Alternative modes of manual wheelchair ambulation: an overview

Force Application During Handcycling and Handrim Wheelchair Propulsion: An Initial Comparison

The aim of the study was to evaluate the external applied forces, the effectiveness of force application and the net shoulder moments of handcycling in comparison with handrim wheelchair propulsion at different inclines. Ten able-bodied men performed standardized exercises on a treadmill at inclines of 1%, 2.5% and 4% with an instrumented handbike and wheelchair that measured three-dimensional propulsion forces. The results showed that during handcycling significantly lower mean forces were applied at inclines of 2.5% (P< .001) and 4% (P< .001) and significantly lower peak forces were applied at all inclines (1%:P= .014, 2.5% and 4%:P< .001). At the 2.5% incline, where power output was the same for both devices, total forces (mean over trial) of 22.8 N and 27.5 N and peak forces of 40.1 N and 106.9 N were measured for handbike and wheelchair propulsion. The force effectiveness did not differ between the devices (P= .757); however, the effectiveness did increase with higher inclines during handcycling whereas it stayed constant over all inclines for wheelchair propulsion. The resulting peak net shoulder moments were lower for handcycling compared with wheelchair propulsion at all inclines (P< .001). These results confirm the assumption that handcycling is physically less straining.

Lever-actuated resonance assistance (LARA): a wheelchair-based method for upper extremity therapy and overground ambulation for people with severe arm impairment

People with severe arm impairment have limited technologies available for retraining their arms, and, if they also have difficulty walking, they often cannot effectively use a manual wheelchair because they cannot grasp and push the pushrim. We are using Lever-Actuated Resonance Assistance (LARA) to solve these problems. A LARA-based device can attach to a manual wheelchair and allow it to be used by people with severe arm weakness in a stationary exercise mode, or for self-powered overground ambulation. LARA uses a lever drive and arm support to appropriately position the arm and to reduce the dexterity required to operate the wheelchair. It also uses mechanical resonance implemented with elastic bands to provide assistance for both stationary exercise and overground ambulation. We first review here pilot results in which we used the LARA method to provide arm therapy to individuals with chronic stroke in stationary exercise mode. We then describe a novel motion-based user interface that allows individuals to control a video game with LARA while operating a wheelchair in resonance. Finally, for overground ambulation mode, we show in simulation that the mechanical resonance provided by LARA theoretically allows people with severe arm weakness to propel themselves with reduced effort and obtain speeds previously unattainable.

Comparison of activities of daily living (ADLs) in two different one arm drive wheelchairs: a study of individuals/participants with hemiplegia

AIMS

This pilot study measured activities of daily living performance in individuals/participants with hemiplegia propelling both a standard dual handrim Action 3 wheelchair and a standard Action 3 wheelchair with a Neater Uni-Wheelchair kit attachment. The kit consists of a steerable front.

RESEARCH QUESTIONS

Does the use of the NUW affect the performance quality of activities of daily living in individuals/participants with hemiplegia. Is there a difference in the motor and process skills during activities of daily living performance, and in the time taken to complete the activities.

METHODS

Four individuals/participants with hemiplegia were used in a cross over, repeated measures trial. Assessment of Motor and Process Skills of users undertaking making a bed and laying a table "Swedish style", tasks were measured and time taken to complete each task were recorded.

RESULTS

Bed making completion time was quicker in the Neater Uni-wheelchair (p < 0.03). Motor skills were significantly higher than the process ability skills (p < 0.05).

CONCLUSION

Activities of daily living tasks in the Neater Uni-wheelchair were completed more efficiently with no loss in quality of motor and process skills performance. This suggests that the Neater Uni-wheelchair is a viable alternative to current one arm drive provision. Implications for Rehabilitation Inappropriate wheelchair provision can result in capacity limitation and poorer quality of ADL motor skill as well-lowered process performance skill. AMPS can help to explain motor and process skill differences in complex activities.

Comparison of metabolic cost, performance, and efficiency of propulsion using an ergonomic hand drive mechanism and a conventional manual wheelchair

OBJECTIVE

To compare the metabolic cost (oxygen uptake per unit time [V˙o2 consumption], heart rate, and number of pushes), performance (velocity and distance traveled), and efficiency (oxygen uptake per distance traveled [Vo2 efficiency]) of propulsion using a novel ergonomic hand drive mechanism (EHDM) and a conventional manual wheelchair (CMW).

DESIGN

Repeated-measures crossover design.

SETTING

Semicircular track.

PARTICIPANTS

Adult full-time manual wheelchair users with spinal cord injuries (N=12; mean age ± SD, 38.8±12.4y; mean body mass ± SD, 73.7±13.3kg; mean height ± SD, 173.6±11.1cm) who were medically and functionally stable and at least 6 months postinjury.

