The biomechanics of wheelchair propulsion in individuals with and without upper-limb impairment.
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We used an instrumented wheelchair ergometer and 3D motion analysis system to collect joint kinematic and temporal data, as well as hand rim and joint kinetics, in 47 manual wheelchair users (MWCUs) (15 with upper-limb impairment and 32 without upper-limb impairment). The group with upper-limb impairment propelled with a higher stroke frequency and reduced hand-rim contact time, and smaller peak joint angles and joint excursion of the wrist, elbow, and shoulder during the contact phase. They also propelled with a reduced power output and reduced hand-rim propulsive and resultant forces, moments, and joint compressive forces. We concluded that these kinematic and kinetic strategies might be a mechanism for allowing MWCUs with upper-limb impairment to remain independent. Additionally, the reduced joint excursion and reduced magnitude of forces may protect them from the development of secondary upper-limb pathologies. (+info)
The effect of seat position on wheelchair propulsion biomechanics.
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This study examined the effect of seat position on handrim biomechanics. Thirteen experienced users propelled a wheelchair over a smooth level floor at a self-selected speed. Kinetic and temporal-distance data were collected with the use of an instrumented rim and a motion analysis system. A custom-designed axle was used to change the seat position. We used repeated measures analysis of variance to evaluate if differences existed in the temporal-distance and kinetic data with change in seat position. Results showed that a shorter distance between the axle and shoulder (low seat height) improved the push time and push angle temporal variables (p < 0.0001). Tangential force output did not change with seat position. Axial and radial forces were highest in the lowest seat position (p < 0.001). Propulsion efficiency as measured by the fraction of effective force did not significantly change with seat position. (+info)
The oxygen uptake-heart rate relationship in trained female wheelchair athletes.
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We examined the relationship between the percentage of peak heart rate (HR) and the percentage of peak oxygen uptake VO2 during steady-rate incremental wheelchair propulsion in 10 trained female wheelchair athletes (WAs) to determine the appropriateness of using American College of Sports Medicine (ACSM) target HRs for training prescription. Oxygen uptake was calculated during each submaximal exercise stage, and HR was monitored continuously. Peak VO2 was determined with the use of a separate protocol. Linear regression equations of percentage of peak HR versus percentage of peak VO2 were measured for each participant. Subsequently, we calculated the percentage of peak HR values corresponding with 40%, 60%, 80%, and 85% peak VO2. The linear regression formula (derived as the group mean of the slope and intercept terms determined from each individual participant) was % peak HR = 0.652 x % peak VO2 + 35.2 (standard error of the estimate [SEE] 3.41). The group mean of the individual correlation coefficients for the VO2-HR relationship was r = 0.973. The percentage peaks of HRs for the WAs were slightly, though not significantly, greater than those suggested by the ACSM across the exercise intensity continuum. These findings suggest that training programs prescribed on the basis of ACSM target HR guidelines need not be altered for trained female WAs with lesions of T6 and below. Notably, the discrepancy between the WA values and the population norm (ACSM) decreased from 6% at 40% peak VO2 (i.e., 61% vs. 55%) to <1% at 85% peak VO2 (i.e., 90.6% vs. 90.0%). This discrepancy indicates a tendency for the use of percentage of HR peak at the lower exercise intensities to slightly underestimate the relative exercise intensity (i.e., percentage of peak VO2) in the WA population. (+info)
The effects of rear-wheel camber on the mechanical parameters produced during the wheelchair sprinting of handibasketball athletes.
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The wheel camber of a wheelchair is a significant parameter that must be taken into account in the search for optimal regulation of a wheelchair. This study examined the effects of different rear-wheel camber (9 degrees , 12 degrees and 15 degrees )-today used mainly in the handibasket championship-on the various kinetic and kinematic parameters of the propulsion cycle. Eight males, all players in the French handibasket championship, were asked to participate in this study. They performed three 8 s maximal sprints as measured by a wheelchair ergometer, 9 degrees , 12 degrees , and 15 degrees of rear-wheel camber. The results of our study show that residual torque increases in proportion to the increase in wheel camber. This could explain other study results, which show a decrease in mean velocity and an increase in both power output and time of the propelling phase, in relation to the wheel camber. These results should provide the information necessary for optimal wheelchair regulation. (+info)
The smart wheelchair component system.
