Differences in knee joint moments between individuals who are living with obesity and those of a healthy weight when negotiating stairs.

BACKGROUND: Individuals who are living with obesity often adopt alternative lower limb walking mechanics compared to persons with a healthy weight. Stair negotiation is a common activity of daily living that, when used consistently with diet and other physical activity, can help promote the reversal of health-related risk factors associated with people who are obese. The purpose of this study was to determine how stair negotiation affects normalized and non-normalized peak knee extension and abduction moments in young adults who live with obesity (BMI between 30 and 40 kg/m2) compared to adults with a healthy weight (BMI between 18.5 and 25 kg/m2). METHODS: Fifteen young adults living with obesity and fifteen with a healthy weight performed stair ascent and descent walking trials on a 3-step instrumented staircase at a self-selected walking speed. A one-way ANCOVA (covariate: gait speed) was used to compare knee moment variables between groups. RESULTS: No significant differences were found between groups in peak knee joint moments normalized to body mass. The individuals living with obesity demonstrated significantly larger non-normalized peak knee extension moments during stair ascent and descent but no differences in the non-normalized peak knee abduction moments for stair ascent or descent. CONCLUSION: Results of this study indicate differences in non-normalized peak knee extension moments between BMI groups. The young age of the obese group may have contributed to minimal differences overall. Future research should determine how these findings differ in an older obese population and how using a handrail would affect these results.

Paretic propulsion changes with handrail Use in individuals post-stroke.

Background: Roughly 800,000 people experience a stroke every year in the United States, and about 30% of people require walking assistance (walker, cane, etc.) after a stroke. Gait training on a treadmill is a common rehabilitation activity for individuals post-stroke and handrails are typically used to assist with walking during this training, however individual interaction with these handrails are not usually considered and quantitatively reported. Individuals may exert force onto the handrails to aid with propulsive force, but the relationship between limb propulsive force and handrail propulsive force are not known. Research question: How do individuals post-stroke alter paretic propulsive force when using an assistive device, such as handrails on a treadmill? Methods: Twenty-one individuals post-stroke (eight current assistive device users and thirteen individuals who do not use an assistive device) walked on a treadmill for 3 min during three conditions: no handrail use, light handrail use (<5% BW) and self-selected handrail use. Three multilevel models were used to compare percent handrail, paretic and nonparetic propulsion between handrail conditions and assistive device groups. Results: The handrail propulsive impulse was more during the self-selected handrail condition compared to the light handrail condition (p = 0.002). The assistive device use group and the handrail condition fixed effects significantly improved the model fit for paretic propulsive impulse (p = 0.01). The interaction between assistive device use group and handrail condition significantly improved the model fit for nonparetic propulsive impulse (p < 0.001). Significance: These results suggest that handrail use may impact paretic propulsive impulse. Our initial results suggest that if the goal of rehabilitation treadmill training is to increase the paretic propulsive impulse, having the clinician encourage walking with the handrails may be optimal to promote paretic propulsion.

Limited total arc range of motion increases sheer stress in the shoulder while pitching in collegiate baseball pitchers.

CONTEXT: Upper extremity injuries in baseball pitchers cause significant time-loss from competing and decreased quality of life. Although shoulder range of motion (ROM) is reported as a key factor to prevent potential injury, it remains unclear how limited glenohumeral ROM affects pitching biomechanics which may contribute to upper extremity injuries. OBJECTIVE: To investigate how pitchers with decreased total arc glenohumeral ROM of the throwing arm differed in upper extremity pitching kinematics and kinetics as well as ball velocity compared to pitchers with greater levels of glenohumeral ROM. DESIGN: Cross-sectional Study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Fifty-seven baseball pitchers (ages 18-24) were divided into either control (≧160° total arc) or lower ROM (<160° total arc) groups. MAIN OUTCOME MEASURE(S): The mean glenohumeral ROM deficits, pitching kinematic and kinetic outcomes, and ball velocity were compared between groups. RESULTS: The control group demonstrated significantly less deficit in total arc ROM between arms than the lower ROM (Control: -1.5±10.0°, Lower ROM: -12.4±13.9°, p<.001). While, the lower ROM group displayed less maximal shoulder external rotation (ER) while pitching, the control group had significantly less difference in ROM between maximal shoulder ER while pitching and clinically-measured ER (Lower ROM: 64.4±12.1°, Control: 55.8±16.6°, p=.025). The control group had significantly faster ball velocity compared to the lower ROM group (Control: 85.0 ± 4.3mph, Lower ROM: 82.4 ± 4.8mph, p=.024). CONCLUSION: Pitchers with decreased total arc glenohumeral ROM (<160° total arc) may undergo over-stretching toward ER in the shoulder during the late cocking phase. Pitchers with higher total arc ROM can pitch the same or faster ball without increasing loading in the upper extremity. Total arc glenohumeral ROM measurement can be a clinical screening tool to monitor shoulder condition over the time, and pitchers with limited total arc ROM might be at higher risk of shoulder injury.

