Using a quantitative assessment of propulsion biomechanics in wheelchair racing to guide the design of personalized gloves: a case study.

This study with a T-52 class wheelchair racing athlete aimed to combine quantitative biomechanical measurements to the athlete's perception to design and test different prototypes of a new kind of rigid gloves. Three personalized rigid gloves with various, fixed wrist extension angles were prototyped and tested on a treadmill in a biomechanics laboratory. The prototype with 45° wrist extension was the athlete's favourite as it reduced his perception of effort. Biomechanical assessment and user-experience data indicated that his favourite prototype increased wrist stability throughout the propulsion cycle while maintaining a very similar propulsion technique to the athlete's prior soft gloves. Moreover, the inclusion of an innovative attachment system on the new gloves allowed the athlete to put his gloves on by himself, eliminating the need for external assistance and thus significantly increasing his autonomy. This multidisciplinary approach helped to prototype and develop a new rigid personalized gloves concept and is clearly a promising avenue to tailor adaptive sports equipment to an athlete's needs.

Tracking the whole-body centre of mass of humans seated in a wheelchair using motion capture.

Estimating the position of the whole-body centre of mass (CoM) based on skin markers and anthropometric tables requires tracking the pelvis and lower body, which is impossible for wheelchair users due to occlusion. In this work, we present a method to track the user's whole-body CoM using visible markers affixed to the user and wheelchair where the user remains seated in their wheelchair, by expressing the pelvis and lower body segments in wheelchair coordinates. The accuracy of this method was evaluated on the anterior-posterior (AP) and medial-lateral (ML) axes by comparing the projected CoM to the centre of pressure measured by four force plates, for 11 able-bodied participants adopting 9 static postures that include extreme reaching postures. The estimation accuracy was within 33 mm (AP) and 9 mm (ML), with a precision within 23 mm (AP) and 12 mm (ML). Tracking the whole-body CoM during wheelchair propulsion will allow researchers to better understand the dynamics of propulsion, which may help devise new approaches to increase the energy transfer from the arms to the ground and reduce the risks of developing musculoskeletal disorders.

Impact of Sprinting and Dribbling on Shoulder Joint and Pushrim Kinetics in Wheelchair Basketball Athletes.

Background: While wheelchair basketball is one of the most popular Paralympic sports, it eventually causes shoulder problems and pain in many athletes. However, shoulder kinetics has never been assessed during propulsion in wheelchair basketball. This study analyzes the impact of sprinting and dribbling on pushrim and shoulder kinetics in terms of external forces and net muscular moments. Methods: A group of 10 experienced wheelchair basketball athletes with various classifications performed four, 9-m sprints on a basketball court using classic synchronous propulsion, and four sprints while dribbling forward. Pushrim and shoulder kinetics were calculated by inverse dynamics, using a motion capture device and instrumented wheels. Findings: Sprinting was associated to peak shoulder load from 13 to 346% higher than in previous studies on standard wheelchair propulsion in most force/moment components. Compared to sprinting without a ball, dribbling reduced the speed, the peak external forces in the anterior and medial direction at the shoulder, and the peak net shoulder moment of internal rotation. Interpretation: The high shoulder load calculated during both sprinting and dribbling should be considered during training sessions to avoid overloading the shoulder. Dribbling generally reduced the shoulder load, which suggests that propelling while dribbling does not put the shoulder at more risk of musculoskeletal disorders than sprinting.

Interpreting the tilt-and-torsion method to express shoulder joint kinematics.

