Machine-Learning-Based Methodology for Estimation of Shoulder Load in Wheelchair-Related Activities Using Wearables.

There is a high prevalence of shoulder problems in manual wheelchair users (MWUs) with a spinal cord injury. How shoulder load relates to shoulder problems remains unclear. This study aimed to develop a machine-learning-based methodology to estimate the shoulder load in wheelchair-related activities of daily living using wearable sensors. Ten able-bodied participants equipped with five inertial measurement units (IMU) on their thorax, right arm, and wheelchair performed activities exemplary of daily life of MWUs. Electromyography (EMG) was recorded from the long head of the biceps and medial part of the deltoid. A neural network was trained to predict the shoulder load based on IMU and EMG data. Different cross-validation strategies, sensor setups, and model architectures were examined. The predicted shoulder load was compared to the shoulder load determined with musculoskeletal modeling. A subject-specific biLSTM model trained on a sparse sensor setup yielded the most promising results (mean correlation coefficient = 0.74 ± 0.14, relative root-mean-squared error = 8.93% ± 2.49%). The shoulder-load profiles had a mean similarity of 0.84 ± 0.10 over all activities. This study demonstrates the feasibility of using wearable sensors and neural networks to estimate the shoulder load in wheelchair-related activities of daily living.

Real-Life Wheelchair Mobility Metrics from IMUs.

Daily wheelchair ambulation is seen as a risk factor for shoulder problems, which are prevalent in manual wheelchair users. To examine the long-term effect of shoulder load from daily wheelchair ambulation on shoulder problems, quantification is required in real-life settings. In this study, we describe and validate a comprehensive and unobtrusive methodology to derive clinically relevant wheelchair mobility metrics (WCMMs) from inertial measurement systems (IMUs) placed on the wheelchair frame and wheel in real-life settings. The set of WCMMs includes distance covered by the wheelchair, linear velocity of the wheelchair, number and duration of pushes, number and magnitude of turns and inclination of the wheelchair when on a slope. Data are collected from ten able-bodied participants, trained in wheelchair-related activities, who followed a 40 min course over the campus. The IMU-derived WCMMs are validated against accepted reference methods such as Smartwheel and video analysis. Intraclass correlation (ICC) is applied to test the reliability of the IMU method. IMU-derived push duration appeared to be less comparable with Smartwheel estimates, as it measures the effect of all energy applied to the wheelchair (including thorax and upper extremity movements), whereas the Smartwheel only measures forces and torques applied by the hand at the rim. All other WCMMs can be reliably estimated from real-life IMU data, with small errors and high ICCs, which opens the way to further examine real-life behavior in wheelchair ambulation with respect to shoulder loading. Moreover, WCMMs can be applied to other applications, including health tracking for individual interest or in therapy settings.

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.

Shoulder Pain Is Associated With Rate of Rise and Jerk of the Applied Forces During Wheelchair Propulsion in Individuals With Paraplegic Spinal Cord Injury.

OBJECTIVE: To investigate the association between propulsion biomechanics, including variables that describe smoothness of the applied forces, and shoulder pain in individuals with spinal cord injury (SCI). DESIGN: Cross-sectional, observational study. SETTING: Non-university research institution. PARTICIPANTS: Community dwelling, wheelchair dependent participants (N=30) with chronic paraplegia between T2 and L1, with and without shoulder pain (age, 48.6±9.3y; 83% men). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Rate of rise and jerk of applied forces during wheelchair propulsion. Participants were stratified in groups with low, moderate, and high pain based on their Wheelchair User Shoulder Pain Index score on the day of measurement. RESULTS: A mixed-effect multilevel analysis showed that wheelchair users in the high pain group propelled with a significantly greater rate of rise and jerk, measures that describe smoothness of the applied forces, compared with individuals with less or no pain, when controlling for all covariables. CONCLUSIONS: Individuals with severe shoulder pain propelled with less smooth strokes compared to individuals with less or no pain. This supports a possible association between shoulder pain and rate of rise and jerk of the applied forces during wheelchair propulsion.

