynamic activity.

Conclusions:

• Findings suggest that conclusions about normal sitting forces from able-bodied individuals cannot be directly applied to WCUs.
• Dynamic activity generally reduces sitting forces for able-bodied individuals.
• The impact of dynamic activity on reducing sitting forces is less definitive for WCUs, highlighting the need for tailored approaches to pressure injury prevention.