Real-Time Visual Kinematic Feedback During Overground Walking Improves Gait Biomechanics in Individuals Post-Stroke.

Treadmill-based gait rehabilitation protocols have shown that real-time visual biofeedback can promote learning of improved gait biomechanics, but previous feedback work has largely involved treadmill walking and not overground gait. The objective of this study was to determine the short-term response to hip extension visual biofeedback, with individuals post-stroke, during unconstrained overground walking. Individuals post-stroke typically have a decreased paretic propulsion and walking speed, but increasing hip extension angle may enable the paretic leg to better translate force anteriorly during push-off. Fourteen individuals post-stroke completed overground walking, one 6-min control bout without feedback, and three 6-min training bouts with real-time feedback. Data were recorded before and after the control bout, before and after the first training bout, and after the third training bout to assess the effects of training. Visual biofeedback consisted of a display attached to eyeglasses that showed one horizontal bar indicating the user's current hip angle and another symbolizing the target hip extension to be reached during training. On average, paretic hip extension angle (p = 0.014), trailing limb angle (p = 0.025), and propulsion (p = 0.011) were significantly higher after training. Walking speed increased but was not significantly higher after training (p = 0.089). Individuals demonstrated a greater increase in their hip extension angle (p = 0.035) and propulsion (p = 0.030) after the walking bout with feedback compared to the control bout, but changes in walking speed did not significantly differ (p = 0.583) between a control walking bout and a feedback bout. Our results show the feasibility of overground visual gait feedback and suggest that feedback regarding paretic hip extension angle enabled many individuals post-stroke to improve parameters important for their walking function.

Comparison of virtual reality to physical box and blocks on cortical an neuromuscualar activations in young adults.

The purpose of this study was to assess the changes in neural activations when performing the box and block test (BBT) in virtual reality (VR) compared to the physical BBT. Young healthy participants performed three trials of the BBT with their left and right hands in both the VR BBT, using VR hand controllers, and physical BBT conditions. Electromyography sensors were placed on the upper extremity of both arms and functional near-infrared spectroscopy was used to measure motor cortex activations throughout each condition. While a reduction in BBT score and increased wrist extensor neuromuscular activity is exhibited during the VR condition, there is no statistical difference in motor cortex activation between the two BBT conditions. This work provides a basis for exploring cortical and neuromuscular responses to VR in patient populations.

A portable visual biofeedback device can accurately measure and improve hip extension angle in individuals post-stroke.

BACKGROUND: Visual biofeedback has shown success in improving gait mechanics in individuals post-stroke but has typically been restricted to use on a treadmill or a short walkway. Using real-time visual biofeedback during overground walking could increase the ease of clinical translation of this method. The objective was to investigate the reliability of a real-time hip extension feedback device during unconstrained, overground walking. We hypothesized that the peak hip extension angle outcome of our device would be comparable to peak hip extension angle measured from a common motion capture system. In addition, we hypothesized that individuals post-stroke would increase their hip extension angle after a single walking bout with visual biofeedback of their hip extension angle. METHODS: Fourteen individuals with chronic stroke walked for one six-minute walking bout with the visual biofeedback device. Before (pre-training) and after (post-training) the feedback walking bout, participants walked in a straight line at their self-selected speed for at least five steps per foot. FINDINGS: Our device was reliable in measuring peak hip extension angle when compared to 3D motion capture equipment (R2 = 0.99). Individuals increased their hip extension angle after one session with the visual biofeedback (+2.886 ± 2.189 deg) compared to a control walking bout (+1.550 ± 1.629 deg) (Z = -2.103, p = 0.035). INTERPRETATION: Our novel and inexpensive biofeedback method may provide benefit for individuals post-stroke and expand the possibilities for feedback in rehabilitation.