Changes in supraspinatus and biceps tendon thickness: influence of fatiguing propulsion in wheelchair users with spinal cord injury.

STUDY DESIGN: A quasi-experimental, pretest-posttest design. OBJECTIVES: To identify acute changes in the supraspinatus and biceps tendon following fatiguing wheelchair propulsion and to associate tendon changes with risk factors associated with shoulder pain in persons with spinal cord injury (SCI). SETTING: Biomechanical laboratory Swiss Paraplegic Research. METHODS: A population-based sample of 50 wheelchair users with SCI at lesion level T2 or below participated. Fatigue was measured by using the rate of perceived exertion and heart rate. Linear regression techniques were used to assess the association between the dependent and independent variables. Dependent variables included absolute differences in supraspinatus and biceps tendon thickness, contrast, and echogenicity ratio assessed with ultrasound before and after a fatiguing wheelchair propulsion intervention. Independent variables included susceptibility to fatigue (Yes/No), the acromio-humeral distance, sex, time since injury, activity levels, and body weight. RESULTS: A reduction in supraspinatus tendon thickness after fatiguing wheelchair propulsion (-1.39 mm; 95% CI: -2.28; -0.51) was identified after controlling for all potential confounders. Females who fatigued (n = 4) displayed a greater reduction in supraspinatus tendon thickness as compared with those who did not fatigue (n = 7). In contrast, higher body weight was associated with an increase in supraspinatus tendon thickness and a greater acromio-humeral distance before the intervention was associated with an increase in biceps tendon thickness. CONCLUSIONS: Acute changes in the supraspinatus and biceps tendon after fatiguing wheelchair propulsion may explain the high prevalence of tendon injuries in this population. Future research should determine the consequences of tendon changes and its relationship to tendinopathy.

The effect of intrinsic loading and reconstruction upon grip capacity and finger extension kinematics.

PURPOSE: To compare active and passive reconstructive procedures for tetraplegia and their ability to produce a powerful grip and allow appropriate finger extension in a cadaveric model. METHODS: Seventeen fresh-frozen hands were used, which included 5 in intrinsic minus and intrinsic activation conditions, 6 with Zancolli-lasso tenodeses, and 6 with modified House tenodeses to simulate intrinsic function. To test grip, flexor digitorum profundus tendons were powered with a motor. Polyvinyl chloride cylinders of diameters 43, 51, 57, 70, or 89 mm and masses 250, 400, or 550 g were used. Grip was considered successful if the cylinder was grasped and resisted gravity. Finger extension was tested by powering the extensor tendons in the same hands. RESULTS: No successful grasps were recorded in the intrinsic minus hands for larger diameter cylinders (≥ 70 mm), whereas multiple successes were seen after intrinsic activation and after Zancolli-lasso and House procedures. Whereas active intrinsic and the House reconstruction reached near full extension, this was not true for the Zancolli-lasso group. CONCLUSIONS: These data demonstrated that active and passive intrinsic reconstruction methods improved basic grasp and release kinematics in experimental cadaver hand models. Using our model and based on the more optimal kinematics and full extension of the House procedure, we suggest that this should be the preferred tenodesis-based intrinsic reconstruction method. Nevertheless, both procedures were equally successful at grasping objects of the sizes and masses studied. CLINICAL RELEVANCE: Comparative clinical studies are indicated to corroborate the findings of this cadaveric hand model.

Shoulder Pain in Persons With Tetraplegia and the Association With Force Application During Manual Wheelchair Propulsion.

