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Lower extremity joint kinetic factors are thought to modulate walk-to-run transition (WRT) and run-to-walk transition (RWT). This study aimed to investigate joint stiffness and energetic patterns during the WRT and RWT processes and identify whether gait transitions occur within a single step or not. Ten healthy subjects participated in treadmill WRT (1.8–2.4 m/s) and RWT (2.4–1.8 m/s) tests. We investigated two steps before transition (S–2, S–1), two steps after transition (S1, S2) and the transition step (S0). We found significant differences between S2 and S–2 for ankle joint stiffness during WRT and RWT (p < 0.001); for hip joint stiffness, we found significant differences between S1 and S–1 during WRT and RWT (p ≤ 0.001). Additionally, stance phase mechanical energy generation was observed to transfer from proximal to distal joints at S0 during WRT, and from distal to proximal at S0 during RWT. Transition step ankle kinematic and kinetic patterns were similar to the target locomotion task gait format in both WRT and RWT. Moreover, RWT required longer adaptation time compared with WRT. These findings indicate that WRT and RWT were modulated before and after the actual transitions, not within a single step. Redistribution of joint mechanical work generation was related to gait transition triggers, which modulate the WRT and RWT processes. [ABSTRACT FROM AUTHOR]

The editorial in the Journal of Musculoskeletal Research discusses the increasing prevalence of degenerative joint diseases and the limitations of pharmacologic treatments and joint replacements. Regenerative medicine, including techniques like stem cell therapies and platelet-rich plasma injections, offers potential benefits such as tissue repair, pain management, enhanced surgical outcomes, and reduced dependency on opioids. The editorial highlights the role of regenerative medicine in promoting healing and improving outcomes for musculoskeletal conditions, with contributions from researchers in the United States and Taiwan. [Extracted from the article]

Demonstration of a very dense or hyper-attenuated liver on the pre-contrast CT images of the abdomen can be an unexpected finding. It may present as a diagnostic challenge if the underlying cause of it is not apparent from the provided clinical history. There are about 12 different pathologic conditions that are associated with deposition of radiopaque elements within the hepatic parenchyma, resulting in diffuse or multi-lobar hyperdense appearance of the liver on abdominal radiographs and CT. Most of them are drug-induced or iatrogenic in nature, while others are the sequelae of genetic disorders like thalassemia, Wilson's disease, and primary hemochromatosis. This pictorial essay will present the CT appearance and etiology of hyper-attenuated liver in various clinical entities. • Hyper-attenuated liver is best diagnosed by non-enhanced CT. • It appears as diffusely increased liver density of over 70 HU. • It indicates deposition of radiopaque elements in the liver parenchyma. • The most common cause of it is iodine from amiodarone therapy. • Various other etiologies of this condition are presented. [ABSTRACT FROM AUTHOR]

Wearable sensors and machine learning algorithms are becoming a viable alternative for biomechanical analysis outside of the laboratory. The purpose of this work was to estimate gait events from inertial measurement units (IMUs) and utilize machine learning for the estimation of ground reaction force (GRF) waveforms. Sixteen healthy runners were recruited for this study, with varied running experience. Force sensing insoles were used to measure normal foot-shoe forces, providing a proxy for vertical GRF and a standard for the identification of gait events. Three IMUs were mounted on each participant, two bilaterally on the dorsal aspect of each foot and one clipped to the back of each participant's waistband, approximating their sacrum. Participants also wore a GPS watch to record elevation and velocity. A Bidirectional Long Short Term Memory Network (BD-LSTM) was used to estimate GRF waveforms from inertial waveforms. Gait event estimation from both IMU data and machine learning algorithms led to accurate estimations of contact time. The GRF magnitudes were generally underestimated by the machine learning algorithm when presented with data from a novel participant, especially at faster running speeds. This work demonstrated that estimation of GRF waveforms is feasible across a range of running velocities and at different grades in an uncontrolled environment. [ABSTRACT FROM AUTHOR]

Zero-velocity assumption has been used for estimation of foot trajectory and stride length during running from the data of foot-mounted inertial measurement units (IMUs). Although the assumption provides a reasonable initialization for foot trajectory and stride length estimation, the other source of errors related to the IMU's orientation still remains. The purpose of this study was to develop an improved foot trajectory and stride length estimation method for the level ground running based on the displacement of the foot. Seventy-nine runners performed running trials at 5 different paces and their running motions were captured using a motion capture system. The accelerations and angular velocities of left and right feet were measured with two IMUs mounted on the dorsum of each foot. In this study, foot trajectory and stride length were estimated using zero-velocity assumption with IMU data, and the orientation of IMU was estimated to calculate the mediolateral and vertical distance of the foot between two consecutive midstance events. Calculated foot trajectory and stride length were compared with motion capture data. The results show that the method used in this study can provide accurate estimation of foot trajectory and stride length for level ground running across a range of running speeds. [ABSTRACT FROM AUTHOR]

The lower–extremity system acts like a spring in the running stance phase. Vertical stiffness ( K v e r t ) and leg stiffness ( K l e g ) reflect the whole–body center of mass (COM) and leg–spring system loading and response in running, while joint stiffness ( K j o i n t ) represents joint–level dynamic loading and response. This study aimed to investigate whether K j o i n t is associated with K v e r t and K l e g across different running speeds. Twenty healthy subjects were recruited into a treadmill running study (1.8 to 3.8 m/s, with 0.4 m/s intervals). We found that K j o i n t accounted for 38.4% of the variance in K v e r t (p = 0.046) and 42.4% of the variance in K l e g (p = 0.028) at 1.8 m/s; K j o i n t also accounted for 49.8% of the variance in K v e r t (p = 0.014) and 79.3% of the variance in K l e g (p < 0.0001) at 2.2 m/s. K k n e e had the strongest unique association with K v e r t and K l e g at 1.8 and 2.2 m/s. K j o i n t was associated with K l e g at a wider range of speeds. These findings built a connection between joint stiffness and limb stiffness within a certain range of running speeds. K k n e e may need to be considered as an important factor in future limb stiffness optimization and general running performance enhancement. [ABSTRACT FROM AUTHOR]

The development of lightweight portable sensors and algorithms for the identification of gait events at steady-state running speeds can be translated into the real-world environment. However, the output of these algorithms needs to be validated. The purpose of this study was to validate the identification of running gait events using data from Inertial Measurement Units (IMUs) in a semi-uncontrolled environment. Fifteen healthy runners were recruited for this study, with varied running experience and age. Force-sensing insoles measured normal foot-shoe forces and provided a standard for identification of gait events. Three IMUs were mounted to the participant, two bilaterally on the dorsal aspect of the foot and one clipped to the back of each participant's waistband, approximating their sacrum. The identification of gait events from the foot-mounted IMU was more accurate than from the sacral-mounted IMU. At running speeds <3.57 m s−1, the sacral-mounted IMU identified contact duration as well as the foot-mounted IMU. However, at speeds >3.57 m s−1, the sacral-mounted IMU overestimated foot contact duration. This study demonstrates that at controlled paces over level ground, we can identify gait events and measure contact time across a range of running skill levels. [ABSTRACT FROM AUTHOR]