The Interplay Between Walking Speed, Economy, and Stability After Stroke.

BACKGROUND AND PURPOSE: Energy minimization is thought to underlie the naturally selected, preferred walking speed; however, people post-stroke walk slower than their most economical speed, presumably to optimize other objectives, such as stability. The purpose of this study was to examine the interplay between walking speed, economy, and stability. METHODS: Seven individuals with chronic hemiparesis walked on a treadmill at 1 of 3 randomized speeds: slow, preferred, and fast. Concurrent measurements of speed-induced changes in walking economy (ie, the energy needed to move 1 kg of bodyweight 1 ml O 2 /kg/m) and stability were made. Stability was quantified as the regularity and divergence of the mediolateral motion of the pelvic center of mass (pCoM) during walking, as well as pCoM motion relative to the base of support. RESULTS: Slower walking speeds were more stable (ie, pCoM motion was 10% ± 5% more regular and 26% ± 16% less divergent) but 12% ± 5% less economical. Conversely, faster walking speeds were 9% ± 8% more economical, but also less stable (ie, pCoM motion was 17% ± 5% more irregular). Individuals with slower walking speeds had an enhanced energetic benefit when walking faster ( rs = 0.96, P < 0.001). Individuals with greater neuromotor impairment had an enhanced stability benefit when walking slower ( rs = 0.86, P = 0.01). DISCUSSION AND CONCLUSIONS: People post-stroke appear to prefer walking speeds that are faster than their most stable speed but slower than their most economical speed. The preferred walking speed after stroke appears to balance stability and economy. To encourage faster and more economical walking, deficits in the stable control of the mediolateral motion of the pCoM may need to be addressed.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A416 ).

Comparison of markerless and marker-based motion capture of gait kinematics in individuals with cerebral palsy and chronic stroke: A case study series.

Background: Three-dimensional (3D) motion analysis is an advanced tool used to quantify movement patterns in adults with chronic stroke and children with cerebral palsy. However, gold-standard marker-based systems have limitations for implementation in clinical settings. Markerless motion capture using Theia3D may provide a more accessible and clinically feasible alternative, but its accuracy is unknown in clinical populations. The purpose of this study was to quantify kinematic differences between marker-based and markerless motion capture systems in individuals with gait impairments. Methods: Three adults with chronic stroke and three children with cerebral palsy completed overground walking trials while marker-based and markerless motion capture data were synchronously recorded. Time-series waveforms of 3D ankle, knee, hip, and trunk angles were stride normalized and compared. Root mean squared error, maximum peak, minimum peak, and range of motion were used to assess discrete point differences. Pearson's correlation and coefficient of multiple correlation were computed to assess similarity between the time series joint angle waveforms from both systems. Results: This study demonstrates that markerless motion capture using Theia3D produces good agreement with marker-based in the measurement of gait kinematics at most joints and anatomical planes in individuals with chronic stroke and cerebral palsy. Conclusions: This is the first investigation to study the feasibility of Theia3D markerless motion capture for use in chronic stroke and cerebral palsy gait analysis. Our results indicate that markerless motion capture may be an acceptable tool to measure gait kinematics in clinical populations to provide clinicians with objective movement assessment data.

Development, validity, and test-retest reliability of a new neurocognitive functional performance test: The choice-reaction hop test.

OBJECTIVES: To validate a choice-reaction hop test (CRHT) by assessing differences in timing versus the side-hop test (SHT), and to determine the CRHT's test-retest reliability. DESIGN: Test-retest reliability. SETTING: Laboratory. PARTICIPANTS: Forty-nine healthy adults participated (16 female; age = 22.7 ± 3.4 years; height = 174.9 ± 9.1 cm; mass = 75.4 ± 14.8 kg). MAIN OUTCOME MEASURES: Participants completed three trials each of the SHT and the CRHT in a counterbalanced order. Participants returned one-week later to repeat the CRHT. The fastest and the mean of the three trials were compared. RESULTS: Participants took significantly longer to complete the CRHT (Mean across 3 trials = 21.4 ± 3.4s, Fastest trial = 19.7 ± 3.0s) compared to the traditional SHT (10.4 ± 2.0s, p < 0.001). The CRHT demonstrated good-excellent test-retest reliability across testing days for both the mean across 3 trials (r = 0.890, p < 0.001, SEM = 1.13) and the fastest trial (r = 0.828, p < 0.001, SEM = 1.24). CONCLUSION: Compared to the SHT, the CRHT took longer to complete indicating its ability to stress neurocognitive function during an FPT. The CRHT demonstrated good-excellent test-retest reliability, which may allow it to be a useful measure in serial evaluations such as during rehabilitation benchmarking. The CRHT may be an effective FPT to assess combined physical and neurocognitive function to assist clinicians in evidence-based decision-making.

