Wheelchair propulsion demands during outdoor community ambulation

Upper limb cranking asymmetry during a Wingate anaerobic test in wheelchair basketball players

INTRODUCTION

Interlimb asymmetry of strength and/or motor coordination could limit the performance of wheelchair athletes or increase their risk of injury. Studies of interlimb asymmetry in the lower limbs have shown high between-subject variability that does not depend on the side of dominance and that does not change with fatigue. Upper limb asymmetry is particularly large in manual wheelchair athletes with a lower degree of impairment. The aim of this study was to evaluate interlimb asymmetry of forces developed during an upper limb Wingate anaerobic test, the effects of fatigue on force, and differences between high- and low-point players.

METHOD

Twenty-five wheelchair basketball players (13 females and 12 males) of male and female national French teams performed a 30s anaerobic Wingate test on an arm ergometer. Participants were classified into two functional categories, high-point (classed from 3 to 4.5) and low-point (classed from 1 to 2.5), according to the International Wheelchair Basketball Federation classification. Left and right arm forces were measured during the pushing and pulling phases at peak power, 10s, and the end of the 30s test.

RESULTS

Upper limb asymmetry changed with fatigue during each phase. Force asymmetry differed between peak power, 10s and 30s, with no consistent increase or decrease. Asymmetry did not differ significantly between low- and high-point players but tended to be greater in high-point players. Asymmetry tended to be greater in the females, with significant differences between the males and females in the push phase.

CONCLUSION

Inter-subject variability was high, but forces were asymmetric for most participants, especially females. The Wingate anaerobic test could highlight problematic asymmetries that might impact daily life or sports performance.

Effects of Incremental Changes to Frame Mass on Manual Wheelchair Propulsion Cost

The objective of this study was to assess the effects of small, incremental additions to wheelchair frame mass (0 kg, +2 kg, and +4 kg) on the mechanical propulsion characteristics in both straight and curvilinear maneuvers. A robotic propulsion system was used to propel a manual wheelchair over a smooth tiled surface following rectilinear ("Straight") and curvilinear ("Slalom") trajectories. Three unique loading conditions were tested. Propulsion costs and system rolling resistance estimations were empirically collected using the robotic wheelchair tester. Propulsion cost values were equivalent across all loading conditions over the Slalom trajectory. In the Straight trajectory, adding 2 kg on the axle had equivalent propulsion cost to the unloaded configuration. Adding 4 kg on axle was comparable, but not equivalent, to the unloaded configuration with small (≤4.1%) increases in propulsion cost. This study demonstrates that small (0-4 kg) changes to the frame mass have no meaningful impacts on the propulsion characteristics of the manual wheelchair system. Differences in propulsion cost and rolling resistance were detectable but contextually insignificant.

Classification of Wheelchair Related Shoulder Loading Activities from Wearable Sensor Data: A Machine Learning Approach

Shoulder problems (pain and pathology) are highly prevalent in manual wheelchair users with spinal cord injury. These problems lead to limitations in activities of daily life (ADL), labor- and leisure participation, and increase the health care costs. Shoulder problems are often associated with the long-term reliance on the upper limbs, and the accompanying "shoulder load". To make an estimation of daily shoulder load, it is crucial to know which ADL are performed and how these are executed in the free-living environment (in terms of magnitude, frequency, and duration). The aim of this study was to develop and validate methodology for the classification of wheelchair related shoulder loading ADL (SL-ADL) from wearable sensor data. Ten able bodied participants equipped with five Shimmer sensors on a wheelchair and upper extremity performed eight relevant SL-ADL. Deep learning networks using bidirectional long short-term memory networks were trained on sensor data (acceleration, gyroscope signals and EMG), using video annotated activities as the target. Overall, the trained algorithm performed well, with an accuracy of 98% and specificity of 99%. When reducing the input for training the network to data from only one sensor, the overall performance decreased to around 80% for all performance measures. The use of only forearm sensor data led to a better performance than the use of the upper arm sensor data. It can be concluded that a generalizable algorithm could be trained by a deep learning network to classify wheelchair related SL-ADL from the wearable sensor data.

