Effect of backrest height on wheelchair propulsion biomechanics for level and uphill conditions

The effect of push frequency and stroke time on wheelchair maneuverability among wheelchair tennis athletes on hard tennis court

Wheelchair propulsion is a fundamental skill in wheelchair sports, particularly in wheelchair tennis. To achieve optimal mobility during wheelchair athletic performance, it is essential to consider propulsion techniques. This study examines the effect of push frequency and stroke duration on wheelchair maneuverability, measured by velocity during propulsion, among wheelchair tennis athletes. The athletes (N = 9; 5 elite and 4 novice) performed three tests; namely the comfortable speed propulsion test, sprint test and round-trip test; with and without holding their racquet, over their hard court. Results revealed that push frequency had positive correlation with propulsion velocity (r = 0.840, p < 0.001) while stroke time was negatively correlated with velocity (r = -0.859, p < 0.001). Propulsion performance between elite and novice wheelchair athletes, and between propelling with and without racquet were also reflected through these parameters. The rate of perceived exertion (RPE) had significantly positive but low correlation with velocity and push frequency, and significant negative correlation with stroke time. This study could serve as a recommendation for wheelchair tennis athletes and coaches in planning their training protocols and techniques.

Steering-by-leaning facilitates intuitive movement control and improved efficiency in manual wheelchairs

BACKGROUND

Manual wheelchair propulsion is widely accepted to be biomechanically inefficient, with a high prevalence of shoulder pain and injuries among users. Directional control during wheelchair movement is a major, yet largely overlooked source of energy loss: changing direction or maintaining straightforward motion on tilted surfaces requires unilateral braking. This study evaluates the efficiency of a novel steering-by-leaning mechanism that guides wheelchair turning through upper body leaning.

METHODS

16 full-time wheelchair users and 15 able-bodied novices each completed 12 circuits of an adapted Illinois Agility Test-course that included tilted, straight, slalom, and 180° turning sections in a prototype wheelchair at a self-selected functional speed. Trials were alternated between conventional and steering-by-leaning modes while propulsion forces were recorded via instrumented wheelchair wheels. Time to completion, travelled distance, positive/negative power, and work done, were all calculated to allow comparison of the control modes using repeated measures analysis of variance.

RESULTS

Substantial average energy reductions of 51% (able-bodied group) and 35% (wheelchair user group) to complete the task were observed when using the steering-by-leaning system. Simultaneously, able-bodied subjects were approximately 23% faster whereby completion times did not differ for wheelchair users. Participants in both groups wheeled some 10% further with the novel system. Differences were most pronounced during turning and on tilted surfaces where the steering-by-leaning system removed the need for braking for directional control.

CONCLUSIONS

Backrest-actuated steering systems on manual wheelchairs can make a meaningful contribution towards reducing shoulder usage while contributing to independent living. Optimisation of propulsion techniques could further improve functional outcomes.

Quantification of the Risk of Musculoskeletal Disorders of the Upper Limb Using Fuzzy Logic: A Study of Manual Wheelchair Propulsion

BACKGROUND

For manual wheelchair users, overuse of the upper limbs can cause upper limb musculoskeletal disorders, which can lead to a loss of autonomy. The main objective of this study was to quantify the risk level of musculoskeletal disorders of different slope propulsions in manual wheelchair users using fuzzy logic.

METHODS

In total, 17 spinal cord injury participants were recruited. Each participant completed six passages on a motorized treadmill, the inclination of which varied between (0° to 4.8°). A motion capture system associated with instrumented wheels of a wheelchair was used. Using a biomechanical model of the upper limb and the fuzzy logic method, an Articular Discomfort Index (ADI) was developed.

RESULTS

We observed an increase in articular discomfort during propulsion on a slope with increasing discomfort at the shoulder, elbow and wrist, due to an increase in kinetics. There was a kinetically significant change in the kinetic global ADI (22 to 25%) and no change in the kinematic. The ADI increased from 14 to 36% during slope propulsion for each joint.

