Gregory S. Sawicki

This study presents an adaptive biarticular thigh exosuit (BATEX) that enhances walking efficiency and speed through bioinspired actuation and a self-tuned, ground reaction force (GRF)-driven controller. The BATEX employs Force-Modulated Compliance (FMC) to coordinate hip and knee assistance via artificial biarticular muscles, with users tuning a single control gain to personalize assistance. Twelve healthy adults participated in experiments evaluating preferred walking speed (PWS), preferred transition speed (PTS), metabolic cost, and muscle activation under no-exosuit (NE), zero-torque (ZT), and assisted (EXO) conditions. Compared with NE, BATEX increased PWS by 14.3% and PTS by 9.0% ( ${p} \lt {0}.{01}$ ). Furthermore, BATEX assistance can also reduce net metabolic cost at PWS of unassisted walking by 9.5% relative to NE and 17.9% relative to ZT ( ${p} \lt {0}.{01}$ ). Electromyography revealed significant reductions in lower-limb muscle activation, particularly in the biceps femoris, gluteus maximus, and gastrocnemius. Moreover, positive exosuit mechanical power was correlated with changes in metabolic cost, indicating that mechanical assistance effectively offset biological energy expenditure. These results demonstrate that GRF-driven, user-tuned biarticular assistance effectively improves walking economy and gait speed in healthy adults, providing a framework that could be adapted in future studies to enhance mobility in broader populations.

BACKGROUND: Financial challenges are common among people with cystic fibrosis (PwCF). We explored the financial and healthcare tradeoffs that PwCF and their care partners make to meet healthcare needs, and how these tradeoffs vary across people from different income levels. METHODS: Adults (≥18 years) with cystic fibrosis and parents/guardians/spouses of PwCF completed the Cystic fibrosis Outcomes, Social needs and Tradeoffs due to Coverage and Financial burden (COST-CF) survey between February and May 2024. We compared financial and healthcare tradeoffs and desired support over the prior 12 months across income groups, based on 2024 US Federal Poverty Level (FPL) guidelines. RESULTS: Sixty-seven percent of 936 respondents experienced one or more financial issues caused by CF medical bills, ranging from 80% among those with ≤500% FPL to 47% among those with >500% FPL. The most common included actions taken to manage finances (64%) (e.g., delay of major purchases), financial consequences (57%) (e.g., inability to accumulate savings), and challenges meeting expenses (31%). Fifty-five percent of 877 respondents reported using one or more strategies to save money on CF healthcare costs, ranging from 65% among people with ≤500% FPL to 39% among those with >500% FPL. While 45% reported proactive cost-reduction strategies (e.g., discussions to reduce costs of care; requesting lower cost medications), more than one-quarter reported delaying or skipping medications (29%) or care (25%). CONCLUSIONS: PwCF and care partners face substantial financial burdens, with greater burdens among those with lower incomes. Many also report healthcare tradeoffs, which may impact long-term health outcomes.

Epically Powerful is an open-source robotics infrastructure that streamlines the underlying framework of wearable robotic systems - managing communication protocols, clocking, actuator commands, visualization, sensor data acquisition, data logging, and more - while also providing comprehensive guides for hardware selection, system assembly, and controller implementation. Epically Powerful contains a code base enabling simplified user implementation via Python that seamlessly interfaces with various commercial state-of-the-art quasi-direct drive (QDD) actuators, single-board computers, and common sensors, provides example controllers, and enables real-time visualization. To further support device development, the package also includes a recommended parts list and compatibility guide and detailed documentation on hardware and software implementation. The goal of Epically Powerful is to lower the barrier to developing and deploying custom wearable robotic systems without a pre-specified form factor, enabling researchers to go from raw hardware to modular, robust devices quickly and effectively. Though originally designed with wearable robotics in mind, Epically Powerful is broadly applicable to other robotic domains that utilize QDD actuators, single-board computers, and sensors for closed-loop control.

Abstract Exoskeletons assist and augment human movement, but their effects on proprioceptive feedback remain poorly understood. We examined how parallel exoskeleton stiffness influences primary muscle spindle firing. In an anesthetized rat preparation, controlled stretches of the medial gastrocnemius were applied with springs (0–0.5 N/mm) attached in parallel to the muscle-tendon unit (MTU) to simulate passive exoskeleton assistance. Fascicle length was measured with sonomicrometry, force and MTU length with a servo motor, and spindle instantaneous firing rate (IFR) with dorsal root recordings. Increasing exoskeleton stiffness decreased biological muscle force (3.1 ± 0.6 N to 1.6 ± 0.6 N, p < 0.001) and stiffness (4.4 ± 1.5 N/mm to 2.3 ± 1.3 N/mm, p < 0.01), while fascicle length increased (7.9 ± 1.3 mm to 8.3 ± 1.5 mm, p < 0.005). Despite these altered mechanics, spindle firing did not significantly change, and showed weak correlations with muscle length, velocity, force, and yank (R 2 ≤ 0.14). These results indicate that exoskeleton stiffness modifies fascicle dynamics without altering spindle firing. Previously proposed models of primary afferent firing did not sufficiently explain these results. This is the first in situ investigation of exoskeleton effects on primary afferent feedback during active contractions.