BACKGROUND: Kinematics is studied by practitioners and researchers in different fields of practice. It is therefore critically important to adhere to a taxonomy that explicitly describes positions and movements. However, current representation methods such as cardan and Euler angles fail to report shoulder angles in a way that is easily and correctly interpreted by practitioners, and that is free from numerical instability such as gimbal lock. METHODS: In this paper, we comprehensively describe the recent Tilt-and-Torsion method and compare it to the Euler YXY method currently recommended by the International Society of Biomechanics. While using the same three rotations (plane of elevation, elevation, humeral rotation), the Tilt-and-Torsion method reports humeral rotation independently from the plane of elevation. We assess how it can be used to describe shoulder angles (1) in a simulated assessment of humeral rotation with the arm at the side, which constitutes a gimbal lock position, and (2) during an experimental functional task, with 10 wheelchair basketball athletes who sprint in straight line using a sports wheelchair. FINDINGS: In the simulated gimbal lock experiment, the Tilt-and-Torsion method provided both humeral elevation and rotation measurements, contrary to the Euler YXY method. During the wheelchair sprints, humeral rotation ranged from 14° (externally) to 13° (internally), which is consistent with typical maximal ranges of humeral rotation, compared to 65° to 50° with the Euler YXY method. INTERPRETATION: Based on our results, we recommend that shoulder angles be expressed using Tilt-and-Torsion angles instead of Euler YXY.

Impact of dribbling on spatiotemporal and kinetic parameters in wheelchair basketball athletes.

BACKGROUND: Wheelchair basketball is one of the most popular Paralympic sports. Dribbling a ball while propelling is a key feature of wheelchair basketball. Very few studies have investigated the biomechanical impact of dribbling. This study aims to analyze the impact of dribbling on the amplitude and symmetry of spatiotemporal and kinetic parameters of wheelchair propulsion. METHODS: Ten experienced wheelchair basketball athletes (31.5 ± 10.6 years old; 7 men, 3 women) with various classifications performed eight 9-m sprints along a straight line on a basketball court: four sprints using classic synchronous propulsion, and four sprints while dribbling a ball down the court. FINDINGS: Dribbling decreased velocity, mean propulsive moments and the force rate of rise, as well as increased push time, force rate of rise asymmetry and angular impulse asymmetry. All kinetic variables were asymmetric and higher on the dominant limb. INTERPRETATION: The combination of reduced velocity and propulsive moments when dribbling indicates that wheelchair basketball athletes may deliberately preserve a safety margin of acceleration to adapt to uncontrolled ball rebounds. Dribbling was not associated with any factors associated with an increased risk of musculoskeletal disorders.

Sprint performance and force application of tennis players during manual wheelchair propulsion with and without holding a tennis racket.

The objective of this exploratory research is to study the impact of holding a tennis racket while propelling a wheelchair on kinetic and temporal parameters in a field-based environment. 13 experienced wheelchair tennis players with disabilities (36.1 ± 8.2 years, 76.8 ± 15.3 kg, 174.8 ± 17.1 cm) classified between 30/8 and first series performed two 20 m sprints in a straight line, on a tennis court: one while holding a tennis racket and the second without a tennis racket. They used their own sports wheelchair. Potential participants were excluded if they had injuries or pain that impaired propulsion. Maximal total force, maximal propulsive moment, rate of rise, maximal power output, push and cycle times and maximal velocity were measured. Sprinting while holding a tennis racket increased the cycle time by 0,051 s and push time by 0,011s. Sprinting while holding a tennis racket decreased the maximal propulsive moment, maximal power output, rate of rise and maximal velocity during propulsion by 6.713 N/m, 151.108 W, 672.500 N/s and 0.429 m/s, respectively. Our results suggest that the biomechanical changes observed associated with racket propulsion are generally in a direction that would be beneficial for the risk of injury. But sprinting holding a racket seems to decrease players propulsion performance. Working on forward accelerations with a tennis racket would be a line of work for coaches.

Impact of Holding a Badminton Racket on Spatio-Temporal and Kinetic Parameters During Manual Wheelchair Propulsion.