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.

Manual wheelchair biomechanics while overcoming various environmental barriers: A systematic review

During manual wheelchair (MWC) locomotion, the user's upper limbs are subject to heavy stresses and fatigue because the upper body is permanently engaged to propel the MWC. These stresses and fatigue vary according to the environmental barriers encountered outdoors along a given path. This study aimed at conducting a systematic review of the literature assessing the biomechanics of MWC users crossing various situations, which represent physical environmental barriers. Through a systematic search on PubMed, 34 articles were selected and classified according to the investigated environmental barriers: slope; cross-slope; curb; and ground type. For each barrier, biomechanical parameters were divided into four categories: spatiotemporal parameters; kinematics; kinetics; and muscle activity. All results from the different studies were gathered, including numerical data, and assessed with respect to the methodology used in each study. This review sheds light on the fact that certain situations (cross-slopes and curbs) or parameters (kinematics) have scarcely been studied, and that a wider set of situations should be studied. Five recommendations were made at the end of this review process to standardize the procedure when reporting materials, methods, and results for the study of biomechanics of any environmental barrier encountered in MWC locomotion: (i) effectively reporting barriers' lengths, grades, or heights; (ii) striving for standardization or a report of the approach conditions of the barrier, such as velocity, especially on curbs; (iii) reporting the configuration of the used MWC, and if it was fitted to the subject's morphology; (iv) reporting rotation sequences for the expression of moments and kinematics, and when used, the definition of the musculoskeletal model; lastly (v) when possible, reporting measurement uncertainties and model reconstruction errors.

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.

A Comparison Between Conventional and Terrain-Specific Adaptive Pushrim-Activated Power-Assisted Wheelchairs

Pushrim-activated power-assisted wheels (PAPAWs) are assistive technologies that provide on-demand propulsion assistance to wheelchair users. In this study, we aimed to develop an adaptive PAPAW controller that responds effectively to changes in environmental conditions (e.g., type of surface or terrain). Experiments were conducted to collect kinematics of wheelchair motion using a frame-mounted inertial measurement unit (IMU) while performing a variety of wheelchair activities on different indoor/outdoor terrains. Statistical characteristics of velocity and acceleration measurements were extracted and used to develop a terrain classification framework to identify certain indoor and outdoor terrains. The terrain classification framework, based on random forest classification algorithms and kinematic features, was implemented and tested in our laboratory-developed PAPAW. This computationally efficient terrain classification framework was successfully implemented and tested in real-time. The power-assist ratio of each wheel was adjusted based on the type of terrain (e.g., more assistance was provided on outdoor terrains). Our findings revealed that propulsion effort (e.g., peak input torque) on asphalt was significantly reduced when using adaptive controllers compared to conventional PAPAW controllers. In addition, subjective views of participants regarding the workload of wheelchair propulsion (e.g., physical/cognitive effort) supported the positive effects of adaptive PAPAW controllers. We believe that the adoption of terrain-specific adaptive controllers has the potential to improve the accessibility of outdoor terrains and to prevent or delay upper extremity joint degeneration or pain.

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.

Scoping review of the rolling resistance testing methods and factors that impact manual wheelchairs

Introduction

Rolling resistance (RR) is a drag force acting on manual wheelchairs that is associated with increased propulsion force and is linked to secondary disabling conditions of the upper limbs. A scoping review was conducted to understand how RR of manual wheelchairs has been measured and to identify limitations of those test methods and the factors tested.

Methods

A total of 42 papers were identified and reviewed, and test methods were categorized based on the measurement style of RR, testing level, and if multiple parameters could be tested. Additionally, 34 articles were reviewed for what factors were tested.

Results

Seven different testing methods categories were identified: drag test, treadmill, motor draw, deceleration, physiological expenditure, ergometer/dynamometer, and robotic test rig. Relevant articles were categorized into testing factor categories: camber, toe, tire type, tire pressure, caster type, mass, mass distribution, and type of surface.

Conclusions

The variety of testing methods suggests the need for a standardized method that can be used for wheelchair wheel design and selection to reduce RR. It is important to use adjustments, such as a forward rear axle position to mitigate RR as well as using high-pressure pneumatic tires that are properly inflated.

