Alternative modes of manual wheelchair ambulation: an overview

Technologies measuring manual wheelchair propulsion metrics: A scoping review

The aim of this review is to investigate existing and developing technologies assessing metrics of manual wheelchair propulsion. A scoping review of scientific and gray literature was performed. Five databases were searched - Medline, Scopus, CINAHL, Institute of Electrical and Electronics Engineers (IEEE), and Embase. The 38 retained articles identified 27 devices categorized into accelerometers, wheelchair-mounted devices, instrumented wheels, and wearables. The devices included in this review can be used by manual wheelchair users to monitor propulsion effort and activity goals, by clinicians to assess rehabilitation programs, and to inform and guide future research. The findings support a need for further research into the development of custom algorithms for manual wheelchair user populations as well as further validation in broader free-living environments with equitable participant populations.

Reinventing the wheel for a manual wheelchair

PURPOSE

Standard manual wheelchairs (MWCs) are inefficient and pushrim propulsion may cause progressive damage and pain to the user's arms. We describe a wheel for a MWC with a novel propulsion mechanism.

METHODS

The wheel has two modes of operation called "Standard" mode and "Run" mode. In Run mode, the wheelchair is propelled forward by pushing a compliant handle forward and then pulling it back, both strokes contributing to forward propulsion. We report the propulsive force and preliminary testing on a rough outdoor circuit by three able-bodied participants.

RESULTS

In Run mode, the peak applied force is reduced to 30% and the maximum force gradient is reduced to 10% of that for standard pushrim propulsion, for the same work output. The travel time for the 1.06 km outdoor circuit is about 60% of that for a brisk walk and about 40% of that for pushrim propulsion. At a propulsion speed of 1 m/s, the cardiovascular effort in Run mode is 56% of that for pushrim propulsion. Automatic hill-hold in Run mode improves safety when ascending slopes. The mechanism has three gears so that it can be used by people with widely varying strength and fitness. Folding the handle away converts the operation to Standard mode with the conventional pushrim propulsion, supplemented by three gears.

CONCLUSIONS

Despite the increased weight, width and friction, the bimodal geared wheels facilitate wheelchair travel on challenging paths. This may bring significant improvement to the quality of life of MWC users.

Design and development of a self-propelled indoor wheelchair with direct toilet accessibility

PURPOSE

Existing wheelchair (WC) designs lack independent toilet accessibility, transferability and indoor manoeuvrability combined in a WC. In this regard, a new WC model is proposed to simultaneously accommodate these distinct and essential features. In this open-source hardware project, the design, analysis and fabrication of a new active commode WC for indoor applications are performed.

MATERIALS AND METHOD

A field survey is conducted to identify the requirements of users so as to choose specific features and design constraints for the WC. In this multipurpose self-propelled model, a temporarily detachable circular section is fitted in the seat position to access the water closet bowl. This hinged portion can be released by gravity before reaching above the closet basin. After the toilet usage, the circular lid can be brought back to the initial seating using a lever mechanism and a spring-loaded lock restrains its downward movement. Thereafter, it can be used as an ordinary WC for indoor applications. Moreover, a small wheel with 22 in diameter and removable hand-rests ensured the transferability between utilities. A CAD model is prepared and numerical simulation is performed to verify the structural stability of the design.

RESULTS

The optimized model is fabricated using standard manufacturing practices and is delivered to different persons with disabilities to collect user feedback. A systematic skill test is conducted to validate the compliance of the prototype with the user requirements including transferability and independent restroom access.

CONCLUSION

The opinions from most of the users are positive which categorically indicated that the proposed design addresses the multipurpose mobility requirements at indoors.Implications for rehabilitationThe expected outcomes and implications of the current commode WC project with regard to rehabilitation purpose are enlisted below:In the present scenario, a WC user is heavily dependent on external assistance to access private spaces in general and toilets in particular. The introduced model is capable to address this shortcoming by enabling the user to access the toilet utility directly by self propelling.Indeed, for a person with locomotor disability, a WC is the natural extension of his physical body. Thereby, this multipurpose commode WC design offers much Independence and greater flexibility to the indoor movements.The proposed design instils confidence to a WC user to access and transfer between facilities by means of self effort. Consequently it is expected to improve the quality of one's personal life significantly.Importantly, this is an open-source project, those who are interested in rehabilitation motives can modify the present design to suit their local requirements especially in resource-limited settings.

Hand-rim biomechanics during geared manual wheelchair propulsion over different ground conditions in individuals with spinal cord injury

Geared manual wheelchair wheels, a recently developed alternative propulsion mechanism, have the potential to alleviate the high upper extremity demands required for wheelchair propulsion and help decrease the risk of secondary injuries in manual wheelchair users. The objective of this study was to investigate the effects of using geared manual wheelchairs on hand-rim biomechanics of wheelchair propulsion in individuals with spinal cord injury (SCI). Seven manual wheelchair users with SCI propelled their wheelchairs equipped with geared wheels over tile, carpet, and up a ramp in low gear (gear ratio 1.5:1) and standard gear (gear ratio 1:1) conditions. Hand-rim kinetics and stroke cycle characteristics were measured using a custom instrumented geared wheel. Using the geared wheels in the low gear condition, propulsion speed (P = 0.013), peak resultant force (P = 0.005), peak propulsive moment (P < 0.006), and peak rate of rise of the resultant force (P = 0.035) decreased significantly in comparison with the standard gear condition. The significant increase in the number of stroke cycles when normalized to distance (P = 0.004) and decrease in the normalized integrated moment (P = 0.030) indicated that although a higher number of stroke cycles are required for travelling a given distance in the low gear than the standard gear condition, the low gear condition might be less demanding for the upper extremity. These results suggest that geared wheels could be a useful technology for manual wheelchair users to independently accomplish strenuous propulsion tasks including mobility on carpeted floors and ramp ascension, while reducing the risk factors contributing to the incidence of secondary upper extremity injuries.

Influence of Wheelchair Type on Kinematic Parameters in Wheelchair Rugby

Introduction

In wheelchair rugby, players use either an offensive or defensive wheelchair depending on their field position and level of impairment. Performance of wheelchair rugby players is related to several parameters, however it is currently unclear if differences in performance are related to wheelchair type or no: the effect of wheelchair type on performance variables has not been evaluated. The aim of this study was to compare offensive and defensive wheelchairs on performance variables during a straight-line sprint.

Methods

Thirteen able-bodied people performed two 20 m sprint trials: one with an offensive and one with a defensive wheelchair. Data were collected using inertial measurement units fixed on the wheelchair. Peak wheelchair velocities and left-right asymmetries in peak wheel velocities were measured during the acceleration and constant peak velocity phases. Sprint time, cycle frequency, and mean and maximum velocity were calculated over the entire sprint.