Introduction: Para badminton entered the Paralympic world for the first time with the 2021 Paralympic Games in Tokyo. The particularity of this sport lies in the handling of the wheelchair and the racket simultaneously. To the best of our knowledge, and considering the youthfulness of this sport, it appears that no study has looked at the impact of the badminton racket on the kinetic and spatiotemporal parameters. Therefore, the aim of our study was to investigate the impact of the badminton racket on the amplitude of kinetic and spatiotemporal parameters of wheelchair propulsion, considered as propulsion effectiveness and risk of injury criteria. We hypothesized that holding a badminton racket while propelling the wheelchair modifies the kinetics and temporal parameters of the athlete's propulsion due to the difficulty to hold the handrim, therefore decreasing propulsion effectiveness and increasing risk of injury. Materials and Methods: For six 90-min sessions, 16 able-bodied individuals were introduced to badminton. No injuries hindered their propulsion. They had to propel with and without a racket held on the dominant side along a 20 m straight line at a constant velocity of 5 km/h. They all used the same sports wheelchair equipped with two instrumented wheels (SmartWheel). Results: Participants increased their maximal total force and force rate of rise but decreased their fraction of effective force with their dominant hand compared to the non-dominant hand when using a racket. In addition, they decreased their fraction of effective force, push time, cycle time, and push angle, and increased their maximal propulsive moment, maximal total force, and force rate of rise when comparing the same dominant hand with and without the racket. Discussion: Using a badminton racket modifies the athlete's force application in a way that is generally related to lower propulsion effectiveness and a higher risk for injury. Indeed, it seems that propulsion with a racket prevents from correctly grabbing the handrim.

A high sample rate, wireless instrumented wheel for measuring 3D pushrim kinetics of a racing wheelchair.

In wheelchair racing, measuring pushrim kinetics such as propulsion forces and moments is paramount for improving performance and preventing injuries. However, there is currently no instrumented racing wheel that records 3D pushrim kinetics wirelessly and at a high sample rate, which is necessary for accurately analysing wheelchair racing biomechanics. In this work, we present an instrumented wheel that measures 3D kinetics at 2500 Hz. Bidirectional wireless communication is used to interface the wheel through a smart phone. The wheel was tested with a world-class racing athlete who propelled at maximal acceleration and maximal speed on a training roller. During acceleration, the peak total force increased continuously from 186 N to 484 N while the peak tangential force was constant at 171 N ± 15 N. At higher speeds, a counterproductive tangential force was measured during the first 15% and the last 25% of the push phase, peaking at -78 N. This wheel may be of great value for both coaches and athletes to help with planning and validating training programs and adaptations to the wheelchair such as positioning. This wheel also has very high potential for further research on wheelchair racing biomechanics and on preventing shoulder pathologies associated with this sport.

Unmatched speed perceptions between overground and treadmill manual wheelchair propulsion in long-term manual wheelchair users.

BACKGROUND: Manual wheelchair (MWC) propulsion is increasingly assessed on a motorized treadmill (TM), which is often considered more ecologically valid than stationary rollers. However, no clear consensus on the similarities between overground (OG) and TM propulsion has yet been reached. Furthermore, no study has investigated the participants' perceptions of propelling a MWC on a TM compared to OG. RESEARCH QUESTION: The present study aims to assess the perception of speed when propelling on a TM vs OG, and to relate this perception to measured spatiotemporal variables, kinetics and work. METHODS: In this repeated-measures study, the propulsion's spatiotemporal variables, kinetics, and work of nineteen experienced wheelchair users with a spinal cord injury were compared between three conditions: 1) OG at a self-selected speed, 2) on a TM at a self-selected speed perceived as being similar to the OG speed (TMperceived), and 3) on a TM at the same speed as OG (TMmatched). Each variable was compared between conditions using an analysis of variance for repeated measures. RESULTS: All participants selected a lower speed for TMperceived than OG, with a difference of -0.6 m/s (-44%). This adaptation may be due to a combination of two factors: 1) the absence of speed information, and 2) the feeling of urgency to grab the wheels during the recovery phase. The power output, work per cycle, and work per minute were also much lower on TMperceived than OG. However, in contrast to other work on MWC propulsion on a TM, the kinetic variables assessed were all similar between the OG and TMmatched conditions. SIGNIFICANCE: Training on a TM should be performed at a speed that matches the OG speed and not at a self-selected speed on the TM, which would reduce the power output and work and therefore reduce the efficiency of the training.

Proposing a new index to quantify instantaneous symmetry during manual wheelchair propulsion.