To report the radiological features of intestinal ascariasis and to review the clinical implications of this re-emerging disease for adult population of the USA. This retrospective observational study involved 12 adult patients, whose radiological examinations disclosed unsuspected presence of ascaris in their intestinal tract. They were evaluated by computed tomography of the abdomen with oral contrast, small bowel series with barium, and magnetic resonance enterography. This series included 7 men and 5 women, who ranged in age from 19 to 72 years (mean age 48 years). The typical configuration of ascaris within the bowel loops was demonstrated on CT of the abdomen in 5 patients, small bowel examination with barium in 3, and by MR enterography in another 4 cases. Our study highlights the radiological appearances of intestinal ascariasis and the clinical implications of this resurging disease. The practicing radiologists should be aware of these findings, particularly when examining patients who have immigrated from or traveled to the endemic regions. [ABSTRACT FROM AUTHOR]

Background: Modifying the longitudinal bending stiffness (LBS) of footwear has become a popular method to improve sport performance. It has been demonstrated to influence running economy by altering lower extremity joint level mechanics. Previous studies have only examined within-participant effects at one running speed.Research Question: Do joint level mechanics differ in response to varying footwear LBS at a range of running speeds?Methods: This study utilized a cross-sectional repeated measure study design using a convenience sample. Ten well trained non-rearfoot strike male distance runners ran at 3.89, 4.70, and 5.56 m/s (14, 17, 20 km/hr) in footwear of three different LBS levels. Mechanics and energetics of the metatarsophalangeal joint (MTPJ), ankle, knee, and hip joints during stance phase were assessed using an 8-camera optical motion capture system (fs = 200 Hz), a force instrumented treadmill (fs = 1000 Hz) and standard inverse dynamics theory.Results: Range of motion and negative work decreased and angular stiffness increased for the MTPJ with increasing LBS at all speeds (p < .001). Peak MTPJ moment did not change at any speed in response to increased LBS. Negative work at the ankle decreased in the stiff shoe at 17 km/hr (p = .036). Peak ankle plantar flexion velocity decreased with increasing LBS at all speeds (p < .05).Significance: While changes in MTPJ mechanics were consistent across speeds, decreased negative ankle work was only observed at 17 km/hr in the stiff shoe, suggesting that perhaps tuned footwear LBS may need to focus primarily on metabolically beneficial changes in ankle plantar flexor mechanical behavior to improve performance in distance runners. Tuning footwear stiffness may also be beneficial to clinical populations, as clinicians seek to optimize their patients' locomotion economy. [ABSTRACT FROM AUTHOR]

The intrinsic foot musculature (IFM) supports the arches of the foot and controls metatarsophalangeal joint (MTPJ) motion. Stronger IFM can increase the effective foot length, potentially altering lower-extremity gearing similar to that of using carbon-fibre-plated footwear. The purpose of this study was to investigate if strengthening of the IFM can alter gait mechanics and improve running economy. Eleven participants were randomly assigned into an experimental group and nine into a control group. The experimental group performed IFM strengthening exercises for ten weeks. Toe-flexor strength, gait mechanics, and running economy were assessed at baseline, five weeks, and ten weeks; using a custom strength testing apparatus, motion capture and force-instrumented treadmill, and indirect calorimetry. Toe-flexor strength increased in the experimental group (p =.006); however, MTPJ and ankle mechanics and running economy did not change. The dearth of changes in mechanics may be due to a lack of mechanical advantage of the IFM, runners staying within their preferred movement path, a need for MTPJ dorsiflexion to facilitate the windlass mechanism, or the primary function of the IFM being to support the longitudinal arch of the foot as opposed to modulating MTPJ mechanics. [ABSTRACT FROM AUTHOR]

Introduction: The current work probes the effectiveness of multimodal touch screen tablet electronic devices in conveying science, technology, engineering, and mathematics graphics via vibrations and sounds to individuals who are visually impaired (i.e., blind or low vision) and compares it with similar graphics presented in an embossed format. Method: A volunteer sample of 22 participants who are visually impaired, selected from a summer camp and local schools for blind students, were recruited for the current study. Participants were first briefly (∼30 min) trained on how to explore graphics via a multimodal touch screen tablet. They then explored six graphic types (number line, table, pie chart, bar chart, line graph, and map) displayed via embossed paper and tablet. Participants answered three content questions per graphic type following exploration. Results: Participants were only 6% more accurate when answering questions regarding an embossed graphic as opposed to a tablet graphic. A paired-samples t test indicated that this difference was not significant, t (14) = 1.91, p =.07. Follow-up analyses indicated that presentation medium did not interact with graphic type, F (5, 50) = 0.43, p =.83, nor visual ability, F (1, 13) = 0.00, p =.96. Discussion: The findings demonstrate that multimodal touch screen tablets may be comparable to embossed graphics in conveying iconographic science and mathematics content to individuals with visual impairments, regardless of the severity of impairment. The relative equivalence in response accuracy between mediums was unexpected, given that most students who participated were braille readers and had experience reading embossed graphics, whereas they were introduced to the tablet the day of testing. Implications for practitioners: This work illustrates that multimodal touch screen tablets may be an effective option for general education teachers or teachers of students with visual impairments to use in their educational practices. Currently, preparation of accessible graphics is time consuming and requires significant preparation, but such tablets provide solutions for offering "real-time" displays of these graphics for presentation in class. [ABSTRACT FROM AUTHOR]

Abstract The forefoot functions as the base of support during late stance, rotating about the dual-axis of the metatarsophalangeal joints. Previous research has shown that joint axis definition affects estimated joint moments about the forefoot. However, little is known about how metatarsophalangeal joint center definition affects estimated joint kinetics. This study compared moments about the metatarsophalangeal joint using four different defined joint centers. There was a significant difference (p <.001) in peak moments between joint center definitions, differing by up to 0.488 N-m/kg for the slow and 0.878 N-m/kg for the fast running speeds tested. Additionally, there was a significant difference (p <.001) for when peak plantar flexor moment occurred during the slower running condition. The more posteriorly oriented joint centers resulted in higher moments and earlier onset of the plantar flexor moment. In addition to careful modeling of the metatarsophalangeal joint axis, it is recommended that joint center definition should be considered as well. [ABSTRACT FROM AUTHOR]