Results

The peak velocities of the first 2 pushes (acceleration phase) were significantly higher with the defensive than the offensive wheelchair (p &lt; 0.04 and p &lt; 0.02). Mean and maximum sprint velocity were significantly higher (p &lt; 0.03 and p &lt; 0.04, respectively) with the defensive wheelchair. Cycle frequency and asymmetry did not differ between wheelchairs.

Conclusion

Performance was higher with the defensive than the offensive wheelchair, suggesting that the frequent finding that the higher performance of offensive as compared to defensive players is not related to the use of an offensive wheelchair.

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

Background

Hand-rim wheelchair propulsion is straining and mechanically inefficient, often leading to upper limb complaints. Previous push–pull lever propulsion mechanisms have shown to perform better or equal in efficiency and physiological strain. Propulsion biomechanics have not been evaluated thus far. A novel push–pull central-lever propulsion mechanism is compared to conventional hand-rim wheelchair propulsion, using both physiological and biomechanical outcomes under low-intensity steady-state conditions on a motor driven treadmill.

Methods

In this 5 day (distributed over a maximum of 21 days) between-group experiment, 30 able-bodied novices performed 60 min (5 × 3 × 4 min) of practice in either the push–pull central lever wheelchair (n = 15) or the hand-rim wheelchair (n = 15). At the first and final sessions cardiopulmonary strain, propulsion kinematics and force production were determined in both instrumented propulsion mechanisms. Repeated measures ANOVA evaluated between (propulsion mechanism type), within (over practice) and interaction effects.

Results

Over practice, both groups significantly improved on all outcome measures. After practice the peak forces during the push and pull phase of lever propulsion were considerably lower compared to those in the handrim push phase (42 ± 10 & 46 ± 10 vs 63 ± 21N). Concomitantly, energy expenditure was found to be lower as well (263 ± 45 vs 298 ± 59W), on the other hand gross mechanical efficiency (6.4 ± 1.5 vs 5.9 ± 1.3%), heart-rate (97 ± 10 vs 98 ± 10 bpm) and perceived exertion (9 ± 2 vs 10 ± 1) were not significantly different between modes.

Conclusion

The current study shows the potential benefits of the newly designed push–pull central-lever propulsion mechanism over regular hand rim wheelchair propulsion. The much lower forces and energy expenditure might help to reduce the strain on the upper extremities and thus prevent the development of overuse injury. This proof of concept in a controlled laboratory experiment warrants continued experimental research in wheelchair-users during daily life.

Turning in Circles: Understanding Manual Wheelchair Use Towards Developing User-Friendly Steering Systems

For people with physical disabilities, manual wheelchairs are essential enablers of mobility, participation in society, and a healthy lifestyle. Their most general design offers great flexibility and direct feedback, but has been described to be inefficient and demands good coordination of the upper extremities while critically influencing users’ actions. Multiple research groups have used Inertial Measurement Units (IMUs) to quantify physical activities in wheelchairs arguing that knowledge over behavioural patterns in manual wheelchair usage can guide technological development and improved designs. The present study investigates turning behaviour among fulltime wheelchair users, laying the foundation of the development of novel steering systems that allow directing kinetic energy by means other than braking. Three wearable sensors were installed on the wheelchairs of 14 individuals for tracking movement over an entire week. During detected “moving windows”, phases where the velocities of the two rear wheels differed by more than 0.05 m/s were considered as turns. Kinematic characteristics for both turns-on-the-spot as well as for moving turns were then derived from the previously reconstructed wheeled path. For the grand total of 334 km of recorded wheelchair movement, a turn was detected every 3.6 m, which equates to about 900 turns per day on average and shows that changing and adjusting direction is fundamental in wheelchair practice. For moving turns, a median turning radius of 1.09 m and a median turning angle of 39° were found. With a median of 89°, typical turning angles were considerably larger for turns-on-the-spot, which accounted for roughly a quarter of the recognised turns and often started from a standstill. These results suggest that a frequent pattern in daily wheelchair usage is to initiate movement with an orienting turn-on-the-spot, and cover distances with short, straightforward sections while adjusting direction in small and tight moving turns. As large bends often require simultaneous pushing and breaking, this is, perhaps, the result of users intuitively optimising energy efficiency, but more research is needed to understand how the design of the assistive devices implicitly directs users’ movement.

The Science of Handcycling: A Narrative Review

The aim of this narrative review is to provide insight as to the history, biomechanics, and physiological characteristics of competitive handcycling. Furthermore, based upon the limited evidence available, this paper aims to provide practical training suggestions by which to develop competitive handcycling performance. Handbike configuration, individual physiological characteristics, and training history all play a significant role in determining competitive handcycling performance. Optimal handcycling technique is highly dependent upon handbike configuration. As such, seat positioning, crank height, crank fore-aft position, crank length, and handgrip position must all be individually configured. In regard to physiological determinants, power output at a fixed blood lactate concentration of 4 mmol·L−1, relative oxygen consumption, peak aerobic power output, relative upper body strength, and maximal anaerobic power output have all been demonstrated to impact upon handcycling performance capabilities. Therefore, it is suggested that that an emphasis be placed upon the development and frequent monitoring of these parameters. Finally, linked to handcycling training, it is suggested that handcyclists should consider adopting a concurrent strength and endurance training approach, based upon a block periodization model that employs a mixture of endurance, threshold, interval, and strength training sessions. Despite our findings, it is clear that several gaps in our scientific knowledge of handcycling remain and that further research is necessary in order to improve our understanding of factors that determine optimal performance of competitive handcyclists. Finally, further longitudinal research is required across all classifications to study the effects of different training programs upon handcycling performance.

Propulsion Cost Changes of Ultra-Lightweight Manual Wheelchairs After One Year of Simulated Use

Manual wheelchairs are available with folding or rigid frames to meet the preferences and needs of individual users. Folding styles are commonly regarded as more portable and storable, whereas rigid frames are commonly regarded as more efficient for frequently daily use. To date, there are no studies directly comparing the performances of the frame types. Furthermore, while differences have been reported in the longevity of the frame types, no efforts have been made to relate this durability back to the real-world performance of the frames. This study investigated the propulsion efficiencies of four folding and two rigid ultra-lightweight frames equipped with identical drive tires and casters. A robotic wheelchair tester was used to measure the propulsion costs of each chair over two surfaces: concrete and carpet. A motorized carousel was used to drive the chairs 511 km around a circular track to simulate one year of use for each wheelchair. After simulated use, five of the six wheelchairs showed no decrease in propulsion effort, indicating that the frames were able to withstand the stresses of simulated use without a detrimental impact on performance. In the unused "new" condition, rigid chairs were found to have superior (>5%) performance over folding frames on concrete and carpet, and in the "worn" condition rigid chairs had superior performance over folding chairs on concrete but were comparable on the carpeted surface.