Propelling a manual wheelchair (MWC) is a strenuous task that causes upper limb musculoskeletal disorders (MSD) in a large proportion of MWC users. Although most studies on MWC propulsion biomechanics assume that MWC propulsion is a relatively symmetric task, recent literature suggests that this is the case only when the assessed outcome measures are averaged over long periods of time, and not over short periods (i.e., instantaneously). No method is currently available to assess instantaneous symmetry. In this work, we present the Instantaneous Symmetry Index (ISI), a new method that quantifies how a variable has been instantaneously asymmetric during a selected time period. Thirteen experienced MWC users propelled on different cross slopes of 0%, 2%, 4%, 6% and 8%. As the cross slope is increased, the upper hand produced less propulsive moments and the lower hand produced more propulsive movements. This has been reflected in the ISI, which increased from 0.20 (0% slope) to 0.84 (8% slope) with a Spearman׳s coefficient of 0.90. The ISI has great potential to evaluate the ability of a user to propel symmetrically and synchronously, and will be a relevant measure to include in future studies on the impact of MWC propulsion asymmetry on MSD risk.

Wheelchair pushrim kinetics measurement: A method to cancel inaccuracies due to pushrim weight and wheel camber.

The commercially available SmartWheelTM is largely used in research and increasingly used in clinical practice to measure the forces and moments applied on the wheelchair pushrims by the user. However, in some situations (i.e. cambered wheels or increased pushrim weight), the recorded kinetics may include dynamic offsets that affect the accuracy of the measurements. In this work, an automatic method to identify and cancel these offsets is proposed and tested. First, the method was tested on an experimental bench with different cambers and pushrim weights. Then, the method was generalized to wheelchair propulsion. Nine experienced wheelchair users propelled their own wheelchairs instrumented with two SmartWheels with anti-slip pushrim covers. The dynamic offsets were correctly identified using the propulsion acquisition, without needing a separate baseline acquisition. A kinetic analysis was performed with and without dynamic offset cancellation using the proposed method. The most altered kinetic variables during propulsion were the vertical and total forces, with errors of up to 9N (p<0.001, large effect size of 5). This method is simple to implement, fully automatic and requires no further acquisitions. Therefore, we advise to use it systematically to enhance the accuracy of existing and future kinetic measurements.

Estimating pushrim temporal and kinetic measures using an instrumented treadmill during wheelchair propulsion: A concurrent validity study.

Using ground reaction forces recorded while propelling a manual wheelchair on an instrumented treadmill may represent a valuable alternative to using an instrumented pushrim to calculate temporal and kinetic parameters during propulsion. Sixteen manual wheelchair users propelled their wheelchair equipped with instrumented pushrims (i.e., SMARTWheel) on an instrumented dual-belt treadmill set a 1m/s during a 1-minute period. Spatio-temporal (i.e., duration of the push and recovery phase) and kinetic measures (i.e. propulsive moments) were calculated for 20 consecutive strokes for each participant. Strong associations were confirmed between the treadmill and the instrumented pushrim for the mean duration of the push phase (r=0.98) and of the recovery phase (r=0.99). Good agreement between these two measurement instruments was also confirmed with mean differences of only 0.028s for the push phase and 0.012s for the recovery phase. Strong associations were confirmed between the instrumented wheelchair pushrim and treadmill for mean (r=0.97) and peak (r=0.96) propulsive moments. Good agreement between these two measurement instruments was also confirmed with mean differences of 0.50Nm (mean moment) and 0.71Nm (peak moment). The use of a dual-belt instrumented treadmill represents an alternative to characterizing temporal parameters and propulsive moments during manual wheelchair propulsion.

A new dynamic model of the wheelchair propulsion on straight and curvilinear level-ground paths.