Objective: To investigate the association between propulsion biomechanics, including force application and spatio-temporal characteristics, and shoulder pain in persons with tetraplegia. Design: Cross-sectional, observational study. Setting: Non-university research institution. Participants: 16 community dwelling, wheelchair dependent persons with a chronic tetraplegia between C4 and C7, with and without shoulder pain (age, 49.1±11.7 years; 94% men, 23.4±9.5 years past injury). Interventions: Not applicable. Main Outcome Measures: Force application and spatio-temporal characteristics of wheelchair propulsion on a treadmill (0.56 m/s, 10W and 0.83 m/s, 15W). Participants were stratified in groups with low, moderate, and high pain based on their Wheelchair User Shoulder Pain Index (WUSPI) score on the day of measurement. Results: The mixed-effect multilevel analysis showed that wheelchair users with high levels of shoulder pain applied propulsion force more effectively (and with a lower medial component) and over a longer push angle, thus shortening the recovery time as compared with persons with low or moderate levels of shoulder pain. Conclusions: In contrast with previous results from persons with a paraplegia, persons with tetraplegia and high levels of shoulder pain propel their wheelchair more optimal with regard to risk factors for shoulder pain. Our results therefore affirm that there is a different interaction of shoulder pain and propulsion biomechanics in persons with a tetraplegia which should be considered when further analyzing risk factors for shoulder pain in wheelchair users or applying literature results to different patient populations.

Intrinsic hand muscle function, part 1: creating a functional grasp.

PURPOSE: Regaining hand function has been identified as the highest priority for persons with tetraplegia. In many patients, finger flexion can be restored with a tendon transfer of extensor carpi radialis longus to flexor digitorum profundus (FDP). In the absence of intrinsic function, this results in a roll-up finger movement, which tends to push large objects out of grasp. To enable patients to grasp objects of varying sizes, a functional grasp is required that has a larger excursion of fingertip-to-palm distance than can be supplied without intrinsic function. The aim of this study was to quantify the role of intrinsic muscle force in creating a functional grasp. METHODS: Finger kinematics during grasp were measured on 5 cadaveric hands. To simulate finger flexion, the FDP was activated by a motor and intrinsic muscles were loaded at various levels (0, 125, 250, 375, or 500 g). Finger movement was characterized by the order of metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joint flexion and by the maximal fingertip-to-palm distance during finger closure. RESULTS: Without any intrinsic muscle contribution (0-g load), FDP activation resulted in flexion of all 3 joints, whereby flexion began at the proximal interphalangeal joint, followed by the distal interphalangeal joint, and then the metacarpophalangeal joint. With increasing intrinsic muscle load, finger flexion was initiated at the metacarpophalangeal joint, followed by the proximal interphalangeal and distal interphalangeal joints. This altered joint flexion order resulted in a larger maximal fingertip-to-palm distance during finger flexion. The difference between the 2 extreme conditions (0 g vs 500 g of intrinsic muscle load) was 19 mm. CONCLUSIONS: These findings demonstrate that simultaneous activation of the FDP and the intrinsic muscles results in an apparently more functional hand closing compared with FDP activation alone because of altered kinematics and larger fingertip-to-palm distances. CLINICAL RELEVANCE: These findings suggest that intrinsic muscle balancing during reconstruction of grasp in tetraplegic patients may improve function.

Intrinsic hand muscle function, part 2: kinematic comparison of 2 reconstructive procedures.