INTERVENTION

Participants propelled themselves for 3.5 minutes at a self-selected pace in a CMW and in the same chair fitted with the EHDM.

MAIN OUTCOME MEASURES

Velocity, distance traveled, number of pushes, V˙o2 consumption, Vo2 efficiency, and heart rate were compared by wheelchair condition for the last 30 seconds of each trial using paired t tests (α=.01).

RESULTS

The CMW condition resulted in more distance traveled (33.6±10.8m vs 22.4±7.8m; P=.001), greater velocity (1.12±0.4m/s vs .75±.30m/s; P=.001), and better Vo2 efficiency (.10±.03mL·kg(-1)·m(-1) vs .15±.03mL·kg(-1)·m(-1); P<.001) than the EHDM condition, respectively. No significant differences were found between the 2 conditions for number of pushes (27.5±5.7 vs 25.7±5.4; P=.366), V˙o2 consumption (6.43±1.9mL·kg(-1)·min(-1) vs 6.19±1.7mL·kg(-1)·min(-1); P=.573), or heart rate (100.5±14.5 beats per minute vs 97.4±20.2 beats per minute; P=.42).

CONCLUSIONS

The results demonstrate that metabolic costs did not differ significantly; however, performance and efficiency were sacrificed with the EHDM. Modifications to the EHDM (eg, addition of gearing) could rectify the performance and efficiency decrements while maintaining similar metabolic costs. Although not an ideal technology, the EHDM can be considered as an alternative mode of mobility by wheelchair users and rehabilitation specialists.

A comparison of vertical reaction forces during propulsion of three different one-arm drive wheelchairs by hemiplegic users

PURPOSE

The aim of this pilot study was to compare the vertical reaction forces (N) generated in three different Action 3 manual one-arm drive wheelchairs: dual handrim, a lever drive and a Neater Uni-wheelchair (NUW). A CONFORmat® Pressure measurement mat, placed on top of the users' prescribed cushion, measured vertical force at the buttock/seat interface on both hemiplegic and non-hemiplegic sides in each wheelchair.

METHODS

Fifteen hemiplegic users were randomly assigned each wheelchair to drive around an indoor obstacle course. During propulsion of a multiple sensor, continuous measurement of force was recorded. Time taken to complete the circuit was recorded. Mean force and confidence intervals for each buttock were calculated per user per wheelchair.

RESULTS

The dual handrim produced the highest vertical force during propulsion under the right buttock (x= 484.43; SD = 55.4; p < 0.001) and the lever drive produced the least force (x= 368.05; SD = 53.55; p < 0.01). The NUW completed the course quickest (p < 0.01).

CONCLUSIONS

The dual-handrim wheelchair requires the greatest vertical force during propulsion. Since increases in this seat vertical reaction force may be related to the propulsive force. Further investigation is indicated as this may be a significant factor for clinicians when prescribing one-arm drive wheelchairs. Implications for Rehabilitation Review of clinical reasoning in prescribing wheelchairs. Addition of the Neater Uni-wheelchair to wheelchair services prescribing lists.

The effect of crank position and backrest inclination on shoulder load and mechanical efficiency during handcycling

Handbikes come in different models and setups, but only limited knowledge is available on the handbike-user interface. The aim of this study was to identify optimal handbike setups, assuming that in such a setup mechanical efficiency is high, while shoulder load is low. Thirteen subjects with a spinal cord injury (paraplegia) performed handcycling with different handbike setups at constant power output: four crank positions (two distances, two heights) and four backrest inclinations. The O2-consumption, kinetics, and kinematics were measured to calculate mechanical efficiency and shoulder load (glenohumeral contact force, net shoulder moments, and rotator cuff force). The analysis showed that more upright backrest positions resulted in lower shoulder load compared with the most reclined position [glenohumeral contact force (260 vs 335 N), supraspinatus (14.4% vs 18.2%), and infraspinatus force (5.4% vs 9.8%)], while there was no difference in efficiency. Except for a reduction in subscapularis force at the distant position, no differences in shoulder load or efficiency were found between crank positions. Recreational handbike users, who want to improve their physical capacity in a shoulder-friendly way, should set up their handbike with a more upright backrest position and a distant crank placement.

Design History and Advantages of a New Lever-Propelled Wheelchair Prototype

Wheelchair propulsion has been reported to be responsible for musculoskeletal pain in the upper extremities. Epidemiological studies have shown a high prevalence of shoulder complaints in paraplegic and quadriplegic spinal cord injured (SCI) people. It has been argued that the high incidence of shoulder complaints in SCI was the result of the weight-bearing or propulsion function of the upper extremity in those subjects.

This work aimed at proposing an alternative wheelchair propulsion technique based on the levers' system. The interface prototype-users, the wheelchair skills evaluation, the oxygen uptake and the cardiac frequency are investigated by an objective and subjective studies.

