Effect of Motor-Assisted Elliptical Training Speed and Body Weight Support on Center of Pressure Movement Variability

Background: A motor-assisted elliptical trainer is being used clinically to help individuals with physical disabilities regain and/or retain walking ability and cardiorespiratory fitness. Unknown is how the device’s training parameters can be used to optimize movement variability and regularity. This study examined the effect of motor-assisted elliptical training speed as well as body weight support (BWS) on center of pressure (CoP) movement variability and regularity during training. Methods: CoP was recorded using in-shoe pressure insoles as participants motor-assisted elliptical trained at three speeds (20, 40, and 60 cycles per minute) each performed at four BWS levels (0%, 20%, 40%, and 60%). Separate two-way repeated measures ANOVAs (3 × 4) evaluated impact of training speed and BWS on linear variability (standard deviation) and nonlinear regularity (sample entropy) of CoP excursion (anterior-posterior, medial-lateral) for 10 dominant limb strides. Findings: Training speed and BWS did not significantly affect the linear variability of CoP in the anterior-posterior or medial-lateral directions. However, sample entropy in both directions revealed the main effect of training speed (p \u3c 0.0001), and a main effect of BWS was observed in the medial-lateral direction (p = 0.004). Faster training speeds and greater levels of BWS resulted in more irregular CoP patterns. Interpretation: The finding that speed and BWS can be used to manipulate CoP movement variability when using a motor-assisted elliptical has significant clinical implications for promoting/restoring walking capacity. Further research is required to determine the impact of motor-assisted elliptical speed and BWS manipulations on functional recovery of walking in individuals who have experienced a neurologic injury or illness

The effect of exoskeleton footwear on joint angular motion during walking in patients with peripheral artery disease

Gait, Lower Extremity, Peripheral Artery Disease, Joint Angle, Exoskeleton Footwear, Exoskeleton, Assistive Device, Walking

Enhancing walking performance in patients with peripheral arterial disease: An intervention with ankle-foot orthosis

Lower extremity peripheral artery disease (PAD) is a cardiovascular condition manifesting from narrowed or blocked arteries supplying the legs. Gait is impaired in patients with PAD. Recent evidence suggests that walking with carbon fiber ankle foot orthoses (AFOs) can improve patient mobility and delay claudication time. This study aimed to employ advanced biomechanical gait analysis to evaluate the impact of AFO intervention on gait performance among patients with PAD. Patients with claudication had hip, knee, and ankle joint kinetics and kinematics assessed using a cross-over intervention design. Participants walked over the force platforms with and without AFOs while kinematic data was recorded with motion analysis cameras. Kinetics and kinematics were combined to quantify torques and powers during the stance period of the gait cycle. The AFOs effectively reduced the excessive ankle plantar flexion and knee extension angles, bringing the patients\u27 joint motions closer to those observed in healthy individuals. After 3 months of the AFO intervention, the hip range of motion decreased, likely due to changes occurring within the ankle chain. With the assistance of the AFOs, the biological power generation required from the ankle and hip during the push-off phase of walking decreased. Wearing AFOs resulted in increased knee flexor torque during the loading response phase of the gait. Based on this study, AFOs may allow patients with PAD to maintain or improve gait performance. More investigation is needed to fully understand and improve the potential benefits of ankle assistive devices

Joint Angle Variability Is Altered in Patients with Peripheral Artery Disease after Six Months of Exercise Intervention

Supervised exercise therapy (SET) is a conservative non-operative treatment strategy for improving walking performance in patients with peripheral artery disease (PAD). Gait variability is altered in patients with PAD, but the effect of SET on gait variability is unknown. Forty-three claudicating patients with PAD underwent gait analysis before and immediately after a 6-month SET program. Nonlinear gait variability was assessed using sample entropy, and the largest Lyapunov exponent of the ankle, knee, and hip joint angle time series. Linear mean and variability of the range of motion time series for these three joint angles were also calculated. Two-factor repeated measure analysis of variance determined the effect of the intervention and joint location on linear and nonlinear dependent variables. After SET, walking regularity decreased, while the stability remained unaffected. Ankle nonlinear variability had increased values compared with the knee and hip joints. Linear measures did not change following SET, except for knee angle, in which the magnitude of variations increased after the intervention. A six-month SET program produced changes in gait variability toward the direction of healthy controls, which indicates that in general, SET improved walking performance in individuals with PAD

