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The primary purpose of a manual wheelchair is to provide mobility for replacing walking in the environment. The more active a wheelchair user is, the more variety of environments they will encounter. The more their wheelchair system is able to effectively function in “walking” environments, the more they will be able to participate in the activities of life. A wheelchair also serves the important function of providing comfortable seating for the wheelchair user. When an able-bodied person is not walking/standing during the day, they typically like to sit down. A wheelchair needs to perform a dual purpose of providing replacement walking mobility and comfortable seating which are two inherently differing needs.
We know these needs diverge because there are no purposely designed seats for able-bodied people that resemble manual wheelchairs. Comfortable seating requires static seating stability, while mobility requires dynamic movement. Generally speaking, the more comfortable a seat is, the less mobile it is. Think of a Lazy Boy recliner. On the other hand, the more mobile a seating system is, the less comfortable it is. Put another way, walking is highly mobile, but uncomfortable as compared to sitting. Sitting is immobile, but comfortable. A wheelchair system needs to provide the functions of both substitute walking and comfortable sitting.
Due to this inverse relationship, knowledgeable wheelchair users are faced with a difficult choice. Should they prioritize dynamic mobility over static comfort or vice versa? As a practical matter, most wheelchair users are unaware of this tradeoff. They don’t realize that their natural desire to seek comfort will result in them having less mobility. Not only that, but I am specifically using the term “dynamic mobility”. Much of the increase in the mobility of a wheelchair comes from the forces created by its motion. A bicycle is more mobile in dynamic motion, so are skateboards, skis, and ice skates. A wheelchair is no different. It is governed by the same laws of physics.
What do bicycles, skateboards, skis, and ice-skates all have in common? They are inherently uncomfortable in the beginning. These mobility devices start out uncomfortable and become more comfortable through increasing performance output and ingraining mobility skills. We all recognize this to be true. But when it comes to wheelchairs, we forget this fundamental fact of “acquired comfort” and focus on creating immediate static comfort. The result is a generation of new wheelchair users who have unknowingly settled for reduced mobility and have little hope of achieving “dynamic comfort” for the sake of increasing their immediate level of static comfort.
For example, how are new wheelchair users to know:
1. That their anti-tippers will stop them from wheelieing down steep hills, curb jumping, using escalators, climbing/descending stairs and steps, and wheelieing over rough terrain?
2. That their armrests will interfere with access to the rear wheel for propelling, and make it difficult to pick up objects on the floor?
3. That their rearward positioned rear axle will reduce their ability to propel their wheelchair and execute wheelie maneuvers, require more effort to turn their wheelchair, as well as increasing their wheelchair length making it harder to deal with small spaces?
4. That their high backrest will prevent them from getting their shoulders back and engage their back muscles for propulsion? That it will make it difficult to unweight their front casters with their body position? That it will make the wheelchair much heavier and more awkward to lift and transport in a vehicle?
5. That the hardware to secure their orthopedic backrest will interfere with their elbow movement and add weight to the wheelchair system?
6. That their reclined backrest will decrease their ability to propel their wheelchair? That its folding mechanism is likely to break at some point?
7. That the sideguard fenders that cover their rear tires also prevents their hand access to gripping the tire for propulsion on difficult terrain?
8. That suspension systems or wheels add considerable weight to their wheelchair system?
9. That suspension front casters will depress and tip their seat forward when they rest their chest on their knees or otherwise put weight on them?
10. That their high mount wheel-locks will interfere with their ability to propel their wheelchair on difficult terrain due to the risk of jamming their thumb into the wheel-lock?
11. That having a high seating position will reduce their power generation for propelling their wheelchair on difficult terrain?
12. That their thick seat cushion will increase their sitting height relative to their wheels, and add weight to the wheelchair system?
13. That their lack of seat dump will reduce their propulsion stability if they have reduced trunk control?
14. That using 24” wheels will reduce their overall propulsion speed, and reduce their sitting height for high transfers?
15. That using “no flat” solid rubber tires will require more effort for propulsion?
16. That their Smartdrive power assist mount and control accessories add weight and interfere with them using the wheelchair frame for grabbing during transfers and loss of upper body balance?
17. That wide tires are more effective for soft terrain and that narrow tires are more effective for hard surfaces?
18. That their large front casters are more likely to flutter when traveling fast? That their small narrow front casters are likely to be stopped by sidewalk cracks and minor obstructions?
19. That on a steep incline, "hill holders" increase the likelihood that they will flip over backwards?
20. That on steep decline, having a far forward center of mass and no ability to wheelie may cause their rear wheels to slide uncontrollably due to lack of friction?
The list goes on.
As a practical matter, there is no way for a new wheelchair user to know these things and more. Why would they know? How would they know that a highly optimized wheelchair used by a skilled and conditioned user provides a high degree of dynamic mobility? That the key to this mobility combines having robust wheelie balancing skills and ample propulsion power? New wheelchair users have neither wheelie balance nor powerful propulsion. Therefore, it is natural for them to seek statically comfortable wheelchair systems with limited optimization for future dynamic mobility.
It is my desire to increase awareness about the tradeoff between comfort and mobility, so wheelchair users are able to make more informed decisions regarding the setup and optimization of their wheelchairs.