Biomedical Engineering Reference
In-Depth Information
(Coutts et al. 1983; Goosey et al. 2000). Pelvic and trunk strength have also been identified
as relevant determinants of wheelchair sports performance (Vanlandewijck et al. 2010).
Remarkable developments in wheelchair technology have been observed in recent
decades, but the central concept of a hand-propelled mechanism has remained (van Der
Woude et al. 2006). Modifications of the conventional wheelchair design may largely be
a response to requirements of sporting use, and many innovations have been found to
originate from sports practice. For instance, wheelchair basketball and wheelchair tennis
require rapid acceleration and quick changes in direction, which have been addressed by
a fifth wheel at the back of the wheelchair, which prevents the wheelchair from flipping
backward during play (Burkett 2010). On the other hand, fitting front and side bumper
guards that have hooks used to trap opponent players have addressed the high-impact
nature of wheelchair rugby. Modern wheelchairs have evolved toward achieving less
weight, greater stability, and longer usability. In terms of specific technical modifications,
much research attention has focused on modifying the design of tires and wheels and
examining its effects on biomechanical functions and kinematic output.
In particular, the wheel camber is an important parameter in seeking the optimal design
of a wheelchair (Faupin et al. 2004). Defined as the angle of the main wheel to the vertical
(Higgs 1983), the camber directly influences other wheelchair parameters; for example,
increased camber results in a slight reduction of seat height and an increased wheel-base
(Faupin et al. 2004). Increased camber results in the mechanical gain of greater lateral
stability (Trudel et al. 1997) and functional benefits of improved hand protection from
contact/collision injuries (Veeger et al. 1989). Although earlier studies indicate beneficial
effects of increased rear wheel camber, recent studies have reported findings that demon-
strated negative effects on kinetic and kinematic aspects. Increased rolling resistance has
been found proportional to increased rear wheel camber, which translates to decreased
velocity of wheelchair propulsion and a congruent increase in required power output by
the user (Faupin et al. 2004). Consistent with these findings, prolonged hand-wheel contact
and pushing time have also been observed as an effect of greater rolling resistance (Veeger
et al. 1989).
Power wheelchairs continue to evolve as a consequence of changing demands of sports
participation for individuals with disabilities. Although the changes have been dramatic
and studies have examined effects on the wheelchair itself and the users, it appears that
the design of power wheelchairs will continue to change because the optimal standard
remains dynamic.
19.4.2 Prosthetic Technology
Technology as an aid for mobility has also been evident in the form of prostheses, which
have facilitated independent ambulation among individuals with lower limb amputations
(Camporesi 2008). The unique requirements and demands of sports events (e.g., javelin
throw and discus throw) have led to the development of sport-specific prostheses. For
instance, the J-leg technology was the result of the need to support lower limb rotation
in the discus throw, which is distinctly different from the demands associated with the
javelin throw (Burkett et al. 2003). The J-leg prosthesis has a fixed knee unit that provides
stability during rotation and consists of an energy-storing foot, which provides the desired
ground push-off before the discus throw release.
The use of prosthetic technology is equally relevant and perhaps highly controver-
sial among runners. Energy-storing prosthetic feet have been shown to result in signif-
icant increases in running speed among sprinters (Brown et al. 2009). The controversy