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While the needs of many individuals with disabilities can be satisfied with power wheelchairs, some members of the disabled community find it difficult or impossible to operate a standard power wheelchair. To accommodate this population, several researchers have used technologies originally developed for mobile robots to create "smart wheelchairs" that reduce the physical, perceptual, and cognitive skills necessary to operate a power wheelchair. We are developing a Smart Wheelchair Component System (SWCS) that can be added to a variety of commercial power wheelchairs with minimal modification. This paper describes the design of a prototype of the SWCS, which has been evaluated on wheelchairs from four different manufacturers. (+info)
Design features of portable wheelchair ramps and their implications for curb and vehicle access.
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This study evaluated a range of portable wheelchair ramps to highlight the effect of different product features on ease of use when wheelchair users climb curbs or access vehicles. Twelve portable ramps were evaluated. Although all the ramps were designed to load powered wheelchairs into motor vehicles, they were manufactured in different designs. The ramps were based on a "singlewide" platform or "channel" design. Some ramps had fixed dimensions, whereas others could be reduced in size because they were telescopic or designed to allow folding. Overall, the ramps could be divided into four subgroups on the basis of their key features. These were horizontally and longitudinally folding ramps, telescopic ramps, and ramps with fixed dimensions. The telescopic ramps could be subdivided into "U"-shaped gutter ramps and reverse profile ramps. Product appraisals and trials involving wheelchair users and caregivers of wheelchair users were done to evaluate each of these ramp designs. Although wheelchair ramps are available in a wide range of designs and configurations, we found that no single ramp design successfully met the needs of all wheelchair users or their caregivers. The evaluation highlighted a number of specific problems and potential hazards. Some ramps were found to move during a maneuver, showed poor stability when used with some vehicles, or were too narrow to allow wheelchair castors to pass through the channel without jamming. Some features, such as handles and locking mechanisms, influenced the ease with which the caregivers could use the ramps. Wheelchair users preferred the wide platform ramps because they were able to drive up these with ease and little preparation. The caregivers preferred folding or telescopic channel ramps because these were easier to handle and store. (+info)
Management of hip posture in cerebral palsy.
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Seating arrangements for cerebral palsy children with total body involvement are often unsatisfactory and can pose considerable problems for the multi-disciplinary team. Hip joints at risk of dislocation must be kept in an abducted position in order to minimize pain. A new wheelchair with a barrel-shaped cylindrical seat has been developed which improves the femoral head location and alleviates pain. (+info)
Speed and physiological cost index of hemiplegic patients pedalling a wheelchair with both legs.
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OBJECTIVE: To determine whether hemiplegic patients can propel a leg-pedalling wheelchair and whether it is easier and faster for them to pedal the wheelchair using both legs alternately than to propel an ordinary wheelchair with their unaffected hand and leg. DESIGN: Within-subject comparison. SUBJECTS: Subjects comprised 10 hemiplegic in-patients (8 males, 2 females), aged 63.7 (SD 12.7) years with severe or moderate gait disturbance due to stroke. METHODS: Subjects were asked to practice propelling the leg-pedalling wheelchair and ordinary wheelchair on both slalom and rectangular courses for a period of 7-10 days. Once they had become skilled in this, the wheelchair speed and patient's heart rate were measured, and a physiological cost index was calculated. RESULTS: Subjects could pedal the leg-pedalling wheelchair using both legs alternately. The speed of this wheelchair was faster than that of the ordinary wheelchair, and the physiological cost index for pedalling it was lower than that for propelling the ordinary wheelchair. However, subjects needed some help in transferring to the leg-pedalling wheelchair. CONCLUSION: The hemiplegic patients could pedal the leg-pedalling wheelchair using both legs alternately faster and more effectively with regard to speed and physiological cost index. (+info)