Optic flow improves step width and length in older adults while performing dual task

Background Dual-task paradigms are used to investigate gait and cognitive declines in older adults (OA). Optic-flow is a virtual reality environment where the scene flows past the subject while walking on a treadmill, mimicking real-life locomotion. Aims To investigate cost of environment (no optic-flow v. optic-flow) while completing single- and dual-task walking and dual-task costs (DTC; single- v. dual-task) in optic-flow and no optic-flow environments. Methods Twenty OA and seven younger adults (YA) walked on a self-paced treadmill in 3-min segments per task and both environments. Five task conditions included: no task, semantic fluency (category), phonemic fluency (letters), word reading, and serial-subtraction. Results OAs had a benefit of optic-flow compared to no optic-flow for step width (p = 0.015) and step length (p = 0.045) during letters compared to the YA. During letters, OA experienced improvement in step width DTC; whereas YA had a decrement in step width DTC from no optic-flow to optic-flow (p = 0.038). During serial-subtraction, OA had less step width DTC when compared to YA in both environments (p = 0.02). Discussion During letters, step width and step length improved in OA while walking in optic-flow. Also, step width DTC differed between the two groups. Sensory information from optic-flow appears to benefit OA. Letters relies more on verbal ability and word knowledge, which are preserved in aging. However, YA use a complex speech style during dual tasking, searching for complex words and an increased speed of speech. Conclusions OA can benefit from optic-flow by improving spatial gait parameters, specifically, step width, during dual-task walking

Machine Learning-Based Peripheral Artery Disease Identification Using Laboratory-Based Gait Data

Peripheral artery disease (PAD) manifests from atherosclerosis, which limits blood flow to the legs and causes changes in muscle structure and function, and in gait performance. PAD is underdiagnosed, which delays treatment and worsens clinical outcomes. To overcome this challenge, the purpose of this study is to develop machine learning (ML) models that distinguish individuals with and without PAD. This is the first step to using ML to identify those with PAD risk early. We built ML models based on previously acquired overground walking biomechanics data from patients with PAD and healthy controls. Gait signatures were characterized using ankle, knee, and hip joint angles, torques, and powers, as well as ground reaction forces (GRF). ML was able to classify those with and without PAD using Neural Networks or Random Forest algorithms with 89% accuracy (0.64 Matthew’s Correlation Coefficient) using all laboratory-based gait variables. Moreover, models using only GRF variables provided up to 87% accuracy (0.64 Matthew’s Correlation Coefficient). These results indicate that ML models can classify those with and without PAD using gait signatures with acceptable performance. Results also show that an ML gait signature model that uses GRF features delivers the most informative data for PAD classification

Machine Learning-Based Peripheral Artery Disease Identification Using Laboratory-Based Gait Data

Peripheral artery disease (PAD) manifests from atherosclerosis, which limits blood flow to the legs and causes changes in muscle structure and function, and in gait performance. PAD is underdiagnosed, which delays treatment and worsens clinical outcomes. To overcome this challenge, the purpose of this study is to develop machine learning (ML) models that distinguish individuals with and without PAD. This is the first step to using ML to identify those with PAD risk early. We built ML models based on previously acquired overground walking biomechanics data from patients with PAD and healthy controls. Gait signatures were characterized using ankle, knee, and hip joint angles, torques, and powers, as well as ground reaction forces (GRF). ML was able to classify those with and without PAD using Neural Networks or Random Forest algorithms with 89% accuracy (0.64 Matthew’s Correlation Coefficient) using all laboratory-based gait variables. Moreover, models using only GRF variables provided up to 87% accuracy (0.64 Matthew’s Correlation Coefficient). These results indicate that ML models can classify those with and without PAD using gait signatures with acceptable performance. Results also show that an ML gait signature model that uses GRF features delivers the most informative data for PAD classification