Limb propulsion deficits are common in a variety of clinical populations and may arise from a decreased plantarflexor moment and/or decreased trailing limb angle (TLA). Ankle exoskeletons (EXOs) can augment plantarflexor moment, but observations of a concurrently reduced TLA has limited the conversion of increased plantarflexor moment to increased propulsion in people following stroke. The purpose of this study was to assess the interaction of unilateral EXO (plantarflexor) assistance and TLA feedback on gait propulsion, joint mechanics, and margins of stability. Ten young, unimpaired individuals walked on an instrumented treadmill with the EXO worn but unpowered to obtain baseline peak TLA. Participants then walked with visual feedback of TLA while attempting to match a target peak TLA of baseline-5°, baseline, or baseline+5° in random order. For each target TLA, participants walked with three EXO plantarflexor torque magnitudes, with peak assistance proportional to bodyweight (0%, 15%, and 35% bodyweight) in random order. Propulsive impulse significantly increased as peak TLA increased but was not affected by EXO assistance. Higher EXO assistance resulted in a proximal-to-distal shift in positive mechanical work performed by the lower limb, observed as an increase in the relative contribution of the ankle to total ankle and hip positive mechanical work. Increased TLA significantly reduced the magnitude of the anteroposterior margin of stability at toe-off, while higher EXO assistance yielded larger anteroposterior margins of stability. Margins of stability in the mediolateral direction were not affected by TLA or EXO assistance. This study highlights the potential for increasing propulsion through feedback of TLA, but with potential negative impacts to stability. For populations with deficits in plantarflexor moment, the use of visual feedback to prevent a reduction in TLA while walking with ankle EXOs may allow conversion of joint benefits to benefits in limb propulsion.

Limb propulsion deficits are common in a variety of clinical populations and may arise from a decreased plantarflexor moment and/or decreased trailing limb angle (TLA). Ankle exoskeletons (EXOs) can augment plantarflexor moment, but observations of a concurrently reduced TLA has limited the conversion of increased plantarflexor moment to increased propulsion in people following stroke. The purpose of this study was to assess the interaction of unilateral EXO (plantarflexor) assistance and TLA feedback on gait propulsion, joint mechanics, and margins of stability. Ten young, unimpaired individuals walked on an instrumented treadmill with the EXO worn but unpowered to obtain baseline peak TLA. Participants then walked with visual feedback of TLA while attempting to match a target peak TLA of baseline-5°, baseline, or baseline+5° in random order. For each target TLA, participants walked with three EXO plantarflexor torque magnitudes, with peak assistance proportional to bodyweight (0%, 15%, and 35% bodyweight) in random order. Propulsive impulse significantly increased as peak TLA increased but was not affected by EXO assistance. Higher EXO assistance resulted in a proximal-to-distal shift in positive mechanical work performed by the lower limb, observed as an increase in the relative contribution of the ankle to total ankle and hip positive mechanical work. Increased TLA significantly reduced the magnitude of the anteroposterior margin of stability at toe-off, while higher EXO assistance yielded larger anteroposterior margins of stability. Margins of stability in the mediolateral direction were not affected by TLA or EXO assistance. This study highlights the potential for increasing propulsion through feedback of TLA, but with potential negative impacts to stability. For populations with deficits in plantarflexor moment, the use of visual feedback to prevent a reduction in TLA while walking with ankle EXOs may allow conversion of joint benefits to benefits in limb propulsion.

Human locomotion exhibits extraordinary adaptability and robustness, yet the mechanisms by which lower limbs adjust to sudden environmental disruptions remain poorly understood. To address this, we employed the bioinspired human-sized EPA-Hopper II robot to examine how lower-limb joints recover from an abrupt drop in ground height, mimicking unexpected perturbations encountered in natural settings. Our study investigates the roles of the monoarticular soleus (SOL) and biarticular gastrocnemius (GAS) muscle configurations, focusing on how their compliance influences the robot’s hopping stability. Experiments reveal that a coordinated interplay between SOL and GAS markedly improves recovery from disturbances, enhancing energy distribution and joint synchronization. Detailed kinematic and power analyses show that GAS facilitates energy transfer across joints, while SOL’s spring-like properties support rapid recovery. These results highlight how bioinspired muscle arrangements enable robust locomotion through intrinsic mechanical interactions. By leveraging a robotic platform to probe these dynamics, this work deepens our understanding of biological locomotion and informs the design of bioinspired bipedal robots and prosthetics capable of thriving in unpredictable environments.

BACKGROUND: Males with cystic fibrosis (MwCF) face many sexual health concerns that have been understudied. We compared sexual health experiences and care utilization of MwCF to the general population and defined CF-related considerations and care preferences. METHODS: We surveyed MwCF aged ≥15 years and compared results to the United States National Survey of Family Growth (NSFG;n = 5206 15-49-year-old males). We used descriptive statistics and adjusted linear and logistic regression analyses for comparisons. RESULTS: A total of 532 MwCF (mean age 35.3 years) participated. Over 75 % of MwCF reported never using a condom. Among those sexually active with ≥2 partners in the prior year, 36 % of 15-49-year-old MwCF reported never using condoms vs. 16 % of NSFG males (p < 0.001). Thirty-two percent of MwCF reported having ever been tested for sexually transmitted infections(STIs). Among MwCF, 8 % had ever received information from a healthcare provider about HIV/AIDS, 14 % about other STIs, and 18 % about condom use. MwCF reported an average pubertal onset of 13.2 ± 1.7 years with the majority reporting undergoing puberty at the same time or earlier than their peers. MwCF reported minimal hypogonadism symptoms; 36 % ever had their testosterone measured and 10 % were diagnosed with hypogonadism. Eighty-two percent of MwCF considered their CF team their main health provider and 45 % reported no primary care provider. CONCLUSION: MwCF report suboptimal STI prevention and counseling compared to males in the general population, highlighting an urgent need to encourage sexual health counseling and care in the CF model and partnerships with primary care providers and other specialists.

