Evidence to inform seat height and seat angle configuration for bilateral foot propulsion

For individuals who propel their manual wheelchair (MWC) with their feet, appropriate assessment and configuration of their mobility device is critical to optimising use. Standard MWC designs favour upper extremity propulsion and pose a risk for functional positioning and injury risk for foot propellers. Limited existing evidence suggests lowering seat height or forward seat inclination can potentially improve propulsion biomechanics but lacks specificity. Obtaining more precise outcomes from varying MWC seat configurations would provide additional evidence to inform clinical decision-making.

This study investigates the impact of modifying seat height and seat angle on propulsion efficiency and comfort with bilateral foot propulsion in a MWC.

Able-bodied graduate students (n = 30) completed trials of five seat heights and four seat angles in random order on a standardised course; outcomes included completion time, push frequency, push effectiveness, perceived difficulty, and lower extremity range of motion.

Overall results demonstrated seat heights 1-2" (2.5-5.1 cm) below lower leg length provided significant improvement, but limited gains beyond this point. Similarly, small seat inclinations of 3-6° produced significant benefits but diminishing benefits at 9°. Sensitivity analysis using lower leg length revealed benefits of seat inclination and height reduction of 1-2" (2.5-5.1 cm) among participants with shorter legs, while those with longer legs benefited from height reduction of 2-3" (5.1-7.6 cm).

These results underscore the importance of individualised tailoring of MWC configuration for foot propulsion to enhance ease and efficiency of mobility. The findings provide additional evidence to guide rehabilitation therapists in clinical practice.