PURPOSE: Reconstruction of grasp is a high priority for tetraplegic patients. Restoration of finger flexion by surgical activation of flexor digitorum profundus can result in roll-up finger flexion, interphalangeal (IP) joint before metacarpophalangeal (MCP) joint flexion, which can be improved by restoring intrinsic function. This study compares grasp kinematics between 2 intrinsic balancing procedures-Zancolli-lasso and House. METHODS: The intrinsic muscles of 12 cadaver hands were reconstructed by either the Zancolli-lasso or the House procedure (n = 6 each) and tested by deforming the flexor digitorum profundus (FDP) with a motor to simulate hand closure. Results were compared with 5 control hands. All 17 hands were studied by video analysis. Kinematics were characterized by the order of MCP joint and IP joint flexion. Optimal grasp was defined as the maximal fingertip-to-palm distance during the arc of finger closure. RESULTS: Kinematics differed between the 2 procedures. The Zancolli-lasso reconstructed hands flexed first in the IP joints, and then in MCP joints, resembling an unreconstructed intrinsic-minus hand whereas the House reconstructed hands flexed first in the MCP joints and then in the IP joints, resembling an intrinsic-activated hand. Maximal fingertip-to-palm distance did not differ significantly between the 2 procedures, and both showed improvement over unreconstructed controls. CONCLUSIONS: Both intrinsic balancing techniques improved grasp. Only the House procedure restored hand kinematics approximating those of an intrinsic-activated hand. Improvement in fingertip-to-palm distance in Zancolli-lasso hands resulted primarily from the initial resting MCP joint flexion of 40°. We therefore advocate the more physiological House procedure for restoration of intrinsic function in tetraplegic patients. CLINICAL RELEVANCE: This study provides a rationale for advocacy of 1 reconstructive procedure over another.

Force application during handcycling and handrim wheelchair propulsion: an initial comparison.

The aim of the study was to evaluate the external applied forces, the effectiveness of force application and the net shoulder moments of handcycling in comparison with handrim wheelchair propulsion at different inclines. Ten able-bodied men performed standardized exercises on a treadmill at inclines of 1%, 2.5% and 4% with an instrumented handbike and wheelchair that measured three-dimensional propulsion forces. The results showed that during handcycling significantly lower mean forces were applied at inclines of 2.5% (P < .001) and 4% (P < .001) and significantly lower peak forces were applied at all inclines (1%: P = .014, 2.5% and 4%: P < .001). At the 2.5% incline, where power output was the same for both devices, total forces (mean over trial) of 22.8 N and 27.5 N and peak forces of 40.1 N and 106.9 N were measured for handbike and wheelchair propulsion. The force effectiveness did not differ between the devices (P = .757); however, the effectiveness did increase with higher inclines during handcycling whereas it stayed constant over all inclines for wheelchair propulsion. The resulting peak net shoulder moments were lower for handcycling compared with wheelchair propulsion at all inclines (P < .001). These results confirm the assumption that handcycling is physically less straining.

Changes in neuromuscular activation, heart rate and rate of perceived exertion over the course of a wheelchair propulsion fatigue protocol.

Shoulder pain is common in persons with spinal cord injury and has been associated with wheelchair use. Fatigue related compensation strategies have been identified as possibly impacting the development of shoulder injury and pain. The purpose of this study was to investigate the progression of performance fatigability (i.e., decline in objective measure of performance including neuromuscular activation and increase in heart rate) and perceived fatigability (i.e., increased perceived exertion) during a 15-min fatigue protocol including maximum voluntary overground wheelchair propulsion. Fifty participants with paraplegic spinal cord injury completed three 4-min rounds of wheelchair propulsion, separated by 90 s of rest, on a figure-8 course consisting of two turns and full stops per lap in their manual wheelchairs (ClinicalTrials.gov: NCT03153033). Electromyography (EMG) signal of five muscles acting on the shoulder joint, heart rate (HR), and rate of perceived exertion (RPE) were measured at the beginning and end of every 4 min of propulsion. Root Mean Square (RMS) and Mean Power Frequency were calculated from EMG data. There was a significant increase in %RMS of the pectoralis major pars sternalis and trapezius pars descendens, HR, and RPE with greatest changes during the first 4 min of the protocol. The observed changes in neuromuscular activation in only two of the shoulder muscles may impact muscular imbalances and the development of shoulder injuries and should be further studied. The current study gives clearer insight into the mechanisms of performance fatigability and perceived fatigability throughout a wheelchair propulsion fatigue protocol.

Comparing rolling resistance of two treadmills and its influence on exercise testing in wheelchair athletics.