Abstract Most assistive exoskeletons in the literature rely on rigid components and direct shoulder joint actuation, which results in excessive load on the user's upper body. To address this limitation, we present the design and development of a daily assistive stroke patient exoskeleton (DASPE), a cable-driven, semicompliant exoskeleton intended to support stroke patients by mirroring the motion of their healthy arm. Motion data from inertial sensors placed on the healthy arm are used to compute joint angles, allowing the exoskeleton to mirror elbow and shoulder movements. The design incorporates compliant elements at the spine and shoulders to allow flexible motion and avoid bulky, rigid components. Initial testing demonstrates the system's ability to perform elbow flexion–extension, shoulder abduction–adduction, and shoulder flexion–extension, with good alignment between user and exoskeleton motion for angles up to 35 deg.

BACKGROUND Reducing treatment burden is a priority within the CF community. Improved outcomes for many people with CF (PWCF) following treatment with Elexacaftor/Tezacaftor/Ivacaftor (ETI) have led to considering whether daily CF regimens can be reduced. It is important to understand perceptions of PWCF when making decisions about care changes. We investigated how PWCF conceptualize treatment burden, including the types of burdens experienced, how burden has changed with ETI therapy, and how burden impacts treatment-related decision-making. METHODS The Qualitative Understanding of Experiences with the SIMPLIFY Trial (QUEST) study recruited PWCF aged 14+ prescribed ETI and caregivers of teenagers for interviews following completion of the SIMPLIFY treatment discontinuation trial. Two semi-structured interviews were conducted, recorded, and transcribed. Treatment burden language was identified, coded, and thematically analyzed without prior hypotheses. RESULTS 68 adults, 23 teenagers, and 23 caregivers participated in at least one interview. Treatment burden codes were identified and organized into 3 themes: 1) Defining Treatment Burden (time, organizational, social-emotional domains), 2) How Treatment Burden has Changed with ETI (increased, decreased), and 3) Strategies to Decrease Treatment Burden (combining treatments, skipping treatments, communicating with care team). CONCLUSION Definitions of CF treatment burden are expansive and personalized. Interventions to reduce treatment burden should be individualized without assuming burden is perceived, or how each individual views and manages burdens. Personalized definitions of treatment burden will allow for tailored assessment and intervention strategies that match the needs of the individual.

Animals maintain locomotor stability following external perturbations by coordinating muscular responses to produce desired mechanical behavior at different levels of description (e.g., muscle-tendon units, joints, legs). To investigate the role of proximal musculature in responding to perturbations during human walking, here we extend a previous analysis relating joint and leg levels down to the level of the rectus femoris. Using in-vivo B-mode ultrasound processed with a custom automated fascicle tracking application and EMG measurements to drive Hill-type models of muscle force, we investigated mechanical energetics of the rectus femoris in 7 individuals who experienced rapid, transient unilateral belt accelerations during walking. We hypothesized that: H1) the rectus femoris would actively lengthen on the perturbed leg during the perturbed stride and H2) on the contralateral leg the rectus femoris would reflect the mechanical energetic demand at the knee and leg levels. H1 was partially supported, with the rectus femoris fascicles being decoupled from muscle-tendon unit lengthening. H2 was not supported, with the rectus femoris best reflecting the energetic role of the hip, as opposed to the knee or leg. Overall, these findings provide a first estimate of the variety of roles proximal muscles play in maintaining stability and lay the groundwork for additional in-vivo measurement informed multi-scale analyses of perturbed locomotion.

Background Age-related deficits in Achilles tendon stiffness have been linked to shorter calf muscle operating lengths. These shorter lengths have the potential to precipitate higher requisite excitations and thereby an earlier onset of local fatigability in older adults. However, the connection between calf muscle operating lengths and muscle fatigability has yet to be systematically explored, even in healthy younger adults. Thus, the goal of this study was to establish a mechanistic pathway between soleus fascicle length, prescribed herein using changes in ankle joint angle, and muscle fatigue in a cohort of younger adults. Methods Participants performed repeated fixed-end calf muscle contractions to task failure in a computerized robotic dynamometer at two ankle joint angles to prescribe relatively shorter ( i.e ., 15° plantarflexion (PF15)) and longer ( i.e ., 15° dorsiflexion (DF15)) soleus fascicle lengths. Results On average, moving from DF15 to PF15 elicited 14% shorter muscle fascicle lengths, a roughly two-fold higher EMG rms amplitude, significant but modest reductions in EMG median frequency, and a 60% reduction in time to task failure ( p -values &lt; 0.05). These findings may have clinical relevance for mechanisms associated with higher metabolic costs and increased fatigability among older adults, who often operate their calf muscles at shorter fascicle lengths due to lesser Achilles tendon stiffness. As a roadmap for comparison and hypothesis generation, this study sets the stage for future work in older adults.

