Differences in Glenohumeral Joint Contact Forces Between Recovery Hand Patterns During Wheelchair Propulsion With and Without Shoulder Muscle Weakness: A Simulation Study.

The majority of manual wheelchair users (MWCU) develop shoulder pain or injuries, which is often caused by impingement. Because propulsion mechanics are influenced by the recovery hand pattern used, the pattern may affect shoulder loading and susceptibility to injury. Shoulder muscle weakness is also correlated with shoulder pain, but how shoulder loading changes with specific muscle group weakness is unknown. Musculoskeletal modeling and simulation were used to compare glenohumeral joint contact forces (GJCFs) across hand patterns and determine how GJCFs vary when primary shoulder muscle groups are weakened. Experimental data were analyzed to classify individuals into four hand pattern groups. A representative musculoskeletal model was then developed for each group and simulations generated to portray baseline strength and six muscle weakness conditions. Three-dimensional GJCF peaks and impulses were compared across hand patterns and muscle weakness conditions. The semicircular pattern consistently had lower shear (anterior-posterior and superior-inferior) GJCFs compared to other patterns. The double-loop pattern had the highest superior GJCFs, while the single-loop pattern had the highest anterior and posterior GJCFs. These results suggest that using the semicircular pattern may be less susceptible to shoulder injuries such as subacromial impingement. Weakening the internal rotators and external rotators resulted in the greatest increases in shear GJCFs and decreases in compressive GJCF, likely due to decreased force from rotator cuff muscles. These findings suggest that strengthening specific muscle groups, especially the rotator cuff, is critical for decreasing the risk of shoulder overuse injuries.

Multi-Site Identification and Generalization of Clusters of Walking Behaviors in Individuals With Chronic Stroke and Neurotypical Controls.

BACKGROUND: Walking patterns in stroke survivors are highly heterogeneous, which poses a challenge in systematizing treatment prescriptions for walking rehabilitation interventions. OBJECTIVES: We used bilateral spatiotemporal and force data during walking to create a multi-site research sample to: (1) identify clusters of walking behaviors in people post-stroke and neurotypical controls and (2) determine the generalizability of these walking clusters across different research sites. We hypothesized that participants post-stroke will have different walking impairments resulting in different clusters of walking behaviors, which are also different from control participants. METHODS: We gathered data from 81 post-stroke participants across 4 research sites and collected data from 31 control participants. Using sparse K-means clustering, we identified walking clusters based on 17 spatiotemporal and force variables. We analyzed the biomechanical features within each cluster to characterize cluster-specific walking behaviors. We also assessed the generalizability of the clusters using a leave-one-out approach. RESULTS: We identified 4 stroke clusters: a fast and asymmetric cluster, a moderate speed and asymmetric cluster, a slow cluster with frontal plane force asymmetries, and a slow and symmetric cluster. We also identified a moderate speed and symmetric gait cluster composed of controls and participants post-stroke. The moderate speed and asymmetric stroke cluster did not generalize across sites. CONCLUSIONS: Although post-stroke walking patterns are heterogenous, these patterns can be systematically classified into distinct clusters based on spatiotemporal and force data. Future interventions could target the key features that characterize each cluster to increase the efficacy of interventions to improve mobility in people post-stroke.

Multi-site identification and generalization of clusters of walking behaviors in individuals with chronic stroke and neurotypical controls.

Background: Walking patterns in stroke survivors are highly heterogeneous, which poses a challenge in systematizing treatment prescriptions for walking rehabilitation interventions. Objective: We used bilateral spatiotemporal and force data during walking to create a multi-site research sample to: 1) identify clusters of walking behaviors in people post-stroke and neurotypical controls, and 2) determine the generalizability of these walking clusters across different research sites. We hypothesized that participants post-stroke will have different walking impairments resulting in different clusters of walking behaviors, which are also different from control participants. Methods: We gathered data from 81 post-stroke participants across four research sites and collected data from 31 control participants. Using sparse K-means clustering, we identified walking clusters based on 17 spatiotemporal and force variables. We analyzed the biomechanical features within each cluster to characterize cluster-specific walking behaviors. We also assessed the generalizability of the clusters using a leave-one-out approach. Results: We identified four stroke clusters: a fast and asymmetric cluster, a moderate speed and asymmetric cluster, a slow cluster with frontal plane force asymmetries, and a slow and symmetric cluster. We also identified a moderate speed and symmetric gait cluster composed of controls and participants post-stroke. The moderate speed and asymmetric stroke cluster did not generalize across sites. Conclusions: Although post-stroke walking patterns are heterogenous, these patterns can be systematically classified into distinct clusters based on spatiotemporal and force data. Future interventions could target the key features that characterize each cluster to increase the efficacy of interventions to improve mobility in people post-stroke.

