Open Access Publications

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Open access publications by faculty, staff, postdocs, and graduate students from the Biomechanics & Movement Science Program.


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    Immediate and Short-Term Effects of In-Shoe Heel-Lift Orthoses on Clinical and Biomechanical Outcomes in Patients With Insertional Achilles Tendinopathy
    (Orthopaedic Journal of Sports Medicine, 2024-02-07) Alghamdi, Nabeel Hamdan; Pohlig, Ryan T.; Seymore, Kayla D.; Sions, Jaclyn Megan; Crenshaw, Jeremy R.; Grävare Silbernagel, Karin
    Background: Physical therapists frequently employ heel lifts as an intervention to reduce Achilles tendon pain and restore function. Purpose: To determine the short-term effect of heel lifts on clinical and gait outcomes in participants with insertional Achilles tendinopathy (IAT). Study Design: Case series; Level of evidence, 4. Methods: Participants with IAT underwent eligibility screening and completed assessments at baseline and 2 weeks later. Primary outcomes included symptom severity (Victoria Institute of Sports Assessment-Achilles [VISA-A]), gait analysis with the 10-m walk-test at 2 speeds (normal and fast), and pain during walking. Pain and gait analysis were assessed under 3 conditions: before fitting 20-mm heel lifts, immediately after heel-lift fitting, and after 2 weeks of wearing heel lifts. Ultrasound images and measurements at the Achilles insertion were obtained from prone and standing positions (with and without heel lifts). Spatiotemporal gait parameters and tibial tilt angles were evaluated at normal speed using inertia measurement units during the 3 study conditions. Differences between the conditions were analyzed using paired t test or analysis of variance. Results: Overall, 20 participants (12 female, 13 with bilateral IAT; mean age, 51 ± 9.3 years; mean body mass index 31.6 ± 6.8 kg/m2) completed all assessments. Symptom severity (VISA-A) of the more symptomatic side significantly improved at 2 weeks (60 ± 20.6) compared with baseline (52.2 ± 20.4; P < .01). Pain during gait (Numeric Pain Rating Scale) was significantly reduced immediately after heel-lift fitting (0.7 ± 2.0) when compared with baseline (2.2 ± 2.7, P = .043). Spatiotemporal gait parameters and tibial tilt angle before and after using heel lifts at normal walking speed were not significantly different; however, gait speed, stride length, and tibial tilt angle on both sides increased significantly immediately after using heel lifts and were maintained after 2 weeks of wear. Conclusion: Using heel lifts not only improved symptom severity after 2 weeks but also immediately reduced pain during gait and had a positive impact on gait pattern and speed.
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    Autism-Related Differences in Cortical Activation When Observing, Producing, and Imitating Communicative Gestures: An fNIRS Study
    (Brain Sciences, 2023-09-04) Su, Wan-Chun; Culotta, McKenzie; Mueller, Jessica; Tsuzuki, Daisuke; Bhat, Anjana N.
    Children with autism spectrum disorder (ASD) have difficulties in gestural communication during social interactions. However, the neural mechanisms involved in naturalistic gestural communication remain poorly understood. In this study, cortical activation patterns associated with gestural communication were examined in thirty-two children with and without ASD (mean age: 11.0 years, SE: 0.6 years). Functional near-infrared spectroscopy (fNIRS) was used to record cortical activation while children produced, observed, or imitated communicative gestures. Children with ASD demonstrated more spatial and temporal errors when performing and imitating communicative gestures. Although both typically developing (TD) children and children with ASD showed left-lateralized cortical activation during gesture production, children with ASD showed hyperactivation in the middle/inferior frontal gyrus (MIFG) during observation and imitation, and hypoactivation in the middle/superior temporal gyrus (MSTG) during gesture production compared to their TD peers. More importantly, children with ASD exhibited greater MSTG activation during imitation than during gesture production, suggesting that imitation could be an effective intervention strategy to engage cortical regions crucial for processing and producing gestures. Our study provides valuable insights into the neural mechanisms underlying gestural communication difficulties in ASD, while also identifying potential neurobiomarkers that could serve as objective measures for evaluating intervention effectiveness in children with ASD.
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    Validating the measurement of upper limb sensorimotor behavior utilizing a tablet in neurologically intact controls and individuals with chronic stroke
    (Journal of NeuroEngineering and Rehabilitation, 2023-09-01) Austin, Devin Sean; Dixon, Makenna J.; Tulimieri, Duncan Thibodeau; Cashaback, Joshua G. A.; Semrau, Jennifer A.