BACKGROUND Adolescents with chronic conditions are at risk for poor health outcomes related to unsuccessful self-management. Additionally, the existing literature suggests that youth with chronic conditions are also at risk for experiencing difficulties in their social and peer relationships. However, the influence of peers and other psychosocial factors on self-management remains poorly understood. OBJECTIVE To describe the interaction between psychosocial and peer relationship factors and self-management behaviors among adolescents with chronic conditions to identify targets for intervention. DESIGN/METHODS We recruited adolescents (12-17 years) with ≥1 chronic condition from a single children's hospital. We conducted semi-structured interviews which were transcribed and independently coded by 2 researchers. An iterative codebook guided content analysis and coders meet weekly to resolve discrepancies. RESULTS 24 adolescents with a range of chronic conditions participated (54 % female, 21 % Black, 13 % Asian, 67 % White, 17 % Hispanic/Latin; mean age 14 years). The overarching theme: Self-management in the Context of Psychosocial Health was characterized by six subthemes: 1) multidimensional support needs, 2) feeling socially excluded, targeted and misunderstood, 3) fitting in versus standing out, 4) to share or not to share, 5) taking care of myself, and 6) "they know what you're going through". CONCLUSIONS Across chronic conditions, peer interactions were complex; negative peer interactions contributed to poor psychosocial health outcomes (i.e., isolation) while positive interactions served as protective factors for self-management. Ownership and acceptance of their diagnosis both influenced and was influenced by an adolescent's relationships with their peers. Peer support was identified as a potential target to improve self-management.

OBJECTIVE: Real-time determination of human kinematics and kinetics could advance biomechanics research and enable valuable applications of biofeedback and generalizable exoskeleton control. This work aims to investigate a task-independent, user-independent method for obtaining precise real-time joint state estimation across lower-body joints during a wide variety of tasks. METHODS: We developed a generalizable sensing approach using a suit comprised of inertial measurement units (IMUs) and pressure insoles. With the suit, we collected a dataset of 33 tasks commonly performed during construction and hazardous waste cleanup (N = 10). We then trained deep learning user-independent, task-agnostic models to estimate joint lower-body kinematics and dynamics using only worn sensor data. We likewise computed joint kinematics and dynamics analytically from sensor data to serve as a comparison tool for model results. RESULTS: Our models achieved overall angle estimation root-mean-squared-errors (RMSE) of 6.56±.92°, 8.60±1.01°, 7.58±.89°, and 6.00±.73° compared to 13.9±.1.3°, 15.31±1.0°, 10.76±.70°, and 7.56±.48° via analytical methods at the lower back, hip, knee, and ankle, respectively. Likewise, our models achieved overall normalized moment estimation RMSEs of .207±.069 Nm/kg, .242±.044 Nm/kg, .202±.038 Nm/kg, and .193±.034 Nm/kg compared to .306±.036 Nm/kg, .407±.021 Nm/kg, 1.18 ±.022 Nm/kg, and 1.73±.071 Nm/kg via analytical methods at the lower back, hip, knee, and ankle, respectively. CONCLUSION: These results are comparable to other state-of-the-art wearable sensing systems, establishing deep learning as a viable sensing approach that generalizes to new users and tasks. SIGNIFICANCE: This work shows promise for enabling accurate real-world biomechanical data collection and enhancement of biofeedback systems and wearable robot control.

BACKGROUND: Nearly all males with cystic fibrosis (MwCF) are infertile and, thus, require the use of assisted reproductive technology (ART) to have biologic children. This study aims to describe the fertility and family-building knowledge, experiences, and care utilization of this population and to compare these findings to the general United States (US) population. METHODS: We conducted an anonymous cross-sectional study of self-reported survey data compared to data from the 2017-2019 US National Survey for Family Growth (NSFG). We recruited MwCF age 15 years and older at seven US cystic fibrosis (CF) centers. RESULTS: A total of 532 MwCF (mean age 35.3 ± 11.6 years) completed the survey. 83% knew that almost all MwCF are infertile and 84% were aware that MwCF can have biological children. 71% correctly identified the most common cause of male CF infertility. One third of MwCF stated they had never been told by anyone they were infertile due to their CF (mean age of discussion 19.3 ± 8.8 years). 31% reported being a parent. Among parents, 66% were a parent to a biological child born of a partner's pregnancy, 20% via step-parenthood, 15% adoption, 4.3% surrogacy, and 0.6% foster parenthood. Compared to 44% of NSFG males, 18% of MwCF age 15-49 years reported being a parent to a biological child born of their partner's pregnancy (p < 0.001). Among all MwCF, 82% with a biological child reported that they required medical assistance. Among those age 15-49 years, 87% of MwCF with a biological child required medical assistance compared to 9.4% of NSFG males (p < 0.001). Nearly three-quarters (73%) of MwCF who were biological parents underwent sperm retrieval via a variety of extraction techniques. 91% of those utilizing ART underwent in vitro fertilization and 9% intrauterine insemination of their partner. CONCLUSIONS: MwCF face significant disease-related fertility and family-building implications with suboptimal counseling. Most MwCF who are parents pursue biological parenthood via a variety of ART services, but one-third chose alternative paths to parenthood. Further research is needed to best understand and support the family-building of MwCF. CLINICAL TRIAL NUMBER: Not applicable.