Does the setting matter? Observing wheelchair transfers across different environmental conditions

The setting in which wheelchair transfers are performed can affect the difficulty and the risks associated with completion. This article presents results from an observational study involving 13 wheelchair users performing independent transfers across four settings. The aim is to understand how the environment affects how different types of independent transfers are performed. Descriptive analysis was performed alongside an objective assessment using the Transfer Assessment Instrument (TAI). The perceived difficulty reported after each transfer was also collected. Two participants exhibited radically different transferring techniques in different scenarios. Additionally, the transferring scenario was found to significantly affect the perceived difficulty of sitting transfers (toilet 2.17 ±.88; bed 1.47 ±.65, p =.001; car 1.63 ±.82, p =.012) and standing transfers (car 3.5 ±.71; bed 1 ± 0, p =.03; toilet 1 ± 0, p =.03), and the TAI score attributed to sitting pivot with use of a transfer board (couch 4.3 ±.88; bed 6.93 ± 1.29, p =.022; car 7.13 ± 1.32, p =.018). Overall, environmental constraints can lead to major technique changes and, more often, to different positioning of hands and feet which could impact the transfer's biomechanics.

Reliability and minimal detectable change of a new treadmill-based progressive workload incremental test to measure cardiorespiratory fitness in manual wheelchair users

BACKGROUND

Cardiorespiratory fitness training is commonly provided to manual wheelchair users (MWUs) in rehabilitation and physical activity programs, emphasizing the need for a reliable task-specific incremental wheelchair propulsion test.

OBJECTIVE

Quantifying test-retest reliability and minimal detectable change (MDC) of key cardiorespiratory fitness measures following performance of a newly developed continuous treadmill-based wheelchair propulsion test (WPT_Treadmill).

METHODS

Twenty-five MWUs completed the WPT_Treadmill on two separate occasions within one week. During these tests, participants continuously propelled their wheelchair on a motorized treadmill while the exercise intensity was gradually increased every minute until exhaustion by changing the slope and/or speed according to a standardized protocol. Peak oxygen consumption (VO_2peak), carbon dioxide production (VCO_2peak), respiratory exchange ratio (RER_peak), minute ventilation (VE_peak) and heart rate (HR_peak) were computed. Time to exhaustion (TTE) and number of increments completed were also measured. Intra-class correlation coefficients (ICC) were calculated to determine test-retest reliability. Standard error of measurement (SEM) and MDC_90% values were calculated.

RESULTS

Excellent test-retest reliability was reached for almost all outcome measures (ICC=0.91-0.76), except for RER_peak (ICC=0.58), which reached good reliability. TTE (ICC=0.89) and number of increments (ICC=0.91) also reached excellent test-retest reliability. For the main outcome measures (VO_2peak and TTE), absolute SEM was 2.27 mL/kg/min and 0.76 minutes, respectively and absolute MDC_90% was 5.30 mL/kg/min and 1.77 minutes, respectively.

CONCLUSION

The WPT_Treadmill is a reliable test to assess cardiorespiratory fitness among MWUs. TTE and number of increments could be used as reliable outcome measures when VO₂ measurement is not possible.

Sensewheel: an adjunct to wheelchair skills training

The purpose of this Letter was to investigate the influence of real-time verbal feedback to optimise push arc during over ground manual wheelchair propulsion. Ten healthy non-wheelchair users pushed a manual wheelchair for a distance of 25 m on level paving, initially with no feedback and then with real-time verbal feedback aimed at controlling push arc within a range of 85°-100°. The real-time feedback was provided by a physiotherapist walking behind the wheelchair, viewing real-time data on a tablet personal computer received from the Sensewheel, a lightweight instrumented wheelchair wheel. The real-time verbal feedback enabled the participants to significantly increase their push arc. This increase in push arc resulted in a non-significant reduction in push rate and a significant increase in peak force application. The intervention enabled participants to complete the task at a higher mean velocity using significantly fewer pushes. This was achieved via a significant increase in the power generated during the push phase. This Letter identifies that a lightweight instrumented wheelchair wheel such as the Sensewheel is a useful adjunct to wheelchair skills training. Targeting the optimisation of push arc resulted in beneficial changes in propulsion technique.