Treatments perceived to be helpful for neuropathic pain after traumatic spinal cord injury: A multicenter cross-sectional survey study.

DESIGN: Cross-sectional survey. OBJECTIVE: To evaluate the perceived helpfulness of pharmacological and non-pharmacological interventions and their combinations for neuropathic pain (NeuP) and subcategories of NeuP after spinal cord injury (SCI). SETTING: Six Spinal Cord Injury Model System Centers. METHODS: Three hundred ninety one individuals at least one year post traumatic SCI were enrolled. A telephone survey was conducted to determine the pharmacologic and non-pharmacologic treatments used in the last 12 months for each participant's three worst pains, whether these treatments were "helpful", and if currently used, each treatments' effectiveness. RESULTS: Two hundred twenty participants (56%) reported 354 distinct NeuPs. Pharmacological treatments rated helpful for NeuP were non-tramadol opioids (opioids were helpful for 86% of opioid treated NeuPs), cannabinoids (83%), and anti-epileptics (79%). Non-pharmacological treatments rated helpful for NeuP were massage (76%), body position adjustment (74%), and relaxation therapy (70%). Those who used both opioids and exercise reported greater NeuP treatment helpfulness compared to participants using opioids without exercise (P = 0.03). CONCLUSIONS: Opioids, cannabinoids, and massage were reported more commonly as helpful than treatments recommended as first-line therapies by current clinical practice guidelines (CPGs) for NeuP after SCI (antiepileptics and antidepressants). Individuals with SCI likely value the modulating effects of pharmacological and non-pharmacological treatments on the affective components of pain in addition to the sensory components of pain when appraising treatment helpfulness.

Prevalence and Impact of Neuropathic and Nonneuropathic Pain in Chronic Spinal Cord Injury.

OBJECTIVE: To compare prevalence, intensity ratings, and interference ratings of neuropathic pain (NeuP) and nociceptive pain in people with chronic spinal cord injury (SCI) DESIGN: Cross-sectional survey. SETTING: Six SCI Model System centers in the United States. PARTICIPANTS: Convenience sample of 391 individuals (N=391) with traumatic SCI, 18 years or older, 81% male, 57% White. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Survey based on the International Spinal Cord Injury Pain Basic Data Set and the Spinal Cord Injury Pain Instrument, including 0-10 numeric ratings of pain intensity and pain interference with daily activities, mood, and sleep RESULTS: A total of 80% of those surveyed reported having at least 1 pain problem; 58% reported 2 or more pain problems; 56% had probable NeuP; and 49% had non-NeuP. When comparing ratings for all pains (n=354 for NeuP, n=290 for non-NeuP) across participants, probable NeuPs were significantly more intense (6.9 vs 5.7) and interfered more with activities (5.2 vs 3.7), mood (4.9 vs 3.2), and sleep (5.4 vs 3.6) than non-NeuPs (all P<.001). However, when comparing ratings for probable NeuPs and non-NeuPs within participants, for the subgroup of 94 participants with both pain types, only ratings for sleep interference were found to be significantly different between the pain types. Additionally, we found significantly greater prevalence of NeuP and non-NeuP for women compared with men and of NeuP for those with paraplegia compared with those with tetraplegia. CONCLUSIONS: Independent assessment of the pain conditions experienced by an individual with SCI is useful in understanding the differential effect that pain type has on quality of life. This is particularly important regarding sleep interference and should be kept in mind when determining treatment strategies for meeting patient-centered outcome goals.

Shoulder Pain Prevention Program for Manual Wheelchair Users With Paraplegia: A Randomized Clinical Trial.

