Systemically Flawed "Research Studies" on Wheelchair Propulsion - Erik Kondo

When it comes to wheelchair use, the ability to propel it determines much of where you can go, how far, and how fast. In the case of a full power or power-assist wheelchair, the drive-system is a large or the largest component of the of the overall cost. For a manual wheelchair, the user’s ability to effectively self-propel their wheelchair determines their resulting mobility. It is also a primary determining factor of whether or not they will require a power-assist device or a full power wheelchair.

Therefore, for manual wheelchair users, effective self-propelling is an incredibly important (if not the most important) aspect of wheelchair use. Given the DME and medical communities acknowledgement of the importance of wheelchair propulsion, it makes sense that research studies are used as a basis to guide best practices in wheelchair seating.

What doesn’t make sense is that much of the studies that seating professionals and clinicians use to determine optimum wheelchair seating positioning are based on studies that use able-bodied subjects in laboratory settings. And it is highly likely that these subjects will be using hospital style wheelchairs that are not representative of the wheelchairs used by full time wheelchair users.

Mobility performance is the result the interaction of the three elements of the person, their device, and the environment in which it is used. In the case of these research studies, the person is able-bodied, the device is a hospital style wheelchair, and the environment is a laboratory setting. All these of these components do not accurately reflect the real world wheelchair mobility of people with disabilities.

The conclusions of these flawed studies are cited and used as “evidence” that informs how people with disabilities are seated and trained on wheelchair propulsion. The end result is medical professionals who are seating wheelchair users in ways that degrade their propulsion. They “don’t know, what they don’t know”. They think they are using the latest scientific evidence when in fact they are using systemically flawed scientific conclusions.

How prevalent is this problem of using able-bodied subjects for wheelchair based studies? Here is an example. Using the National Library of Medicine, I looked at the following study which I found by Googling “wheelchair propulsion”:

Manual wheelchair propulsion: effects of power output on physiology and technique.

van der Woude LH, Hendrich KM, Veeger HE, van Ingen Schenau GJ, Rozendal RH, de Groot G, Hollander AP.Med Sci Sports Exerc. 1988.

Next, I captured the eleven studies that cited it in order to generate a sample of research studies that are related to wheelchair propulsion. I now looked at each study to determine the demographics of the research subjects. Of these eleven studies:

· Five studies used exclusively able-bodied subjects.

· One study used 50% able-bodied subjects and 50% wheelchair users

· One study used a robot.

· Four studies used wheelchair users.

According to my limited sampling, the much of studies that are used to determine how wheelchair users propel their custom wheelchairs in their community recruit non-wheelchair using participants seated in rented/borrowed hospital style wheelchairs for testing in laboratory settings. This type of situation would be completely unacceptable in any other performance domain involving the able-bodied population.

The study of human performance is not a new discipline. For example, when scientists study optimum bicycling dynamics, they don’t recruit non-bicyclists and put them on old style rental bicycles. They examine world class bicyclists and use appropriately sophisticated testing equipment. Talking about the importance of “evidence based wheelchair seating” means nothing if the method of gathering the evidence is systemically flawed.

In my opinion, there is a lack of deep knowledge on effective wheelchair propulsion among wheelchair professionals and the medical community. This lack of knowledge could be remedied by studying the dynamics of actual wheelchair users who provide real life examples of efficient and high power propulsion.

• What enables this demographic to move so much faster and farther than the average wheelchair user?

• Why can they power up steep hills?

• Why do they not get tired from everyday wheelchair usage?

• Why can they navigate rough terrain in their wheelchairs?

• Why can they go up and downstairs and escalators?

• Why can they push long distances and not get sore or injured?

• Why can they easily jump up and down curbs?

In other words, study wheelchair users using the same standards you would apply to able-bodied human performance domains.