Noninvasive assessment of muscle mechanical properties in clinical and performance settings tends to rely on manual palpation and emphasizes examination of musculotendinous stiffness. However, measurement standards are highly subjective. The purpose of the study was to compare musculotendinous stiffness in adult women with varying resistance training history while exploring the use of multiple tissue compliance measures. We identified relationships between tissue stiffness and morphology, and tested the hypothesis that combining objective measures of mor-phology and stiffness would better predict indices of contractile performance. Resistance-trained (RT) women (n = 11) and nontrained (NT) women (n = 10) participated in the study. Muscle echogenicity and morphology were measured using B-mode ultrasonography (US). Vastus lateralis (VL) and patellar tendon (PT) stiffness were measured using digital palpation and US across submaximal isometric contractions. Muscle function was evaluated during maximal voluntary isometric contraction (MVIC) of the knee extensors (KEs). Resistance trained had significantly greater PT stiffness and reduced echogenicity (p < 0.01). Resistance trained also had greater strength per body mass (p < 0.05). Muscle echogenicity was strongly associated with strength and rate of torque development (RTD). Patellar tendon passive stiffness was associated with RTD normalized to MVIC (RTDrel; r = 0.44, p < 0.05). Patellar tendon stiffness was greater in RT young women. No predictive models of muscle function incorporated both stiffness and echogenicity. Because RTDrel is a clinically relevant measure of rehabilitation in athletes and can be predicted by digital palpation, this might represent a practical and objective measure in settings where RTD may not be easy to measure directly. [ABSTRACT FROM AUTHOR]

Gait adaptation is a task that requires fine-tuned coordination of all degrees of freedom in the lower limbs by the central nervous system. However, when individuals change their gait it is unknown how this coordination is organized, and how it can be influenced by contextual interference during practice. Such knowledge could provide information about measurement of gait adaptation during rehabilitation. Able-bodied individuals completed an acute bout of asymmetric split-belt treadmill walking, where one limb was driven at a constant velocity and the other according to one of three designed practice paradigms: serial practice, where the variable limb belt velocity increased over time; random blocked practice, where every 20 strides the variable limb belt velocity changed randomly; random practice, where every stride the variable limb belt velocity changed randomly. On the second day, subjects completed one of two different transfer tests; one with a belt asymmetry close to that experienced on the acquisition day (transfer 1; 1.5:1), and one with a greater asymmetry (transfer 2; 2:1) . To reduce this inherently high-dimensional dataset, principal component analyses were used for kinematic data collected throughout the acquisition and transfer phases; resulting in extraction of the first two principal components (PCs). For acquisition, PC1 and PC2 were related to sagittal and frontal plane control. For transfer 1, PC1 and PC2 were related to frontal plane control of the base of support and whole-body center of mass. For transfer 2, PC1 did not have any variables with high enough coefficients deemed to be relevant, and PC2 was related to sagittal plane control. Observations of principal component scores indicate that variance structuring differs among practice groups during acquisition and transfer 1, but not transfer 2. These results demonstrate the main kinematic coordinative structures that exist during gait adaptation, and that control of sagittal plane and frontal plane motion are perhaps a trade-off during acquisition of a novel asymmetric gait pattern. [ABSTRACT FROM AUTHOR]

Locomotion task and speed changes affect dynamic joint function. Walking and running require different coordination patterns of lower extremity joint mechanics. These coordination differences can result in measurable changes in kinematic and kinetic patterns. When locomotion speed changes, the functional role and movement strategy of each joint is altered. A deeper understanding of joint level mechanics and functional interactions will benefit rehabilitation programs and assistive device development. In this study, joint stiffness, joint mechanical work and power were assessed, as they relate to dynamic function of joints during locomotion. Ten young healthy subjects (5 males, 5 females) participated in a treadmill walking (0.8-2.0 m/s) and running (1.8-3.8 m/s) study. When running speed increased, the stiffness of all three joints tended to increase. The ankle joint played a dominant role during the stance phase of running, generating more positive work than the knee (p = .003) and hip (p = .0001). The knee and hip joint were more dominant in walking and running swing phase energy absorption and generation, respectively. When locomotion speeds increased, stance phase ankle positive work, swing phase knee negative work, and hip joint positive work tended to increase. These findings suggest that change of locomotion speed or task results in definitive changes to lower extremity joint level mechanics patterns. [ABSTRACT FROM AUTHOR]

Unilateral hand contractions increase activation in the motor cortex of the contralateral hemisphere, providing a means to alter the relative degree of activation in the right hemisphere versus the left hemisphere through spreading activation. Prior research reported enhanced verbal creativity as measured by performance on remote associate problems in Hebrew from left-hand contractions (right-hemisphere activation). We sought to extend the previous findings to English problems and to homograph interpretation. In Experiment 1, unilateral hand contractions in fact altered performance on the English remote associates, but in the direction of improved performance following right-hand contractions and left-hemisphere activation. In Experiment 2, the probability of retrieving atypical interpretations of homographs with multiple meanings was least likely for left-hemisphere dominant strong right handers, but the hand contraction manipulation had no effect. [ABSTRACT FROM AUTHOR]

The hip and ankle strategies that affect learning of a novel gait have not been fully determined, and could be of importance in design of clinical gait interventions. The authors' purpose was to determine the effects of asymmetric split-belt treadmill walking on ankle and hip work during propulsion. Participants were randomized into either a gradual training group or a sudden training group and later returned for a retention test. The gradual training group performed significantly more work at the hip joint of the slow limb during acquisition, and decreased the hip joint work performed during retention. These findings reveal the hip joint on the slow limb during initial swing as a possible site of adaptation to a novel locomotor pattern. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Gradual introduction of task demand strengthens learning of novel reaching tasks. [•] Efficacy of Gradual vs. Sudden Training for locomotor tasks remains unknown. [•] Gradual Training reduced practice difficulty and preserved learning of walking task. [•] Influence of Gradual Training on balance control and movement efficiency unknown. [ABSTRACT FROM AUTHOR]

Relatively little attention has been given to the use of well-established motor learning strategies to enable individuals with lower limb loss to effectively and safely learn to walk with their prostheses in the home and community. Traditionally, such outcomes have been pursued by focusing on the design and function of a patient's prosthesis, rather than on how he or she should learn to use it. The use of motor learning strategies may enhance physical rehabilitation outcomes among individuals with lower limb loss. This review explores these motor learning strategies and ways in which they can be applied to the physical rehabilitation of individuals with lower limb loss and highlights some of the challenges to their implementation, as well as unanswered research questions. [ABSTRACT FROM AUTHOR]