Relative to motorized devices, passive hip exoskeletons with elastic actuation provide cheaper and lower-profile solutions to assist locomotion during walking. However, the influence of elastic hip assistance on stability during walking is poorly understood. Here, we investigated the effects on stability of a hip exoskeleton that provided elastic flexion torque during late stance. We quantified stability using both sagittal whole-body angular momentum (WBAM) range and whole-body mechanical work during walking with unexpected anteroposterior treadmill belt accelerations among 11 healthy uninjured individuals. We hypothesized that during perturbations, 1) an elastic hip exoskeleton would improve stability as measured by a smaller range in sagittal WBAM and a lower whole-body energetic demand imposed by the perturbation, and 2) this improvement in whole-body energetic demand would be mediated by the exoskeleton shifting the local mechanical energetics of the hip joint to oppose the energetic demands of the perturbation. Contrary to our hypotheses, the elastic hip exoskeleton did not influence whole-body work demands imposed by perturbations (p>0.226). Additionally, while sagittal WBAM ranges were larger during unperturbed walking with increasing exoskeleton stiffness due to alterations in trunk kinematics (p<0.001), this effect did not extend to perturbed walking (p>0.419). Further, while higher exoskeleton stiffnesses (0.66-1.0 Nm/deg) shifted ipsilateral hip joint work in opposition to whole-body work demands, the same stiffnesses shifted contralateral hip joint work toward whole-body work demands. Our findings demonstrate conclusions drawn about stability from sagittal WBAM range do not carry over from unperturbed to perturbed walking.

OBJECTIVES We explored the impact of taking part in a medication discontinuation study for people with cystic fibrosis (CF) on subsequent clinical conversations and what interviewees valued as characteristics of these conversations. METHODS This analysis is part of the Qualitative Understanding of the Experience of SIMPLIFY Trial (QUEST), a qualitative companion study to a discontinuation trial of two commonly prescribed medications for people with CF. We interviewed 109 total individuals (87 people with CF and 22 caregivers). The interviews were analyzed to explore the influence of participation in a discontinuation study on clinical conversations. RESULTS Respect emerged as an overarching theme of these interviews: how much the interviewees respected their clinicians and how they appreciated having their autonomy respected too. Other desirable attributes of clinical conversations surfaced including the importance of reciprocity, empowerment, sensitivity, partnership, empathy, consideration and transparency; (R.E.S.P.E.C.T). CONCLUSIONS Communication is a fundamental aspect of chronic disease management. This population study focused on patient perspectives of clinical conversations after sharing the experience of being in a novel discontinuation study. Since the acronym R.E.S.P.E.C.T. emerged from the data, we believe it has value as a framework for clinical conversations with people who have chronic conditions that require active selfmanagement.

Abstract Fall-related injuries are a large public health concern for older adults (OA). Delayed or inappropriate afferent signaling may hinder detection of balance perturbation (e.g., slip), predisposing OA to falls and less efficacious corrective actions. Perturbation detection is largely governed by proprioceptive acuity, consisting of sensory information from skin and musculotendinous receptors. While skin and muscle receptors’ signaling thresholds increase with age, feedback from muscle may be uniquely delayed and diminished by age-related decreases in series elastic tissue stiffness which, during a rapid, unanticipated joint position change, could decrease the velocity of muscle stretch, delaying detection. Ultimately, the association between skin and muscle afferent signaling integrity and muscle reflex timing in response to walking balance perturbations has yet to be well established. This study evaluated the associations between plantar cutaneous sensitivity (PS) and Achilles tendon stiffness (k AT ) to muscle reflex responsiveness of ankle plantar- and dorsiflexor muscles following treadmill-induced slip perturbations in younger and OA. Compared to younger adults (YA), we found that OA had lesser PS and k AT and delayed tibialis anterior excitation onset. However, neither sensory outcome associated with muscle onset times. Later in stance, OA exhibited earlier triceps surae onsets than YA. However, only in YA did earlier gastrocnemius activity associate with greater k AT , which may indicate an ankle dominant balance recovery strategy in YA. Our results point to specific age-related changes in the timing of neuromuscular corrections to mitigate instability, which may underlie age-related differences in balance recovery efficacy and subsequent injury severity.

Abstract Rationale Providing medical care outside the traditional clinic setting via telehealth (TH) is now familiar to both clinicians and patients due to rapid adoption during the COVID19 pandemic. Now that in-person care has been fully restored, the optimal role of TH is unknown. We sought to understand patient and caregiver perceptions of TH as experienced in a large pediatric pulmonary clinic post-pandemic. Methods This is a cross-sectional survey administered to caregivers of children and patients 18-25 years evaluated in the Boston Children's Hospital pulmonary clinic via TH by a pulmonologist or NP in 2023. The survey included 18 multiple choice questions addressing the visit reason, perceptions of convenience, efficiency and effectiveness of the TH visit, barriers related to the TH visit and preferences for future use. It was distributed electronically by email between June and October 2024. Results 1,178 patients were identified as having a TH visit in the pediatric pulmonary clinic in 2023. 993 (84%) were sent the electronic survey and 186 people responded (response rate 16%). Self-reported demographics, diagnosis and reason for visit are shown in Table 1. Self-reported travel times to usual in-person clinic site ranged from less than 30 minutes (10%), 30-59 minutes (28%), 1-2 hours (42%), to more than two hours (19%). The most commonly reported barriers to travel to in-person visits included missed time from work/school (59%), finding childcare (31%) and associated travel cost (29%). A majority (85%) reported their TH visit was more convenient than usual in-person care. Almost all (98%) felt all concerns were addressed during their TH visit and 94% endorsed TH is an acceptable alternative to in person care. 97% did not have a technology challenge associated with their TH visit. Most (95%) felt their privacy was protected similarly to (73%) or better than (22%) during in-person care. Considering lack of in-person assessments, most (75%) were not concerned, 20% felt somewhat concerned, and 4% felt very concerned. 92% reported they would use TH again in the future, with the most desired visit reasons being a follow-up to change in treatment (80%), reviewing test results (77%) and routine follow-up of chronic condition (68%). Conclusions Post-pandemic, patients and caregivers seen in pediatric pulmonary clinic report high acceptability of the TH care model. Importantly, some report concern over lack of in-person assessments. Most wish to use TH for future visits, underscoring the importance of its continued availability and efforts to evaluate associated outcomes.