Objectives: To compare prevalence of shoulder pain (SP) onset over 3 years for individuals with paraplegia from spinal cord injury who participate in one of two shoulder pain prevention program (SPPP) formats with that of a similar population without intervention, and to compare exercise adherence between two SPPP formats. Methods: The randomized clinical trial (compared to historical controls) included a volunteer sample of 100 individuals without SP at study entry. Eighty-seven participants returned for assessments at 18 and 36 months after study entry. Control group included 220 volunteers from a 3-year observational study with identical inclusion criteria. SPPPs included shoulder home exercises and recommendations to improve mobility techniques that are effective in reducing existing SP in this population. Participants were randomly assigned to receive either one instruction session and a refresher session 4 weeks later with a physical therapist or a 4-week series of 2-hour group classes taught by a physical therapist and peer mentor. Prevalence of SP onset at 18 and 36 months and self-reported average weekly exercise frequency were the main outcome measures. Results: SP onset was identical in the two SPPPs but was significantly lower at 18 and 36 months in both groups (11% and 24%) compared to controls (27% and 40%, p < .05). Self-reported average weekly exercise frequency was similar between intervention groups but was significantly lower during the first 4 months in participants who developed SP compared to those without pain (2.12 ± 1.0 vs. 3.01 ± 1.13, p < .05). Conclusion: SPPPs reduced SP onset prevalence regardless of instruction format. Exercise adherence was important to the outcome of shoulder pain.

Using Biofeedback to Reduce Step Length Asymmetry Impairs Dynamic Balance in People Poststroke.

BACKGROUND: People poststroke often walk with a spatiotemporally asymmetric gait, due in part to sensorimotor impairments in the paretic lower extremity. Although reducing asymmetry is a common objective of rehabilitation, the effects of improving symmetry on balance are yet to be determined. OBJECTIVE: We established the concurrent validity of whole-body angular momentum as a measure of balance, and we determined if reducing step length asymmetry would improve balance by decreasing whole-body angular momentum. METHODS: We performed clinical balance assessments and measured whole-body angular momentum during walking using a full-body marker set in a sample of 36 people with chronic stroke. We then used a biofeedback-based approach to modify step length asymmetry in a subset of 15 of these individuals who had marked asymmetry and we measured the resulting changes in whole-body angular momentum. RESULTS: When participants walked without biofeedback, whole-body angular momentum in the sagittal and frontal plane was negatively correlated with scores on the Berg Balance Scale and Functional Gait Assessment supporting the validity of whole-body angular momentum as an objective measure of dynamic balance. We also observed that when participants walked more symmetrically, their whole-body angular momentum in the sagittal plane increased rather than decreased. CONCLUSIONS: Voluntary reductions of step length asymmetry in people poststroke resulted in reduced measures of dynamic balance. This is consistent with the idea that after stroke, individuals might have an implicit preference not to deviate from their natural asymmetry while walking because it could compromise their balance. Clinical Trials Number: NCT03916562.

Treatments that are perceived to be helpful for non-neuropathic pain after traumatic spinal cord injury: a multicenter cross-sectional survey.

STUDY DESIGN: Cross-sectional survey. OBJECTIVES: The objective of the study was to identify the treatments that people with traumatic spinal cord injury (SCI) used for their non-neuropathic pains (nonNeuPs) and how they subjectively rated the helpfulness of those treatments. SETTING: Six centers from the Spinal Cord Injury Model Systems. METHODS: Three hundred ninety one individuals who were at least 1-year post-traumatic SCI were enrolled. A telephone survey was conducted for pharmacologic and non-pharmacologic treatments utilized in the last 12 months for each participant's three worst pains and the perceived helpfulness of each treatment for each pain. RESULTS: One hundred ninety (49%) participants reported at least one nonNeuP (Spinal Cord Injury Pain Instrument score < 2) in the previous 7 days. NSAIDs/aspirin, acetaminophen, opioids, and cannabinoids were the most commonly used and helpful pharmacologic treatments for overall nonNeuP locations (helpful in 77-89% of treated pains). Body position adjustment, passive exercise, massage, resistive exercise, and heat therapy were reported as the most commonly used non-pharmacological treatments for nonNeuPs. Heat therapy, aerobic exercise, massage, and body position adjustment were the most helpful non-pharmacological treatments for overall nonNeuP locations (helpful in 71-80% of treated pains). Perceived helpfulness of treatments varied by pain locations, which may be due to different mechanisms underlying pains in different locations. CONCLUSIONS: Results of the study may help guide clinicians in selecting pain-specific treatments for nonNeuPs. The self-reported helpfulness of heat therapy, exercise, and massage suggests a possible direction for clinical trials investigating these treatments of nonNeuP while limiting the side effects accompanying pharmacologic treatments.