Our prototype is designed to be an attempt in the field of disabled athletes having some advantages of a non-conventional manual wheelchair propulsion technique, avoiding complications induced by the conventional one.

Beyond the wheelchair: development of motorised transport for people with severe mobility impairments in developing countries

PURPOSE

In developing countries, lack of over-the-road transportation reduces a vast number of disabled people to a life of begging, dependency and social isolation. Although there have been some excellent efforts to provide low-cost wheelchairs and hand-powered tricycles, little has been done to further provide transport for disabled people.

METHODS

To address this problem directly we devised a low-cost motorised wheelchair transporter prototype (the Skeeter) using a combination of bicycle parts, a custom built frame, and an inexpensive small engine for propulsion.

RESULTS

The Skeeter can provide independent operation and travel by a wheelchair user. It is an economically feasible solution to the lack of over-the-road transportation for people with mobility impairments in developing countries.

CONCLUSIONS

The Skeeter has the potential to provide a major enhancement in the quality of life for people with disabilities in developing countries around the world.

Evaluation of a wheelchair prototype with non-conventional, manual propulsion

OBJECTIVE

To evaluate the results of a user satisfaction questionnaire on a new type of lever-propelled wheelchair designed to avoid the discomfort and potential repetitive strain injuries related to conventional hand-rim propulsion.

METHODS

Seventeen participants filled out a questionnaire to rate their conventional wheelchair and the prototype (after 2 days' use) in terms of comfort, adjustability, steering/ride, manoeuvrability, stability when crossing obstacles, safety, weight, size, portability and appearance. Overall satisfaction was also scored.

RESULTS

According to the user questionnaire results, the lever-propelled prototype chair was rated as significantly superior than conventional wheelchairs in terms of comfort, safety and overall satisfaction. The prototype was rated significantly inferior in terms of size, adaptability, appearance and crossing obstacles.

CONCLUSION

We conclude that the prototype wheelchair is highly acceptable and comfortable and can be recommended to disabled sportspersons. The prototype's weak points are mainly related to ergonomic aspects, which could be improved in future models.

Comparison of shoulder muscle electromyographic activity during standard manual wheelchair and push-rim activated power assisted wheelchair propulsion in persons with complete tetraplegia

OBJECTIVES

To compare spatio-temporal propulsion characteristics and shoulder muscle electromyographic activity in persons with cervical spinal cord injury propelling a standard pushrim wheelchair (WC) and a commercially available pushrim-activated power assisted wheelchair (PAPAW) design on a stationary ergometer.

DESIGN

Repeated measures.

SETTING

Motion analysis laboratory within a rehabilitation hospital.

PARTICIPANTS

Men (N=14) with complete (American Spinal Injury Association grade A or B) tetraplegia (C6=5; C7=9).

INTERVENTION

Participants propelled a standard pushrim WC and PAPAW during 3 propulsion conditions: self-selected free and fast and simulated 4% or 8% graded resistance propulsion.

MAIN OUTCOME MEASURES

Median speed, cycle length, cadence, median and peak electromyographic activity intensity, and duration of electromyographic activity in pectoralis major, anterior deltoid, supraspinatus, and infraspinatus muscles were compared between standard pushrim WC and PAPAW propulsion.

RESULTS

A significant (P<.05) decrease in electromyographic activity intensity and duration of pectoralis major, anterior deltoid, and infraspinatus muscles and significantly reduced intensity and push phase duration of supraspinatus electromyographic activity at faster speeds and with increased resistance were seen during PAPAW propulsion.

CONCLUSIONS

For participants with complete tetraplegia, push phase shoulder muscle activity was decreased in the PAPAW compared with standard pushrim WC, indicating a reduction in demands when propelling a PAPAW.

Effect of different handgrip angles on work distribution during hand cycling at submaximal power levels

The effect of different handle angles on work distribution during hand cycling was determined. Able-bodied subjects performed hand cycling at 20% of maximum power level (mean (SD) power level: 90.0 (25.8) W) at a cadence of 70 rpm using handle angles of +/-30 degrees, +/-15 degrees and 0 degrees. The handle angle had a significant effect on work during the pull down (p < 0.001) and lift up (p = 0.005) sector, whereby the highest work was performed with handle angles of +30 degrees and -15 degrees respectively. The cycle sector had a significant effect on work (p < 0.001) and significantly (p = 0.002) higher work was performed in the pull down sector (25% higher than mean work over one cycle) as compared to the lift up sector (30% lower than mean work over one cycle). Therefore, a fixed handle angle of +30 degrees is suggested to be optimal for power generation. The results of this study help to optimise the handbike-user interface. A more pronated handle angle compared to the one conventionally used was found to improve the performance of hand cycling and thereby the mobility of disabled people.