Ankle stiffness modulation during different gait speeds in individuals post-stroke.

BACKGROUND: Neurotypical individuals alter their ankle joint quasi-stiffness in response to changing walking speed; however, for individuals post-stroke, the ability to alter their ankle quasi-stiffness is unknown. Individuals post-stroke commonly have weak plantarflexor muscles, which may limit their ability to alter ankle quasi-stiffness. The objective was to investigate the relationship between ankle quasi-stiffness and propulsion, at two walking speeds. We hypothesized that in individuals post-stroke, there would be no difference in their paretic ankle quasi-stiffness between walking at a self-selected versus a fast speed. However, we hypothesized that ankle quasi-stiffness would correlate with gait speed and propulsion across individuals. METHODS: Twenty-eight participants with chronic stroke walked on an instrumented treadmill at their self-selected and fast-walking speeds. Multilevel models were used to determine the relationships between ankle quasi-stiffness, speed, and propulsion. FINDINGS: Overall, ankle quasi-stiffness did not increase within individuals from a self-selected to a fast gait speed (p = 0.69). A 1 m/s increase in speed across participants predicted an increase in overall ankle quasi-stiffness of 0.02 Nm/deg./kg (p = 0.03) and a 1 N/BW change in overall propulsion across participants predicted a 0.265 Nm/deg./kg increase in overall ankle quasi-stiffness (p < 0.0001). INTERPRETATION: Individuals post-stroke did not modulate their ankle quasi-stiffness with increased speed, but across individuals there was a positive relationship between ankle quasi-stiffness and both speed and peak propulsion. Walking speed and propulsion are limited in individuals post-stroke, therefore, improving either could lead to a higher functional status. Understanding post-stroke ankle stiffness may be important in the design of therapeutic interventions and exoskeletons, where these devices augment the biological ankle quasi-stiffness to improve walking performance.

A Comparison of Pitching Biomechanics and Sport Specialization in High School Pitchers.

Background: The prevalence of sport specialization in high school athletes continues to rise, particularly among baseball players. Previous research has focused on the incidence of injury among specialized and non-specialized athletes but has yet to examine the level of sport specialization and pitching biomechanics. Hypotheses/Purpose: The purpose of this study was to investigate differences in pitching volume and biomechanics between low-, moderate-, and high-level specialized baseball pitchers. It was hypothesized that high-level specialized pitchers would have the most pitching volume within the current and previous years while low-level specialized pitchers would exhibit the least amount. The second hypothesis states that kinematics and kinetics commonly associated with performance and injury risk would differ between low-, moderate-, and high-level specialized pitchers. Study Design: Case-Control Study. Methods: Thirty-six high school baseball pitchers completed a custom sport specialization questionnaire before participating in a three-dimensional pitching motion analysis. Sport specialization was based off current guidelines and categorized as low-, moderate-, and high-level specialized based upon self-reported outcomes. Pitchers then threw ≈10 fastballs from a mound engineered to professional specifications. Data averaged across fastballs was used for biomechanics variables. Key pitching biomechanical and pitching volume variables were compared between low-, moderate-, and high-level specialized pitchers. Results: High-level specialized pitchers were older (p = 0.003), had larger body mass (p = 0.05) and BMI (p = 0.045), and threw faster (p = 0.01) compared to low-level specialized pitchers. Pitching volume and pitching biomechanics were similar across groups. Conclusions: Pitching biomechanics were similar across groups, although high-level specialized pitchers threw with significantly higher throwing velocity compared to low-level pitchers. The low amount of pitching volume throughout the season may be responsible for the lack of additional observed differences. Further research should examine the relationship between pitching biomechanics, upper extremity strength and flexibility, and sport specialization. Level of Evidence: Level III.