The relationship between the hand pattern used during fast wheelchair propulsion and shoulder pain development.

Up to 84% of manual wheelchair users (MWCU) with spinal cord injury experience shoulder pain, which is correlated with shoulder adductor weakness in this population. Modeling studies have shown weak shoulder adductors lead to compensations from the deltoid and rotator cuff muscles during propulsion, which may lead to altered propulsion mechanics. However, the role recovery phase hand pattern has in pain development is unclear, as each hand pattern is associated with unique mechanics and different levels of muscle demand. Previous research found no correlation between hand pattern and shoulder pain at self-selected speeds. However, fast propulsion may exacerbate poor mechanics caused by shoulder muscle weakness, which may reveal those at risk for pain development. The present study evaluated whether the hand pattern used during fast wheelchair propulsion is correlated with shoulder pain. We also assessed whether shoulder adductor strength was correlated with hand pattern. Fast propulsion data from two subsets of MWCU were analyzed at three time points (baseline, 18 months, 36 months). All participants were pain-free at baseline. Subset 1 compared individuals who remained pain-free to those who developed shoulder pain. Subset 2 compared individuals with chronic pain at follow-up to those whose pain resolved over time. The hand pattern used was not different between groups in either subset. However, more over-rim patterns were correlated with lower adductor strength in Subset 1. These results suggest that although the hand pattern used during fast propulsion is not correlated with shoulder pain, more over-rim hand patterns may indicate weaker shoulder adductors.

A Primary Care Provider's Guide to Shoulder Pain After Spinal Cord Injury.

Shoulder pain is a common occurrence after spinal cord injury (SCI) and can have significant negative effects on health and function as many individuals with SCI are reliant on their upper extremities for mobility and self-care activities. Shoulder pain after SCI can be caused by acute injury or chronic pathology, but it is most often related to overuse injuries of the rotator cuff. Both acute strain and chronic overuse shoulder injuries in persons with SCI typically result from increased weight bearing on the upper extremities during transfers, weight-relief raises, and wheelchair propulsion, which are often performed in poor postural alignment owing to strength deficits. This article discusses management of patients with SCI who present with shoulder pain from the perspective of primary care physicians including evaluation and diagnostic procedures, interventions appropriate for both acute and chronic shoulder pain, and strategies for prevention.

International Spinal Cord Injury Physical Therapy-Occupational Therapy Basic Data Set (Version 1.2).

STUDY DESIGN: Expert workgroup consensus, focused literature review, and vetting via feedback from international presentations and spinal cord professional membership groups. OBJECTIVES: Develop and refine a basic dataset to enable standardized documentation of physical therapy (PT) and occupational therapy (OT) interventions delivered in a controlled clinical trial intended to improve voluntary motor function. SETTING: International Expert Working Group. METHODS: An international working group with expertise in spinal cord injury, PT, OT, and measurement developed a draft of the International Spinal Cord Injury (ISCI) Physical Therapy-Occupational Therapy (PT-OT) Basic Data Set (BDS). Emphasis was placed on efficiency and practicality of use. The BDS was iteratively refined based on applicable literature, and feedback collected from presentations at the 2017 and 2019 International Spinal Cord Society meetings. RESULTS: The ISCI PT-OT BDS contains seven broad categories of interventions: bed/seated mobility, standing activities, walking/stairs, gross motor upper extremity, fine motor upper extremity, strength training, and endurance training. The first five categories are classified as activity-directed and the last two as impairment-directed interventions. Time spent on interventions per category is recorded in 15-min intervals. CONCLUSIONS: The ISCI PT-OT BDS enables standardized documentation of PT-OT activity-directed or impairment-directed interventions. The ISCI PT-OT BDS is a documentation tool to facilitate evaluation of the influence of rehabilitation therapies on motor function in clinical trials of biologic or pharmacologic agents or rehabilitation technologies that are delivered in the clinical setting.