In Vivo Biomechanical Assessment of a Novel Handle-Based Wheelchair Drive

Push-rim wheelchair propulsion frequently causes severe upper limb injuries in people relying on the wheelchair for ambulation. To address this problem, we developed a novel handle-based wheelchair propulsion method that follows a cyclic motion within ergonomic joint ranges of motion. The aim of this study was to measure hand propulsion forces, joint excursions and net joint torques for this novel propulsion device and to compare its performance against traditional push-rim wheelchair propulsion. We hypothesized that under similar conditions, joint excursions of this novel handle-based device will remain within their ergonomic range and that the effectiveness of the propulsion forces will be higher, leading to lower average propulsion forces compared to push-rim propulsion and reducing the risk of injury. Eight paraplegic subjects propelled the new device at two different loads on a custom-made wheelchair-based test rig. Video motion capture and force sensors were used to monitor shoulder and wrist joint kinematics and kinetics. Shoulder and wrist loads were calculated using a modified upper-extremity Wheelchair Propulsion Model available in OpenSim. The results show that with this novel propulsion device joint excursions are within their recommended ergonomic ranges, resulting in a reduced range of motion of up to 30% at the shoulder and up to 80% at the wrist, while average resultant peak forces were reduced by up to 20% compared to push-rim propulsion. Furthermore, the lower net torques at both the shoulder and wrist demonstrate the potential of this novel propulsion system to reduce the risk of upper-extremity injuries.

Perceptions of power-assist devices: interviews with manual wheelchair users

PURPOSE

The study had three main objectives. (1) To investigate the perceived impact of power-assist devices (PADs) on manual wheelchair (MWC) user mobility. (2) To compare perceptions about different types of PADs. (3) To identify preferred features and design characteristics of PADs.

METHODS

Semi-structured interviews were conducted with community-dwelling MWC users aged 31 years and older, with at least 2.5 years of experience using an MWC independently (n = 16). Data were thematically analysed using an inductive approach.

RESULTS

Two main themes related to participants' perceptions about the effects of PAD use were identified: (1) "Expanding my world", which illustrated the perceived benefits of using PADs (e.g., gaining a sense of autonomy and access to new environments, maintaining physical health) and (2) "Falling short", which described challenges with PADs (e.g., safety, reliability and portability issues). Participants also identified strengths and limitations of different types of PADs that were mainly related to specific user-device and device-environment interactions as well as various functional characteristics. Moreover, participants outlined their priorities for future PAD design, including improving controllability, customizability and affordability of these devices.

CONCLUSIONS

Participants' perceptions about PADs varied across different types of devices and in different contexts. However, PADs were generally perceived as enhancing the capabilities of MWCs. Our findings provide insight into the factors that can be considered when selecting a PAD and can inform the development of future PADs that are better equipped to overcome challenges that MWC users frequently encounter.Implications for RehabilitationPower-assist devices (PADs) for manual wheelchairs (MWCs) have the potential to improve the mobility, community participation and well-being of users.Some of the existing PADs have safety and reliability issues that affect their performance and limit their use by MWC users.The three types of PADs (front-mounted attachments, rear-mounted attachments, powered wheels) offer different types of assistance that can benefit users with various capabilities.

Do Handcycling Time-Trial Velocities Achieved by Para-Cycling Athletes Vary Across Handcycling Classes?

The classification system for handcycling groups athletes into five hierarchical classes, based on how much their impairment affects performance. Athletes in class H5, with the least impairments, compete in a kneeling position, while athletes in classes H1 to H4 compete in a recumbent position. This study investigated the average time-trial velocity of athletes in different classes. A total of 1,807 results from 353 athletes who competed at 20 international competitions (2014-2018) were analyzed. Multilevel regression was performed to analyze differences in average velocities between adjacent pairs of classes, while correcting for gender, age, and event distance. The average velocity of adjacent classes was significantly different (p < .01), with higher classes being faster, except for H4 and H5. However, the effect size of the differences between H3 and H4 was smaller (d = 0.12). Hence, results indicated a need for research in evaluating and developing evidence-based classification in handcycling, yielding a class structure with meaningful performance differences between adjacent classes.

Physiological parameters depending on two different types of manual wheelchair propulsion

OBJECTIVE

The purpose of this study was to compare aerobic parameters in the multistage field test (MFT) in hand rim wheelchair propulsion and lever wheelchair propulsion.

METHODS

Twenty-one men performed MFT using two different types of propulsion, i.e., lever and hand rim wheelchair propulsion. The covered distance and physiological variables (oxygen uptake (VO₂), minute ventilation (VE), carbon dioxide output (VCO₂), respiratory coefficient (RQ), and heart rate (HR)) were observed. Physiological variables were measured with Cosmed K5 system. Kolmogorov-Smirnov test, t-test, Wilcoxon test and effect sizes (ESs) were used to assess differences. Statistical significance was set at p < .05.

RESULTS

A significantly longer distance was observed in lever wheelchair propulsion than in hand rim wheelchair propulsion (1,194 and 649 m, respectively). VO_2max and RQ were higher in hand rim wheelchair propulsion. All physiological variables for the last (fifth) level of the test in hand rim propulsion were significantly higher than in lever wheelchair propulsion. ES was large for each observed difference.

CONCLUSION

The lever wheelchair propulsion movement is less demanding than hand rim wheelchair propulsion and longer distances can be achieved by the user. There is a need to check lever wheelchair propulsion in different types of field tests.

Rehabilitation: mobility, exercise & sports; a critical position stand on current and future research perspectives

BACKGROUND

Human movement, rehabilitation, and allied sciences have embraced their ambitions within the cycle of "RehabMove" congresses over the past 30 years. This combination of disciplines and collaborations in the Netherlands has tried to provide answers to questions in the fields of rehabilitation and adapted sports, while simultaneously generating new questions and challenges. These research questions help us to further deepen our understanding of (impaired) human movement and functioning, with and without supportive technologies, and stress the importance of continued multidisciplinary (inter)national collaboration.

METHODS

This position stand provides answers that were conceived by the authors in a creative process underlining the preparation of the 6th RehabMove Congress.

RESULTS

The take-home message of the RehabMove2018 Congress is a plea for continued multidisciplinary research in the fields of rehabilitation and adapted sports. This should be aimed at more individualized notions of human functioning, practice, and training, but also of performance, improved supportive technology, and appropriate "human and technology asset management" at both individual and organization levels and over the lifespan.