    Background Intact sensorimotor function of the upper extremity is essential for successfully performing activities of daily living. After a stroke, upper limb function is often compromised and requires rehabilitation. To develop appropriate rehabilitation interventions, sensitive and objective assessments are required. Current clinical measures often lack precision and technological devices (e.g. robotics) that are objective and sensitive to small changes in sensorimotor function are often unsuitable and impractical for performing home-based assessments. Here we developed a portable, tablet-based application capable of quantifying upper limb sensorimotor function after stroke. Our goal was to validate the developed application and accompanying data analysis against previously validated robotic measures of upper limb function in stroke. Methods Twenty individuals with stroke, twenty age-matched older controls, and twenty younger controls completed an eight-target Visually Guided Reaching (VGR) task using a Kinarm Robotic Exoskeleton and a Samsung Galaxy Tablet. Participants completed eighty trials of the VGR task on each device, where each trial consisted of making a reaching movement to one of eight pseudorandomly appearing targets. We calculated several outcome parameters capturing various aspects of sensorimotor behavior (e.g., Reaction Time, Initial Direction Error, Max Speed, and Movement Time) from each reaching movement, and our analyses compared metric consistency between devices. We used the previously validated Kinarm Standard Analysis (KSA) and a custom in-house analysis to calculate each outcome parameter. Results We observed strong correlations between the KSA and our custom analysis for all outcome parameters within each participant group, indicating our custom analysis accurately replicates the KSA. Minimal differences were observed for between-device comparisons (tablet vs. robot) in our outcome parameters. Additionally, we observed similar correlations for each device when comparing the Fugl-Meyer Assessment (FMA) scores of individuals with stroke to tablet-derived metrics, demonstrating that the tablet can capture clinically-based elements of upper limb impairment. Conclusions Tablet devices can accurately assess upper limb sensorimotor function in neurologically intact individuals and individuals with stroke. Our findings validate the use of tablets as a cost-effective and efficient assessment tool for upper-limb function after stroke.
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    Contact or Collision Sport History, Repetitive Neurotrauma, and Patient-Reported Outcomes in Early to Midadulthood
    (Journal of Athletic Training, 2023-12-18) Hunzinger, Katherine J.; Caccese, Jaclyn B.; Mannix, Rebekah; Meehan, William P.; Swanik, C. Buz; Buckley, Thomas A.
    Context Data on the early to midlife effects of repetitive neurotrauma on patient-reported outcomes have been delimited to homogeneous samples of male athletes without comparison groups or accounting for modifying factors such as physical activity. Objective To determine the effect of contact or collision sport participation and repetitive neurotrauma on patient-reported outcomes among early to middle-aged adults. Design Cross-sectional study. Setting Research laboratory. Patients or Other Participants A total of 113 adults (53 [46.9%] men, 60 [53.1%] women; age = 34.88 ± 11.80 years) in 4 groups: (1) physically inactive individuals with no repetitive head impact (RHI) exposure (NON); (2) noncontact sport athletes and nonathletes with no RHI exposure who were currently physically active (NCA); (3) former high-risk sport athletes with an RHI history who were physically active (HRS); and (4) former rugby players with prolonged RHI exposure who remained physically active. Main Outcome Measure(s) The 12-Item Short-Form Health Survey (SF-12), Apathy Evaluation Scale–self-rated version (AES-S), Satisfaction With Life Scale (SWLS), and Sport Concussion Assessment Tool–5th Edition (SCAT5) Symptom and Symptom Severity Checklist. Results The NON group had worse self-rated physical function than the NCA group as assessed by the SF-12 physical component summary (P = .03) and worse self-rated apathy (AES-S) and satisfaction with life (SWLS) than the NCA (P = .03 for both) and HRS groups (P = .03 and P = .040, respectively). We observed no group differences for self-rated mental health (SF-12 mental component summary; P = .26) or symptoms (SCAT5; P = .42). Career duration was not associated with any patient-reported outcomes. Conclusions A history of contact or collision sport participation and career duration did not negatively affect patient-reported outcomes in physically active, early to middle-aged adults. However, physical inactivity status was negatively associated with patient-reported outcomes in these individuals in the absence of an RHI history. Key Points - The midlife and later-life effects of repetitive head impacts paired with physical activity on patient-reported outcomes need to be elucidated. - Contact or collision sport participation and career duration were unrelated to worse patient-reported outcomes in early to midadulthood among physically active individuals. - Physical inactivity may be a more important modifier of patient-reported outcomes in early to midadulthood than repetitive neurotrauma exposure.