New design and development of a manual wheelchair for India

PURPOSE

The most common methods of delivering assistive technology in developing countries are charitable donation and workshops. This describes a new approach to solving the problem, a collaboration undertaken by a US-based lab and a manufacturer in India to produce quality wheelchairs. One goal is to publicize the design free of charge to manufacturers and interested parties world-wide. The process, a demonstration of a new technology transfer method, and the product, an adult manual wheelchair, are described.

METHOD

An iterative process occurred over four years to design and produce the wheelchair. This consisted of prototypes, small production runs, ANSI/RESNA testing, hardness and tensile testing and informal user testing.

RESULTS

The design is a manual folding cross-brace design with several points of adjustability. Final pre-production prototypes experienced fastener failures during durability testing. Higher grade bolts were specified. Trial-run production has begun. An ANSI/RESNA wheelchair test lab was constructed in India. Subsequent projects include power and pediatric tilt-in-space wheelchairs.

CONCLUSIONS

The approach seems promising as a method to improve the quality of assistive technology available in India and begin to meet the vast need in India. Pitfalls encountered throughout the collaboration are described in this paper along with solutions to remedy these problems for future projects.

Influence of crank length and crank width on maximal hand cycling power and cadence

The effect of different crank lengths and crank widths on maximal hand cycling power, cadence and handle speed were determined. Crank lengths and crank widths were adapted to anthropometric data of the participants as the ratio to forward reach (FR) and shoulder breadth (SB), respectively. 25 able-bodied subjects performed maximal inertial load hand cycle ergometry using crank lengths of 19, 22.5 and 26% of FR and 72, 85 and 98% of SB. Maximum power ranged from 754 (246) W for the crank geometry short wide (crank length x crank width) to 873 (293) W for the combination long middle. Every crank length differed significantly (P < 0.05) from each other, whereas no significant effect of crank width to maximum power output was revealed. Optimal cadence decreased significantly (P < 0.001) with increasing crank length from 124.8 (0.9) rpm for the short to 107.5 (1.6) rpm for the long cranks, whereas optimal handle speed increased significantly (P < 0.001) with increasing crank length from 1.81 (0.01) m/s for the short to 2.13 (0.03) m/s for the long cranks. Crank width did neither influence optimal cadence nor optimal handle speed significantly. From the results of this study, for maximum hand cycling power, a crank length to FR ratio of 26% for a crank width to SB ratio of 85% is recommended.

Power output and metabolic cost of synchronous and asynchronous submaximal and peak level hand cycling on a motor driven treadmill in able-bodied male subjects

PURPOSE

To evaluate external power output and physiological responses of synchronous (SYNC) and asynchronous hand cycling (ASYNC) at submaximal and peak levels of exercise.

METHODS

n=9 able-bodied male subjects (age: 20.1+/-2.1 years) performed two (sub)maximal continuous hand cycle exercise tests, using the SYNC and ASYNC mode in a standardized commercial add-on hand cycle unit (counter-balanced order). Treadmill speed (1.89 and 2.17 m s(-1)) and slope (steps of +1%) were changed in a fixed sequence of 3-min exercise steps. Gears were adjusted to 65 rpm. External power output (PO) was continuously monitored with a strain-gauge instrumented chain ring ((SRM) Schoberer Rad Messtechnik). A conventional wheelchair drag test was performed to validate mean external power for each speed-slope combination. Heart rate (HR; bpm) and oxygen uptake (VO2; ml kg(-1) min(-1), SMTP) were continuously monitored. Paired T-tests and ANOVA for repeated measures evaluated effects of mode and exercise level (p<0.05).

RESULTS

Subjects reached peak levels of performance (RER: 1.05+/-0.07 versus 1.10+/-0.1 for SYNC and ASYNC). Peak PO and V(o2) were significantly higher for SYNC (81.6+/-11.8 W versus 68.5+/-10.6 W; 26.4+/-4.5 ml kg(-1) min(-1) versus 21.2+/-3.0 ml kg(-1) min(-1)). At submaximal exercise levels, gross mechanical efficiency (ME) was significantly higher for SYNC (12.1+/-0.9% versus 9.7+/-1.4% at 41 W). No significant differences were found for PO (at equal velocity and slope), as derived from the SRM (SYNC and ASYNC), and from the drag test.

DISCUSSION

The absence of any differences in PO between SYNC and ASYNC, and with respect to the drag test, rules out 'additional external work due to maintain the desired heading' in the ASYNC as an explanation for the lower performance in this mode. Lower peak performance and ME in ASYNC may be explained by the increased stabilizing muscle effort in the upper extremities and trunk in order to combine power production with stable steering. ASYNC is less efficient compared to SYNC. Similarly, peak performance capacity was higher for SYNC.