CONCLUSIONS

With this, we anticipate to support the development of rehabilitation sciences and technology and to stimulate the use of rehabilitation notions in general health care. We also hope to help ensure a stronger embodiment of preventive and lifestyle medicine in rehabilitation practice. Indeed, general health care and rehabilitation practice require a healthy and active lifestyle management and research agenda in the context of primary, secondary, and tertiary prevention.IMPLICATIONS FOR REHABILITATIONContinued multidisciplinary (international) collaboration will stimulate the development of rehabilitation and human movement sciences.Notions from "human and technology asset management and ergonomics" are fundamental to rehabilitation practice and research.The rehabilitation concept will further merge into general health care and the quality there-off.

Effect of seat height on manual wheelchair foot propulsion, a repeated-measures crossover study: part 2 - wheeling backward on a soft surface

Purpose: The aim of this study was to test the hypotheses that, during manual-wheelchair foot propulsion backward on a soft surface, lowering the seat height increases speed, push frequency and push effectiveness, and decreases perceived difficulty.Materials and methods: In a repeated-measures crossover study, 50 able-bodied participants used one foot to propel a manual wheelchair 5 m backward on a soft surface at 5 seat heights, ranging from 5.08 cm below to about 5.08 cm above lower-leg length, in random order. We recorded Wheelchair Skills Test (WST) capacity scores and used the Wheelchair Propulsion Test (WPT) to calculate speed (m/s), push frequency (cycles/s) and push effectiveness (m/cycle). We also recorded the participants' perceived difficulty (0-4) and video-recorded each trial.Results: WST capacity scores were reduced at the higher seat heights. Using repeated-measures models (adjusted for age, sex and order), there were negative relationships between seat height and speed (p < 0.0001) and push effectiveness (p < 0.0001). Lowering the seat height by 5.08 cm below lower-leg length corresponded to improvements in speed of 0.097 m/s and in push effectiveness of 0.101 m/cycle. The trend for push frequency was also significant (p = 0.035) but the effect size was smaller. Perceived difficulty increased with seat height (p < 0.0001). The video-recordings provided qualitative kinematic data regarding the seated "gait cycles".Conclusions: During manual-wheelchair foot propulsion backward on a soft surface, lowering the seat height increases speed and push effectiveness, and decreases perceived difficulty.IMPLICATIONS FOR REHABILITATIONBackward wheelchair foot propulsion on soft surfaces is affected by seat height.Speed (m/s) is improved if the seat height is lowered.Push effectiveness (m/gait cycle) is improved if the seat height is lowered.Perceived difficulty of propulsion is lower if the seat height is lowered.

Effect of seat height on manual wheelchair foot propulsion, a repeated-measures crossover study: part 1 - wheeling forward on a smooth level surface

Purpose: To test the hypotheses that, during manual wheelchair foot propulsion forward on smooth level surfaces, lowering the seat height increases speed, push frequency and push effectiveness, and decreases perceived difficulty.Materials and methods: In a repeated-measures crossover study, 50 able-bodied participants used one foot to propel a manual wheelchair 10 m on a smooth level surface at 5 seat heights in random order, ranging from 5.08 cm below to about 5.08 cm above lower-leg length. We recorded Wheelchair Skills Test (WST) capacity scores and used the Wheelchair Propulsion Test (WPT) to calculate speed (m/s), push frequency (cycles/s) and push effectiveness (m/cycle). We also recorded the participants' perceived difficulty (0-4) and video-recorded each trial.Results: WST capacity scores were reduced at the higher seat heights. Using repeated-measures models (adjusted for age, sex and order), there were negative relationships between seat height and speed (p < 0.0001) and push effectiveness (p < 0.0001). Lowering the seat height by 5.08 cm below lower-leg length corresponded to improvements in speed of 0.20 m/s and in push effectiveness of 0.20 m/cycle. The trend for push frequency was also significant (p = 0.003) but the effect size was smaller. Perceived difficulty increased with seat height (p < 0.001). The video-recordings provided qualitative kinematic data regarding the seated "gait cycles".Conclusions: During manual wheelchair foot propulsion forward on smooth level surfaces, lowering the seat height increases speed and push effectiveness, and decreases perceived difficulty.Clinical Trial Registration Number: NCT03330912.Implications for RehabilitationGenerally, wheelchairs used for forward foot propulsion should have a seat height that is 2.54-5.08 cm less than the sitting lower-leg length.Clinicians should, however, take into consideration other functions that may be adversely affected by lowering the seat height.

Biomechanical and physiological differences between synchronous and asynchronous low intensity handcycling during practice-based learning in able-bodied men

BACKGROUND

Originally, the cranks of a handcycle were mounted with a 180° phase shift (asynchronous). However, as handcycling became more popular, the crank mode switched to a parallel mounting (synchronous) over the years. Differences between both modes have been investigated, however, not into great detail for propulsion technique or practice effects. Our aim is to compare both crank modes from a biomechanical and physiological perspective, hence considering force and power production as a cause of physiological outcome measures. This is done within a practice protocol, as it is expected that motor learning takes place in the early stages of handcycling in novices.

METHODS

Twelve able-bodied male novices volunteered to take part. The experiment consisted of a pre-test, three practice sessions and a post-test, which was subsequently repeated for both crank modes in a counterbalanced manner. In each session the participants handcycled for 3 × 4 minutes on a leveled motorized treadmill at 1.94 m/s. Inbetween sessions were 2 days of rest. 3D forces, handlebar and crank angle were measured on the left hand side. Kinematic markers were placed on the handcycle to monitor the movement on the treadmill. Lastly, breath-by-breath spirometry combined with heart-rate were continuously measured. The effects of crank mode and practice-based learning were analyzed using a two way repeated measures ANOVA, with synchronous vs asynchronous and pre-test vs post-test as within-subject factors.

RESULTS

In the pre-test, asynchronous handcycling was less efficient than synchronous handcycling in terms of physiological strain, force production and timing. At the post-test, the metabolic costs were comparable for both modes. The force production was, also after practice, more efficient in the synchronous mode. External power production, crank rotation velocity and the distance travelled back and forwards on the treadmill suggest that asynchronous handcycling is more constant throughout the cycle.

CONCLUSIONS

As the metabolic costs were reduced in the asynchronous mode, we would advise to include a practice period, when comparing both modes in scientific experiments. For handcycle users, we would currently advise a synchronous set-up for daily use, as the force production is more effective in the synchronous mode, even after practice.

Bioenergetics and Biomechanics of Handcycling at Submaximal Speeds in Athletes with a Spinal Cord Injury

BACKGROUND

A study aimed at comparing bioenergetics and biomechanical parameters between athletes with tetraplegia and paraplegia riding race handbikes at submaximal speeds in ecological conditions.

