March 2001

The Yin and Yang of Wheelchair Use

By Brian T. Fay, MS; Tricia A. Thorman, MOT; and Rosemarie Cooper, MPT

The Yin and Yang of Wheelchair Use
Addressing gender-based differences in manual wheelchair users.

Agencies supported by the government currently mandate that all federally funded clinical research must include both men and women in the investigation. Ironically, the efforts toward equity have fostered a greater appreciation of the differences between genders.

Compared to females, males have longer linear measurements such as height and limb length as well as larger girth measurements like circumferences of the upper arm, wrist, fist, and stomach.¹ It was found that men have significantly larger body dimensions, but more than this, the ratio of upper arm length to circumference is significantly higher in men. This suggests that men have more muscle mass in the upper arm, which can produce more force.

Wheelchair Configuration

In the present day, the failure of a health care provider to customize the dimensions of a manual wheelchair to the user is bordering on malpractice. But given the explosion of adjustability in the manual wheelchair, what measures are essential?

Rear wheel axle position is probably the most powerful tool. Moving the axle forward places more of the user’s weight over the rear axle. This in turn reduces the amount of force required to push the wheelchair. Rear wheel axle position also affects stability and the tendency for the wheelchair to tip over backwards. A compromise axle position should be found that allows for stability, but does not unduly increase the force required to push the wheelchair.² Using antitip bars can also prevent rearward tipping.

Seat height and width determine how easily the pushrim can be reached. Moving the seat up too much forces the user to bend the trunk to reach the pushrim. Moving the seat too low causes the user to move their arms outward (abduct), causing the shoulder muscles to tire. A general rule is to have an elbow angle of 120 degrees when the hand is at the top of the pushrim and the user is sitting upright.³ Too wide a seat causes the arms to be moved outward and the hands bent in an uncomfortable posture in order to reach the pushrim. The width of a wheelchair is more comfortable when the arms are moved outward (abducted) about 15 degrees.⁴

Camber, or the angling of the rear wheel, improves side-to-side stability. It also allows easier access to the pushrim when pushing by hand and reduces the effort required to turn the wheelchair. The cost of camber is that it increases the overall width of the wheelchair.⁵ This may be a consideration for individuals living in older housing or pseudo-accessible environments in which ease of maneuvering the wheelchair is compromised by architectural barriers such as bathroom doorways or tight turning radiuses.

Considering these basic wheelchair characteristics, the stereotypical hospital wheelchair with no adjustability is inappropriate for daily use. This is true for women with smaller body dimensions since they will need to reach out and around the armrests to access the pushrim. Such a wheelchair can also affect the ability of men with larger body dimensions to effectively push the wheelchair since their weight may be disproportionately positioned over the front casters, making the wheelchair more difficult to push.

Pushing Technique and Force Production Wheelchair users typically use one of three propulsion patterns: an arc (following the pushrim), a figure 8 (looping during recovery), and circular (the hand drops down and swings back during recovery).⁶ Wheelchair research has not found that men or women use any particular propulsion technique.⁷

However, men produce more force at the pushrim than do women. This causes women to require more propulsion cycles than men to maintain the same speed.⁸ Another important observation is that women need a higher percentage of their maximum effort to maintain typical propulsion speeds. This can cause women to fatigue more quickly.⁹

Seating Considerations The seat is the foundation of the manual wheelchair because it controls the relative dimensions of the person-machine system and provides the base upon which the trunk is positioned and moves. When considering gender differences, seating takes on important significance. The importance of pressure relief between the buttocks and seating surface has rightfully been recognized, but another major concern for any wheelchair user is genitourinary and bowel hygiene.

Men have some obvious structural advantages here. For the most part, a stable base allowing for ease of transfer or catheter use from the wheelchair addresses the needs of men. Options for men without incontinence include contoured foam, gel-based, layered honeycomb, and air-bellows designs.