CONCLUSION

External work does not differ between SYNC and ASYNC hand cycling. SRM readings appear valid for PO monitoring in hand cycling within the studied range of PO. SYNC is more efficient than ASYNC and leads to higher peak performance.

Shoulder muscular demand during lever-activated vs pushrim wheelchair propulsion in persons with spinal cord injury

BACKGROUND/OBJECTIVE

The high demand on the upper limbs during manual wheelchair (WC) use contributes to a high prevalence of shoulder pathology in people with spinal cord injury (SCI). Lever-activated (LEVER) WCs have been presented as a less demanding alternative mode of manual WC propulsion. The objective of this study was to evaluate the shoulder muscle electromyographic activity and propulsion characteristics in manual WC users with SCI propelling a standard pushrim (ST) and LEVER WC design.

METHODS

Twenty men with complete injuries (ASIA A or B) and tetraplegia (C6, n = 5; C7, n = 7) or paraplegia (n = 8) secondary to SCI propelled ST and LEVER WCs at 3 propulsion conditions on a stationary ergometer: self-selected free, self-selected fast, and simulated graded resistance. Average velocity, cycle distance, and cadence; median and peak electromyographic intensity; and duration of electromyography of anterior deltoid, pectoralis major, supraspinatus, and infraspinatus muscles were compared between LEVER and ST WC propulsion.

RESULTS

Significant decreases in pectoralis major and supraspinatus activity were recorded during LEVER compared with ST WC propulsion. However, anterior deltoid and infraspinatus intensities tended to increase during LEVER WC propulsion. Participants with tetraplegia had similar or greater anterior deltoid, pectoralis major, and infraspinatus activity for both ST and LEVER WC propulsion compared with the men with paraplegia.

CONCLUSIONS

Use of the LEVER WC reduced and shifted the shoulder muscular demands in individuals with paraplegia and tetraplegia. Further studies are needed to determine the impact of LEVER WC propulsion on long-term shoulder function.

The natural-fit handrim: factors related to improvement in symptoms and function in wheelchair users

BACKGROUND/OBJECTIVE

People with spinal cord injury (SCI) may spend several decades using a wheelchair as their primary means of mobility. Secondary injury and a decline in independence over time are common with manual wheelchair users who, in turn, may require increased assistance as time passes. The Natural-Fit contoured handrim has been shown to improve symptoms and function in people with SCI who use manual wheelchairs and who have experienced upper extremity pain. The objective of this study was to determine the factors associated with improved symptoms and functions.

PARTICIPANTS

87 people who purchased the ergonomic wheelchair handrims. Participants were predominately men, with a median age of 51 to 55 years, median level of injury T10 to T12, median time in a wheelchair of 15 years, and they had used the contoured rims for 1 to 2 years.

METHODS

This was a mail survey of 217 people who purchased the rims. The survey was mailed out from the manufacturer and was anonymously returned to the physical therapy department of a university. A $10 incentive was offered for returning the survey.

RESULTS

The majority of participants reported improvements in upper extremity symptoms, ease of wheelchair propulsion, and functional status. Longer use of the rims was associated with reported improvement in ease of wheelchair propulsion and reduction in pain in hands and wrists.

CONCLUSION

If a simple modification of the wheelchair can help bring about significant changes in the users' symptoms and function, this modification should be incorporated by people who use manual wheelchairs before decline in function begins. Proactive intervention may alleviate symptoms, help the person maintain maximal independence, and prolong the length of time the individual remains independent.

The influence of crank length and cadence on mechanical efficiency in hand cycling

The purpose of this study was to determine the effect of crank length and cadence on mechanical efficiency in hand cycling. Eight wheelchair dependent, high performance athletes completed four 4-min submaximal exercise bouts at a constant power output of 90 W over the different experimental conditions (crank length, pedal rate) using a sports hand bike (Draft, Godmanchester, UK). Two different crank lengths (180 and 220 mm) were tested at two different cadences (70 and 85 rev min(-1)) using the synchronous mode of cranking. Physiological measures of oxygen uptake (VO2) minute ventilation, blood lactate (B[La]), heart rate (HR), rate of perceived exertion (RPE) were recorded, gross (GE) and net (NE) efficiency were calculated. A two-way ANOVA with repeated measures was applied to determine the effects of crank length, cadence and their interaction on these physiological measures. Both GE and NE were significantly higher and V(O)(2) significantly lower for the 180 mm crank (P < 0.05). No significant main effect was found for cadence on the physiological measures (P > 0.05). Likewise, no interactions between crank length and pedal rate were found. There was however, a trend observed with HR and B[La] often lower with the 180 mm crank, indicating lower physiological stress. The RPE data supported this finding, with a tendency for lower ratings with the 180 mm crank (9 +/- 2 vs. 10 +/- 3). The short crank length when used at 85 rev min(-1) was found to be the most efficient (GE 21.4 +/- 3.1%). In conclusion, crank length has a significant effect on ME in hand cycling. A shorter crank length of 180 mm was found to be more efficient than the 220 mm, regardless of pedal rate during hand cycling.