METHODS

Five athletes with tetraplegia (C6-T1, 43 ± 6 yrs, 63 ± 14 kg) and 12 athletes with paraplegia (T4-S5, 44 ± 7 yrs, 72 ± 12 kg) rode their handbikes at submaximal speeds under metabolic measurements. A deceleration method (coasting down) was applied to calculate the rolling resistance and frontal picture of each participant was taken to calculate air resistance. The net overall Mechanical Efficiency (Eff) was calculated by dividing external mechanical work to the corresponding Metabolic Power.

RESULTS

Athletes with tetraplegia reached a lower aerobic speed (4.7 ± 0.6 m s^-1 vs. 7.1 ± 0.9 m s^-1, P = 0.001) and Mechanical Power (54 ± 15 W vs. 111 ± 25 W, P = 0.001) compared with athletes with paraplegia. The metabolic cost was around 1 J kg^-1 m^-1 for both groups. The Eff values (17 ± 2% vs. 19 ± 3%, P = 0.262) suggested that the handbike is an efficient assisted locomotion device.

CONCLUSION

Handbikers with tetraplegia showed lower aerobic performances but a similar metabolic cost compared with handbikers with paraplegia at submaximal speeds in ecological conditions.

Perceptions of Fall Circumstances, Recovery Methods, and Community Participation in Manual Wheelchair Users

OBJECTIVE

The aim of the study was to examine the circumstances surrounding the worst fall experienced by full-time manual wheelchair users in the past 12 mos, the recovery process, and influence on community participation.

DESIGN

A mixed-method research study was conducted. Semistructured interviews were conducted to understand the circumstances of the worst fall experienced and the recovery process. A quantitative fear of falling assessment and the community participation indicators were used to further evaluate the influence of the fall.

RESULTS

There were 20 manual wheelchair users (mean ± SD, 47 ± 13 yrs, 55% male). Falls most commonly occurred outside during wheelchair propulsion. Falls were attributed to both intrinsic and extrinsic factors. Seventy percent of participants reported a fear of falling and 80% required assistance to recovery. No significant correlations were found between fall frequency and community participation indicator scores. Participants who needed assistance to recover (56.70 ± 17.66) had lower community participation indicator importance scores compared with participants able to recover independently (88.93 ± 22.13), P = 0.05.

CONCLUSIONS

Falls are complex and most manual wheelchair users need assistance to recover. Comprehensive programs including education on prevention and postfall management are needed. Results may increase understanding of the circumstances associated with falls and inform the development of evidenced-based clinical practice guidelines.

Prototyping of manual wheelchair with alternative propulsion system

Aim: This paper presents the study, design and prototyping of a manual wheelchair, named handwheelchair.q, with an innovative propulsion's system. The research is based on a novel system of propulsion that is more efficient and ergonomic than the hand rim one. The main goal of the designed prototype is to facilitate the mobility and to extend the reachable areas while reducing the required time.Methods: The propulsion is realised through a rowing-inspired gesture.Results: This gesture avoids the damages caused on shoulders by the compressive force of the hand rim and lever systems.Conclusion: The prototyping allowed the analysis of the project parameters and their influence on the kinematic characteristics of the prototype and the biomechanical characteristics of the gesture. The same propulsion's system can be adopted on wheelchairs devoted to sport activities, representing the starting point for a future prototype of racing wheelchairs. In this regard, the wheelchair's braking system has been redesigned in order to improve efficiency and safety.Implication for rehabilitationThe use of the Handwheelchair.q may have positive impacts in terms of the quality of life, in order to reduce the shoulder pain caused by the handrim and lever system.In addition, it can be a good tool for rehabilitation because the activity can be performed outdoor.

The Design of a New Manual Wheelchair for Sport

In this paper, an innovative system of propulsion inspired by a rowing gesture for manual wheelchairs is shown. The innovative system of propulsion, named Handwheelchair.q, can be applied to wheelchairs employed in everyday life and to sports wheelchairs for speed races, such as Handbike and Wheelchair racing. The general features of the innovative system of propulsion and the functional designs of the different solutions are described in detail. In addition, the design of the mechanism for the transmission of motion, employed in a second prototype, Handwheelchair.q02, is presented and analysed. Finally, the dynamic model of the Handwheelchair.q has been developed in order to obtain important results for the executive design of Handwheelchair.q.

Peak power output in handcycling of individuals with a chronic spinal cord injury: predictive modeling, validation and reference values

Purpose: To develop and validate predictive models for peak power output to provide guidelines for individualized handcycling graded exercise test protocols for people with spinal cord injury (SCI); and to define reference values.Materials and methods: Power output was measured in 128 handcyclists with SCI during a synchronous handcycling exercise test. Eighty percent of the data was used to develop four linear regression models: two theoretical and two statistical models with peak power output (in W and W/kg) as dependent variable. The other 20% of the data was used to determine agreement between predicted versus measured power output. Reference values were based on percentiles for the whole group.Results: Lesion level, handcycling training hours and sex or body mass index were significant determinants of peak power output. Theoretical models (R² = 42%) were superior to statistical models (R²=39% for power output in W, R² = 30% for power output in W/kg). The intraclass correlation coefficients varied between 0.35 and 0.60, depending on the model. Absolute agreement was low.Conclusions: Both models and reference values provide insight in physical capacity of people with SCI in handcycling. However, due to the large part of unexplained variance and low absolute agreement, they should be used with caution. Implications for rehabilitationIndividualization of the graded exercise test protocol is very important to attain the true peak physical capacity in individuals with spinal cord injury.The main determinants to predict peak power output during a handcycling graded exercise test for individuals with a spinal cord injury are lesion level, handcycling training hours and sex or body mass index.The predictive models for peak power output should be used with caution and should not replace a graded exercise test.

Forward dynamic optimization of handle path and muscle activity for handle based isokinetic wheelchair propulsion: A simulation study

Push-rim wheelchair propulsion is biomechanically inefficient and physiologically stressful to the musculoskeletal structure of human body. This study focuses to obtain a new, optimized propulsion shape for wheelchair users, which is within the ergonomic ranges of joint motion, thus reducing the probability of injuries. To identify the propulsion movement, forward dynamic optimization was performed on a 3D human musculoskeletal model linked to a handle based propulsion mechanism, having shape and muscle excitations as optimization variables. The optimization resulted in a handle path shape with a circularity ratio of 0.95, and produced a net propulsion power of 34.7 watts for an isokinetic propulsion cycle at 50 rpm. Compared to push-rim propulsion, the compact design of the new propulsion mechanism along with the ergonomically optimized propulsion shape may help to reduce the risk of injuries and thus improve the quality of life for wheelchair users.