Abstract: Non-articulated energy storage and return prosthetic feet lack any true articulation or obvious point of rotation. This makes it difficult to select a joint center about which to estimate their kinetics. Despite this absence of any clear point of rotation, methods for estimating the kinetic performance of this class of prosthetic feet typically assume that they possess a fixed center of rotation and that its location is well approximated by the position of the contralateral lateral malleolus. To evaluate the validity of this assumption we used a finite helical axis approach to determine the position of the center of rotation in the sagittal plane for a series of non-articulated energy storage and return prosthetic feet. We found that over the course of stance phase, the sagittal finite helical axis position diverged markedly from the typically assumed fixed axis location. These results suggest that researchers may need to review center of rotation assumptions when assessing prosthetic foot kinetics, while clinicians may need to reconsider the criteria by which they prescribe these prosthetic feet. [Copyright &y& Elsevier]

Introduction: The biomechanical performance of the Darrach procedure, its stabilizing methods and the effectiveness of an ulnar head prosthesis was evaluated in this experiment. Purpose: The purpose of this study was to: (1) analyze the dynamic effects of the resection of the distal ulna on radioulnar convergence; and (2) evaluate the mechanical performance of two soft tissue stabilizing procedures (pronator quadratus advancement flap and ECU/FCU tenodesis) for the unstable distal ulnar stump and the implantation of an ulnar head prosthesis (uHead) following a distal ulnar resection (Darrach procedure) on radioulnar convergence. Method: With a dynamic PC-controlled forearm simulator, cadaveric forearm rotation was actively and passively performed while simultaneously loading the relevant muscles. The resultant total forearm torque and the three-dimensional kinematics of the ulna, radius and third metacarpal were simultaneously recorded in seven fresh-frozen cadaver upper extremities. Results: The resection of the distal ulna created an extreme instability of the forearm with movement of the radius toward the ulna (0.92-0.38 cm compared to the intact state) in each particular loading condition. The implantation of the ulnar head prosthesis effectively restored the stability of the DRUJ by simulating the geometry of the ulnar head. There were significantly better results after the implantation of the prosthesis compared with the Darrach and the soft tissue stabilization procedures. Conclusion: This study provides laboratory validity to the option of implanting an ulnar head endoprosthesis as an attempt to stabilize the distal forearm with instability after Darrach resection in lieu of performing soft tissue stabilization techniques. [ABSTRACT FROM AUTHOR]

The article focuses on potential errors that spring from estimates of lower limb joint kinematics by means of inverse dynamic calculations for individuals who have undergone lower limb amputation. It notes that link-segment models based on anatomy and physiology may not be valid when applied to designs of lower limb prosthetics. Furthermore, it stresses that clinicians should be aware of limitations of application of link-segment models to inverse dynamic calculations on gait analysis.

• Design of a novel optoelectronic shear strain sensor. • Comparison of seven retroreflective color pixel patterns and 22 data classification algorithms for measuring shear strain. • Randomized color pixel pattern coupled with weighted k-nearest-neighbor classifier was the optimal sensor configuration (98% accuracy; 0.07 mm error). [Display omitted] There is an increasing need to measure shear stress and strain for biomedical and robotics applications. Many shear sensors exist, but are often impractical for these applications as they can be bulky, require wired power sources, or are sensitive to electromagnetic interference from the human body or mechatronic systems. This paper presents an optical-based sensor, which measures shear strain based on a red, green, and blue (RGB) light-emitting diode (LED) projecting a cyclical pattern of RGB light onto a color pattern. As shear strain causes displacement between the LED and color pattern, the relative intensities of the reflected RGB lights change due to the shift of the color pattern position. A photoresistor captures the reflected light intensity during each color illumination, allowing determination of shear strain along two axes. The purpose of this work was to determine the optimal sensor configuration by studying the efficacy of different color patterns and data classification algorithms to measure two-axis shear strain. The optimal sensor configuration was a randomized color pixel pattern with a weighted k-nearest-neighbor classifier. Accuracy was 97.5% and 98.0%, and misclassification cost was 0.11 mm and 0.07 mm in the horizontal and vertical directions, respectively. Importantly, this sensing technique allows determination of directionality of shear measurement, overcoming a major limitation of other optical-based shear sensors. These properties, along with its small, low-cost, and scalable design support the use of this sensor and sensing paradigm for a variety of biomedical and robotics applications [ABSTRACT FROM AUTHOR]

The study's aim was to determine the initial effects of a dynamic seating system as a therapeutic intervention in children with cerebral palsy. A two-factor, repeated-measures design was used. Twelve children with neuromuscular dysfunction (mean age 6.0, SD 2.7 years) were included in the study, randomly assigned to an experimental or a control group. At study initiation the experimental group received a wheelchair with dynamic seating components that allows limited range of motion in the hip and knee, and the control group received a static setting wheelchair. Participants were evaluated for range of motion, muscle spasticity (Modified Ashworth Scale), motor function (Gross Motor Function Measure), and level of disability (Pediatric Evaluation of Disability Inventory) at study initiation, 3-months, and 6-months post intervention. Both groups improved in motor function over time, particularly in the categories of Sitting and Crawl/Kneel. Measures of disability improved in both groups for the categories of self-care, mobility, and social function. A larger, more homogeneous sample would likely show significant group differences in measures of muscle spasticity, gross motor function and disability. [ABSTRACT FROM AUTHOR]

Simple Summary: Excessive movements, or inadequate timing in movement patterns, during running may contribute to the development of some running-related injuries. Specifically, excessive movement at the rearfoot, influencing lower leg rotation, has been a focus on different running-related injuries. One method to change how the lower limbs move is to increase step rate, or cadence. There is little research available describing how the rearfoot is affected by changes in step rate; therefore, the primary purpose of this study was to evaluate the effects of increasing step rate on rearfoot motion during running. Reflective markers were placed on twenty runners' lower legs and feet in order to capture leg and foot movements while running on a treadmill at the runners' preferred speed and step rate. Step rate was increased by 5% and 10%, while runners were cued by a metronome. Three-dimensional rearfoot motion was calculated during the stance phase (foot in contact with the ground) of running. The main finding of this study was that increasing step rate decreased peak rearfoot and lower leg rotation. These findings may be useful for rehabilitation for some running-related injuries. Relatively high frontal and transverse plane motion in the lower limbs during running have been thought to play a role in the development of some running-related injuries (RRIs). Increasing step rate has been shown to significantly alter lower limb kinematics and kinetics during running. The purpose of this study was to evaluate the effects of increasing step rate on rearfoot kinematics, and to confirm how ground reaction forces (GRFs) are adjusted with increased step rate. Twenty runners ran on a force instrumented treadmill while marker position data were collected under three conditions. Participants ran at their preferred pace and step rate, then +5% and +10% of their preferred step rate while being cued by a metronome for three minutes each. Sagittal and frontal plane angles for the rearfoot segment, tibial rotation, and GRFs were calculated during the stance phase of running. Significant decreases were observed in sagittal and frontal plane rearfoot angles, tibial rotation, vertical GRF, and anteroposterior GRF with increased step rate compared with the preferred step rate. Increasing step rate significantly decreased peak sagittal and frontal plane rearfoot and tibial rotation angles. These findings may have implications for some RRIs and gait retraining. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop a model to estimate lower extremity joint moments during level gait. A three-layer artificial neural network was developed to map diverse inputs (demographics, anthropometrics, electromyography, kinematics) onto sagittal plane resultant joint moments for a sample of healthy young adults. Overall model performance and prediction accuracy were acceptable for the hip, knee, and ankle, with coefficients of determination (r2) reaching 0.90 for the hip and knee and 0.95 for the ankle. Estimates in the case-specific validation produced r2 values of 0.95, 0.94, and 0.99 for the hip, knee, and ankle, respectively. Absolute errors of estimation for peak data were within the ranges published previously for other joint moment models. The results indicated that the model used in this study is accurate in estimating sagittal plane joint moments about the hip, knee, and ankle. Furthermore, the model retained accuracy with a reduced list of inputs (kinematics and demographics). Future development will include clinical samples to determine the adaptability of this model to the diverse conditions of musculoskeletal gait dysfunction common in the clinical setting. [ABSTRACT FROM AUTHOR]