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    Visual accuracy dominates over haptic speed for state estimation of a partner during collaborative sensorimotor interactions
    (Journal of Neurophysiology, 2023-07-01) Lakesh, Rakshith; Sullivan, Seth R.; Germain, Laura St.; Roth, Adam M.; Calalo, Jan A.; Buggeln, John; Ngo, Truc; Marchhart, Vanessa R. F.; Carter, Michael J.; Cashaback, Joshua G. A.
    We routinely have physical interactions with others, whether it be handing someone a glass of water or jointly moving a heavy object together. These sensorimotor interactions between humans typically rely on visual feedback and haptic feedback. Recent single-participant studies have highlighted that the unique noise and time delays of each sense must be considered to estimate the state, such as the position and velocity, of one’s own movement. However, we know little about how visual feedback and haptic feedback are used to estimate the state of another person. Here, we tested how humans utilize visual feedback and haptic feedback to estimate the state of their partner during a collaborative sensorimotor task. Across two experiments, we show that visual feedback dominated haptic feedback during collaboration. Specifically, we found that visual feedback led to comparatively lower task-relevant movement variability, smoother collaborative movements, and faster trial completion times. We also developed an optimal feedback controller that considered the noise and time delays of both visual feedback and haptic feedback to estimate the state of a partner. This model was able to capture both lower task-relevant movement variability and smoother collaborative movements. Taken together, our empirical and modeling results support the idea that visual accuracy is more important than haptic speed to perform state estimation of a partner during collaboration. NEW & NOTEWORTHY Physical collaboration between two or more individuals involves both visual and haptic feedback. Here, we investigated how visual and haptic feedback is used to estimate the movements of a partner during a collaboration task. Our experimental and computational modeling results parsimoniously support the notion that greater visual accuracy is more important than faster yet noisier haptic feedback when estimating the state of a partner.
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    Limitations in utilization and prioritization of standardized somatosensory assessments after stroke: A cross-sectional survey of neurorehabilitation clinicians
    (Topics in Stroke Rehabilitation, 2023-04-16) Hoh, Joanna Eskander; Borich, Michael R.; Kesar, Trisha M.; Reisman, Darcy S.; Semrau, Jennifer A.
    Background and Purpose Somatosensory impairments are common after stroke, but receive limited evaluation and intervention during neurorehabilitation, despite negatively impacting functional movement and recovery. Objectives Our objective was to understand the scope of somatosensory assessments used by clinicians in stroke rehabilitation, and barriers to increasing use in clinical practice. Methods An electronic survey was distributed to clinicians (physical therapists, occupational therapists, physicians, and nurses) who assessed at least one individual with stroke in the past 6 months. The survey included questions on evaluation procedures, type, and use of somatosensory assessments, as well as barriers and facilitators in clinical practice. Results Clinicians (N = 431) indicated greater familiarity with non-standardized assessments, and greater utilization compared to standardized assessments (p < 0.0001). Components of tactile sensation were the most commonly assessed modality of somatosensation (25%), while proprioception was rarely assessed (1%). Overall, assessments of motor function were prioritized over assessments of somatosensory function (p < 0.0001). Discussion Respondents reported assessing somatosensation less frequently than motor function and demonstrated a reliance on rapid and coarse non-standardized assessments that ineffectively capture multi-modal somatosensory impairments, particularly for proprioceptive deficits common post-stroke. In general, clinicians were not familiar with standardized somatosensory assessments, and this knowledge gap likely contributes to lack of translation of these assessments into practice. Conclusions Clinicians utilize somatosensory assessments that inadequately capture the multi-modal nature of somatosensory impairments in stroke survivors. Addressing barriers to clinical translation has the potential to increase utilization of standardized assessments to improve the characterization of somatosensory deficits that inform clinical decision-making toward enhancing stroke rehabilitation outcomes.
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    Information Available to Parents Seeking Education about Infant Play, Milestones, and Development from Popular Sources
    (Behavioral Sciences, 2023-05-19) Orlando, Julie M.; Cunha, Andrea B.; Alghamdi, Zainab; Lobo, Michele A.
    Parents commonly seek information about infant development and play, yet it is unclear what information parents find when looking in popular sources. Play, Milestone, and Development Searches in Google identified 313 sources for content analysis by trained researchers using a standardized coding scheme. Sources included websites, books, and apps created by professional organizations, commercial entities, individuals, the popular press, and government organizations/agencies. The results showed that for popular sources: (1) author information (i.e., qualifications, credentials, education/experience) is not consistently provided, nor is information about the developmental process, parents’ role in development, or determining an infant’s readiness to play; (2) milestones comprise a majority of the content overall; (3) search terminology impacts the information parents receive; (4) sources from the Milestone and Development Searches emphasized a passive approach of observing developmental milestones rather than suggesting activities to actively facilitate learning and milestone development. These findings highlight the need to discuss parents’ online information-gathering process and findings. They also highlight the need for innovative universal parent-education programs that focus on activities to facilitate early development. This type of education has potential to benefit all families, with particular benefits for families with children who have unidentified or untreated developmental delays.