The effects of arm crank strategy on physiological responses and mechanical efficiency during submaximal exercise

The purpose of this study was to compare submaximal physiological responses and indices of mechanical efficiency between asynchronous and synchronous arm ergometry. Thirteen wheelchair-dependent trained athletes performed eight steady-state incremental bouts of exercise (0 to 140 W), each lasting 4 min, using synchronous and asynchronous arm-cranking strategies. Physiological measures included oxygen uptake (VO2), heart rate, and blood lactate concentration. The power outputs corresponding to fixed whole blood lactate concentrations of 2.0 to 4.0 mmol x l(-1) were calculated using linear interpolation. Mechanical efficiency indices - gross efficiency, net efficiency, and work efficiency - were also calculated. An analysis of variance with repeated measures was applied to determine the effect of crank mode on the physiological parameters. Oxygen uptake was on average 10% lower (P < 0.01), and both net efficiency (P < 0.01) and gross efficiency (P < 0.01) were higher, during the asynchronous strategy at both 60 and 80 W (gross efficiency: 16.9 +/- 2.0% vs. 14.7 +/- 2.4% and 17.5 +/- 1.8% vs. 15.9 +/- 2.6% at 60 and 80 W respectively). There were no differences in heart rate, blood lactate concentration or power output at either of the blood lactate reference points between the asynchronous and synchronous strategies (P > 0.05). In conclusion, test specificity is an important consideration. If a synchronous strategy is to be adopted, it is likely to result in lower efficiency than an asynchronous strategy. The exercise testing scenario may help dictate which method is ultimately chosen.

Manual wheelchairs: Research and innovation in rehabilitation, sports, daily life and health

Those with lower limb disabilities are often dependent on manually propelled wheelchairs for their mobility, in Europe today some 3.3 million people. This implies a transfer from leg to arm work for ambulation and all other activities of daily living (ADL). Compared to the legs, arm work is less efficient and more straining, and leads to a lower physical capacity. Also, there is a major risk of mechanical overuse. Problems of long-term wheelchair use are not only pain or discomfort, but also a risk of a physically inactive lifestyle. Subsequently, serious secondary impairments (obesity, diabetes and cardiovascular problems) may eventually emerge. Wheelchair quality, including the ergonomic fitting to the individual may play a preventive role here, but also other modes of physical activity, and the understanding of training, rehabilitation, active lifestyle and sports on health and wellbeing. The 'International Classification of Functioning, Health and Disability' (ICF) model, a stress-strain-work capacity model, as well as the ergonomics model that relates human-activity-assistive technology are instrumental to the concepts, structure and aims of research in assistive technology for mobility. Apart from empirical developments and innovations from within wheelchair sports, systematic research has played a role in wheelchair development and design in three important areas: (1) the vehicle mechanics, (2) the human movement system and (3) the wheelchair-user interface. Current practical developments in design and technology are discussed. A position stand on the key-issues of a current and future research agenda in this area is presented.

Kinematic analysis of handbike propulsion in various gear ratios: implications for joint pain

BACKGROUND

Though considered more efficient and less constraining than the hand-rim wheelchair, the handbike has rarely been studied especially as regards its kinematic parameters. The hypothesis of this investigation is that the range of upper extremity motions are risk factors for joint pain during handbiking as is the case during hand-rim wheelchair propulsion. This paper aims to study handbike propulsion in maximal sprint conditions in order to determine potential risk factors for joint pain.

METHODS

Eight able-bodied participants with no experience in handbike propulsion performed three sprints of 8 s each using three gear ratios in a handbike mounted on a home-trainer. The mean velocity per arm cycle, the cycle frequency, the angular parameters for the upper extremities were calculated, as well as the corresponding angular accelerations, with the help of a 3D movement analysis.

FINDINGS

An increase in gear ratio (22/21, 32/21, and 44/21) significantly increases the maximal velocity, the flexion/extension of the trunk, as well as the adduction/abduction of the elbow, while it reduces the frequency of movements and the flexion/extension angular accelerations of the shoulder and the elbow. Regardless of what gear ratio is used, maximal angular amplitudes of the upper extremities are comparable to the values obtained with a hand-rim wheelchair. Interpretation. The high amplitudes and fast angular joint accelerations of the upper extremity found in this study are near or superior to the ergonomic recommendations generally advised. These considerations could be taken into account to prevent overuse injuries.

The individual relationship between heart rate and oxygen uptake in people with a tetraplegia during exercise

STUDY DESIGN

Descriptive study.