Abstract: Many studies have investigated the relationships between electromyography (EMG) and torque production. A few investigators have used adjusted learning algorithms and feed-forward artificial neural networks (ANNs) to estimate joint torque in the elbow. This study sought to estimate net isokinetic knee torque using ANN models. Isokinetic knee extensor and flexor torque data were measured simultaneously with agonist and antagonist EMG during concentric and eccentric contractions at joint velocities of 30°/s and 60°/s. Age, gender, height, body mass, agonist EMG, antagonist EMG, joint position and joint velocity were entered as predictive variables of net torque. A three-layer ANN model was developed and trained using an adjusted back-propagation algorithm. Accuracy results were compared against those of forward stepwise regression models. Stepwise regression models included body mass, body height and joint position as the most influential predictors, followed by agonist EMG for concentric and eccentric contractions. Estimation of eccentric torque included antagonist EMG following the agonist activation. ANN models resulted in more accurate torque estimation , compared to the stepwise regression models . ANN model accuracy increased greatly when the number of hidden units increased from 5 to 10, continuing to increase gradually with additional hidden units. The average number of training epochs necessary for solution convergence and the relative accuracy of the model indicate a strong ability for the ANN model to generalize these estimations to a broader sample. The ANN model appears to be a feasible technique for estimating joint torque in the knee. [Copyright &y& Elsevier]

Abstract: Skeletal muscle strength is known to decline with age. Although lower extremity (LE) muscle strength is critical to maintaining dynamic stability, few studies have investigated lower extremity muscle challenge during activities of daily living. The purpose of this study was to investigate the effects of age and obstructed gait on relative lower extremity muscular challenge, with respect to available joint strength. Fifteen healthy young and fifteen healthy older adults were asked to walk over level ground and step over obstacles. Pre-amplified surface electrodes were used to measure bilateral muscular activation of the gluteus medius (GM), vastus lateralis (VL), and gastrocnemius (GA). Muscle activation signals were normalized to peak magnitudes collected during maximal manual muscle testing (MMT). Normalized magnitudes were analyzed during the double-support phase for gluteus medius and vastus lateralis and during the single-support phase for gastrocnemius. A two-factor ANOVA was used to test for age group effect, with repeated measure of obstacle height. In general, older adults demonstrated greater relative activation levels compared to young adults. Gluteus medius activity was significantly greater in the elderly as compared to young during periods of double-support (weight transfer). Increased obstacle height resulted in greater relative activation in all muscles, confirming the increased challenge to the musculo-skeletal system. While healthy elderly adults were able to successfully negotiate obstacles of different heights during walking, their muscular strength capacity was significantly lower than young adults, resulting in relatively higher muscular demands. The resulting potential for muscular fatigue during locomotion may place individuals at higher risk for trips and/or falls. [Copyright &y& Elsevier]

Gait patterns of the elderly are often adjusted to accommodate for reduced function in the balance control system and a general reduction in skeletal muscle strength. Recent studies have demonstrated that measures related to motion of whole body center of mass (COM) can distinguish elderly individuals with balance impairment from healthy peers. Accurate COM estimation requires a multiple-segment anthropometric model, which may restrict its broad application in assessment of dynamic instability. Although temporal-distance measures and electromyography have been used in evaluation of overall gait function and determination of gait dysfunction, no studies have examined the use of gait measurements in predicting COM motion during gait. The purpose of this study was to demonstrate the effectiveness of an artificial neural network (ANN) model in mapping gait measurements onto COM motion in the frontal plane. Data from 40 subjects of varied age and balance impairment were entered into a 3-layer feed-forward model with back-propagated error correction. Bootstrap re-sampling was used to enhance the generalization accuracy of the model, using 20 re-sampling trials. The ANN model required minimal processing time (5 epochs, with 20 hidden units) and accurately mapped COM motion (R-values up to 0.89). As training proportion and number of hidden units increased, so did model accuracy. Overall, this model appears to be effective as a mapping tool for estimating balance control during locomotion. With easily obtained gait measures as input and a simple, computationally efficient architecture, the model may prove useful in clinical scenarios where electromyography equipment exists. [Copyright &y& Elsevier]

Chemistry-driven strategies for modifying, controlling and monitoring protein function in vitro and in vivo have attracted widespread interest among chemists in recent years. Several strategies have now emerged that complement standard genetics-based approaches, and they are being increasingly adopted by biologists to address issues in relevant contexts from cells to animals. With the development of these chemical biology tools, we might be approaching a time when detailed quantitative analysis of protein function, to a degree previously available only in reconstituted systems, is attainable in an in vivo setting. [Copyright &y& Elsevier]

Accidental falls are a leading cause of injury and death in the growing elderly population. Traumatic falls are frequent, costly, and debilitating. Control of balance during locomotion is critical for safe ambulation, but relatively little is known about the natural effect of aging on dynamic balance control. Samples of healthy young (n=13) and elderly (n=13) subjects were compared in the interactive measures of center of mass (COM) and center of pressure (COP) during level walking and obstacle crossing conditions. Obstacle heights were normalized to individual body height (2.5%, 5%, 10%, and 15%). Temporal-distance (T-D) variables of gait were also compared. Statistical analyses were conducted using a two-way ANOVA for subject group and obstacle height. T-D parameters were not significantly different between groups; nor were frontal plane COM and COP parameters. Significant age differences did exist for antero-posterior (A/P) motion of the COM (decreased motion in the elderly), and its relationship with the COP (reduced separation between the two variables in the elderly). Anterior COM velocities were also significantly lower in the elderly group. The results confirm the ability of healthy elderly adults to maintain dynamic balance control in the frontal plane during locomotion. Reduced A/P distances between the COM and COP indicate a conservative reduction of the mechanical load on joints of the supporting limb. This conservative strategy may be related to a reduction in muscle strength as it occurs in the natural aging process. [Copyright &y& Elsevier]