Prediction of Stability during Walking at Simulated Ship's Rolling Motion Using Accelerometers.

Due to a ship's extreme motion, there is a risk of injuries and accidents as people may become unbalanced and be injured or fall from the ship. Thus, individuals must adjust their movements when walking in an unstable environment to avoid falling or losing balance. A person's ability to control their center of mass (COM) during lateral motion is critical to maintaining balance when walking. Dynamic balancing is also crucial to maintain stability while walking. The margin of stability (MOS) is used to define this dynamic balancing. This study aimed to develop a model for predicting balance control and stability in walking on ships by estimating the peak COM excursion and MOS variability using accelerometers. We recruited 30 healthy individuals for this study. During the experiment, participants walked for two minutes at self-selected speeds, and we used a computer-assisted rehabilitation environment (CAREN) system to simulate the roll motion. The proposed prediction models in this study successfully predicted the peak COM excursion and MOS variability. This study may be used to protect and save seafarers or passengers by assessing the risk of balance loss.

Comparison of brain activation and functional outcomes between physical and virtual reality box and block test: a case study.

PURPOSE: Immersive Virtual Reality (VR) systems allow for highly repetitive tasks to be performed within a virtual environment that increases practice in home environments. VR can increase access to rehabilitation by reducing access barriers. However, rehabilitation outcomes between immersive VR systems and conventional physical rehabilitation are not well understood. The purpose of this case study was to assess the use of a custom clinically based VR simulation for testing gross hand dexterity with an individual with chronic stroke. MATERIALS AND METHODS: The participant performed the box and blocks test (BBT) in an immersive VR environment and a physical environment. Three trials of the BBT were performed with their less-affected and affected hands each in both environments while measuring cortical activity using fNIRS. Rests were given between trials and environment conditions. RESULTS: Our results show that there was no statistical difference in the number of blocks moved between the physical and VR BBT for both the affected and less-affected hands. Furthermore, our results also indicate no statistically significant difference between the physical BBT and VR BBT conditions on contralateral motor cortex activation, suggesting that cortical involvement is comparable between physical and VR conditions. CONCLUSIONS: These results suggest that an immersive VR system may be able to elicit functional and motor cortex activations that are comparable to the conventional physical BBT. Importantly, these findings highlights the potential benefits of VR therapy as a remote therapy intervention and/or to increase the effectiveness and practicality of current in-person rehabilitation programs.Implications for rehabilitationThese findings highlight the potential benefits of immersive virtual reality as a remote therapy intervention.Immersive virtual reality use has potential benefits to increase the effectiveness and practicality of current in-person rehabilitation programs.

Neuroticism and Extraversion Are Related to Changes in Postural Stability During Anatomically-Related Cognitive Tasks.

The relationship between personality and postural stability has received little attention. This study addressed whether neuroticism and extraversion correlate with changes in postural stability while performing cognitive tasks related to brain regions selectively associated with neuroticism and extraversion. Thirty-two adults stood on a foam mat in tandem stance and completed a 2-back task and a weather prediction task (WPT). As predicted, higher neuroticism was related to increased dual task sway during the 2-back task, r = 0.40, p = 0.023, and lower extraversion was related to increased dual task sway during the WPT, r = -0.43, p = 0.013, suggesting that personality is related to postural stability in healthy young adults and that personality could be considered in the prediction and treatment of individuals with balance difficulties.

Wearable Sensor-Based Prediction Model of Timed up and Go Test in Older Adults.

The Timed Up and Go (TUG) test has been frequently used to assess the risk of falls in older adults because it is an easy, fast, and simple method of examining functional mobility and balance without special equipment. The purpose of this study is to develop a model that predicts the TUG test using three-dimensional acceleration data collected from wearable sensors during normal walking. We recruited 37 older adults for an outdoor walking task, and seven inertial measurement unit (IMU)-based sensors were attached to each participant. The elastic net and ridge regression methods were used to reduce gait feature sets and build a predictive model. The proposed predictive model reliably estimated the participants' TUG scores with a small margin of prediction errors. Although the prediction accuracies with two foot-sensors were slightly better than those of other configurations (e.g., MAPE: foot (0.865 s) > foot and pelvis (0.918 s) > pelvis (0.921 s)), we recommend the use of a single IMU sensor at the pelvis since it would provide wearing comfort while avoiding the disturbance of daily activities. The proposed predictive model can enable clinicians to assess older adults' fall risks remotely through the evaluation of the TUG score during their daily walking.