When considering a seating system for females, the clinician needs to consider the age, frequency of menstrual cycle, type of catheterization/bathroom use, ability to transfer to/from toilet, history of skin breakdown/infections, and reproductive plans. While these items are highly personal, the health care professional must not shy away from addressing them because effective communication between wheelchair user and health care provider can prevent illness and improve quality of life on a daily basis. Seating systems that breathe, such as air-bellows or layered honeycomb, may be preferable since they let moisture out. Combining these seating systems with a regimen of pressure relief is often sufficient to control the moisture level. Ease of cleaning is also an important consideration.

When considering manual wheelchair prescription, gender is an important factor because of the documented differences in body dimensions, force production, percent maximum force required, and cumulative trauma disorders between men and women. N Brian T. Fay, MS, is a research associate and a doctoral candidate with the Department of Rehabilitation Science and Technology, Human Engineering Research Laboratories, University of Pittsburgh. He can be reached at (412) 365-4850 or via email: bfay@pitt.edu. Tricia A. Thorman, MOT, is clinical coordinator, Center for Excellence in Wheelchairs and Related Technologies, Veterans Affairs Pittsburgh Healthcare System. Rosemarie Cooper, MPT, is clinical coordinator, Department of Rehabilitation Science and Technology, Human Engineering Research Laboratories, University of Pittsburgh. References

1. Fay BT, Boninger ML, Cooper RA, Koontz AM. Gender-based anthropometric differences of manual wheelchair users. Proceedings of the 2000 RESNA Annual Conference. Arlington, Va;2000:144-146.

2. Kirby RL, Ackroyd-Stolarz SA, Brown MG, Kirkland SA, MacLeod DA. Wheelchair-related accidents caused by tips and falls among noninstitutionalized users Scotia. American Journal of Physical Medicine and Rehabilitation. 1994;73:319-330.

3. van der Woude LHV, Veeger DJ, Rozendal RH, Sargeant TJ. Seat height in handrim wheelchair propulsion. Journal of Rehabilitation Research and Development. 1989;26:31-50.

4. Phillips L, Nicosia A. An overview…with reflections past and present of a consumer. In: Todd S, ed. Journal of Rehabilitation Research and Development Clinical Supplement No. 2: Choosing a Wheelchair System. Baltimore, MD: Department of Veterans Affairs; May 1992.

5. Cooper RA. Wheelchair Selection and Configuration. New York: Demos. 1998.

6. Shimada S, Robertson R, Boninger ML, Cooper RA. Kinematic Characterization of Wheelchair Propulsion. Journal of Rehabilitation Research and Development. 1998;35:210-218.

7. Fay BT, Boninger ML, Cooper RA, Koontz AM, Baldwin MA. Gender differences in the kinematics features of manual wheelchair propulsion. Proceedings of the 1999 RESNA Annual Conference. Arlington, Va:1999:376-378.

8. Fay BT, Boninger ML, Cooper RA, Koontz AM. Gender-based differences in pushrim kinetics during manual wheelchair propulsion. Proceedings of the 24th Annual Conference of the American Society of Biomechanics. Arlington, Va:2000;207-208.

9. Fay BT, Boninger ML, Cooper RA, Koontz AM. Considering gender differences in manual wheelchair propulsion kinetics: use of a pushrim force ratio. Proceedings of the 2001 Annual Conference of RESNA. Arlington, Va:2001. In review.

LOOKING FOR EXPERT ADVICE? Experts here are available to answer all your questions! Please contact us for more information about this feature, or to become an expert.

MEDIA CENTER Interactive Media  Archives  · November 2008  · October 2008  · August/September 2008  · Fall 2008 Product Directory  · July 2008  · June 2008  · May 2008  · April 2008  · March 2008  · January/February 2008  · All Archives  Newsletter  · Rehab Today Resources Classifieds Calendar Consumer Resources Media Kit Advertiser Index EAB Reprints Submit an Article