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    Clinical Mental Health Measures and Prediction of Postconcussion Musculoskeletal Injury
    (Journal of Athletic Training, 2023-07-31) Buckley, Thomas A.; Bryk, Kelsey N.; Enrique, Alexander L.; Kaminski, Thomas W.; Hunzinger, Katherine J.; Oldham, Jessie R.
    Context The rate of lower extremity musculoskeletal injury (LE MSK) is elevated after concussion; however, the underlying mechanism has not been elucidated. Physical characteristics have been investigated despite poorer mental health being a common postconcussion complaint and linked to MSKs. Objective To evaluate the role of mental health as a predictor of postconcussion LE MSK. Design Case-control study. Setting Intercollegiate athletic training facility. Patients or Other Participants A total of 67 National Collegiate Athletic Association Division I student-athletes (n = 39 females) who had been diagnosed with a sport-related concussion. Main Outcome Measure(s) The Brief Symptom Inventory-18, Hospital Anxiety and Depression Scale, and Satisfaction With Life Scale (SWLS) measures were completed at baseline (preseason) and on the day participants were cleared for unrestricted return to play (RTP) after a concussion. Two binary logistic regressions were used to predict postconcussion LE MSK within a year, one for the baseline time point and the second for the RTP time point. A 2 (group: LE MSK, no LE MSK)-by-2 (time: baseline, RTP) repeated-measures analysis of variance compared performance between baseline and RTP. Results Subsequent LE MSKs were sustained by 44 participants (65.7%). The only significant predictor of postconcussion LE MSK was the SWLS score at RTP, with Exp(B) = 0.64, indicating that an increased (improved) SWLS score was associated with a lower LE MSK rate. No significant interactions were present between mental health measures and subsequent MSK (P values = .105–.885). Conclusions Limited associations were evident between postconcussion LE MSK and scores on commonly used measures of anxiety, depression, and satisfaction with life. Reported increased satisfaction with life was associated with a decreased injury risk, which warrants further attention. Our results suggest that these measures of anxiety, depression, and satisfaction with life have limited value in assisting sports medicine clinicians with determining which student-athletes are at elevated risk of postconcussion LE MSK. Key Points Measures of anxiety and depressive symptoms were not predictive of elevated postconcussion lower extremity musculoskeletal injury. Greater satisfaction with life was associated with a decreased risk of postconcussion lower extremity musculoskeletal injury.
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    The nervous system tunes sensorimotor gains when reaching in variable mechanical environments
    (iScience, 2023-06-16) Maurus, Philipp; Jackson, Kuira; Cashaback, Joshua G.A.; Cluff, Tyler
    Highlights: • The control of reaching is altered when facing time-varying physical disturbances • The changes in control increase responses to proprioceptive and visual feedback • Responses to feedback are tuned to the variability of the time-varying disturbances Summary: Humans often move in the presence of mechanical disturbances that can vary in direction and amplitude throughout movement. These disturbances can jeopardize the outcomes of our actions, such as when drinking from a glass of water on a turbulent flight or carrying a cup of coffee while walking on a busy sidewalk. Here, we examine control strategies that allow the nervous system to maintain performance when reaching in the presence of mechanical disturbances that vary randomly throughout movement. Healthy participants altered their control strategies to make movements more robust against disturbances. The change in control was associated with faster reaching movements and increased responses to proprioceptive and visual feedback that were tuned to the variability of the disturbances. Our findings highlight that the nervous system exploits a continuum of control strategies to increase its responsiveness to sensory feedback when reaching in the presence of increasingly variable physical disturbances. Graphical abstract available at:
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    Challenging the assumption of uniformity in patellar tendon structure: Regional patellar tendon morphology and mechanical properties in vivo
    (Journal of Orthopaedic Research, 2023-04-08) Ito, Naoaki; Scattone Silva, Rodrigo; Sigurðsson, Haraldur B.; Cortes, Daniel H.; Silbernagel, Karin Grävare
    Patellar tendons are assumed to be uniform in morphology and mechanical properties despite a higher prevalence of tendinopathies observed in the medial region. The purpose of this study was to compare the thickness, length, viscosity, and shear modulus of the medial, central, and lateral regions of healthy patellar tendons of young males and females in vivo. B-mode ultrasound and continuous shear wave elastography were performed on 35 patellar tendons (17 females, 18 males) over three regions of interest. A linear mixed-effects model (α = 0.05) was used to determine differences between the three regions and sexes followed by pairwise comparisons for significant findings. The lateral region (mean [95% confidence interval] = 0.34 [0.31–0.37] cm) was thinner compared with the medial (0.41 [0.39–0.44] cm, p < 0.001), and central (0.41 [0.39–0.44] cm, p < 0.001) regions regardless of sex. Viscosity was lower in the lateral (19.8 [16.9–22.7] Pa-s) versus medial region (27.4 [24.7–30.2] Pa-s, p = 0.001). Length had a region-by-sex interaction (p = 0.003) characterized by a longer lateral (4.83 [4.54–5.13] cm) versus medial (4.42 [4.12–4.72] cm) region in males (p < 0.001), but not females (p = 0.992). Shear modulus was uniform between regions and sexes. The thinner, and less viscous lateral patellar tendon may reflect the lower load the tendon experiences explaining the differences in regional prevalence of developing tendon pathology. Statement of Clinical Significance: Healthy patellar tendons are not uniform in morphology or mechanical properties. Considering regional tendon properties may help guide targeted interventions for patellar tendon pathologies.