Outdoor walking exhibits peak ankle and knee flexion differences compared to fixed and adaptive-speed treadmills in older adults.

BACKGROUND: Walking mechanics recorded with a traditional treadmill may not be the same as the mechanics exhibited during activities of daily living due to constrained walking speeds. Adaptive-speed treadmills allow for unconstrained walking speeds similar to outdoor walking. The aim of this study was to determine differences in kinematic walking parameters of older adults between adaptive-speed treadmill (AST), fixed-speed treadmill (FST) and outdoor walking. We hypothesized that self-selected walking speed (SSWS) during AST walking and outdoor walking would increase compared to FST walking. Furthermore, we hypothesized that AST walking and outdoor walking would increase peak knee flexion, hip flexion, and ankle plantarflexion angles compared to FST walking independent of walking speed changes. METHODS: Fourteen older adult participants were asked to complete 3 min of FST and AST walking on a split-belt treadmill. Participants were also asked to complete 6 min of outdoor walking following a circular route in a neighboring park. A wireless inertial measurement unit-based motion capture system was used to record lower extremity kinematics during all walking conditions. RESULTS: The outdoor walking condition produces significantly higher SSWS compared to FST (p < 0.001) and AST (p = 0.02) conditions. A significantly faster SSWS was exhibited during the AST condition compared to the FST condition (p = 0.026). Significantly higher peak ankle plantarflexion angles are exhibited during the outdoor walking condition compared to the AST (p < 0.001, g = 1.14) and FST (p < 0.001, g = 1.13) conditions after accounting for walking speed. There was a significantly lowered difference between the outdoor walking condition and both AST (p = 0.029, g = 0.49) and FST (p = 0.013, g = 0.63) conditions in peak knee flexion angles after accounting for SSWS. There are no significant differences between outdoor, AST, and FST conditions on peak hip flexion angles. Older adults exhibit changes in peak ankle plantarflexion and peak knee flexion angles during outdoor walking compared to treadmill walking but not between treadmill controller types. We found no differences in the kinematics exhibited by older adults between both AST and FST walking. CONCLUSIONS: Incorporating unconstrained walking speed with the AST while maintaining similar FST sagittal plane kinematics may allow for more translatable conditional balance and walking rehabilitation.

Effect of isolated hip abductor fatigue on single-leg landing mechanics and simulated ACL loading.

BACKGROUND: Altered movement biomechanics are a risk factor for ACL injury. While hip abductor weakness has been shown to negatively impact landing biomechanics, the role of this musculature and injury risk is not clear. The aim of this musculoskeletal simulation study was to determine the effect of hip abductor fatigue-induced weakness on ACL loading, force production of lower extremity muscles, and lower extremity biomechanics during single-leg landing. METHODS: Biomechanical data from ten healthy adults were collected before and after a fatigue protocol and used to derive subject-specific estimates of muscle forces and ACL loading using a 5-degree of freedom (DOF) model. RESULTS: There were no significant differences in knee joint angles and ACL loading between pre and post-fatigue. However, there were significant differences, due to fatigue, in lateral trunk flexion angle, total excursion of trunk, muscle forces, and joint moments. CONCLUSION: Altered landing mechanics, due to hip abductor fatigue-induced weakness, may be associated with increased risk of ACL injury during single-leg landings. Clinical assessment or screening of ACL injury risk will benefit from subject-specific musculoskeletal models during dynamic movements. Future study considering the type of the fatigue protocols, cognitive loads, and various tasks is needed to further identify the effect of hip abductor weakness on lower extremity landing biomechanics.

Mechanisms used to increase propulsive forces on a treadmill in older adults.

