Trunk and neck kinematics during overground manual wheelchair propulsion in persons with tetraplegia

Towards an accurate rolling resistance: Estimating intra-cycle load distribution between front and rear wheels during wheelchair propulsion from inertial sensors

Accurate assessment of rolling resistance is important for wheelchair propulsion analyses. However, the commonly used drag and deceleration tests are reported to underestimate rolling resistance up to 6% due to the (neglected) influence of trunk motion. The first aim of this study was to investigate the accuracy of using trunk and wheelchair kinematics to predict the intra-cyclical load distribution, more particularly front wheel loading, during hand-rim wheelchair propulsion. Secondly, the study compared the accuracy of rolling resistance determined from the predicted load distribution with the accuracy of drag test-based rolling resistance. Twenty-five able-bodied participants performed hand-rim wheelchair propulsion on a large motor-driven treadmill. During the treadmill sessions, front wheel load was assessed with load pins to determine the load distribution between the front and rear wheels. Accordingly, a machine learning model was trained to predict front wheel load from kinematic data. Based on two inertial sensors (attached to the trunk and wheelchair) and the machine learning model, front wheel load was predicted with a mean absolute error (MAE) of 3.8% (or 1.8 kg). Rolling resistance determined from the predicted load distribution (MAE: 0.9%, mean error (ME): 0.1%) was more accurate than drag test-based rolling resistance (MAE: 2.5%, ME: -1.3%).

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.

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.

Kinematics and pushrim kinetics in adolescents propelling high-strength lightweight and ultra-lightweight manual wheelchairs

PURPOSE

The purpose of this study is to describe and compare pushrim forces, propulsive work cost, and upper body kinematics in adolescents propelling (1) a standard high strength lightweight wheelchair, and (2) an ultra-lightweight wheelchair with adjustable main axle positioning, on a level tiled floor ("Tile"), ascending a ramp ("Ramp"), and across a foam mat ("Mat").

METHODS

A within-subjects repeated measures study design was used. Eight adolescent manual wheelchair users propelled the standard and ultra-lightweight wheelchairs across the three conditions. Average pushrim tangential force, propulsive power and work per unit distance travelled, as well as upper body kinematic angles, were analyzed.

RESULTS

Average pushrim tangential force (1.80 ± 0.7 N, p = .042) and propulsive work per unit distance travelled (8.3 ± 1.7 J·m^{- 1}, p = .002) were higher for the standard lightweight wheelchair, whereas average speed was lower (0.12 ± 0.03 m/s, p = .006). Maximum shoulder (9.2 ± 2.0°, p = .003) and elbow flexion (8.0 ± 2.2°, p = .009) were higher for the ultra-lightweight wheelchair. Compared with Tile, propulsion on Mat and Ramp was associated with higher average tangential force, work per unit distance, power, and maximum flexion of the neck and trunk, whereas shoulder extension and average speed were lower for Mat and Ramp.

CONCLUSIONS

Compared with the standard lightweight wheelchair, ultra-lightweight wheelchair propulsion was associated with lower pushrim forces, lower energy costs, higher self-selected speeds, and increased shoulder and elbow flexion. These variables have been linked to injury risk and mobility efficiency, and the results provided evidence that differences in weight and configuration options are both contributors. Findings can inform decision-making in the prescription of manual wheelchairs for pre-adult populations. Implications for Rehabilitation A significant proportion of manual wheelchair users are children and adolescents, and due to the early onset of use they may be especially predisposed to the development of chronic overuse injuries. The study reports differences in energy costs, pushrim forces, and upper body kinematics measured when adolescents propelled standard and ultra-lightweight wheelchairs across three trial conditions. In the ultra-lightweight wheelchair, reduced energy cost is linked to more efficient mobility, and lower forces may be linked to lower risk of chronic injury. Significant differences in elbow and shoulder kinematics are also reported, and the findings support the importance of both weight and setup options in the selection of manual wheelchairs.

A motor learning approach to training wheelchair propulsion biomechanics for new manual wheelchair users: A pilot study

CONTEXT/OBJECTIVE

Developing an evidence-based approach to teaching wheelchair skills and proper propulsion for everyday wheelchair users with a spinal cord injury (SCI) is important to their rehabilitation. The purpose of this project was to pilot test manual wheelchair training based on motor learning and repetition-based approaches for new manual wheelchair users with an SCI.

DESIGN

A repeated measures within-subject design was used with participants acting as their own controls.

METHODS

Six persons with an SCI requiring the use of a manual wheelchair participated in wheelchair training. The training included nine 90-minute sessions. The primary focus was on wheelchair propulsion biomechanics with a secondary focus on wheelchair skills.

OUTCOME MEASURES

During Pretest 1, Pretest 2, and Posttest, wheelchair propulsion biomechanics were measured using the Wheelchair Propulsion Test and a Video Motion Capture system. During Pretest 2 and Posttest, propulsion forces using the WheelMill System and wheelchair skills using the Wheelchair Skills Test were measured.

RESULTS

Significant changes in area of the push loop, hand-to-axle relationship, and slope of push forces were found. Changes in propulsion patterns were identified post-training. No significant differences were found in peak and average push forces and wheelchair skills pre- and post-training.

CONCLUSIONS

This project identified trends in change related to a repetition-based motor learning approach for propelling a manual wheelchair. The changes found were related to the propulsion patterns used by participants. Despite some challenges associated with implementing interventions for new manual wheelchair users, such as recruitment, the results of this study show that repetition-based training can improve biomechanics and propulsion patterns for new manual wheelchair users.

The Effects of Body Mass Composition and Cushion Type on Seat-Interface Pressure in Spinal Cord Injured Patients

Objective

To investigate the effects of body mass composition and cushion type on seat-interface pressure in spinal cord injured (SCI) patients and healthy subjects.

Methods

Twenty SCI patients and control subjects were included and their body mass composition measured. Seat-interface pressure was measured with participants in an upright sitting posture on a wheelchair with three kinds of seat cushion and without a seat cushion. We also measured the pressure with each participant in three kinds of sitting postures on each air-filled cushion. We used repeated measure ANOVA, the Mann-Whitney test, and Spearman correlation coefficient for statistical analysis.

Results

The total skeletal muscle mass and body water in the lower extremities were significantly higher in the control group, whilst body fat was significantly higher in the SCI group. However, the seat-interface pressure and body mass composition were not significantly correlated in both groups. Each of the three types of seat cushion resulted in significant reduction in the seat-interface pressure. The SCI group had significantly higher seatinterface pressure than the control group regardless of cushion type or sitting posture. The three kinds of sitting posture did not result in a significant reduction of seat-interface pressure.

Conclusion

We confirmed that the body mass composition does not have a direct effect on seat-interface pressure. However, a reduction of skeletal muscle mass and body water can influence the occurrence of pressure ulcers. Furthermore, in order to minimize seat-interface pressure, it is necessary to apply a method fitted to each individual rather than a uniform method.