Effect of reverse manual wheelchair propulsion on shoulder kinematics, kinetics and muscular activity in persons with paraplegia.

Objective: Shoulder pain after spinal cord injury (SCI) is attributed to increased mobility demands on the arms and negatively impacts independence and quality of life. Repetitive superior and posterior shoulder joint forces produced during traditional wheelchair (WC) locomotion can result in subacromial impingement if unopposed, as with muscular fatigue or weakness. ROWHEELS® (RW), geared rear wheels that produce forward WC movement with backward rim pulling, could alter these forces. Design: Cross sectional. Setting: Research laboratory at a rehabilitation hospital. Participants: Ten manual WC users with paraplegia. Outcome measures: Propulsion characteristics and right upper extremity/trunk kinematics and shoulder muscle activity were collected during ergometer propulsion: (1) self-selected free speed reverse propulsion with RW, (2) matched-speed reverse (rSW), and (3) forward propulsion (fSW) with instrumented Smartwheels (SW). Inverse dynamics using right-side SW rim kinetics and kinematics compared shoulder kinetics during rSW and fSW. Results: Free propulsion velocity, cycle distance and cadence were similar during RW, rSW and fSW. Overall shoulder motion was similar except that peak shoulder extension was significantly reduced in both RW and rSW versus fSW. Anteriorly and inferiorly directed SW rim forces were decreased during rSW versus fSW propulsion, but posteriorly and superiorly directed rim forces were significantly greater. Superior and posterior shoulder joint forces and flexor, adductor, and external rotation moments were significantly less during rSW, without a significant difference in net shoulder forces and moments. Traditional propulsive-phase muscle activity was significantly reduced and recovery-phase muscle activity was increased during reverse propulsion. Conclusion: These results suggest that reverse propulsion may redirect shoulder demands and prevent subacromial impingement, thereby preventing injury and preserving independent mobility for individuals with paraplegia.

Predictors of shoulder pain in manual wheelchair users.

BACKGROUND: Manual wheelchair users rely on their upper limbs to provide independent mobility, which leads to high muscular demand on their upper extremities and often results in shoulder pain and injury. However, the specific causes of shoulder pain are unknown. Previous work has shown that decreased shoulder muscle strength is predictive of shoulder pain onset, and others have analyzed joint kinematics and kinetics, propulsion technique and intra-individual variability for their relation to shoulder pathology. The purpose of this study was to determine in a longitudinal setting whether there are specific biomechanical measures that predict shoulder pain development in manual wheelchair users. METHODS: All participants were asymptomatic for shoulder pain and categorized into pain and no pain groups based on assessments at 18 and 36 months later. Shoulder strength, handrim and joint kinetics, kinematics, spatiotemporal measures, intra-individual standard deviations and coefficients of variation were evaluated as predictors of shoulder pain. FINDINGS: Individuals who developed shoulder pain had weaker shoulder adductor muscles, higher positive shoulder joint work during recovery, and less trunk flexion than those who did not develop pain. In addition, relative intra-individual variability was a better predictor of shoulder pain than absolute variability, however future work is needed to determine when increased versus decreased variability is more favorable for preventing shoulder pain. INTERPRETATION: These predictors may provide insight into how to improve rehabilitation training and outcomes for manual wheelchair users and ultimately decrease their likelihood of developing shoulder pain and injuries.

Telehealth monitor to measure physical activity and pressure relief maneuver performance in wheelchair users.

This study demonstrated the feasibility of a device for monitoring pressure relief maneuvers and physical activity for wheelchair users. The device counts the number of wheel pushes based on wheelchair acceleration and measures pressure relief maneuvers using a seat sensor consisting of three force sensing resistors (FSRs). To establish the feasibility of the seat sensor for the detection of pressure relief maneuvers, 10 wheelchair users and 10 non-disabled controls completed a series of wheelchair depression raises, forward trunk leans, and lateral trunk leans. The seat sensor was placed underneath the user's seat cushion. To establish the feasibility of wheel push counting, 10 full-time wheelchair users navigated a flat 50-m outdoor track and a 100-m outdoor obstacle course during self-propulsion (e.g., wheel pushes) and during assisted-propulsion (e.g., no wheel pushes). Of the 240 performed pressure relief, 225 were properly classified by the seat sensor (accuracy: 94%, sensitivity: 96%, specificity: 80%). Sensitivity was highest for depression raises (98%) and lowest for front lean maneuvers (80%). The wheelchair activity monitor measured 2,112 pushes during the self-propulsion trials compared to 2,162 pushes measured with the instrumented push-rim (97.7%). During assisted-propulsion trials, there were 477 incorrectly identified pushes (8.0 per trial).