Recent advancements in wearable exoskeletons for human lower extremities have primarily focused on augmenting walking capacity by either reducing metabolic costs or providing joint torque support based on measured electromyography or predicted joint torques. However, less attention has been given to the use of robotic exoskeletons for controlling the mechanics of specific biological tissues, such as elastic tendons. Achieving closed-loop control over in-vivo musculotendon mechanics during movement could revolutionize injury prevention and personalized rehabilitation. Here, we introduce a framework utilizing musculoskeletal modeling and nonlinear model predictive control (NMPC) to close the loop around tendon force in a simulation of cyclic force production of the human ankle plantarflexors in parallel with a powered exoskeleton. The proposed framework integrates a computationally efficient model comprising explicit closed-form ordinary differential equations governing musculotendon and ankle joint with parallel actuation dynamics. The model’s computational time, in the microsecond range, allows prediction of future states in real-time closed-loop control. Compared to a predictive proportional-derivative controller, the NMPC-based framework more effectively maintained Achilles tendon force within a predetermined threshold across varying levels of muscle excitation amplitude and frequency. Remarkably, the NMPC framework demonstrates robustness to muscle excitation variations during cyclic motions, making it suitable for real-world applications.

Abstract Rationale Clinical and real-world studies show that elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) is efficacious and safe in people with cystic fibrosis (CF) ≥12 years of age with at least one F508del allele. Objectives Given the potential for lifelong ELX/TEZ/IVA use, the long-term safety and efficacy of ELX/TEZ/IVA was assessed. Methods In this phase 3, open-label, single-arm extension study, participants with F508del-minimal function genotypes (from 24-wk parent study 445-102 [n = 399]) or with the F508del-F508del genotype (from 4-wk parent study 445-103 [n = 107]) received ELX/TEZ/IVA (ELX 200 mg once daily, TEZ 100 mg once daily, and IVA 150 mg every 12 h) over 192 weeks. Measurements and Main Results The primary endpoint was safety and tolerability. Mean exposure to ELX/TEZ/IVA was 172.6 weeks. Most participants had adverse events classified as mild (12.8%) or moderate (60.7%) in severity. Eighteen participants (3.6%) had adverse events that led to treatment discontinuation. After starting ELX/TEZ/IVA, participants had consistent increases in percent predicted FEV1 (ppFEV1), Cystic Fibrosis Questionnaire–Revised respiratory domain score, and body mass index, with decreases in sweat chloride concentration and pulmonary exacerbation rates; these improvements were maintained through 192 weeks. The mean annualized rate of change in ppFEV1 was 0.02 percentage points (95% confidence interval, −0.14 to 0.19) after initiation of ELX/TEZ/IVA. Conclusions During this 192-week open-label extension study, the longest clinical study of a CFTR (cystic fibrosis transmembrane conductance regulator) modulator to date, ELX/TEZ/IVA remained generally safe and well tolerated. Participants had sustained improvements in lung function, respiratory symptoms, CFTR function, pulmonary exacerbation rates, and nutritional status. The estimated annualized rate of change in ppFEV1 suggests no evidence of pulmonary function loss across the study population over the 4-year treatment period. These results confirm the favorable long-term safety profile and durable disease-modifying clinical benefits of ELX/TEZ/IVA in adolescents and adults with CF. Clinical trial registered with www.clinicaltrials.gov (NCT03525574).

BACKGROUND: Males with cystic fibrosis (MwCF) face general and disease-specific sexual and reproductive health (SRH) concerns. Using concept mapping (CM), this study identified the SRH topics valued by members of the CF community. METHODS: MwCF 18 years and older, parents and partners of MwCF, and healthcare providers participated in an online CM study. Participants individually brainstormed, sorted, and rated SRH topics important for MwCF. Using multidimensional scaling, hierarchical cluster analyses, and t tests to assess rating differences, participants interpreted results during an online meeting. RESULTS: Eighty-nine participants (32 MwCF; 6 parents; 9 partners; and 42 providers) generated 125 statements on male SRH in CF. Seventy-eight percent completed sorting and 73% rated statements based on importance. During interpretation, 20 participants named six clusters of SRH topics: 1) Family building and fertility; 2) Psychosocial aspects of SRH; 3) Being a parent or partner as a MwCF; 4) Sexual development, function, and treatments; 5) SRH education, communication, and awareness; and 6) SRH risks, comorbidities, and aging. Participants rated family building and fertility as highest in importance (mean = 4.06±0.36 of 5). Providers issued higher importance ratings compared to MwCF and parent/partner participants. Participants identified patient-centered outcomes for each cluster and focused on enhancing SRH knowledge, decision-making, and patient-provider communication in CF care. CONCLUSIONS: The SRH topics, importance, and patient-centered outcomes identified in this study can inform future interventions and research to optimize the comprehensive clinical care delivery for MwCF.