Standardized laboratory exercise testing is common in sport settings and rehabilitation. The advantages of laboratory-based compared to field testing include the use of calibrated equipment and the possibility of keeping environmental conditions within narrow limits, making test results highly comparable and reproducible. However, when using different equipment (e.g., treadmills), the results might deviate and impair comparability. The aim of this study was to compare the biomechanical properties (rolling resistance, speed, inclination) of two treadmills regularly used for exercise testing in elite wheelchair athletes. During the experiment, speed and inclination of two treadmills (same model and producer, different manufacturing year and belt material) were verified. Standardized drag tests were performed to assess rolling resistance. Power output conducted by the athlete during later exercise tests was calculated based on the results. Speed and inclination deviated only slightly from the values indicated by the producer. Rolling resistance caused by different belt material was mainly accountable for the differences in power output between the treadmills. In general, athletes had to deliver 10% more power output on one of the treadmills compared to the other. Concluding from these results: if different treadmills are used for testing, a proper validation is recommended to avoid misleading interpretations of test results.

Effect of Fatiguing Wheelchair Propulsion and Weight Relief Lifts on Subacromial Space in Wheelchair Users.

Objective: This study aimed to identify targets of intervention for reducing shoulder pain in wheelchair users with spinal cord injury (SCI) by (1) examining changes in subacromial space [acromiohumeral distance (AHD) and occupation ratio (OccRatio)] with fatiguing wheelchair propulsion, and different loading conditions [unloaded position vs. weight relief lifts (WRL)]; (2) associating these changes with wheelchair user capacity, as well as (3) identifying subject characteristics associated with subacromial space, such as sex, lesion level, time since injury, body mass index and impaired shoulder range of motion. Methods: Fifty manual wheelchair users with SCI [11 females, age = 50.5 (9.7) years, time since injury = 26.2 (11.4) years] participated in this quasi-experimental one-group pretest-posttest study. Ultrasound images were used to define AHD during an unloaded position, and during personal and instructed WRL before and after fatiguing wheelchair propulsion. Furthermore, supraspinatus and biceps thickness defined from ultrasound images were used to calculate OccRatios. Wheelchair user capacity was quantified as functional strength (maximum resultant force reached during maximum isometric forward push) and anaerobic work capacity (highest power output reached during 15-m sprint test). Multilevel mixed-effects linear regression analyses controlling for between subject variability and covariables were performed to address the research questions. Results: AHD was significantly smaller during personal WRL (p < 0.001) and instructed WRL (p = 0.009, AHD both 11.5 mm) compared to the unloaded position (11.9 mm). A higher wheelchair user capacity (higher anaerobic work capacity) reduced the impact of WRL on AHD decrease. The fatiguing wheelchair propulsion had no effect on AHD (p = 0.570) and on OccRatio of supraspinatus (p = 0.404) and biceps (p = 0.448). Subject characteristics related to a larger subacromial space were lower lesion level, shorter time since injury, impaired external rotation, a lower body mass index and a higher anaerobic work capacity. Conclusion: This study showed a significant reduction in AHD during WRL with no effect of fatiguing wheelchair propulsion on the subacromial space in wheelchair users with SCI. A higher anaerobic work capacity was beneficial in stabilizing the shoulder during WRL. Our findings may assist clinicians in designing a shoulder injury prevention program.

MRI evaluation of shoulder pathologies in wheelchair users with spinal cord injury and the relation to shoulder pain.