Validity of activity monitors in wheelchair users: A systematic review

Assessing physical activity (PA) in manual wheelchair users (MWUs) is challenging because of their different movement patterns in comparison to the ambulatory population. The aim of this review was to investigate the validity of portable monitors in quantifying PA in MWUs. A systematic literature search was performed. The data source was full reports of validation and evaluation studies in peer-reviewed journals and conference proceedings. Eligible articles between January 1, 1999, and September 18, 2015, were identified in three databases: PubMed, Institute of Electrical and Electronics Engineers, and Scopus. A total of 164 articles (158 from the databases and 6 from the citation/reference tracking) were identified, and 29 met the eligibility criteria. Two investigators independently extracted the characteristics from each selected article following a predetermined protocol and completed seven summary tables describing the study characteristics and key outcomes. In the identified studies, the monitors were used to assess three types of PA measures: energy cost, user movement, and wheelchair movement. The customized algorithms/monitors did not estimate energy cost in MWUs as well as the commercial monitors did in the ambulatory population; however, they showed fair accuracy in measuring both wheelchair and user movements.

Evaluation and validation of musculoskeletal force feasible set indices: Application to manual wheelchair propulsion

The aim of this work was to assess handrim wheelchair propulsion effectiveness, related to the applied forces on the handrim, through the force feasible set. For a given posture of the upper-limb, it represents the set of isometric forces that can be applied on the handrim in any direction. The force feasible set was predicted from a musculoskeletal model of the upper-limb and trunk (10 degrees of freedom and 56 muscles). The aim of the first part of the study was to compare the force feasible set prediction and the force currently applied on the handrim. The second part proposes the creation of a new index called "Musculoskeletal Postural Performance Index" (MPPI) derived from the force feasible set and its comparison with the Mechanical Efficiency Force (MEF). These comparisons were conducted at 60, 80, 100, 120 and 140% of the Freely Chosen Frequency at submaximal and maximal conditions on 5 different phases of the push phase. The values of the MPPI were significantly correlated with those of the MEF. During the course of the push phase, the orientation of the force feasible set main axis approached that of the measured force and the force effectiveness evaluated through the MPPI increased.

Shoulder complaints in wheelchair athletes: A systematic review

Background

In recent years the popularity of disabled sports and competition among disabled athletes has grown considerably. With this rise in exposure of, and participation in wheelchair sports comes an increase in related stressors, including musculoskeletal load. External mechanical loading may increase the risk of shoulder complaints. The objective of this literature review was to 1) identify and describe the prevalence and/or incidence of shoulder complaints in wheelchair athletes in the literature, to 2) examine the factors and underlying mechanisms that could be potentially involved, and 3) provide some insights into the development of preventative measures.

Methods

A literature search was conducted using PubMed, Scopus and Embase databases, to identify relevant published articles. All articles in the English language that contained any type of shoulder complaint in relation with a wheelchair sports player, at any level of status (recreational to elite), of any sport, were included. Articles were excluded if they did not include any statistical analysis. Articles that included studies with wheelchair athletes in combination with athletes of other disability sports were excluded in order to be able to differentiate between the two. Narrative, exploratory and case studies were also excluded. Two reviewers independently assessed articles for inclusion. Thirteen articles matched the selection criteria. These were judged on their quality by use of an adapted version of the Webster checklist.

Results

Of the included studies the overall quality was low. A relatively high prevalence of complaints was found, ranging from 16% to 76%. Pain was found to be a common complaint in wheelchair athletes. Based on the current literature the cause of shoulder problems is difficult to identify and is likely multifactorial, nevertheless characteristics of the user (i.e. increased years of disability, age and BMI) were shown to increase risk. Preventative measures were indistinct. There may be a role for balanced strength training regimens to decrease risk.

Conclusion

Shoulder complaints in wheelchair athletes are a common problem that must be addressed further. Future studies on shoulder overuse injuries of wheelchair athletes should be directed towards biomechanical modeling to develop knowledge of load and its effects.

Effect of wheelchair design on wheeled mobility and propulsion efficiency in less-resourced settings

Background

Wheelchair research includes both qualitative and quantitative approaches, primarily focuses on functionality and skill performance and is often limited to short testing periods. This is the first study to use the combination of a performance test (i.e. wheelchair propulsion test) and a multiple-day mobility assessment to evaluate wheelchair designs in rural areas of a developing country.

Objectives

Test the feasibility of using wheel-mounted accelerometers to document bouts of wheeled mobility data in rural settings and use these data to compare how patients respond to different wheelchair designs.

Methods

A quasi-experimental, pre- and post-test design was used to test the differences between locally manufactured wheelchairs (push rim and tricycle) and an imported intervention product (dual-lever propulsion wheelchair). A one-way repeated measures analysis of variance was used to interpret propulsion and wheeled mobility data.

Results

There were no statistical differences in bouts of mobility between the locally manufactured and intervention product, which was explained by high amounts of variability within the data. With regard to the propulsion test, push rim users were significantly more efficient when using the intervention product compared with tricycle users.

Conclusion

Use of wheel-mounted accelerometers as a means to test user mobility proved to be a feasible methodology in rural settings. Variability in wheeled mobility data could be decreased with longer acclimatisation periods. The data suggest that push rim users experience an easier transition to a dual-lever propulsion system.

Different cadences and resistances in sub-maximal synchronous handcycling in able-bodied men: Effects on efficiency and force application

BACKGROUND

With the introduction of an add-on handcycle, a crank system that can be placed in front of a wheelchair, handcycling was made widely available for daily life. With it, people go into town more easily, e.g. to do groceries; meet up with friends, etc. They have more independency and can be socially active. Our aim is to explore some settings of the handcycle, so that it can be optimally used as a transportation device. Therefore, the effects of cadence and added resistance on gross mechanical efficiency and force application during sub-maximal synchronous handcycling were investigated. We hypothesized that a cadence of 52 rpm with a higher resistance (35 W) would lead to a higher gross mechanical efficiency and a more tangential force application than a higher cadence of 70 rpm and no extra resistance (15 W).

METHODS

Twelve able-bodied men rode in an instrumented add-on handcycle on a motorized level treadmill at 1.94 m/s. They performed three sessions of three four-minute blocks of steady state exercise. Gear (70, 60 and 52 rpm) was changed in-between the blocks and resistance (rolling resistance +0 W, +10 W, +20 W) was changed across sessions, both in a counterbalanced order. 3D force production, oxygen uptake and heart rate were measured continuously. Gross mechanical efficiency (ME) and fraction of effective force (FEF) were calculated as main outcomes. The effects of cadence and resistance were analyzed using a repeated measures ANOVA (P<0.05) with Bonferroni-corrected post-hoc pairwise comparisons.