Repetitive manual labor tasks involving twisting, bending, and lifting commonly lead to lower back and knee injuries in the workplace. To identify tasks with high injury risk, we recruited N = 9 participants to perform industry-relevant, 2-handed lifts with a 11-kg weight. These included symmetrical/asymmetrical, ascending/descending lifts that varied in start-to-end heights (knee-to-waist and waist-to-shoulder). We used a data-driven musculoskeletal model that combined force and motion data with a muscle activation-informed solver (OpenSim, CEINMS) to estimate 3-dimensional internal joint contact forces (JCFs) in the lower back (L5/S1) and knee. Symmetrical lifting resulted in larger peak JCFs than asymmetrical lifting in both the L5/S1 (+20.2% normal [P < .01], +20.3% shear [P = .001], +20.6% total [P < .01]) and the knee (+39.2% shear [P = .001]), and there were no differences in peak JCFs between ascending versus descending motions. Below-the-waist lifting generated significantly greater JCFs in the L5/S1 and knee than above-the-waist lifts (P < .01). We found a positive correlation between knee and L5/S1 peak total JCFs (R2 = .60, P < .01) across the task space, suggesting motor coordination that favors sharing of load distribution across the trunk and legs during lifting.

This study introduces a robust planning framework that utilizes a model predictive control (MPC) approach, enhanced by incorporating signal temporal logic (STL) specifications. This marks the first-ever study to apply STL-guided trajectory optimization for bipedal locomotion, specifically designed to handle both translational and orientational perturbations. Existing recovery strategies often struggle with reasoning complex task logic and evaluating locomotion robustness systematically, making them susceptible to failures caused by inappropriate recovery strategies or lack of robustness. To address these issues, we design an analytical stability metric for bipedal locomotion and quantify this metric using STL specifications, which guide the generation of recovery trajectories to achieve maximum robustness degree. To enable safe and computational-efficient crossed-leg maneuver, we design data-driven self-leg-collision constraints that are 1000 times faster than the traditional inverse-kinematics-based approach. Our framework outperforms a state-of-the-art locomotion controller, a standard MPC without STL, and a linear-temporal-logic-based planner in a high-fidelity dynamic simulation, especially in scenarios involving crossed-leg maneuvers. Additionally, the Cassie bipedal robot achieves robust performance under horizontal and orientational perturbations such as those observed in ship motions. These environments are validated in simulations and deployed on hardware. Furthermore, our proposed method demonstrates versatility on stepping stones and terrain-agnostic features on inclined terrains.

Research in lower limb wearable robotic control has largely focused on reducing the metabolic cost of walking or compensating for a portion of the biological joint torque, for example, by applying support proportional to estimated biological joint torques. However, due to different musculotendon unit (MTU) contractile speed properties, less attention has been given to the development of wearable robotic controllers that can steer MTU dynamics directly. Therefore, closed-loop control of MTU dynamics needs to be robust across fiber phenotypes, that is ranging from slow type I to fast type IIx in humans. The ability to perform closed-loop control the in-vivo dynamics of MTUs could lead to a new class of wearable robots that can provide precise support to targeted MTUs for preventing onset of injury or providing precision rehabilitation to selected damaged tissues. In this paper, we introduce a novel closed-loop control framework that utilizes nonlinear model predictive control to keep the peak Achilles tendon force within predetermined boundaries during diverse range of cyclic force production simulations in the human ankle plantarflexors. This control framework employs a computationally efficient model comprising a modified Hill-type MTU contraction dynamics component and a model of the ankle joint with parallel actuation. Results indicate that the closed-form muscle-actuation model's computational time is in the order of microseconds and is robust to different muscle contraction velocity properties. Furthermore, the controller achieves tendon force control within a time frame below , aligning with the physiological electromechanical delay of the MTU and facilitating its potential for future real-world applications.

Post-stroke gait is slow, energetically costly, and unstable. Rehabilitation is necessary to encourage, retrain, and assist proper gait mechanics in stroke survivors. Evidence indicates robotic ankle exoskeletons can improve gait outcomes in stroke survivors, however challenges remain with proper lower limb positioning for optimal receipt of the assistance. Biofeedback can be used to improve positioning of the limb for receipt of robotic ankle exoskeleton assistance. In this study, four stroke survivors used bilateral powered robotic ankle exoskeletons (Dephy Exoboots) and an innovative, custom-designed vibrotactile-audio biofeedback interface targeting trailing limb angle to test the hypotheses that each intervention alone improves gait outcomes over baseline, and when combined they improve outcomes over either intervention alone. Compared to baseline, we found increases in average paretic propulsive impulse during the biofeedback-only and exoskeleton-plus-biofeedback conditions. Biofeedback alone induced the greatest increase on average self-selected walking speed, and the combination of exoskeleton assistance and biofeedback increased speed more compared to the robotic exoskeleton-only condition. Our preliminary results indicate that biofeedback in combination with a robotic exoskeleton produces greater synergistic benefits on gait performance than the use of an exoskeleton alone.

Reactive balance control requires coordination of neurally-mediated feedforward and feedback pathways to generate stabilizing joint torques at the hip, knee, and ankle. Using a sensorimotor response model, we decomposed reactive joint torques into feedforward and feedback contributions based on delays relative to the center of mass kinematics. Responses across joints were driven by the same signals, but contributions from feedforward versus feedback pathways differed, likely due to differences in musculotendon properties between proximal and distal muscles.