OBJECTIVE: To describe the number, specifics and co-occurrence of shoulder pathologies detected by MRI in manual wheelchair users with spinal cord injury and to evaluate the association between shoulder pathologies and presence of shoulder pain. DESIGN: Cross-sectional observation study. SETTING: Community. PARTICIPANTS: Fifty-one wheelchair-dependent persons with spinal cord injury (44 males, 7 females, median age 50 years (IQR 14), median time since injury 24 years (IQR 16)) were allocated to pain or no-pain group based on the Wheelchair User Shoulder Pain Index. INTERVENTIONS: Not applicable. OUTCOME MEASURES: All persons underwent shoulder MRI. Pathologies were scored blinded by two experienced radiologists. Participant characteristics, number and severity of shoulder pathologies were analyzed descriptively. Logistic regression was performed to evaluate the association between MRI findings and shoulder pain. RESULTS: The median number of co-occurring MRI findings per person ranged from 0 to 19 (out of 31 possible findings). The cluster of MRI findings occurring most often together were tendon tears of supraspinatus (present in 84%), subscapularis (69%) and biceps (67%) and osteoarthritis of acromioclavicular joint (80%). When correcting for age and time since injury, the logistic regression showed no statistically significant correlation between the individual pathologies and shoulder pain. CONCLUSION: MRI findings of shoulder pathology are very frequent in persons with and without shoulder pain. Therefore, when diagnosing the cause of shoulder pain and planning interventions, health care professionals should keep this finding in mind and MRI should not be interpreted without careful consideration of clinical history and functional testing.

Change in mobility independence over 5 years for persons with chronic spinal cord injury.

OBJECTIVES: To evaluate change in mobility independence (MI) in community dwelling persons with spinal cord injury (SCI). PARTICIPANTS: Community Survey. DESIGN: Cohort study. Rasch analysis was applied to the mobility subscale of the Spinal Cord Independence Measure - Self-Report data from years 2012 to 2017, resulting in a Rasch Mobility Independence Score (RMIS). We employed multilevel modeling to examine RMIS and its change over 5 years, adjusting for demographics and SCI severity; random forest regression was applied to determine the impact of modifiable factors (e.g. environmental factors, home-support) on its change. RESULTS: The analysis included 728 participants. The majority (≈85%) of participants demonstrated little or no change in RMIS from 2012 to 2017; however, a smaller proportion (15%) showed considerably large change of more than 10 on the 100-point scale. A mixed-effects model with random slopes and intercepts described the dataset very well (conditional R2 of 0.95) in terms of demographics and SCI severity. Age was the main predictor of change in RMIS. Considering SCI severity, change in RMIS was related to age for the subgroup with paraplegia, and to time since injury for the subgroup with tetraplegia. No impact of modifiable factors was found. CONCLUSION: RMIS in persons with SCI changes over a period of 5 years, especially in elder patients with paraplegia and persons with incomplete tetraplegia with more than 15 years of time since injury. During routine follow-up change in mobility independence should be assessed in order to timely intervene and prevent mobility loss and participation limitations.

Shoulder Tendon Adaptations Following a Graded Exercise Test to Exhaustion in Highly Trained Wheelchair Rugby Athletes With Different Impairments.

Objective: This study aimed to identify acute changes in biceps and supraspinatus tendon characteristics before and after a graded exercise test to exhaustion (GXT) in highly trained wheelchair rugby (WR) athletes. A secondary aspect was to define chronic tendon adaptations related to the impairment of the athlete and the occupation of the tendon within the subacromial space (occupation ratio). Methods: Twelve WR athletes with different impairments (age = 32 ± 6 years; body mass = 67.2 ± 11.2 kg; 9.0 ± 3.6 years competing) volunteered for this study. Performance Corrected Wheelchair Users Shoulder Pain Index was used to quantify shoulder pain. Quantitative Ultrasound Protocols (QUS) were used to define supraspinatus and biceps tendon thickness, echogenicity, and echogenicity ratio of both dominant and non-dominant shoulder before and after the GXT including 22 ± 3.1 min submaximal propulsion and 10.2 ± 1.7 min maximal propulsion on a treadmill. Furthermore, the acromio-humeral distance (AHD) defined from ultrasound (US) images was used to calculate the occupation ratios. Results: A mixed-effect multilevel analysis that included shoulder as grouping variable, demonstrated a significant reduction in the echogenicity of the biceps following GXT whilst controlling for impairment [spinal cord injury (SCI) and non-SCI] and the occupation ratio (ß = -9.01, SEß = 2.72, p = 0.001, 95% CI = [-14.34; -3.68]). This points toward fluid inflow into the tendon that may be related to overload and acute inflammation. In addition, persons with a SCI (n = 8) had a thicker supraspinatus tendon in comparison to persons with non-SCI (n = 3) which may be related to chronic tendon adaptations (ß = -0.53 mm, SEß = 0.26, p = 0.038, 95% CI = [-1.04; -0.03]). Finally, a greater occupation ratio was associated with signs of tendinopathy (i.e., greater biceps and supraspinatus tendon thickness, and lower supraspinatus echogenicity and echogenicity ratio). Conclusion: Acute biceps tendon adaptations in response to the GXT in highly trained WR athletes were evident with chronic adaptations in the supraspinatus tendon being related to the impairment of the athlete. Ultrasound can be used to monitor tendon adaptations in WR athletes for medical diagnosis to assist the scheduling and type of training.