Wheeled mobility skills of wheelchair basketball players: a randomized controlled study

PURPOSE

The aim of this study was to assess the influence of wheelchair basketball sport on the functional abilities of wheelchair users.

METHOD

This is a randomized controlled study. Wheelchair basketball players (n = 111) and non-player (n = 85) were included in this study. We administered the questionnaire version of the wheelchair skills test questionnaire (WST_Q), recording the participants' capacity and performance scores on each of 32 skills.

RESULTS

Player group have the baseline values of WST_Q higher than control group. The mean total percentage score of player group was significantly greater than control group (p < 0.05). The get over 15 cm level (respectively, rations of capacity and performance of groups: player/control: 50.5-20% and 54.1-24.7%) and the ascends 10° incline (player/control 96.4-48.2% and 98.2-54.1%).

CONCLUSIONS

Participation in regular wheelchair basketball sport may preserve and augment functional abilities in with wheelchair user Implications for rehabilitation The skills-sports relationship is reciprocal. With increased wheelchair skills, people may be more inclined to engage in sports; subsequently, with greater sports, wheelchair skills could improve. Wheelchair mobility skills during clinical rehabilitation should reflect the daily activities and needs of each wheelchair user. WST-Q provides advantages in terms of requiring less time and material in using of clinical.

Linking wheelchair kinetics to glenohumeral joint demand during everyday accessibility activities

The aim of the study was to investigate if push-rim kinetics could be used as markers of glenohumeral joint demand during manual wheelchair accessibility activities; demonstrating a method of biomechanical analysis that could be used away from the laboratory. Propulsion forces, trunk and upper limb kinematics and surface electromyography were recorded during four propulsion tasks (level, 2.5% cross slope, 6.5% incline and 12% incline). Kinetic and kinematic data were applied to an OpenSim musculoskeletal model of the trunk and upper limb, to enable calculation of glenohumeral joint contact force. Results demonstrated a positive correlation between propulsion forces and glenohumeral joint contact forces. Both propulsion forces and joint contact forces increased as the task became more challenging. Participants demonstrated increases in trunk flexion angle as the requirement for force application increased, significantly so in the 12% incline. There were significant increases in both resultant glenohumeral joint contact forces and peak and mean normalized muscle activity levels during the incline tasks. This study demonstrated the high demand placed on the glenohumeral joint during accessibility tasks, especially as the gradient of incline increases. A lightweight instrumented wheelchair wheel has potential to guide the user to minimize upper limb demand during daily activity.

An Investigation of Bilateral Symmetry During Manual Wheelchair Propulsion

Studies of manual wheelchair propulsion often assume bilateral symmetry to simplify data collection, processing, and analysis. However, the validity of this assumption is unclear. Most investigations of wheelchair propulsion symmetry have been limited by a relatively small sample size and a focus on a single propulsion condition (e.g., level propulsion at self-selected speed). The purpose of this study was to evaluate bilateral symmetry during manual wheelchair propulsion in a large group of subjects across different propulsion conditions. Three-dimensional kinematics and handrim kinetics along with spatiotemporal variables were collected and processed from 80 subjects with paraplegia while propelling their wheelchairs on a stationary ergometer during three different conditions: level propulsion at their self-selected speed (free), level propulsion at their fastest comfortable speed (fast), and propulsion on an 8% grade at their level, self-selected speed (graded). All kinematic variables had significant side-to-side differences, primarily in the graded condition. Push angle was the only spatiotemporal variable with a significant side-to-side difference, and only during the graded condition. No kinetic variables had significant side-to-side differences. The magnitudes of the kinematic differences were low, with only one difference exceeding 5°. With differences of such small magnitude, the bilateral symmetry assumption appears to be reasonable during manual wheelchair propulsion in subjects without significant upper-extremity pain or impairment. However, larger asymmetries may exist in individuals with secondary injuries and pain in their upper extremity and different etiologies of their neurological impairment.