Objective. To determine if medio-lateral motion of the head, trunk, or pelvis demonstrates dynamic stability as well as whole-body center of mass during obstructed walking.Design. Group comparison of two elderly populations using whole-body motion analysis.Background. Detection of imbalance through analysis of center of mass motion is commonly adopted, requiring three-dimensional reconstruction of a multi-link biomechanical model. It would be advantageous clinically if similar detection could be made by analyzing segmental displacements of the pelvis, trunk, or head.Methods. Healthy elderly adults and elderly patients with balance disorders walked over level ground and crossed obstacles of height ranging from 2.5% to 15% of body height. Whole-body center of mass was calculated as the weighted sum of segmental centers of mass. Group differences in medio-lateral displacements and peak velocities of head, trunk, pelvis, and the center of mass were analyzed using a two-way ANOVA with repeated measures for obstacle height.Results. Elderly patients with balance disorders exhibited greater medio-lateral displacement and peak velocities of all segments. However, significant group differences were only detected in the center of mass displacement and peak velocity.Conclusion. Whole-body center of mass motion distinguishes elderly patients with balance disorders from healthy peers more consistently than markers representing the head, trunk, or pelvis. Large variation of individual segment motion makes dynamic stability difficult to assess. This study demonstrates that center of mass motion allows more sensitive detection of dynamic instability.RelevanceDetection of dynamic instability in at-risk individuals before falls occur will allow preventative interventions, preserving quality of life in the elderly population. [Copyright &y& Elsevier]

The focal radiation therapy (RT) boost technique was shown in a phase III randomized controlled trial (RCT) to improve prostate cancer outcomes without increasing toxicity. This technique relies on the accurate delineation of prostate tumors on MRI. A recent prospective study evaluated radiation oncologists' accuracy when asked to delineate prostate tumors on MRI and demonstrated high variability in tumor contours. We sought to evaluate the impact of contour variability and inaccuracy on predicted clinical outcomes. We hypothesized that radiation oncologists' contour inaccuracies would yield meaningfully worse clinical outcomes. Forty-five radiation oncologists and 2 expert radiologists contoured prostate tumors on 30 patient cases. Of these cases, those with CT simulation or diagnostic CT available were selected for analysis. A knowledge-based planning model was developed to generate focal RT boost plans for each contour per the RCT protocol. The probability of biochemical failure (BF) was determined using a model from the RCT. The primary metric evaluated was delta BF (DBF = Participant BF – Expert BF). An absolute increase in BF ≥5% was considered clinically meaningful. Eight patient cases and 394 target volumes for focal RT boost planning were included in this analysis. In general, participant plans were associated with worse predicted clinical outcomes compared to the expert plan, with an average absolute increase in BF of 4.3%. Of participant plans, 37% were noted to have an absolute increase in BF of 5% or more. Radiation oncologists' attempts to contour tumor targets for focal RT boost are frequently inaccurate enough to yield meaningfully inferior clinical outcomes for patients. [ABSTRACT FROM AUTHOR]

Polymers of norbornenyl-modified peptide-based enzyme substrates have been prepared via ring-opening metathesis polymerization (ROMP). Peptides displayed on water-soluble homopolymers retain the ability to be enzymatically processed by a disease-associated enzyme. In contrast, when the peptides are densely arrayed on a nanoparticle derived from a self-assembled amphiphilic block-copolymer, they function with reduced activity as enzymatic substrates. [ABSTRACT FROM AUTHOR]

Abstract: This study sought to determine whether the need to actively control lateral balance is consistent within a step. Variability of the frontal plane COM-Ankle angle was calculated over 50 strides at discrete gait events for twenty-one healthy young adults to quantify active control of lateral balance within a step. Frontal plane COM-Ankle angle variability was found to vary significantly between all gait events, decreasing progressively within a step. This suggests that active control of lateral balance varies significantly within a step and that the greatest degree of active control occurs at heel-strike. The increased active control of lateral balance during heel-strike indicates a degree of preparation to ensure sufficient lateral balance control prior to more challenging events. These results provide insight into the mechanisms of lateral balance control and how to assess and treat locomotor balance control impairments. [Copyright &y& Elsevier]

Multi-segment foot models (MFMs) provide a better understanding of the intricate biomechanics of the foot, yet it is unclear if they accurately differentiate foot type function during locomotion. We employed an MFM to detect subtle kinematic differences between foot types, including: pes cavus, neutrally aligned, and asymptomatic and symptomatic pes planus. The study investigates how variable the results of this MFM are and if it can detect kinematic differences between pathologic and non-pathologic foot types during the stance phase of gait. Independently, three raters instrumented three subjects on three days to assess variability. In a separate cohort, each foot type was statically quantified for ten subjects per group. Each subject walked while instrumented with a four-segment foot model to assess static alignment and foot motion during the stance phase of gait. Statistical analysis performed with a linear mixed effects regression. Model variability was highest for between-day and lowest for between–rater, with all variability measures being within the true sample variance. Almost all static measures (radiographic, digital scan, and kinematic markers) differed significantly by foot type. Sagittal hindfoot to leg and forefoot to leg kinematics differed between foot types during late stance, as well as coronal hallux to forefoot range of motion. The MFM had low between-rater variability and may be suitable for multiple raters to apply to a single study sample without introducing significant error. The model, however, only detected a few dynamic differences, with the most dramatic being the hallux to forefoot coronal plane range of motion. Significance: Results only somewhat aligned with previous work. It remains unclear if the MFM is sensitive enough to accurately detect different motion between foot types (pathologic and non-pathologic). A more accurate method of tracking foot bone motion (e.g., biplane fluoroscopy) may be needed to address this question. • The majority of static measures differed significantly by foot type. • Sagittal hind- and forefoot to leg kinematics differed between groups during stance. • Coronal hallux to forefoot range of motion varied by foot type during gait. • All variability measures were within the true sample variance. [ABSTRACT FROM AUTHOR]