CONCLUSION

The quantification of the level of discomfort helps us to highlight the situations with the most high-risk exposures and to identify the parameters responsible for this discomfort.

Influence of sitting posture on anterior buttock sliding during wheelchair propulsion of hemiplegic stroke patients

Miyasaka H, Nakagawa Y, Okazaki H, Sonoda S. Influence of sitting posture on anterior buttock sliding during wheelchair propulsion of hemiplegic stroke patients. Jpn J Compr Rehabil Sci 2023; 14: 54-59.

Objectives

This study investigated the influence of different sitting postures on wheelchair propulsion ability.

Methods

The subjects were stroke patients who scored at least 2 points on the Stroke Impairment Assessment Set for abdominal muscle strength and trunk verticality and 3 points for non-paralytic side lower-limb muscle strength. Moreover, the patients were divided by their everyday wheelchair propulsion posture: Lean on Back Support (LBS); n = 8), those who leaned their back against the back support; and non-LBS (n = 11), those who moved their back away from the back support. For the wheelchair propulsion method, straight one-hand, one-leg propulsion was used on the non-paralyzed side for 10 m, followed by turning around a target 3 m ahead on each of the paralyzed and non-paralyzed sides. We then compared the propulsion times, number of propulsions, and difference in length from the front end of the patella on the non-paralyzed side to the front end of the seat surface (buttock sliding distance) between the groups.

Results

The buttock sliding distance was significantly shorter in the non-LBS group than in the LBS group in the paralyzed and non-paralyzed side turning tasks (p < 0.05). Propulsion times, number of propulsions, and grip strength did not differ significantly between the groups.

Conclusion

Even in patients with good trunk function, propulsion while leaning against the back support can easily result in anterior buttock sliding, leading to a secondary risk of injury. These results suggest that it is necessary to provide guidance on the propulsion posture and seating to hold the trunk vertically to minimize anterior sliding during propulsion.

Manual Wheelchair Equipped with a Planetary Gear-Research Methodology and Preliminary Results

The purpose of the study was to create a research methodology for testing the newly developed wheelchair drive, which allows the operator to choose the gear ratio and, thus, makes it possible to change the propulsion torque value. The aim was to choose such conditions in the experiment, that would result in great enough changes in the participant’s muscle load and body kinematics for it to be possible to register them with applied measuring methods. Surface electromyography was used to assess the effort that was required for the propulsion of a wheelchair under different conditions. Additionally, upper limb motion capture measurements were also performed. The preliminary results show that the muscular effort of the participant propelling the wheelchair increases with the load—resulting from both the gear ratio and the inclination angle. At the same time, the position of the motion range of upper limb individual segments changes significantly. Simultaneously, the mean value of the shoulder displacement and its angle of rotation decreases.

How Was Studied the Effect of Manual Wheelchair Configuration on Propulsion Biomechanics: A Systematic Review on Methodologies

Background

For both sports and everyday use, finding the optimal manual wheelchair (MWC) configuration can improve a user's propulsion biomechanics. Many studies have already investigated the effect of changes in MWC configuration but comparing their results is challenging due to the differences in experimental methodologies between articles.

Purpose

The present systematic review aims at offering an in-depth analysis of the methodologies used to study the impact of MWC configuration on propulsion biomechanics, and ultimately providing the community with recommendations for future research.

Methods

The reviewing process followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart on two databases (Scopus and PubMed) in March 2022.

Results

Forty-five articles were included, and the results highlighted the multiplicity of methodologies regarding different experimental aspects, including propulsion environment, experimental task, or measurement systems, for example. More importantly, descriptions of MWC configurations and their modifications differed significantly between studies and led to a lack of critical information in many cases.