How assistive technology use by individuals with disabilities impacts their caregivers: a systematic review of the research evidence

Informal caregivers are a critical yet frequently unacknowledged part of the healthcare system. It is commonly presumed that providing assistive technology will decrease the burden of their care provision; however, no review has evaluated the evidence behind this assumption. Therefore, a systematic review was undertaken to evaluate evidence of the impact of assistive technology use by care recipients on their informal caregivers. Data sources included EMBASE, MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Web of Science, PsychINFO, PubMed, and active researchers in this area. Twenty-two studies met the specified inclusion criteria. Collectively, the findings suggest that assistive technology use helps caregivers by diminishing some of the physical and emotional effort entailed in supporting individuals with disability. However, confidence in this causal connection is limited because of the study designs that were used. This undermines the understanding of the impacts of assistive technology use on the users' informal caregivers.

Validation of a biofeedback system for wheelchair propulsion training

This paper describes the design and validation of the OptiPush Biofeedback System, a commercially available, instrumented wheel system that records handrim biomechanics and provides stroke-by-stroke biofeedback and targeting for 11 propulsion variables. Testing of the system revealed accurate measurement of wheel angle (0.02% error), wheel speed (0.06% error), and handrim loads. The maximum errors in static force and torque measurements were 3.80% and 2.05%, respectively. Measured forces were also found to be highly linear (0.985 < slope < 1.011) and highly correlated to the reference forces (r² > .998). Dynamic measurements of planar forces (F_x and F_y) and axle torque also had low error (−0.96 N to 0.83 N for force and 0.10 Nm to 0.14 Nm for torque) and were highly correlated (r > .986) with expected force and torque values. Overall, the OptiPush Biofeedback System provides accurate measurement of wheel dynamics and handrim biomechanics and may be a useful tool for improving manual wheelchair propulsion.

Comparison between overground and dynamometer manual wheelchair propulsion

Laboratory-based simulators afford many advantages for studying physiology and biomechanics; however, they may not perfectly mimic wheelchair propulsion over natural surfaces. The goal of this study was to compare kinetic and temporal parameters between propulsion overground on a tile surface and on a dynamometer. Twenty-four experienced manual wheelchair users propelled at a self-selected speed on smooth, level tile and a dynamometer while kinetic data were collected using an instrumented wheel. A Pearson correlation test was used to examine the relationship between propulsion variables obtained on the dynamometer and the overground condition. Ensemble resultant force and moment curves were compared using cross-correlation and qualitative analysis of curve shape. User biomechanics were correlated (R ranging from 0.41 to 0.83) between surfaces. Overall, findings suggest that although the dynamometer does not perfectly emulate overground propulsion, wheelchair users were consistent with the direction and amount of force applied, the time peak force was reached, push angle, and their stroke frequency between conditions.

Elbow kinematics during overground manual wheelchair propulsion in individuals with tetraplegia

PURPOSE

The purpose of this study was to describe horizontal and vertical translation of the elbow and elbow angle in two planes and three speeds during manual wheelchair overground propulsion in individuals with tetraplegia.

METHODS

Seven individuals with tetraplegia who used manual wheelchairs wheeled overground at three different speeds were recruited for the study. Video motion capture methods quantified their movements. Video data were tracked and used to calculate variables describing three-dimensional elbow translation and angular orientation. Repeated measures ANOVA were used to determine effects of speed on elbow translation and elbow angle. Paired t-tests were used to evaluate left to right differences.

RESULTS

Right elbow anterior-posterior translation was found to be significantly different during slow and fast and slow and normal speeds. Vertical and medial-lateral translation of the right elbow was significantly different between slow and fast speeds. No significant effects for speed during left elbow movement or side-to-side movement were found. No significant effects were found for elbow angle across speeds or from side-to-side. Three patterns of elbow movement emerged for anterior-posterior and medial-lateral translation and for elbow angle.

CONCLUSIONS

Results indicated that elbow translation was related to propulsion speed. Work involving this population is needed for further understanding of upper extremity kinematic patterns.