OBJECTIVE

To examine the individual heart rate-oxygen uptake (HR-VO(2)) relationship during exercise in persons with tetraplegia (TP).

SETTING

Rehabilitation Centre Heliomare, Wijk aan Zee, The Netherlands.

METHODS

The HR-VO(2) relationship was determined in untrained subjects with motor complete TP (C5 or C6, n=10 and C7 or C8, n=10) during a discontinuous graded exercise hand cycle test. The mean HR and VO(2) of the final 60 s of 2-min exercise blocks were used for calculation of the individual correlation coefficient and the standard error of the estimate (SEE).

RESULTS

Two subjects of the C5-C6 group were not able to complete the test. Individual Pearson's correlation coefficients (r) ranged from 0.68 to 0.97 and SEE from 2.6 to 22.4% VO(2)-Reserve (VO(2)R). The mean Pearson's r and SEE were 0.81+/-0.12 and 10.6+/-5.6% VO(2)R in the C5-C6 group and 0.91+/-0.07 and 7.0+/-3.2% VO(2)R in the C7-C8 group, respectively. Two subjects of the C5-C6 group and six subjects of the C7-C8 group attained a linear HR-VO(2) relationship with an acceptable SEE (< or =6.0%) and r (>0.90).

CONCLUSIONS

The HR-VO(2) relationship appeared linear in only eight out of 18 subjects. An individual analysis of the HR-VO(2) relationship is necessary to determine whether HR can be used to quantify exercise intensity. The use of HR to prescribe training intensity should be reconsidered in persons with TP.

SPONSORSHIP

This study is supported from a grant by ZON-MW.

Effect of a pushrim-activated power-assist wheelchair on the functional capabilities of persons with tetraplegia

OBJECTIVES

To test the differences between a pushrim-activated power-assisted wheelchair (PAPAW) and a traditional manual wheelchair while performing common driving activities and to assess their relative merits for people with tetraplegia.

DESIGN

Repeated measures.

SETTING

An activities of daily living (ADL) laboratory within a rehabilitation research center.

PARTICIPANTS

Fifteen full-time manual wheelchair users with tetraplegia due to a spinal cord injury.

INTERVENTIONS

Participants propelled both their own manual wheelchairs and a PAPAW 3 times over an ADL course. The order in which the 2 different wheelchairs were presented to the participants was randomized.

MAIN OUTCOME MEASURES

Each participant's heart rate was monitored throughout testing by a digital, wireless heart-rate monitor. Time to complete the course was recorded, and participants were surveyed with a visual analog scale after the first, third, fourth, and sixth trials to determine the ease of completing each obstacle and their ergonomic preferences between the 2 wheelchairs. Participants also were observed throughout the trials to determine how much assistance they needed to complete each obstacle course.

RESULTS

After using a Bonferroni adjustment, 4 obstacles (carpet, dimple strips, up a ramp, up a curb cut) were rated as being significantly easier ( P <.001) to complete when using the PAPAW. Participants also showed a significant decrease in mean heart rate throughout all 3 trials ( P =.015, P =.001, P =.003, respectively) when using a PAPAW. The amount of assistance needed by participants, the responses to ergonomic questions, and the overall time to complete the ADL course did not differ significantly between the 2 wheelchairs.

CONCLUSIONS

For subjects with tetraplegia, PAPAWs have the potential to improve functional capabilities during certain ADLs, especially when propelling up ramps, over uneven surfaces, and over thick carpet.

Submaximal physical strain and peak performance in handcycling versus handrim wheelchair propulsion

STUDY DESIGN

Experimental study in subjects with paraplegia and nondisabled subjects.

OBJECTIVE

To compare submaximal physical strain and peak performance in handcycling and handrim wheelchair propulsion in wheelchair-dependent and nondisabled control subjects

SETTING

Amsterdam, The Netherlands.

METHODS

Nine male subjects with paraplegia and 10 nondisabled male subjects performed two exercise tests on a motor-driven treadmill using a handrim wheelchair and attach-unit handcycle system. The exercise protocol consisted of two 4-min submaximal exercise bouts at 25 and 35 W, followed by 1-min exercise bouts with increasing power output until exhaustion.

RESULTS

Analysis of variance for repeated measures showed a significantly lower oxygen uptake (VO2), ventilation (Ve), heart rate (HR), rate of perceived exertion and a higher gross efficiency for handcycling at 35 W in both subject groups, while no significant differences were found at 25 W. Peak power output and peak VO2, Ve and HR were significantly higher during handcycling in both groups. The differences between handcycling and wheelchair propulsion were the same in subjects with paraplegia and the nondisabled subjects.