Discussion

Studying the effect of MWC configuration on propulsion requires recommendations that must be clarified: (1) the formalism chosen to describe MWC configuration (absolute or relative) should be consistent with the type of study conducted and should be documented enough to allow for switching to the other formalism; (2) the tested MWC characteristics and initial configuration, allowing the reproduction or comparison in future studies, should be properly reported; (3) the bias induced by the experimental situation on the measured data must be considered when drawing conclusions and therefore experimental conditions such as propulsion speed or the effect of the instrumentation should be reported.

Conclusion

Overall, future studies will need standardization to be able to follow the listed recommendations, both to describe MWC configuration and mechanical properties in a clear way and to choose the experimental conditions best suited to their objectives.

Assessment of Wheelchair Propulsion Performance in an Immersive Virtual Reality Simulator

Maneuvering a wheelchair is an important necessity for the everyday life and social activities of people with a range of physical disabilities. However, in real life, wheelchair users face several common challenges: articulate steering, spatial relationships, and negotiating obstacles. Therefore, our research group has developed a head-mounted display (HMD)-based intuitive virtual reality (VR) stimulator for wheelchair propulsion. The aim of this study was to investigate the feasibility and efficacy of this VR stimulator for wheelchair propulsion performance. Twenty manual wheelchair users (16 men and 4 women) with spinal cord injuries ranging from T8 to L2 participated in this study. The differences in wheelchair propulsion kinematics between immersive and non-immersive VR environments were assessed using a 3D motion analysis system. Subjective data of the HMD-based intuitive VR stimulator were collected with a Presence Questionnaire and individual semi-structured interview at the end of the trial. Results indicated that propulsion performance was very similar in terms of start angle (p = 0.34), end angle (p = 0.46), stroke angle (p = 0.76), and shoulder movement (p = 0.66) between immersive and non-immersive VR environments. In the VR episode featuring an uphill journey, an increase in propulsion speed (p < 0.01) and cadence (p < 0.01) were found, as well as a greater trunk forward inclination (p = 0.01). Qualitative interviews showed that this VR simulator made an attractive, novel impression and therefore demonstrated the potential as a tool for stimulating training motivation. This HMD-based intuitive VR stimulator can be an effective resource to enhance wheelchair maneuverability experiences.

Seating and positioning system in wheelchairs of people with disabilities: a retrospective study

OBJECTIVE

To characterize and quantify the seating and positioning items in wheelchairs prescribed and dispensed from 2005-2018 in relation to the necessities of the diagnoses served.

METHODS

A convenience cross-sectional sample survey was used in the setting of an occupational therapy service from a specialized orthopaedic hospital. Records of people with disabilities who use a wheelchair (n = 1730) were surveyed for the following data: sociodemographic information (gender and age), diagnosis, whether a new wheelchair was received, whether wheelchair seating and positioning system were received, and the prescribed items.

RESULTS

Of the 1730 users, 73.7% received a new wheelchair and 26.3% already had one donated by other services and/or purchased by the patient. Almost all the wheelchairs needed seating and positioning system in their structure (82.3%), and only 307 wheelchairs (17.7%) did not require any. The most frequent item was the hip belt (82.3%), followed by the removable solid wooden seat, and removable solid wooden backrest (81.3 and 80.9%, respectively).

CONCLUSIONS

It is noted that the sample studied required many seating and positioning items for their wheelchairs. Despite the high demand for these assistive technological resources, research in this area is scarce. Little is known about which seating and positioning system is ideal for each user profile, which makes it difficult to organize the services that act in the provision of such equipment and the professional practice based on evidence.Implications for RehabilitationSeating and positioning system in wheelchair provide the user with the postural control necessary for daily activities, the maintenance of independence, and interaction with the environment.Indicating the best seating and positioning system is one of the most challenging tasks for healthcare professionals specializing in its prescription because it can be difficult to assess which components best meet the needs of an individual.The research proposed by this study has produced important evidences for the clinical practice of professionals that act on the prescription of wheelchairs and seating and positioning items for people with disabilities, presenting data that contribute to a better indication of these equipment's.