The influence of wheelchair propulsion hand pattern on upper extremity muscle power and stress.

The hand pattern (i.e., full-cycle hand path) used during manual wheelchair propulsion is frequently classified as one of four distinct hand pattern types: arc, single loop, double loop or semicircular. Current clinical guidelines recommend the use of the semicircular pattern, which is based on advantageous levels of broad biomechanical metrics implicitly related to the demand placed on the upper extremity (e.g., lower cadence). However, an understanding of the influence of hand pattern on specific measures of upper extremity muscle demand (e.g., muscle power and stress) is needed to help make such recommendations, but these quantities are difficult and impractical to measure experimentally. The purpose of this study was to use musculoskeletal modeling and forward dynamics simulations to investigate the influence of the hand pattern used on specific measures of upper extremity muscle demand. The simulation results suggest that the double loop and semicircular patterns produce the most favorable levels of overall muscle stress and total muscle power. The double loop pattern had the lowest full-cycle and recovery-phase upper extremity demand but required high levels of muscle power during the relatively short contact phase. The semicircular pattern had the second-lowest full-cycle levels of overall muscle stress and total muscle power, and demand was more evenly distributed between the contact and recovery phases. These results suggest that in order to decrease upper extremity demand, manual wheelchair users should consider using either the double loop or semicircular pattern when propelling their wheelchairs at a self-selected speed on level ground.

Objective and Self-Reported Physical Activity Measures and Their Association With Depression and Satisfaction With Life in Persons With Spinal Cord Injury.

OBJECTIVE: To identify associations between objective and self-reported measures of physical activity (PA) and relationships with depression and satisfaction with life (SWL) in persons with spinal cord injury (SCI). DESIGN: Retrospective, cross-sectional study of objectively measured wheelchair propulsion (WCP) from 2 studies in which an odometer was attached to participants' wheelchairs to record daily speed and distance. Self-reported data were collected in a separate study examining dyspnea, PA, mood, and SWL. SETTING: Outpatient clinic in a rehabilitation center. PARTICIPANTS: Individuals (N=86) with traumatic SCI who use a manual wheelchair. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Objective measures of PA included average daily distance and speed of WCP measured by an odometer. Self-report questionnaires included demographics, the 24-hour recall of transfers, Physical Activity Recall Assessment for People with SCI, the Patient Health Questionnaire-2 (PHQ-2) to document depressive symptoms, and the Satisfaction With Life Scale (SWLS). RESULTS: Both objective measures of WCP, average daily distance and speed, were predicted by the combination of self-reported daily time away from home/yard and lower frequency of car transfers ([r=.367, P=.002] and [r=.434, P<.001], respectively). Daily distance of WCP was negatively correlated with depression (PHQ-2) (r=-.309, P=.004). Time in leisure PA was the only significant predictor of SWLS scores (r=.321, P=.003). CONCLUSIONS: Short-term recall of hours away from home/yard not spent driving or riding in a vehicle is suggested as a self-report measure that is moderately related to overall WCP PA in this population. Results of this study suggest that depression is related to decreased PA and WCP activity, while SWL is related to leisure PA.

Compensatory strategies during manual wheelchair propulsion in response to weakness in individual muscle groups: A simulation study.