Biophysical aspects of handcycling performance in rehabilitation, daily life and recreational sports; a narrative review.

AIM: In this narrative review the potential and importance of handcycling are evaluated. Four conceptual models form the framework for this review; (1) the International Classification of Functioning, Disability and Health; (2) the Stress-Strain-Capacity model; (3) the Human-Activity-Assistive Technology model; and (4) the power balance model for cyclic exercise. METHODS: Based on international handcycle experience in (scientific) research and practice, evidence-based benefits of handcycling and optimization of handcycle settings are presented and discussed for rehabilitation, daily life and recreational sports. RESULTS: As the load can be distributed over the full 360° cycle in handcycling, peak stresses in the shoulder joint and upper body muscles reduce. Moreover, by handcycling regularly, the physical capacity can be improved. The potential of handcycling as an exercise mode for a healthy lifestyle should be recognized and advocated much more widely in rehabilitation and adapted sports practice.The interface between handcycle and its user should be optimized by choosing a suitable person-specific handcycle, but mainly by optimizing the handcycle dimensions to one's needs and desires. These dimensions can influence efficient handcycle use and potentially improve both endurance and speed of handcycling. CONCLUSION: To optimize performance in rehabilitation, daily life and recreational sports, continued and more systematic research is required.Implications for rehabilitationHandcycling allows users to travel farther distances at higher speeds and to train outdoors. It should be recognized as an alternative exercise modality for daily outdoor use, also already in early rehabilitation, while it contributes to a healthy lifestyle.To individualize handcycle performance, the user-handcycle (assistive device) interface as well as the vehicle mechanics should be optimized to minimize external power and reduce friction, so that the upper body capacity can be efficiently used.To optimize handcycling individual performance, both the physiological and biomechanical aspects of handcycling should be considered when monitoring or testing handcycle exercise.

Need and availability of assistive devices to compensate for impaired hand function of individuals with tetraplegia.

Context/Objective: To evaluate the availability and self-declared unmet need of assistive devices to compensate for impaired hand function of individuals with tetraplegia in Switzerland.Design: Cross-sectional survey.Setting: Community.Participants: Individuals with tetraplegia, aged 16 years or older, living in Switzerland.Interventions: not applicable.Outcome Measures: The self-report availability and unmet need of 18 assistive devices for impaired hand function was analyzed descriptively. The availability of devices was further evaluated stratified by sex, age, SCI severity, independence in grooming, time since injury, living situation, working status, and income. Associations between availability of devices and person characteristics were investigated using logistic regression analysis.Results: Overall 32.7% of participants had any assistive device for impaired hand function at their disposal. The most frequent devices were adapted cutlery (14.8%), type supports (14.1%), environmental control systems (11.4%), and writing orthosis (10.6%). In the bivariate analysis several factors showed significant associations with at least one assistive device. Nevertheless, when controlling for potential confounding in multivariate analysis only independence in grooming (adapted cutlery, environmental control systems, type support, speech recognition software), SCI severity (writing orthosis, type support), and sex (adapted kitchenware) remained significantly associated with the availability of the mentioned assistive devices. The self-declared unmet need was generally low (0.7% - 4.3%), except for adapted kitchenware with a moderate unmet need (8.9%).Conclusion: This study indicates that most individuals with tetraplegia in Switzerland are adequately supplied with assistive devices to compensate for impaired hand function. The availability depends mainly on SCI severity and independence in grooming.