CONCLUSIONS

Handcycling induces significantly less strain at a moderate submaximal level of 35 W, and shows noticeably higher maximal exercise responses than wheelchair propulsion, which is consistent in subjects with paraplegia and nondisabled controls. These results demonstrate that handcycling is beneficial for mobility in daily life of wheelchair users.

Hand rim configuration: effects on physical strain and technique in unimpaired subjects?

OBJECTIVE

Hand rim wheelchair propulsion is inefficient and physically straining. To evaluate the possibly advantageous role in this respect of three different prototype hand rim configurations (a rubber foam-coated cylindrical (II) hand rim and two profiled rubber foam-coated hand rims (wide and narrow: III, IV)), a group of 10 unimpaired subjects conducted four submaximal discontinuous wheelchair exercise tests on a computer-controlled wheelchair ergometer, thus allowing a comparison with a standard hand rim (chromium-plated round hand rim (I)).

METHODS

Apart from physiological measures (oxygen uptake, heart rate (HR), ventilation, mechanical efficiency (ME)), a subjective score for the rating of each of the hand rims was determined, as well as characteristics of the force application in the propulsion phase during each test condition. Timing parameters of the push and recovery phase were determined. Each exercise test was conducted with one of the four hand rim configurations in a counter-balanced order.

RESULTS

Analysis of variance with repeated measures (hand rim configuration, power output) revealed no significant effects (P>0.05) on any of the physiological parameters and force application characteristics for the main factor 'hand rim configuration'. Only the subjective score (scale 0-10) for rating of the hand rims proved significantly different between the round rubber (7.5+/-0.53) coated hand rim-receiving the highest score-versus the narrow rubber-coated flat profiled hand rim (5.5+/-1.72).

DISCUSSION

In this subject group and under the selected tasks and submaximal conditions of wheelchair propulsion, the studied hand rim configurations did not introduce critical shifts in the technique of (de-)coupling and power production in the push phase. As a consequence, no systematic shifts in ME are found among the different hand rim configurations. It is suggested that the biological constraints of the task overrule the possible effects of small design variations of the different hand rim configurations within the studied subject group and under the limited test conditions. The hand rim design characteristics may however be much more critical in (1) experienced wheelchair users, (2) especially those subjects with a limited hand-arm and/or trunk function and/or (3) under much more extreme conditions of daily wheelchair ambulation (i.e. turning, stopping/starting, negotiating a slope) or during peak performance. These issues clearly require continued future research. As such, the current results can be viewed as preliminary results only.

A comparison of functional mobility in standard vs. ultralight wheelchairs as measured by performance on a community obstacle course

PURPOSE

Appropriate wheelchair prescription requires maximizing user function while justifying cost. The purpose of this study was to investigate differences in a user's performance of mobility skills (on a community obstacle course) between an ultralight (UWC) and standard wheelchair (SWC).

SUBJECTS

Sixty healthy adults (mean = 28.3 years) without wheelchair experience performed one course trial.

METHODS

Participants were randomly assigned to an UWC or a SWC. Researchers recorded time for completion, Rating of Perceived Exertion (RPE), and number, location, and types of errors committed. Errors included contact of WC and any obstacle, front casters leaving the ground, or loss of directional control (veering).

RESULTS

A MANOVA of the data (p < 0.05) showed a significant difference in numbers of contact errors (higher in the SWC) and castor errors (higher in the UWC) between the two wheelchairs. Number of veering errors, time to complete, and RPE were not significantly different.

CONCLUSIONS

Differences in wheelchair design can lead to differences in a user's performance of functional mobility skills. Choice of wheelchair may affect a user's ability to be independent in a community setting.

Biomechanics and physiology in active manual wheelchair propulsion

Manual wheelchair propulsion in daily life and sports is increasingly being studied. Initially, an engineering and physiological perspective was taken. More recently a concomitant biomechanics interest is seen. Themes of biomechanical and physiological studies today are performance enhancing aspects of wheelchair use and the ergonomics of wheelchair design. Apart from the propulsion technique the focus of biomechanics research of manual wheelchair propulsion is mainly towards injury mechanisms, especially phenomena of overuse to the upper extremity. Obviously, the vehicle mechanics of wheelchairs must be included within this biological framework. Scientific research is progressing, but is still hampered by methodological limitations, such as the heterogeneity and small numbers of the population at study as well as the inconsistency of employed technologies and methodologies. There is a need for consensus regarding methodology and research strategy, and a strong need for collaboration to improve the homogeneity and size of subject groups and thus the power of the experimental results. Thus a sufficiently strong knowledge database will emerge, leading to an evidence-base of performance enhancing factors and the understanding of the risks of wheelchair sports and long-term wheelchair use. In the light of the current biomechanical and physiological knowledge of manual wheelchair propulsion there seems to be a need for the stimulation of other than hand rim propelled manual wheelchairs.