Increased Seat Dump Angle in a Manual Wheelchair Is Associated With Changes in Thoracolumbar Lordosis and Scapular Kinematics During Propulsion

OBJECTIVE

To quantify and compare spinal curvature and shoulder kinematics throughout the manual wheelchair (MWC) propulsion cycle for individuals with spinal cord injury (SCI) who were seated at 2 different seat dump angles.

DESIGN

Single-group, repeated-measures study.

SETTING

Academic medical center.

PARTICIPANTS

Individuals (N=28) with SCI or spinal cord disease who used MWCs completed a telephone screening, and 21 of them were eligible and completed the study.

INTERVENTIONS

Participants' personal MWCs were modified to have seat dump angles of 0° or 14°, with a vertical backrest. Participants completed at least 3 propulsion cycles in each condition, during which spine and shoulder motion data were collected with fiberoptic and electromagnetic sensors, respectively.

MAIN OUTCOME MEASURES

Thoracolumbar spinal curvature, glenohumeral kinematics, and scapulothoracic kinematics at the start of push (SP), mid-push (MP), end of push (EP), and mid-recovery.

RESULTS

Participants had significantly less lordosis in the 14° condition for all propulsion events. Median differences ranged from 2.0° to 4.6°. Lordosis differences were more pronounced in those with low SCI. Scapulothoracic internal rotation was increased in the 14° condition at SP and MP (mean differences, 2.5° and 2.7°, respectively). Relative downward rotation increased in the 14° condition at SP and MP (mean differences, 2.4° and 2.1°, respectively). Scapulothoracic differences were more pronounced in those with high SCI. No glenohumeral rotations were significantly different between the conditions.

CONCLUSIONS

Scapulothoracic kinematics and spinal curvature differences during propulsion may be associated with the position of other body segments or postural stability. Because no differences were observed at the glenohumeral joint, the risk of subacromial impingement may not be affected by this seat angle change.

A study on effects of backrest thickness on the upper arm and trunk muscle load during wheelchair propulsion

[Purpose] The purpose of this study was to investigate the effects of the thickness of a wheelchair backrest provided for support and comfort on upper arm and trunk muscle load during wheelchair propulsion by using accelerometers. [Subjects and Methods] The Fourteen healthy participants were enrolled in this study. The study compared effects of three backrest conditions including no pad, a 3-cm-thick lumbar pad, and a 6-cm-thick lumbar pad. The instruments used for measurement were used two accelerometers. The participants were asked to propel their wheelchairs, which had been equipped with two accelerometers, 30 times. [Results] The intensity of muscle movement with the 3-cm-thick lumbar pad was significantly lower than the intensities with no lumbar pad and the 6-cm-thick lumbar pad. The muscle intensity did not differ significantly between the no pad and 6-cm-thick lumbar pad conditions. [Conclusion] An appropriately thick backrest has good effects on upper arm and trunk muscles during wheelchair propulsion. In the future, we must consider the appropriate backrest thickness for providing wheelchair users with a comfortable wheelchair.

Trunk and shoulder kinematic and kinetic and electromyographic adaptations to slope increase during motorized treadmill propulsion among manual wheelchair users with a spinal cord injury

The main objective was to quantify the effects of five different slopes on trunk and shoulder kinematics as well as shoulder kinetic and muscular demands during manual wheelchair (MWC) propulsion on a motorized treadmill. Eighteen participants with spinal cord injury propelled their MWC at a self-selected constant speed on a motorized treadmill set at different slopes (0°, 2.7°, 3.6°, 4.8°, and 7.1°). Trunk and upper limb movements were recorded with a motion analysis system. Net shoulder joint moments were computed with the forces applied to the handrims measured with an instrumented wheel. To quantify muscular demand, the electromyographic activity (EMG) of the pectoralis major (clavicular and sternal portions) and deltoid (anterior and posterior fibers) was recorded during the experimental tasks and normalized against maximum EMG values obtained during static contractions. Overall, forward trunk flexion and shoulder flexion increased as the slope became steeper, whereas shoulder flexion, adduction, and internal rotation moments along with the muscular demand also increased as the slope became steeper. The results confirm that forward trunk flexion and shoulder flexion movement amplitudes, along with shoulder mechanical and muscular demands, generally increase when the slope of the treadmill increases despite some similarities between the 2.7° to 3.6° and 3.6° to 4.8° slope increments.