Children in rural communities consume more energy-dense foods relative to their urban peers. Identifying effective interventions for improving energy intake patterns are needed to address these geographic disparities. The primary aim of this study was to harness the benefits of physical activity on children's executive functioning to see if these improvements lead to acute changes in eating behaviors. In a randomized crossover design, 91 preadolescent (8-10y; M age = 9.48 ± 0.85; 50.5% female; 85.7% White, 9.9% Multiracial, 9.9% Hispanic) children (86% rural) completed a 20-minute physical activity condition (moderate intensity walking) and time-matched sedentary condition (reading and/or coloring) ~ 14 days apart. Immediately following each condition, participants completed a behavioral inhibition task and then eating behaviors (total energy intake, relative energy intake, snack intake) were measured during a multi-array buffet test meal. After adjusting for period and order effects, body fat (measured via DXA), and depressive symptoms, participants experienced significant small improvements in their behavioral inhibition following the physical activity versus sedentary condition (p = 0.04, Hedge's g = 0.198). Eating behaviors did not vary by condition, nor did improvements in behavioral inhibition function as a mediator (ps > 0.09). Thus, in preadolescent children, small improvements in behavioral inhibition from physical activity do not produce acute improvements in energy intake. Additional research is needed to clarify whether the duration and/or intensity of physical activity sessions would produce different results in this age group, and whether intervention approaches and corresponding mechanisms of change vary by individual factors, like age and degree of food cue responsivity. [ABSTRACT FROM AUTHOR]

Altering the longitudinal bending stiffness of footwear has the potential to affect mechanics of the metatarsophalangeal (MTP) joint. Recent efforts have been put forth to identify an optimal bending stiffness of footwear to improve running performance. However, little is known about how this optimal bending stiffness may change with running speed. The purpose of this study was to investigate how dynamic angular stiffness about the MTP joint changes across running speeds. Eighteen participants ran at five speeds from 3.89 to 6.11 m/s. Metatarsophalangeal joint angles, moments, and stiffness were estimated for each speed. Two MTPJ load-displacement metrics were defined, active and critical stiffness. Instantaneous stiffness of the MTP joint was also quantified. There was a significant main effect of speed on critical stiffness (p < .001), maximum MTP moment (p < .001), MTP moment at maximum dorsiflexion (p < .001), and MTP range of motion (p = .013). There was no effect of speed on active stiffness (p = .094). These results support the notion that involvement of the MTP joint increases with running speed. Individual contributions of the foot and shoe to the MTP joint moment and stiffness suggest that the foot appears to dominate the stiffness of the foot-shoe complex and torque generation about the MTP joint. Instantaneous stiffness fluctuated throughout stance phase, suggesting that foot-shoe complex stiffness is time dependent. The ratio by which critical stiffness and MTP joint range of motion increase with running speed may provide insight for how to guide construction of performance footwear. These results suggest that when utilizing MTP joint mechanics for insights into designing a shoe for performance purposes, the effect of speed should be taken into consideration. [ABSTRACT FROM AUTHOR]

Objective: To identify vaginal morphology and position factors associated with prolapse recurrence following vaginal surgery. Design: Secondary analysis of magnetic resonance images (MRI) of the Defining Mechanisms of Anterior Vaginal Wall Descent cross‐sectional study. Setting: Eight clinical sites in the US Pelvic Floor Disorders Network. Population or Sample: Women who underwent vaginal mesh hysteropexy (hysteropexy) with sacrospinous fixation or vaginal hysterectomy with uterosacral ligament suspension (hysterectomy) for uterovaginal prolapse between April 2013 and February 2015. Methods: The MRI (rest, strain) obtained 30–42 months after surgery, or earlier for participants with recurrence who desired reoperation before 30 months, were analysed. MRI‐based prolapse recurrence was defined as prolapse beyond the hymen at strain on MRI. Vaginal segmentations (at rest) were used to create three‐dimensional models placed in a morphometry algorithm to quantify and compare vaginal morphology (angulation, dimensions) and position. Main outcome measures: Vaginal angulation (upper, lower and upper–lower vaginal angles in the sagittal and coronal plane), dimensions (length, maximum transverse width, surface area, volume) and position (apex, mid‐vagina) at rest. Results: Of the 82 women analysed, 12/41 (29%) in the hysteropexy group and 22/41 (54%) in the hysterectomy group had prolapse recurrence. After hysteropexy, women with recurrence had a more laterally deviated upper vagina (p = 0.02) at rest than women with successful surgery. After hysterectomy, women with recurrence had a more inferiorly (lower) positioned vaginal apex (p = 0.01) and mid‐vagina (p = 0.01) at rest than women with successful surgery. Conclusions: Vaginal angulation and position were associated with prolapse recurrence and suggestive of vaginal support mechanisms related to surgical technique and potential unaddressed anatomical defects. Future prospective studies in women before and after prolapse surgery may distinguish these two factors. [ABSTRACT FROM AUTHOR]

The characterization of molecular processes as they occur inside cells is essential to a comprehensive understanding of living organisms. Although several genetic and chemical approaches have been employed successfully to undertake such a challenge, there is still a need for the development of new methodologies. The article authors have reasoned that if protein photocaging and fluorescence labeling were combined, one might achieve these desirable features. Their approach consists of modifying a fluorescently labeled protein with a photocleavable group that can both suppress the protein activity and quench its fluorescence.

In a phase III randomized trial, adding a radiation boost to tumor(s) visible on MRI improved prostate cancer (PCa) disease-free and metastasis-free survival without additional toxicity. Radiation oncologists' ability to identify prostate tumors is critical to widely adopting intraprostatic tumor radiotherapy boost for patients. A diffusion MRI biomarker, called the Restriction Spectrum Imaging restriction score (RSIrs), has been shown to improve radiologists' identification of clinically significant PCa. We hypothesized that (1) radiation oncologists would find accurately delineating PCa tumors on conventional MRI challenging and (2) using RSIrs maps would improve radiation oncologists' accuracy for PCa tumor delineation. In this multi-institutional, international, prospective study, 44 radiation oncologists (participants) and 2 expert radiologists (experts) contoured prostate tumors on 39 total patient cases using conventional MRI with or without RSIrs maps. Participant volumes were compared to the consensus expert volumes. Contouring accuracy metrics included percent overlap with expert volume, Dice coefficient, conformal number, and maximum distance beyond expert volume. 1604 participant volumes were produced. 40 of 44 participants (91%) completely missed ≥1 expert-defined target lesion without RSIrs, compared to 13 of 44 (30%) with RSIrs maps. On conventional MRI alone, 134 of 762 contour attempts (18%) completely missed the target, compared to 18 of 842 (2%) with RSIrs maps. Use of RSIrs maps improved all contour accuracy metrics by approximately 50% or more. Mixed effects modeling confirmed that RSIrs maps were the main variable driving improvement in all metrics. System Usability Scores indicated RSIrs maps significantly improved the contouring experience (72 vs. 58, p < 0.001). Radiation oncologists struggle with accurately delineating visible PCa tumors on conventional MRI. RSIrs maps improve radiation oncologists' ability to target MRI-visible tumors for prostate tumor boost. [ABSTRACT FROM AUTHOR]