RESULTS

With a decrease in cadence a slight increase in ME (70 rpm: 5.5 (0.2)%, 60 rpm: 5.7 (0.2)%, 52 rpm: 5.8 (0.2)%, P = 0.008, η2p = 0.38), while an increase in FEF (70 rpm: 58.0 (3.2)%, 60 rpm: 66.0 (2.8)%, 52 rpm: 71.3 (2.3)%, P<0.001, η2p = 0.79) is seen simultaneously. Also with an increase in resistance an increase in ME (+0 W: 4.0 (0.2)%, +10 W: 6.0 (0.3)%, +20 W: 7.0 (0.2)%, P<0.001, η2p = 0.92) and FEF (+0 W: 59.0 (2.9)%, +10 W: 66.1 (3.4)%, +20 W: 70.2 (2.4)%, P<0.001, η2p = 0.56) was found.

INTERPRETATION

A cadence of 52 rpm against a higher resistance of about 35 W leads to a more optimal direction of forces and is more mechanically efficient than propelling at a higher cadence or lower resistance. Therefore, changing gears on a handcycle is important, and it is advised to keep the linear hand velocity relatively low for locomotion purposes.

Handcycling: training effects of a specific dose of upper body endurance training in females

PURPOSE

This study aims to evaluate a handcycling training protocol based on ACSM guidelines in a well-controlled laboratory setting. Training responses of a specific dose of handcycling training were quantified in a homogeneous female subject population to obtain a more in depth understanding of physiological mechanisms underlying adaptations in upper body training.

METHODS

22 female able-bodied participants were randomly divided in a training (T) and control group (C). T received 7-weeks of handcycling training, 3 × 30 min/week at 65 % heart rate reserve (HRR). An incremental handcycling test was used to determine local, exercise-specific adaptations. An incremental cycling test was performed to determine non-exercise-specific central/cardiovascular adaptations. Peak oxygen uptake (peakVO2), heart rate (peakHR) and power output (peakPO) were compared between T and C before and after training.

RESULTS

T completed the training sessions at 65 ± 3 % HRR, at increasing power output (59.4 ± 8.2 to 69.5 ± 8.9 W) over the training program. T improved on handcycling peakVO2 (+18.1 %), peakPO (+31.9 %), and peakHR (+4.0 %). No improvements were found in cycling parameters.

CONCLUSION

Handcycling training led to local, exercise-specific improvements in upper body parameters. Results could provide input for the design of effective evidence-based training programs specifically aimed at upper body endurance exercise in females.

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

Objective. To study whether values for peak oxygen uptake (VO_2peak) and work economy (WE) at a standardized workload are different when tested by arm crank ergometry (ACE) and wheelchair ergometry (WCE). Methods. Twelve paraplegic men with spinal cord injury (SCI) in stable neurological condition participated in this cross-sectional repeated-measures study. We determined VO_2peak and peak power output (PO_peak) values during ACE and WCE in a work-matched protocol. Work economy was tested at a standardized workload of 30 Watts (W) for both ACE and WCE. Results. There were no significant differences in VO_2peak (mL·kg⁻¹·min⁻¹) between ACE (27.3 ± 3.2) and WCE (27.4 ± 3.8) trials, and a Bland-Altman plot shows that findings are within 95% level of agreement. WE or oxygen consumption at 30 W (VO_2-30W) was significantly lower during WCE compared to ACE (P < 0.039). Mean (95% CI) PO_peak (W) were 130 (111–138) and 100 (83–110) during ACE and WCE, respectively. Conclusion. The findings in the present study support the use of both ACE and WCE for testing peak oxygen uptake. However, WE differed between the two test modalities, meaning that less total energy is used to perform external work of 30 W during wheelchair exercise when using this WCE (VP100 Handisport ergometer). Clinical Trials Protocol Record is NCT00987155/4.2007.2271.

Exploration des cadres de construction des rampes d'accessibilité

Accessibility to buildings promotes social participation through the application of inclusive design. However, architectural frameworks for constructing accessibility ramps are based on scant scientific evidence. This article presents a statement of established standards for construction criteria for accessibility ramps and makes recommendations from the perspective of inclusive design. A literature review was performed using the databases Medline, OTseeker, PsycINFO, and CINAHL (2000 to 2013), combining keywords referring to: universal accessibility, inclusive design, accessibility ramps, biomechanics, obesity, and disabilities. Non-scientific literature was also explored (e.g. building codes). The fifty-eight articles selected were grouped under five themes: 1) ramps and users; 2) materials and climate; 3) visual reference; 4) "wayfinding"; 5) durability, aesthetics and culture. Recommendations encouraging interdisciplinary practice, pegged to inclusive design, are exhibited (e.g. tracking, tilt, contrast).

Simulation model of a lever-propelled wheelchair

Wheelchair efficiency depends significantly on the individual adjustment of the wheelchair propulsion interface. Wheelchair prescription involves reconfiguring the wheelchair to optimize it for specific user characteristics. Wheelchair tuning procedure is a complicated task that is performed usually by experienced rehabilitation engineers. In this study, we report initial results from the development of a musculoskeletal model of the wheelchair lever propulsion. Such a model could be used for the development of new advanced wheelchair approaches that allow wheelchair designers and practitioners to explore virtually, on a computer, the effects of the intended settings of the lever-propulsion interface. To investigate the lever-propulsion process, we carried out wheelchair lever propulsion experiments where joint angle, lever angle and three-directional forces and moments applied to the lever were recorded during the execution of defined propulsion motions. Kinematic and dynamic features of lever propulsion motions were extracted from the recorded data to be used for the model development. Five healthy male adults took part in these initial experiments. The analysis of the collected kinematic and dynamic motion parameters showed that lever propulsion is realized by a cyclical three-dimensional motion of upper extremities and that joint torque for propulsion is maintained within a certain range. The synthesized propulsion model was verified by computer simulation where the measured lever-angles were compared with the angles generated by the developed model simulation. Joint torque amplitudes were used to impose the torque limitation to the model joints. The results evidenced that the developed model can simulate successfully basic lever propulsion tasks such as pushing and pulling the lever.

Design of a Robotic System to Measure Propulsion Work of Over-Ground Wheelchair Maneuvers

A wheelchair-propelling robot has been developed to measure the efficiency of manual wheelchairs. The use of a robot has certain advantages compared to the use of human operators with respect to repeatability of measurements and the ability to compare many more wheelchair configurations than possible with human operators. Its design and implementation required significant engineering and validation of hardware and control systems. The robot can propel a wheelchair according to pre-programmed accelerations and velocities and measures the forces required to achieve these maneuvers. Wheel velocities were within 0.1 m/s of programmed values and coefficients of variation . Torque measurements were also repeatable with . By determining the propulsion torque required to propel the wheelchair through a series of canonical maneuvers, task-dependent input work for various wheelchairs and configurations can be compared. This metric would serve to quantify the combined inertial and frictional resistance of the mechanical system.