Pushrim biomechanical changes with progressive increases in slope during motorized treadmill manual wheelchair propulsion in individuals with spinal cord injury

The purpose of this study was to quantify the effects of five distinct slopes on spatiotemporal and pushrim kinetic measures at the nondominant upper limb during manual wheelchair (MWC) propulsion on a motorized treadmill in individuals with spinal cord injury (SCI). Eighteen participants with SCI propelled their MWC at a self-selected natural speed on a treadmill at different slopes (0, 2.7, 3.6, 4.8, and 7.1 degrees). Spatiotemporal parameters along with total force and tangential components of the force applied to the pushrim, including mechanical effective force, were calculated using an instrumented wheel. The duration of the recovery phase was 54% to 70% faster as the slope increased, whereas the duration of the push phase remained similar. The initial contact angles migrated forward on the pushrim, while the final and total contact angles remained similar as the slope increased. As the slope increased, the mean total force was 93% to 201% higher and the mean tangential component of the force was 96% to 176% higher than propulsion with no slope. Measures were similar for the 2.7 and 3.6 degrees slopes. Overall, the recovery phase became shorter and the forces applied at the pushrim became greater as the slope of the treadmill increased during motorized treadmill MWC propulsion.

Aspects of manual wheelchair configuration affecting mobility: a review

Many aspects relating to equipment configuration affect users' actions in a manual wheelchair, determining the overall mobility performance. Since the equipment components and configuration determine both stability and mobility efficiency, configuring the wheelchair with the most appropriate set-up for individual users' needs is a difficult task. Several studies have shown the importance of seat/backrest assembly and the relative position of the rear wheels to the user in terms of the kinetics and kinematics of manual propulsion. More recently, new studies have brought to light evidence on the inertial properties of different wheelchair configurations. Further new studies have highlighted the handrim as a key component of wheelchair assembly, since it is the interface through which the user drives the chair. In light of the new evidence on wheelchair mechanics and propulsion kinetics and kinematics, this article presents a review of the most important aspects of wheelchair configuration that affect the users' actions and mobility.

Using a mobility assistance dog reduces upper limb effort during manual wheelchair ramp ascent in an individual with spinal cord injury

OBJECTIVE

To compare the mechanical and muscular efforts generated in the non-dominant upper limb (U/L) when ascending a ramp with and without the use of a mobility assistance dog (AD(Mob)) in a manual wheelchair user with a spinal cord injury.

METHOD

The participant ascended a ramp at natural speed using his personal wheelchair with (three trials) and without (three trials) his AD(Mob). Movement parameters of the wheelchair, head, trunk, and non-dominant U/L (i.e. hand, forearm, and arm segments) were recorded with a motion analysis system. The orthogonal force components applied on the hand rims by the U/Ls were computed with instrumented wheels. Muscular activity data of the clavicular fibers of the pectoralis major, the anterior fibers of the deltoid, the long head of the biceps brachii, and the long head of the triceps brachii were collected at the non-dominant U/L.

RESULTS

During uphill propulsion with the AD(Mob), the total and tangential forces applied at the non-dominant handrim, along with the rate of rise of force, were reduced while mechanical efficiency was improved compared to uphill propulsion without the AD(Mob). Similarly, the resultant net joint movements (wrist, elbow, and shoulder) and the relative muscular demands (biceps, triceps, anterior deltoid, pectoralis major) decreased during uphill propulsion with an AD(Mob) versus without an AD(Mob).

CONCLUSION

Propelling uphill with the assistance of an AD(Mob) reduces U/L efforts and improves efficiency compared to propelling uphill without its assistance in a manual wheelchair user with a spinal cord injury.