Comparative evaluation of serum zinc level in head and neck cancer patients before and after radiation therapy

Background: Head and neck cancers (HNCs) include 5.3 of all cancers and they are the cause of the same 5.3 of cancer deaths. Oxidative stress has a crucial role in cancer progression and cancer therapy. Ionizing radiation causes cell malfunction and death by creating reactive oxygen species. Due to its antioxidant activity, immune system power enhancement and role in apoptosis, zinc is a crucial trace element in oncology including HNCs. We decided to compare serum zinc level of HNC patients before and after RT, to assess the potential effects of ionizing radiation therapy on serum zinc. Methods: Fifty-seven HNC patients, who were candidates for curative radiation therapy (RT), were enrolled and their serum zinc level just before and 2 months after completion of RT were checked in a single laboratory. RT was prescribed by linear accelerator with 60 to 70 Gy by conventional method. Data were analyzed by SPSS 20. Results: Mean serum zinc prior to RT and following RT were 77.64±13.45 mg/dl and 68.28±11.93 mg/dl, respectively, which was lower following RT (p<0.001). Patients’ sex, age and duration from diagnosis to treatment and site of disease didn’t have any impact on serum zinc difference. Conclusion: This study showed that RT of HNCs leads to serum zinc reduction, which is greater in nodal disease because of either larger field or higher dose of radiation. Taking zinc supplements while being treated by RT, may be necessary. &#160

Flexible Energy Storage Devices, Electric Double Layer Capacitor (Supercapacitor) with Gel Polymer Electrolyte

Due to the fast development in portable, flexible, and wearable electronic devices, it is vital to develop high-performance energy storage devices. Among these various energy storage systems, batteries and Supercapacitors are the two key technological systems holding a broad range of applications. Supercapacitors (SCs) have a higher power density than batteries. Also, they exhibit longer cycling life and better safety. Supercapacitors with gel polymer electrolytes are lightweight and flexible. Hence, they can show a great potential in which we need power sources for flexible, portable electronics. In this thesis, a flexible, lightweight, safe, and flame-retardant supercapacitor was fabricated, and the effects of molecular weight and supporting salt were studied. Characterization results indicate that PVA polymer with a molecular weight of 47000 presents higher ionic conductivity. The reason is attributed to the free volume theory. Since, in polymers with lower molecular weight, polymer chains are shorter and present more movement. Moreover, characterizations showed that gel polymer electrolytes with higher molecular weight provided a transparent and uniform structure. Stress-strain plots indicated that PVA with higher molecular weight provided higher mechanical stability. Also, the fabricated supercapacitor presented excellent ionic conductivity of 1.7 s/cm and specific capacitance of 100 after 1000 cycles. Moreover, results indicated capacity retention of 100%. In addition, experiments showed that adding boric acid to the gel polymer electrolyte improved electrochemical performance. Current challenges and future perspectives are also discussed

The Effect of Storage Environment on Dimensional Changes of Acrylic Resin Post Patterns

Introduction: The purpose of this study was to compare dimensional changes of two types of auto polymerizing acrylic resin patterns (APARPs) in three different storing environments. Methods: 60 acrylic post and core patterns were made of two types of Duralay acrylic resins (Aria dent, Iran and Reliance, Dental Mfg. Co, USA) using a canine model. Then coronal, apical diameter and coronoapical length of patterns were measured. Afterwards, they were divided into two categories of 30 for each type of Duralay acrylic resin type. Each category was divided into three groups of ten randomly to immerse in three storage environments (Deconex®53plus Borer ChemieAG, Switzerland), Unident ® Impre(USF Healthcare S.A, Sweitzerland) and water. After one hour, three mentioned values were measured again. Data were analyzed by SPSS20 using t-test, paired t-test and ANOVA. Results: Results showed that there were no statistically difference (p value> 0.05) about all dimensions of auto polymerizing acrylic post and core patterns except apical diameter and coronoapical length of Dental Mfg. Co, USA in Deconex®53 plus. Conclusion: The best environment to store Duralay APARPs with minimal changes was water and for disinfection, Deconex®53plus and Unident ® Imprecan showed acceptable properties with both of Duralay types