BACKGROUND: The considerable physical demand placed on the upper extremity during manual wheelchair propulsion is distributed among individual muscles. The strategy used to distribute the workload is likely influenced by the relative force-generating capacities of individual muscles, and some strategies may be associated with a higher injury risk than others. The objective of this study was to use forward dynamics simulations of manual wheelchair propulsion to identify compensatory strategies that can be used to overcome weakness in individual muscle groups and identify specific strategies that may increase injury risk. Identifying these strategies can provide rationale for the design of targeted rehabilitation programs aimed at preventing the development of pain and injury in manual wheelchair users. METHODS: Muscle-actuated forward dynamics simulations of manual wheelchair propulsion were analyzed to identify compensatory strategies in response to individual muscle group weakness using individual muscle mechanical power and stress as measures of upper extremity demand. FINDINGS: The simulation analyses found the upper extremity to be robust to weakness in any single muscle group as the remaining groups were able to compensate and restore normal propulsion mechanics. The rotator cuff muscles experienced relatively high muscle stress levels and exhibited compensatory relationships with the deltoid muscles. INTERPRETATION: These results underline the importance of strengthening the rotator cuff muscles and supporting muscles whose contributions do not increase the potential for impingement (i.e., the thoracohumeral depressors) and minimize the risk of upper extremity injury in manual wheelchair users.

Active Lifestyle Is Associated With Reduced Dyspnea and Greater Life Satisfaction in Spinal Cord Injury.

OBJECTIVE: To assess the relations between measures of activity with dyspnea and satisfaction with life in chronic spinal cord injury (SCI). DESIGN: Cross-sectional survey. SETTING: Five SCI centers. PARTICIPANTS: Between July 2012 and March 2015, subjects (N=347) with traumatic SCI ≥1 year after injury who used a manual wheelchair or walked with or without an assistive device reported hours spent away from home or yard on the previous 3 days, sports participation, and planned exercise. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Satisfaction with Life Scale (SWLS) and dyspnea. Dyspnea was defined as shortness of breath when hurrying on the level or going up a slight hill, going slower than people the same age on the level because of breathlessness, or stopping for breath when going at your own pace, or after about 100yd (or after a few minutes) on the level. RESULTS: Dyspnea prevalence was 30%. Adjusting for asthma or chronic obstructive pulmonary disease, mobility mode, race, and season, there was a significant linear trend between greater SWLS scores and quartiles of time spent away from the home or yard (P=.0002). SWLS score was greater if participating in organized sports (P=.01), although was not significantly greater with planned exercise (P=.093). Planned exercise was associated with a reduced odds ratio (OR) of dyspnea (.57; 95% confidence interval [CI], .34-.95; P=.032), but organized sports was not (P=.265). Dyspnea was not significantly increased in persons who spent the fewest hours outside their home or yard (≤7h) compared with people who spent the most hours outside their home or yard (>23h) (OR=1.69; 95% CI, 0.83-3.44; P=.145). CONCLUSIONS: In SCI, a planned exercise program is associated with less dyspnea. An active lifestyle characterized by greater time spent away from home or yard and sports participation is associated with greater SWLS scores.

Body mass index changes over 3 years and effect of obesity on community mobility for persons with chronic spinal cord injury.

OBJECTIVE: To identify the prevalence of obesity in persons with chronic spinal cord injury (SCI), determine change in body mass index (BMI) over time, and identify impact of obesity on community mobility. DESIGN: Prospective three year longitudinal study. SETTING: Outpatient clinic of rehabilitation center. PARTICIPANTS: Convenience sample of 222 persons with paraplegia between 2-20 years post SCI. OUTCOME MEASURES: BMI at baseline and three years; community mobility (daily wheelchair propulsion distance and velocity, average number of daily transfers and depression raises). RESULTS: Participants were 34.1 (27.3, 40.3) years of age and median duration of SCI was 8.7 (3.2, 15.1) years. The SCI adjusted BMI classification identified 44% of participants as obese. BMI increased over time with 13% moving into a higher weight category. Median change in BMI was 0.46 (-0.92, 1.50) kg/m (2) (z = -2.684, P = 0.007), and increased at a rate of 0.15 kg/m(2)/yr. Average BMI was negatively correlated with daily wheelchair propulsion distance (r = -0.179, P = 0.009), however there was no significant relationship with velocity, number of daily transfers or depression raises. CONCLUSION: The majority of participants with chronic SCI were overweight (23%) or obese (44%) and BMI increased by 0.46 kg/m(2) over three years. Those with higher BMIs pushed their wheelchairs shorter distances, but other mobility measures were not impacted by body weight. Continued mobility activities with increasing body weight can increase risk for shoulder injury. Identifying persons who are obese allows for directed and timely health and mobility intervention.