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    Clinically relevant subgroups exist among athletes who have ruptured their anterior cruciate ligaments: A Delaware-Oslo Cohort Study
    (Arthritis Care & Research, 2023-03-01) Arhos, Elanna K.; Pohlig, Ryan T.; Di Stasi, Stephanie; Risberg, May Arna; Snyder-Mackler, Lynn; Grävare Silbernagel, Karin
    Objective: To identify subgroups of individuals with anterior cruciate ligament (ACL) injuries based on patient characteristics, self-reported outcomes, and functional performance at baseline, and to associate subgroups with long-term outcomes after ACL rupture. Methods: A total of 293 participants (45.7% male, mean ± SD age 26.2 ± 9.4 years, days from injury 58 ± 35) were enrolled after effusion, pain, and range of motion impairments were resolved and quadriceps strength was at least 70% of the uninvolved limb. Mixture modeling was used to uncover latent subgroups without a prior group classification using probabilistic assignment. Variables include demographics, functional testing, and self-reported outcome measures. Radiographic evidence of osteoarthritis (OA; i.e., Kellgren/Lawrence grade of ≥1) in the involved knee at 5 years after injury was the primary outcome of interest. Chi-square tests assessed differences in the presence of radiographic OA in the involved knee between subgroups at 5 years after ACL rupture. Secondary outcomes of interest included radiographic OA in the uninvolved knee, return to preinjury sport by 2 years, operative status, and clinical OA (classified using Luyten et al criteria) at 5 years. Results: Four distinct subgroups exist after ACL rupture (younger good self-report, younger poor self-report, older poor self-report, older good self-report) with 30%, 31%, 47%, and 53%, respectively, having involved knee OA. The percentage of radiographic OA was not significantly different between the groups (P = 0.059). Conclusion: The prevalence of OA in all subgroups is highly concerning. These results suggest there are unique subgroupings of individuals that may guide treatment after ACL rupture and reconstruction by providing support for developing a patient-centered approach.
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    Comparing an Expanded Versus Brief Telehealth Physical Therapist Intervention for Knee Osteoarthritis: Study Protocol for the Delaware PEAK Randomized Controlled Trial
    (Physical Therapy & Rehabilitation Journal, 2023-02-01) Jakiela, Jason T.; Voinier, Dana; Hinman, Rana S.; Copson, Jennifer; Schmitt, Laura A.; Leonard, Tara R.; Aily, Jéssica B; Bodt, Barry A.; White, Daniel K.
    Objective The purpose of this study is to investigate whether a remotely delivered physical therapist intervention increases physical activity (PA) over 12 weeks, compared with existing web-based resources, in adults with knee osteoarthritis (OA). Methods This will be a single-center, randomized controlled trial with 2 parallel arms: (1) the Expanded Intervention (Delaware PEAK [Physical Exercise and Activity for Knee osteoarthritis]), which includes five 45- to 60-minute video conference-based sessions of supervised exercise (strengthening exercises, step goals) that are remotely delivered over 12 weeks by a physical therapist; or (2) the Brief Intervention (control group), a website that includes prerecorded videos directing participants to web-based resources for strengthening, PA, and pain management for knee OA that are freely available. The trial will enroll 100 participants who meet the National Institute for Health and Care Excellence OA clinical criteria (≥45 years old, have activity-related knee pain, and have no morning stiffness or it lasts ≤30 minutes), reside in the contiguous United States (excluding Alaska and Hawaii), and are seeking to be more physically active. Outcomes include PA (time in moderate-to-vigorous and light PA, steps per day), sedentary behaviors, treatment beliefs, and self-efficacy for exercise. Our primary outcome is moderate-to-vigorous PA. Outcomes will be measured at baseline, 12 weeks, and 24 weeks. Impact This protocol focuses on the remote delivery of physical therapy via telehealth to adults with knee OA and comes at a critical time, because the burden of inactivity is of particular concern in this population. If successful, the findings of this work will provide strong support for the broad implementation of Delaware PEAK, highlight the utility of telehealth in physical therapy, and address the critical need to utilize exercise to manage adults with knee OA through physical therapists.