Referenced Studies Subjects = 15 Able-bodied men and women

Learning of Wheelchair Racing Propulsion Skills Over Three Weeks of Wheeling Practice on an Instrumented Ergometer in Able-Bodied Novices.

de Klerk R, van der Jagt G, Veeger D, van der Woude L, Vegter R.Front Rehabil Sci. 2022 Mar 9;3:777085. doi: 10.3389/fresc.2022.777085. eCollection 2022.PMID: 36188930

Subjects = 30 Able-bodied men and women

A novel push-pull central-lever mechanism reduces peak forces and energy-cost compared to hand-rim wheelchair propulsion during a controlled lab-based experiment.

le Rütte TA, Trigo F, Bessems L, van der Woude LHV, Vegter RJK.J Neuroeng Rehabil. 2022 Mar 18;19(1):30. doi: 10.1186/s12984-022-01007-5.PMID: 35300710

Subject = 1 Robot

Effects of wheels and tires on high-strength lightweight wheelchair propulsion cost using a robotic wheelchair tester.

Misch J, Sprigle S.Disabil Rehabil Assist Technol. 2021 Dec 27:1-11. doi: 10.1080/17483107.2021.2012274. Online ahead of print.PMID: 34958616

Subjects = 17 Able-bodied men and women

Physiological and biomechanical comparison of overground, treadmill, and ergometer handrim wheelchair propulsion in able-bodied subjects under standardized conditions.

de Klerk R, Velhorst V, Veeger DHEJ, van der Woude LHV, Vegter RJK.J Neuroeng Rehabil. 2020 Oct 17;17(1):136. doi: 10.1186/s12984-020-00767-2.PMID: 33069257

Subjects = 11 Paraplegic men

Effects of variable practice on the motor learning outcomes in manual wheelchair propulsion.

Leving MT, Vegter RJ, de Groot S, van der Woude LH.J Neuroeng Rehabil. 2016 Nov 23;13(1):100. doi: 10.1186/s12984-016-0209-7.PMID: 27881124

Subjects = 26 Able-bodied men and women

Arm Crank and Wheelchair Ergometry Produce Similar Peak Oxygen Uptake but Different Work Economy Values in Individuals with Spinal Cord Injury.

Tørhaug T, Brurok B, Hoff J, Helgerud J, Leivseth G.Biomed Res Int. 2016;2016:5481843. doi: 10.1155/2016/5481843. Epub 2016 Apr 10.PMID: 27144169

Subjects = 170 manual wheelchair users

The influence of speed and grade on wheelchair propulsion hand pattern.

Slowik JS, Requejo PS, Mulroy SJ, Neptune RR.Clin Biomech (Bristol, Avon). 2015 Nov;30(9):927-32. doi: 10.1016/j.clinbiomech.2015.07.007. Epub 2015 Jul 21.PMID: 26228706

Subjects = 39 Able-bodied men and women

Inter-individual differences in the initial 80 minutes of motor learning of handrim wheelchair propulsion.

Vegter RJ, Lamoth CJ, de Groot S, Veeger DH, van der Woude LH.PLoS One. 2014 Feb 21;9(2):e89729. doi: 10.1371/journal.pone.0089729. eCollection 2014.PMID: 24586992 Free

Subjects = Unknown number of wheelchair users

Hand rim wheelchair propulsion training using biomechanical real-time visual feedback based on motor learning theory principles.

Rice I, Gagnon D, Gallagher J, Boninger M.J Spinal Cord Med. 2010;33(1):33-42. doi: 10.1080/10790268.2010.11689672.PMID: 20397442

Subjects = 7 Paraplegic men

Comparison of treadmill exercise testing protocols for wheelchair users.

Hartung GH, Lally DA, Blancq RJ.Eur J Appl Physiol Occup Physiol. 1993;66(4):362-5. doi: 10.1007/BF00237783.PMID: 8495700

Subjects = 6 Wheelchair users and 6 Non-wheelchair users

Optimum cycle frequencies in hand-rim wheelchair propulsion. Wheelchair propulsion technique.

van der Woude LH, Veeger HE, Rozendal RH, Sargeant AJ.Eur J Appl Physiol Occup Physiol. 1989;58(6):625-32. doi: 10.1007/BF00418509.PMID: 2731532