Measurement of hand/handrim grip forces in two different one arm drive wheelchairs

Purpose. The aim of this study was to explore the total and regional grip forces in the hand when propelling two different manual one arm drive wheelchairs: the Neater Uni-wheelchair (NUW) and a foot steered Action3 wheelchair. Methods. 17 nondisabled users were randomly assigned to each wheelchair to drive around an indoor obstacle course. The Grip, a multiple sensor system taking continuous measurement of handgrip force, was attached to the propelling hand. Total grip force in each region of the hand and total grip force across the whole hand were calculated per user per wheelchair. Results. The Action3 with foot steering only generated significantly greater total grip force in straight running compared to the NUW and also in the fingers and thumb in straight running. Conclusions. The results suggest that the Action3 with foot steering generated greater grip forces which may infer a greater potential for repetitive strain injury in the upper limb. Further work is required to explore whether the difference in grip force is of clinical significance in a disabled population.

Validity of heart rate indexes to assess wheeling efficiency in patients with spinal cord injuries

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To validate heart rate (HR) indexes for the evaluation of energy expenditure during wheelchair propulsion in people with spinal cord injury (SCI).

SETTING

SARAH Rehabilitation Hospital Network-Brasilia, Brazil.

METHODS

Forty-eight men aged 29.0±7.8 years with a SCI between C6 and L3 causing complete motor impairment were enrolled in the study. The assessment consisted of 5 min of rest while seated in the wheelchair, followed by 5 min of wheelchair propulsion at a self-selected comfortable speed. The main outcomes measured were oxygen consumption, HR, physiological cost index (PCI), total heart beat index (THBI) and propulsion cardiac cost index (PCCI).

RESULTS

Using oxygen uptake as gold standard, the highest correlations were found between this and PCCI (r=0.59, P<0.001, 95% confidence interval (CI) 0.36-0.75) and THBI (r=0.58, P<0.001, 95% CI 0.36-74.0), independently of the injury level. The PCI had the lowest correlation coefficient (r=0.38, P<0.01, 95% CI 0.11-0.60). Spearman correlation analysis showed that the indexes mostly associated with lesion level were PCCI (ρ=-0.531; P<0.001; 95% CI -0.708 to -0.291) and THBI (ρ=-0.524; P<0.001; 95% CI -0.704 to -0.282).

CONCLUSIONS

Both THBI and PCCI seem to be valid measures for assessing energy expenditure. Both indexes showed a coherent correlation with the spinal injury level.

Trajectories of musculoskeletal shoulder pain after spinal cord injury: Identification and predictors

OBJECTIVE/BACKGROUND

Although shoulder pain is a problem in up to 86% of persons with a spinal cord injury (SCI), so far, no studies have empirically identified longitudinal patterns (trajectories) of musculoskeletal shoulder pain after SCI. The objective of this study was: (1) to identify distinct trajectories of musculoskeletal shoulder pain in persons with SCI, and (2) to determine possible predictors of these trajectories.

DESIGN/METHODS

Multicenter, prospective cohort study in 225 newly injured persons with SCI.

OUTCOME MEASURE

Shoulder pain was assessed on five occasions up to 5 years after discharge. Latent class growth mixture modeling was used to identify the distinct shoulder pain trajectories.

RESULTS

Three distinct shoulder pain trajectories were identified: (1) a "No or Low pain" trajectory (64%), (2) a "High pain" (30%) trajectory, and (3) a trajectory with a "Decrease of pain" (6%). Compared with the "No or Low pain" pain trajectory, the "High pain" trajectory consisted of more persons with tetraplegia, shoulder pain before injury, limited shoulder range of motion (ROM), lower manual muscle test scores, or more spasticity at t1. Multiple logistic regression analysis showed two significant predictors for the "High pain" trajectory (as compared with the "No or Low pain" trajectory): having a tetraplegia (odds ratio (OR) = 3.2; P = 0.002) and having limited shoulder ROM (OR = 2.8; P = 0.007).

CONCLUSION

Shoulder pain in people with SCI follows distinct trajectories. At risk for belonging to the "High pain" trajectory are persons with tetraplegia and those with a limited shoulder ROM at start of active rehabilitation.

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion

The purpose of this study was to (1) evaluate the mechanical efficiency (ME) of two commercially available lever-propulsion mechanisms for wheelchairs and (2) compare the ME of lever propulsion with hand rim propulsion within the same wheelchair. Of the two mechanisms, one contained a torsion spring while the other used a roller clutch design. We hypothesized that the torsion spring mechanism would increase the ME of propulsion due to a passive recovery stroke enabled by the mechanism. Ten nondisabled male participants with no prior manual wheeling experience performed submaximal exercise tests using both lever-propulsion mechanisms and hand rim propulsion on two different wheelchairs. Cardiopulmonary parameters including oxygen uptake (VO2), heart rate (HR), and energy expenditure (En) were determined. Total external power (Pext) was measured using a drag test protocol. ME was determined by the ratio of Pext to En. Results indicated no significant effect of lever-propulsion mechanism for all physiological measures tested. This suggests that the torsion spring did not result in a physiological benefit compared with the roller clutch mechanism. However, both lever-propulsion mechanisms showed decreased VO2 and HR and increased ME (as a function of slope) compared with hand rim propulsion (p < 0.001). This indicates that both lever-propulsion mechanisms tested are more mechanically efficient than conventional hand rim propulsion, especially when slopes are encountered.

Changes in inertia and effect on turning effort across different wheelchair configurations

When executing turning maneuvers, manual wheelchair users must overcome the rotational inertia of the wheelchair system. Differences in wheelchair rotational inertia can result in increases in torque required to maneuver, resulting in greater propulsion effort and stress on the shoulder joints. The inertias of various configurations of an ultralightweight wheelchair were measured using a rotational inertia-measuring device. Adjustments in axle position, changes in wheel and tire type, and the addition of several accessories had various effects on rotational inertias. The configuration with the highest rotational inertia (solid tires, mag wheels with rearward axle) exceeded the configuration with the lowest (pneumatic tires, spoke wheels with forward axle) by 28%. The greater inertia requires increased torque to accelerate the wheelchair during turning. At a representative maximum acceleration, the reactive torque spanned the range of 11.7 to 15.0 N-m across the wheelchair configurations. At higher accelerations, these torques exceeded that required to overcome caster scrub during turning. These results indicate that a wheelchair's rotational inertia can significantly influence the torque required during turning and that this influence will affect active users who turn at higher speeds. Categorizing wheelchairs using both mass and rotational inertia would better represent differences in effort during wheelchair maneuvers.