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    Markerless motion capture: What clinician-scientists need to know right now
    (Journal of Science and Medicine in Sport Plus, 2022-11-14) Ito, Naoaki; Sigurðsson, Haraldur B.; Seymore, Kayla D.; Arhos, Elanna K.; Buchanan, Thomas S.; Snyder-Mackler, Lynn; Grävare Silbernagel, Karin
    Markerless motion capture (mocap) could be the future of motion analysis. The purpose of this report was to describe our team of clinicians and scientists’ exploration of markerless mocap (Theia 3D) and share data for others to explore (link: Simultaneous mocap was performed using markerless and marker-based systems for walking, squatting, and forward hopping. Segment lengths were more variable between trials using markerless mocap compared to marker-based mocap. Sagittal plane angles were most comparable between systems at the knee joint followed by the ankle and hip. Frontal and transverse plane angles were not comparable between systems. The data collection experience using markerless mocap was simpler, faster, and user friendly. The ease of collection was in part offset by the added data transfer and processing times, and the lack of troubleshooting flexibility. If used selectively with proper understanding of limitations, markerless mocap can be exciting technology to advance the field of motion analysis.
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    Reliability of Continuous Shear Wave Elastography in the Pathological Patellar Tendon
    (Journal of Ultrasound in Medicine, 2022-10-27) Ito, Naoaki; Sigurðsson, Haraldur B.; Pohlig, Ryan T.; Cortes, Daniel H.; Grävare Silbernagel, Karin; Sprague, Andrew L.
    Objectives Patellar tendon injuries occur via various mechanisms such as overuse, or due to surgical graft harvest for anterior cruciate ligament reconstruction (ACLR). Quantified patellar tendon stiffness after injury may help guide clinical care. Continuous shear wave elastography (cSWE) allows for the assessment of viscosity and shear modulus in tendons. The reliability of the measure, however, has not been established in the patellar tendon. The purpose of this study was to investigate the interrater reliability, intrarater reliability, and between-day stability of cSWE in both healthy and pathological patellar tendons. Methods Participants with patellar tendinopathy (n = 13), history of ACLR using bone-patellar tendon-bone autograft (n = 9), and with no history of patellar tendon injury (n = 13) were recruited. cSWE was performed 4 times by multiple raters over 2 days. Intraclass correlations (ICC) and minimum detectable change (MDC95%) were calculated. Results Good to excellent between-day stability were found for viscosity (ICC = 0.905, MDC95% = 8.3 Pa seconds) and shear modulus (ICC = 0.805, MDC95% = 27.4 kPa). The interrater reliability measures, however, were not as reliable (ICC = 0.591 and 0.532). Conclusions cSWE is a reliable assessment tool for quantifying patellar tendon viscoelastic properties over time. It is recommended, however, that a single rater performs the measure as the interrater reliability was less than ideal.
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    Metatarsophalangeal Joint Dynamic Stiffness During Toe Rocker Changes With Walking Speed
    (Journal of Applied Biomechanics, 2022-09-12) Nigro, Luke; Arch, Elisa S.
    Dynamic joint stiffness (or simply “stiffness”) is a customization criteria used to tune mechanical properties of orthotic and prosthetic devices. This study examines metatarsophalangeal (MTP) joint stiffness during the toe-rocker phase of barefoot walking and establishes baseline characteristics of MTP joint stiffness. Ten healthy individuals walked at 4 speeds (0.4, 0.6, 0.8, and 1.0 statures·s−1) over level ground. MTP sagittal plane joint angles and moments were calculated during the toe-rocker phase of stance. Least-squares linear regressions were conducted on the MTP moment versus angle curve to determine joint stiffness during early toe rocker and late toe rocker. Multilevel linear models were used to test for statistically significant differences between conditions. Early toe rocker stiffness was positive, while late toe rocker was negative. Both early toe rocker and late toe rocker stiffness increased in magnitude significantly with speed. This study establishes baseline characteristics of MTP joint stiffness in healthy walking, which previously had not been examined through a range of controlled walking speeds. This information can be used in the future as design criteria for orthotic and prosthetic ankle and ankle–foot devices that can imitate, support, and facilitate natural human foot motion during walking better than existing devices.