Independent-roller ergometers (IREs) are commonly used to simulate the behaviour of a wheelchair propelled in a straight line. They cannot, however, simulate curvilinear propulsion. To this effect, a motorised wheelchair ergometer could be used, provided that a dynamic model of the wheelchair-user system propelled on straight and curvilinear paths (WSC) is available. In this article, we present such a WSC model, its parameter identification procedure and its prediction error. Ten healthy subjects propelled an instrumented wheelchair through a controlled path. Both IRE and WSC models estimated the rear wheels' velocities based on the users' propulsive moments. On curvilinear paths, the outward wheel shows root mean square (RMS) errors of 13% in an IRE vs 8% in a WSC. The inward wheel shows RMS errors of 21% in an IRE vs 11% in a WSC. Differences between both models are highly significant (p < 0.001). A wheelchair ergometer based on this new WSC model will be more accurate than a roller ergometer when simulating wheelchair propulsion in tight environments, where many turns are necessary.

Characterization of the immediate effect of a training session on a manual wheelchair simulator with haptic biofeedback: towards more effective propulsion.

Eighteen manual wheelchair users (MWUs) with spinal cord injury participated in a training session on a new manual wheelchair simulator with haptic biofeedback (HB). The training aimed to modify participants' mechanical effective force (MEF) along the push phase to achieve a target MEF pattern slightly more effective than their pre-training pattern. More HB was provided if the participants' achieved MEF pattern deviated from the target. Otherwise, less HB was provided. The deviation between the participants' achieved MEF and the target, as well as the mean achieved MEF, were computed before, during and after the training session. During the training, participants generally exceeded the target pattern at the beginning of the push cycle and achieved it towards the end. On average, participants also increased their mean MEF by up to 15.7% on the right side and 12.4% on the left side between the pre-training and training periods. Finally, eight participants could modify their MEF pattern towards the target in post-training. The simulator tested in this study represents a valuable tool for developing new wheelchair propulsion training programs. Haptic biofeedback also provides interesting potential for training MWUs to improve propulsion effectiveness.

Effect of wheelchair frame material on users' mechanical work and transmitted vibration.

Wheelchair propulsion exposes the user to a high risk of shoulder injury and to whole-body vibration that exceeds recommendations of ISO 2631-1:1997. Reducing the mechanical work required to travel a given distance (WN-WPM, weight-normalized work-per-meter) can help reduce the risk of shoulder injury, while reducing the vibration transmissibility (VT) of the wheelchair frame can reduce whole-body vibration. New materials such as titanium and carbon are used in today's wheelchairs and are advertised to improve both parameters, but current knowledge on this matter is limited. In this study, WN-WPM and VT were measured simultaneously and compared between six folding wheelchairs (1 titanium, 1 carbon, and 4 aluminium). Ten able-bodied users propelled the six wheelchairs on three ground surfaces. Although no significant difference of WN-WPM was found between wheelchairs (P < 0.1), significant differences of VT were found (P < 0.05). The carbon wheelchair had the lowest VT. Contrarily to current belief, the titanium wheelchair VT was similar to aluminium wheelchairs. A negative correlation between VT and WN-WPM was found, which means that reducing VT may be at the expense of increasing WN-WPM. Based on our results, use of carbon in wheelchair construction seems promising to reduce VT without increasing WN-WPM.

A new dynamic model of the manual wheelchair for straight and curvilinear propulsion.

Due to their mechanical design, current wheelchair ergometers cannot simulate the behaviour of a wheelchair propelled on curvilinear paths. This is because they implement a dynamic model of the Wheelchair-user system propelled on Straight Line only (WSL). In this paper, we present a new dynamic model of the Wheelchair-user propelled on Straight and Curvilinear paths (WSC), along with a characterization method based on measurements recorded on the field. Other than measured geometrical constants and kinetic/kinematic data from instrumented wheels, no information about the dynamic parameters such as the system's mass and its moment of inertia are necessary. The accuracy of the new WSC model was compared with the WSL model. To this end, ten subjects propelled an instrumented wheelchair following straight and curvilinear patterns. The recorded kinetics were fed to both models, and their estimated kinematics were compared to the recorded ones. For the curvilinear patterns, the RMS relative error between the estimated and measured rear wheels velocities over a complete push cycle are lower for the WSC model than for the WSL model. Outward wheel: 7.98% (WSC) vs 12.98% (WSL). Inward wheel: 10.76% (WSC) vs 20.73% (WSL).