Compensation Strategies in Response to Fatiguing Propulsion in Wheelchair Users: Implications for Shoulder Injury Risk.

OBJECTIVE: The aims of the study were to examine whether fatigue-inducing wheelchair propulsion changes neuromuscular activation and propulsion biomechanics and to determine predictor variables for susceptibility to fatigue. DESIGN: This study with a quasi-experimental, one-group, pretest-posttest design investigates a population-based sample of wheelchair users with a spinal cord injury (n = 34, age: 50.8 ± 9.7 yrs, 82% males). Neuromuscular activation and propulsion biomechanics during treadmill propulsion at 25 W and 45 W were assessed before and after a protocol designed to cause fatigue. RESULTS: With the induced fatigue, wheelchair users propelled with increased neuromuscular activation in the pectoralis major pars sternalis, deltoideus pars acromialis and upper trapezius (45 W, P < 0.05), and a slightly reduced push angle (25 W: 75-74 degrees, P < 0.05, 45 W: 78-76 degrees, P < 0.05). Wheelchair users susceptible to fatigue (47%) were more likely to have a complete lesion, to be injured at an older age, and had less years since injury. This group propelled in general with shorter push angle and greater maximum resultant force, had a greater anaerobic capacity, and had less neuromuscular activation. CONCLUSIONS: Compensation strategies in response to fatiguing propulsion could increase the risk for shoulder injury. Predictor variables for susceptibility to fatigue inform interventions preserving shoulder health and include lesion characteristics, propulsion technique, anaerobic capacity, and neuromuscular activation. TO CLAIM CME CREDITS: Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Explain a neuromuscular compensation strategy and the corresponding muscles in response to fatiguing wheelchair propulsion; (2) Recommend propulsion biomechanics associated to reduced susceptibly to fatiguing wheelchair propulsion; and (3) List examples of predictor variables of susceptibility to fatigue. LEVEL: Advanced. ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Start-up propulsion biomechanics changes with fatiguing activity in persons with spinal cord injury.

Objective: Shoulder pathology is a common condition in wheelchair users that can considerably impact quality of life. Shoulder muscles are prone to fatigue, but it is unclear how fatigue affects start-up propulsion biomechanics. This study determines acute changes in start-up wheelchair propulsion biomechanics at the end of a fatiguing propulsion protocol. Design: Quasi-experimental one-group pretest-postest design. Setting: Biomechanics laboratory. Participants: Twenty-six wheelchair users with spinal cord injury (age: 35.5 ± 9.8 years, sex: 73% males and 73% with a paraplegia). Interventions: Protocol of 15 min including maximum voluntary propulsion, right- and left turns, full stops, start-up propulsion, and rests. Outcome measures: Maximum resultant force, maximum rate of rise of applied force, mean velocity, mean fraction of effective force, and mean contact time at the beginning and end of the protocol during start-up propulsion. Results: There was a significant reduction in maximum resultant force (P < 0.001) and mean velocity (P < 0.001) at the end of the protocol. Also, contact time was reduced in the first stroke of start-up propulsion (P < 0.001). Finally, propelling with a shorter contact time was associated with a greater reduction in performance (maximum velocity) at the end of the protocol. Conclusion: There are clear changes in overground propulsion biomechanics at the end of a fatiguing propulsion protocol. While reduced forces could protect the shoulder, these reduced forces come with shorter contact times and lower velocity. Investigating changes in start-up propulsion biomechanics with fatigue could provide insight into injury risk.