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    Predictors of non-stepping time in people with chronic stroke
    (Topics in Stroke Rehabilitation, 2022-08-22) Miller, Allison; McCartney, Kiersten; Wright, Tamara; Reisman, Darcy
    Background: Sedentary time is an independent construct from active time. Previous studies have examined variables associated with sedentary time to inform behavior change programs; however, these studies have lacked data sets that encompass potentially important domains. Objectives: The purpose of this study was to build a more comprehensive model containing previously theorized important predictors of sedentary time and new predictors that have not been explored. We hypothesized that variables representing the domains of physical capacity, psychosocial, physical health, cognition, and environmental would be significantly related to sedentary time in individuals post-stroke. Methods: This was a cross-sectional analysis of 280 individuals with chronic stroke. An activity monitor was used to measure sedentary (i.e. non-stepping) time. Five domains (8 predictors) were entered into a sequential linear regression model: physical capacity (6-Minute Walk Test, assistive device use), psychosocial (Activities Specific Balance Confidence Scale and Patient Health Questionnaire-9), physical health (Charlson Comorbidity Index and body mass index), cognition (Montreal Cognitive Assessment), and environmental (Area Deprivation Index). Results: The 6-Minute Walk Test (β = −0.39, p < .001), assistive device use (β = 0.15, p = .03), Patient Health Questionnaire-9 (β = 0.16, p = .01), and body mass index (β = 0.11, p = .04) were significantly related to non-stepping time in individuals with chronic stroke. The model explained 28.5% of the variability in non-stepping time. Conclusions: This work provides new perspective on which variables may need to be addressed in programs targeting sedentary time in stroke. Such programs should consider physical capacity, depressive symptoms, and physical health.
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    Knee joint biomechanics during gait improve from 3 to 6 months after anterior cruciate ligament reconstruction
    (Journal of Orthopaedic Research, 2022-01-06) Neal, Kelsey; Williams, Jack R.; Alfayyadh, Abdulmajeed; Capin, Jacob J.; Khandha, Ashutosh; Manal, Kurt; Snyder‐Mackler, Lynn; Buchanan, Thomas S.
    Gait alterations after anterior cruciate ligament reconstruction (ACLR) are commonly reported and have been linked to posttraumatic osteoarthritis development. While knee gait alterations have been studied at several time points after ACLR, little is known about how these biomechanical variables change earlier than 6 months after surgery, nor is much known about how they differ over the entire stance phase of gait. The purpose of this study was to examine knee gait biomechanical variables over their entire movement pattern through stance at both 3 and 6 months after ACLR and to study the progression of interlimb asymmetry between the two postoperative time points. Thirty-five individuals underwent motion analysis during overground walking 3 (3.2 ± 0.5) and 6 (6.4 ± 0.7) months after ACLR. Knee biomechanical variables were compared between limbs and across time points through 100% of stance using statistical parametric mapping; this included a 2 × 2 (Limb × Time) repeated measures analysis of variance and two-tailed t-tests. Smaller knee joint angles, moments, extensor forces, and medial compartment forces were present in the involved versus uninvolved limb. Interlimb asymmetries were present at both time points but were less prevalent at 6 months. The uninvolved limb's biomechanical variables stayed relatively consistent over time, while the involved limb's trended toward that of the uninvolved limb. Statement of Clinical Significance: Interventions to correct asymmetrical gait patterns after ACLR may need to occur early after surgery and may need to focus on multiple parts of stance phase.