BACKGROUND Elexacaftor/tezacaftor/ivacaftor (ETI) has profoundly affected the health and lives of many people with CF (pwCF). The rapid change in health for pwCF taking ETI provided them an opportunity to reflect on what "being healthy" means. The goal of this secondary analysis was to document changes in the health and well-being of pwCF after starting ETI, beyond the expected physical benefits. METHODS The Qualitative Understanding of Experiences with the SIMPLIFY Trial (QUEST) study evaluated pwCF's experiences on ETI, including participation in a withdrawal study, treatment burden, and experiences of health. Two sixty-minute interviews were conducted approximately four months apart, audio-recorded and transcribed. A phenomenological approach was used to identify text of interest and create a formal codebook. RESULTS Ninety-one pwCF (mean age=27.8 years; range 14-67; 51 % male) and 23 caregivers of the teenagers completed at least one interview. Beyond the expected benefits of ETI, four themes were identified: (1) Night and Day Change in Health, (2) Reduced Cognitive Burden, (3) Shifting to Managing Overall Wellness and Co-Morbidities, and (4) Social/Self Identity Changes. CONCLUSION ETI has raised pwCF's expectations for their health and well-being. Current symptom and QOL measures may no longer capture the less perceptible ways pwCF on ETI experience changes in symptoms or health. CF care may need to adapt to focus more on general health, managing other comorbidities, and planning for the future.

Abstract The knee joint, serving as a critical nexus in human locomotion, presents a unique set of challenges and opportunities for enhancing mobility through assistive technologies. Assistance with knee function is frequently required due to conditions like arthritis, injuries, or age-related changes, affecting one’s ability to walk and carry out daily tasks. Compliant mechanisms integrate flexible members that go under large deformation when loaded which is very similar to the nature as opposed to relative motion generation between adjunct links as in rigid mechanisms. Their ability to be manufactured in a single piece, coupled with enhanced performance due to the absence of friction loss, positions them as an excellent choice for a range of applications, particularly in the development of robotic and biomedical devices. In this study, we designed a compliant knee joint featuring variable stiffness, characterized by initially pre-buckled beams, to mimic the nonlinear stiffness behavior seen in the human gait cycle. We designed various combinations of pre-buckled beams having different geometries to analyze the torque and angular deformation as well as force and displacement relations. The knee joints are built as a single piece using a dual extruder 3D printer.

This study provides the first empirical evidence to our knowledge that age-related decreases in k AT exact a potentially significant metabolic penalty during walking. These results pave the way for interventions focused on restoring ankle muscle-tendon unit structural stiffness to improve walking energetics in aging.

Introduction: To achieve and maintain adequate weight, people with cystic fibrosis (CF) May often consume energy-dense, nutrient-poor foods high in added sugars and refined carbohydrates; however, little is known about the glycemic and metabolic effects of dietary composition in this patient population. The objective of this pilot study was to investigate the safety and tolerability of a low glycemic load (LGL) diet in adults with CF and abnormal glucose tolerance (AGT). Methods: Ten adults with CF and AGT completed this prospective, open-label pilot study. Mean age was 27.0 ± 2.1 years, 64% were female, and all had pancreatic insufficiency. Each participant followed his/her typical diet for 2 weeks, then transitioned to a LGL diet via meal delivery service for 8 weeks. The primary outcome was change in weight from baseline to study completion, with safety established if no significant decline was noted. Other key safety outcomes included change in hypoglycemia measured by patient report and continuous glucose monitoring (CGM). Exploratory outcomes included changes in other CGM measures, body composition by dual energy X-ray absorptiometry (DXA), and patient reported outcomes. Results: There were no significant changes in weight or in subjectively-reported or objectively-measured hypoglycemia. Favorable non-significant changes were noted in CGM measures of hyperglycemia and glycemic variability, DXA measures of fat mass, and gastrointestinal symptom surveys. Discussion: A LGL dietary intervention was safe and well tolerated in adults with CF and AGT. These results lay the groundwork for future trials investigating the impact of low-glycemic dietary interventions on metabolic outcomes in the CF population.

BACKGROUND Highly effective CFTR modulator therapy (HEMT) has improved the health of many people with cystic fibrosis (pwCF), offering opportunities to discontinue burdensome therapies. SIMPLIFY included randomized, controlled trials that confirmed non-inferiority of discontinuing versus continuing dornase alfa (DA) or hypertonic saline (HS) for 6 weeks in pwCF on HEMT. In this study of post-trial treatment use by SIMPLIFY participants, we hypothesized that randomization to discontinue DA or HS during the trial would be associated with a higher likelihood of non-use of each medication during follow-up. METHODS We electronically surveyed SIMPLIFY participants every 4 weeks for 24 weeks after trial completion but before the main trial results were publicly disclosed. We asked them how often they used medications during the previous week. We estimated covariate-adjusted odds ratios (ORs) of DA or HS non-use by logistic regression with generalized estimating equations. RESULTS After exclusions mostly due to lack of any surveys, 472 participants were included in the analysis population, 181 from the HS trial and 291 from the DA trial. Approximately half of the analysis population completed all six surveys. At every month of follow-up in both trials, the percentage of individuals reporting non-use of DA or HS during the previous week was greater among those randomized to discontinue therapy. Among participants with responses at 24 weeks, 30/122 (24.6 %) in the HS trial and 79/222 (35.6 %) in the DA trial reported non-use of the respective study medication. After adjusting for covariates, participants randomized to discontinue DA were 8.7-times (95 % CI: 4.3-17.7) more likely to not use DA during follow-up than those randomized to continue DA, and participants randomized to discontinue HS were 5.2-times (95 % CI: 2.1-12.8) more likely to not use HS during follow-up compared to those randomized to continue. CONCLUSIONS In healthy pwCF on ETI, randomization to discontinue DA or HS during SIMPLIFY was associated with greater odds of not using each medication after the trial compared to randomization to continue. These findings suggest that participation in a treatment discontinuation trial can influence participants' post-trial treatment decisions. This possibility may be relevant during discussions about research participation and clinical care.