Older adults typically demonstrate reductions in overground walking speeds and propulsive forces compared to young adults. These reductions in walking speeds are risk factors for negative health outcomes. Therefore, this study aimed to determine the effect of an adaptive speed treadmill controller on walking speed and propulsive forces in older adults, including the mechanisms and strategies underlying any change in propulsive force between conditions. Seventeen participants completed two treadmill conditions, one with a fixed comfortable walking speed and one with an adaptive speed controller. The adaptive speed treadmill controller utilized a set of inertial-force, gait parameters, and position-based controllers that respond to an instantaneous anterior inertial force. A biomechanical-based model previously developed for individuals post-stroke was implemented for older adults to determine the primary gait parameters that contributed to the change in propulsive forces when increasing speed. Participants walked at faster average speeds during the adaptive speed controller (1.20 m/s) compared to the fixed speed controller conditions (0.98 m/s); however, these speeds were not as fast as their overground speed (1.44 m/s). Although average trailing limb angle (TLA) (p < 0.001) and ankle moment (p = 0.020) increased when speed also increased between treadmill conditions, increasing TLA contributed more to the increased propulsive forces seen during faster treadmill speeds. Our findings show that older adults chose faster walking speeds and increased propulsive force when walking on an adaptive speed treadmill compared to a fixed speed treadmill, suggesting that an adaptive speed treadmill controller has the potential to be a beneficial alternative to current exercise interventions for older adults.

Testing of a 3D printed hand exoskeleton for an individual with stroke: a case study.

INTRODUCTION: Many individuals with stroke still have functional difficulties with their affected hand after going through a rehabilitation program. A 3D printed upper limb exoskeleton was designed for an individual who had a stroke. Functional and neuromuscular outcomes were measured using his affected hand with and without a 3D printed passive exoskeleton. The goal of this study was to determine the functional and neuromuscular changes induced by the 3D printed exoskeleton in a participant with stroke. MATERIALS AND METHODS: The functional ability of the exoskeleton was assessed using the Fugl-Meyer Assessment and the Box and Block Test. Strength testing and muscle activation of the participant's forearms were measured during maximal voluntary contractions. Furthermore, EMG was measured during the Box and Block Test and satisfaction and usability of the 3D printed exoskeleton were assessed using standardized questionnaires. RESULTS: The exoskeleton improved both the participant's Fugl-Meyer Assessment scores and Box and Block test scores compared to not wearing the device. The subject had increased EMG activation in his extensor when wearing the exoskeleton. CONCLUSION: The inexpensive 3D printed exoskeleton was effective in assisting the participant with stroke during the functional assessments and has the potential to be used to help regain function of the hand in the home setting of an individual with stroke.IMPLICATIONS FOR REHABILITATIONA 3D printed passive hand exoskeleton may assist to accomplish rehabilitation outcomes by increasing function of the affected hand of patients with stroke.The use of this hand exoskeleton may be used to improve gross hand dexterity and assist with functional grasps during rehabilitation sessions with a lower patient's level of perceived exertion.The use of new antimicrobial 3D printing polymers can be effectively implemented to manufacture assistive devices to prevent skin infections during rehabilitation.

Relationships of Linear and Non-linear Measurements of Post-stroke Walking Activity and Their Relationship to Weather.

Background: Stroke survivors are more sedentary than the general public. Previous research on stroke activity focuses on linear quantities. Non-linear measures, such as Jensen-Shannon Divergence and Lempel-Ziv Complexity, may help explain when and how stroke survivors move so that interventions to increase activity may be designed more effectively. Objectives: Our objective was to understand what factors affect a stroke survivor's physical activity, including weather, by characterizing activity by step counts, structure, and complexity. Methods: A custom MATLAB code was used to analyze clinical trial (NCT02835313, https://clinicaltrials.gov/ct2/show/NCT02835313) data presented as minute by minute step counts. Six days of data were analyzed for 142 participants to determine the regularity of activity structure across days and complexity patterns of varied cadences. The effect of steps on structure and complexity, the season's effect on steps, structure, and complexity, and the presence of precipitation's effect on steps and complexity were all analyzed. Results: Step counts and regularity were linearly related (p < 0.001). Steps and complexity were quadratically related (r 2 = 0.70 for mean values, 0.64 for daily values). Season affected complexity between spring and winter (p = 0. 019). Season had no effect on steps or structure. Precipitation had no effect on steps or complexity. Conclusions: Stroke survivors with high step counts are active at similar times each day and have higher activity complexities as measured through patterns of movement at different intensity levels. Non-linear measures, such as Jensen-Shannon Divergence and Lempel-Ziv Complexity, are valuable in describing a person's activity. Weather affects our activity parameters in terms of complexity between spring and winter.