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    Identifying candidates for targeted gait rehabilitation after stroke: better prediction through biomechanics-informed characterization
    (Biomed Central Ltd, 9/23/16) Awad,Louis N.; Reisman,Darcy S.; Pohlig,Ryan T.; Binder-Macleod,Stuart A.; Darcy S. Reisman PT, PhD, Ryan T. Pohlig PhD and Stuart A. Binder-MacleodPT, PhD; Reisman, Darcy S;Pohlig, Ryan Todd;Binder-Macleod, Stuart
    Background: Walking speed has been used to predict the efficacy of gait training; however, poststroke motor impairments are heterogeneous and different biomechanical strategies may underlie the same walking speed. Identifying which individuals will respond best to a particular gait rehabilitation program using walking speed alone may thus be limited. The objective of this study was to determine if, beyond walking speed, participants' baseline ability to generate propulsive force from their paretic limbs (paretic propulsion) influences the improvements in walking speed resulting from a paretic propulsion-targeting gait intervention. Methods: Twenty seven participants > 6 months poststroke underwent a 12-week locomotor training program designed to target deficits in paretic propulsion through the combination of fast walking with functional electrical stimulation to the paretic ankle musculature (FastFES). The relationship between participants' baseline usual walking speed (UWSbaseline), maximum walking speed (MWSbaseline), and paretic propulsion (prop(baseline)) versus improvements in usual walking speed (Delta UWS) and maximum walking speed (Delta MWS) were evaluated in moderated regression models. Results: UWSbaseline and MWSbaseline were, respectively, poor predictors of Delta UWS (R-2 = 0.24) and Delta MWS (R-2 = 0.01). Paretic propulsion x walking speed interactions (UWSbaseline x propbaseline and MWSbaseline x propbaseline) were observed in each regression model (R(2)s = 0.61 and 0.49 for Delta UWS and Delta MWS, respectively), revealing that slower individuals with higher utilization of the paretic limb for forward propulsion responded best to FastFES training and were the most likely to achieve clinically important differences. Conclusions: Characterizing participants based on both their walking speed and ability to generate paretic propulsion is a markedly better approach to predicting walking recovery following targeted gait rehabilitation than using walking speed alone.
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    Baseline predictors of treatment gains in peak propulsive force in individuals poststroke
    (Biomed Central Ltd, 1/15/16) Hsiao,HaoYuan; Higginson,Jill S.; Binder-Macleod,Stuart A.; HaoYuan Hsiao, Jill S. Higginson, Stuart A. Binder-Macleod; Higginson, Jill Startzell; Binder-Macleod, Stuart
    Background: Current rehabilitation for individuals poststroke focuses on increasing walking speed because it is an indicator of community walking ability and quality of life. Propulsive force generated from the paretic limb is critical to walking speed and may reflect actual neural recovery that restores the affected neural systems. A wide variation across individuals in the improvements in paretic propulsive force was observed following an intervention that targeted paretic propulsive force. This study aimed to determine if specific baseline characteristics can be used to predict patients who would respond to the intervention. Methods: Participants (N = 19) with chronic poststroke hemiparesis walked at their self-selected and maximal walking speeds on a treadmill before and after a 12-week gait training program. Propulsive forces from the paretic limb were analyzed. Pearson correlation coefficient was used to determine the relationships between (1) treatment gains in walking speed and propulsive force following intervention, and (2) treatment gains in propulsive force and baseline propulsive forces. Results: Treatment gains in self-selected walking speed were correlated to treatment gains in paretic propulsive force following intervention. In addition, changes in paretic propulsive force between self-selected and maximal walking speeds at baseline were strongly correlated to treatment gains in paretic propulsive force. Conclusions: The capacity to modulate paretic propulsive force, rather than the absolute propulsive force during self-selected or maximal walking speed, predicted treatment gains in propulsive force following the intervention. Findings from this research could help to inform clinicians and researchers to target the appropriate patient population for rehabilitation interventions.
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    Muscle Force-Velocity Relationships Observed in Four Different Functional Tests
    (DE GRUYTER OPEN LTD, 2017-03-13) Zivkovic, Milena Z.; Djuric, Sasa; Cuk, Ivan; Suzovic, Dejan; Jaric, Slobodan; Milena Z. Zivkovic, Sasa Djuric, Ivan Cuk, Dejan Suzovic, Slobodan Jaric; Jaric, Slobodan
    The aims of the present study were to investigate the shape and strength of the force-velocity relationships observed in different functional movement tests and explore the parameters depicting force, velocity and power producing capacities of the tested muscles. Twelve subjects were tested on maximum performance in vertical jumps, cycling, bench press throws, and bench pulls performed against different loads. Thereafter, both the averaged and maximum force and velocity variables recorded from individual trials were used for force-velocity relationship modeling. The observed individual force–velocity relationships were exceptionally strong (median correlation coefficients ranged from r = 0.930 to r = 0.995) and approximately linear independently of the test and variable type. Most of the relationship parameters observed from the averaged and maximum force and velocity variable types were strongly related in all tests (r = 0.789-0.991), except for those in vertical jumps (r = 0.485-0.930). However, the generalizability of the force-velocity relationship parameters depicting maximum force, velocity and power of the tested muscles across different tests was inconsistent and on average moderate. We concluded that the linear force-velocity relationship model based on either maximum or averaged force-velocity data could provide the outcomes depicting force, velocity and power generating capacity of the tested muscles, although such outcomes can only be partially generalized across different muscles.
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