Shoulder demands in manual wheelchair users across a spectrum of activities

OBJECTIVE

Investigate shoulder joint kinetics over a range of daily activity and mobility tasks associated with manual wheelchair propulsion to characterize demands placed on the shoulder during the daily activity of manual wheelchair users.

DESIGN

Case series.

SUBJECTS

Twelve individuals who were experienced manual wheelchair users.

METHODS

Upper extremity kinematics and handrim wheelchair kinetics were measured over level propulsion, ramp propulsion, start and stop over level terrain, and a weight relief maneuver. Shoulder intersegmental forces and moments were calculated from inverse dynamics for all conditions.

RESULTS

Weight relief resulted in significantly higher forces and ramp propulsion resulted in significantly higher moments than the other conditions. Surprisingly, the start condition resulted in large intersegmental moments about the shoulder equivalent with that of the ramp propulsion, while the demand imparted by the stop condition was shown to be equivalent to level propulsion across all forces and moments.

CONCLUSIONS

This study provides characterization of daily living and mobility activities associated with manual wheelchair propulsion not previously reported and identifies activities that result in higher shoulder kinetics when compared to standard level propulsion.

Use of a geared wheelchair wheel to reduce propulsive muscular demand during ramp ascent: analysis of muscle activation and kinematics

BACKGROUND

Shoulder muscle overuse has been linked to the high prevalence of shoulder injuries in manual wheelchair users. Ramp ascent is a barrier that is often faced by manual wheelchair users that requires higher muscle activations than level wheelchair propulsion. Additionally, reported subjective measures of shoulder pain are reduced amongst manual wheelchair users when using a wheelchair wheel outfitted with a gear mechanism. The purpose of the current investigation was to investigate shoulder muscle activation levels and upper limb kinematics during ramp ascent with and without the use of a geared wheel.

METHODS

Thirteen healthy participants (6 male and 7 female) performed ramp ascent on four ramp grades (1:12, 1:10, 1:8, 1:6) using three wheel conditions (gear, no gear, standard). Electromyographic (EMG) activity of select shoulder muscles as well as kinematics of the right upper limb were collected during ramp ascent. Peak and integrated EMG as well as peak wrist, elbow, and shoulder kinematics were obtained from all ramp ascent trials.

FINDINGS

Peak EMG of the shoulder flexors decreased by an average of 17% (P0.0229) during ramp ascent with the geared wheel. Integrated EMG increased by 67% (P0.0034) as a consequence of an 86% increase (P=0.0009) in ramp ascent duration during the geared wheel condition. There were no significant differences between the non-geared and standard wheel conditions.

INTERPRETATION

Caution must be used if using the gear ratio for prolonged periods due to potential for muscle fatigue since the overall muscle effort to move a fixed distance is higher with the gear ratio. Reducing peak demands may benefit wheelchair users with performing more strenuous tasks of daily living.

Influence of varying level terrain on wheelchair propulsion biomechanics

OBJECTIVE

To evaluate manual wheelchair propulsion across level ground conditions that are encountered during everyday life.

DESIGN

Subjects included 14 individuals (13 with spinal cord injury [SCI], 1 with spina bifida) who were experienced manual wheelchair users and had no current upper extremity injury or pain complaints. Subjects propelled their wheelchairs at a self-selected speed across four different level ground conditions, including smooth and aggregate concrete and tile and carpet flooring. Temporal and kinetic measurements were obtained bilaterally from instrumented wheelchair rims during the steady-state phase of propulsion.

RESULTS

There were no side-to-side differences for any of the temporal or kinetic variables. Propulsion velocity and pushrim contact time were consistent across ground conditions. Propulsion frequency was significantly greater during both concrete conditions than either tile or carpet ground conditions. Forces and moments were greatest during the aggregate concrete ground condition and lowest during propulsion across tile flooring.

CONCLUSIONS

The rolling resistance of level surface terrain significantly impacts wheelchair propulsion biomechanics. Identification of environmental conditions that may contribute to upper extremity pathology is a step toward injury prevention and maintenance of functional abilities for the manual wheelchair user. These results may be used to assist with home and community terrain design to minimize the demands associated with wheelchair propulsion.