Many studies have reported the effects of different foot prostheses on gait, but most results cannot be generalized because the prostheses' properties are seldom reported. We varied hindfoot and forefoot stiffness in an experimental foot prosthesis, in increments of 15N/mm, and tested the parametric effects of these variations on treadmill walking in unilateral transtibial amputees, at speeds from 0.7 to 1.5m/s. We computed outcomes such as prosthesis energy return, center of mass (COM) mechanics, ground reaction forces, and joint mechanics, and computed their sensitivity to component stiffness. A stiffer hindfoot led to reduced prosthesis energy return, increased ground reaction force (GRF) loading rate, and greater stance-phase knee flexion and knee extensor moment. A stiffer forefoot resulted in reduced prosthetic-side ankle push-off and COM push-off work, and increased knee extension and knee flexor moment in late stance. The sensitivity parameters obtained from these tests may be useful in clinical prescription and further research into compensatory mechanisms of joint function. [ABSTRACT FROM AUTHOR]

Electromyogram (EMG) signal representation is crucial in classification applications specific to locomotion and transitions. For a given signal, classification can be performed using discriminant functions or if-else rule sets, using learning algorithms derived from training examples. In the present work, a spectrogram based approach was developed to classify (EMG) signals for locomotion mode. Spectrograms for each muscle were calculated and summed to develop a histogram. If-else rules were used to classify test data based on a matching score. Prior knowledge of locomotion type reduced class space to exclusive locomotion modes. The EMG data were collected from seven leg muscles in a sample of able-bodied subjects while walking over ground (W), ascending stairs (SA) and the transition between (W-SA). Three muscles with least discriminating power were removed from the original data set to examine the effect on classification accuracy. Initial classification error was <20% across all modes, using leave one out cross validation. Use of prior knowledge reduced the average classification error to <11%. Removing three EMG channels decreased the classification accuracy by 10.8%, 24.3%, and 8.1% for W, W-SA, and SA respectively, and reduced computation time by 42.8%. This approach may be useful in the control of multi-mode assistive devices. [ABSTRACT FROM AUTHOR]

Simple Summary: Women at high risk for breast cancer are regularly screened using contrast-enhanced magnetic resonance imaging (MRI) to identify potential malignancy. Diffusion-weighted MRI (DW-MRI) is a non-contrast technique that measures the differential movement of water molecules in tissues and is sensitive to cancer cells. In this study, we use a multi-exponential advanced DW-MRI model called restriction spectrum imaging (RSI) to characterize the diffusion characteristics of malignant lesions, benign lesions, and healthy breast tissue to help differentiate benign from malignant disease. In a cohort of patients, we show that cancer exhibits more restricted diffusion compared to benign breast lesions and healthy tissue, whereas benign and healthy tissue are not different from each other. Diffusion-weighted MRI (DW-MRI) offers a potential adjunct to dynamic contrast-enhanced MRI to discriminate benign from malignant breast lesions by yielding quantitative information about tissue microstructure. Multi-component modeling of the DW-MRI signal over an extended b-value range (up to 3000 s/mm2) theoretically isolates the slowly diffusing (restricted) water component in tissues. Previously, a three-component restriction spectrum imaging (RSI) model demonstrated the ability to distinguish malignant lesions from healthy breast tissue. We further evaluated the utility of this three-component model to differentiate malignant from benign lesions and healthy tissue in 12 patients with known malignancy and synchronous pathology-proven benign lesions. The signal contributions from three distinct diffusion compartments were measured to generate parametric maps corresponding to diffusivity on a voxel-wise basis. The three-component model discriminated malignant from benign and healthy tissue, particularly using the restricted diffusion C1 compartment and product of the restricted and intermediate diffusion compartments (C1 and C2). However, benign lesions and healthy tissue did not significantly differ in diffusion characteristics. Quantitative discrimination of these three tissue types (malignant, benign, and healthy) in non-pre-defined lesions may enhance the clinical utility of DW-MRI in reducing excessive biopsies and aiding in surveillance and surgical evaluation without repeated exposure to gadolinium contrast. [ABSTRACT FROM AUTHOR]

Myoelectric control algorithms have the potential to detect an amputee's motion intent and allow the prosthetic to adapt to changes in walking mode. The development of a myoelectric walking mode classifier for transtibial amputees is outlined. Myoelectric signals from four muscles (tibialis anterior, medial gastrocnemius (MG), vastus lateralis, and biceps femoris) were recorded for five nonamputee subjects and five transtibial amputees over a variety of walking modes: level ground at three speeds, ramp ascent/descent, and stair ascent/descent. These signals were decomposed into relevant features (mean absolute value, variance, wavelength, number of slope sign changes, number of zero crossings) over three subwindows from the gait cycle and used to test the ability of classification algorithms for transtibial amputees using linear discriminant analysis (LDA) and support vector machine (SVM) classifiers. Detection of all seven walking modes had an accuracy of 97.9% for the amputee group and 94.7% for the nonamputee group. Misclassifications occurred most frequently between different walking speeds due to the similar nature of the gait pattern. Stair ascent/descent had the best classification accuracy with 99.8% for the amputee group and 100.0% for the nonamputee group. Stability of the developed classifier was explored using an electrode shift disturbance for each muscle. Shifting the electrode placement of the MG had the most pronounced effect on the classification accuracy for both samples. No increase in classification accuracy was observed when using SVM compared to LDA for the current dataset. [ABSTRACT FROM PUBLISHER]

Lower limb amputee gait during stance phase is related to the angular stiffness of the prosthetic foot, which describes the dependence of ankle torque on angular progression of the shank. However, there is little data on angular stiffness of prosthetic feet, and no method to directly measure it has been described. The objective of this study was to derive and evaluate a method to estimate the angular stiffness of prosthetic feet using a simple linear compression test. Linear vertical compression tests were performed on nine configurations of an experimental multicomponent foot (with known component stiffness properties and geometry), which allowed for parametric adjustment of hindfoot and forefoot stiffness properties and geometries. Each configuration was loaded under displacement control at distinct pylon test angles. Angular stiffness was calculated as a function of the pylon angle, normal force, and center of pressure (COP) rate of change with respect to linear displacement. Population root mean square error (RMSE) between the measured and predicted angular stiffness values for each configuration of the multicomponent foot was calculated to be 4.1 N-mldeg, dominated by a bias of the estimated values above the predicted values of 3.8 ±1.6 N-mldeg. The best-fit line to estimated values was approximately parallel to the prediction, with R2 = 0.95. This method should be accessible for a variety of laboratories to estimate angular stiffness of experimen¬tal and commercially available prosthetic feet with minimal equipment. [ABSTRACT FROM AUTHOR]

The cognitive demand required for a range of locomotor tasks has been described for a variety of populations. However, the effect of different training strategies on the cognitive demand required while learning novel locomotor tasks is not well understood and may inform physical rehabilitation. The authors examined whether two training strategies, gradual and sudden training, influenced the cognitive demand required while practicing a novel locomotor task, asymmetric split-belt treadmill walking. Simple reaction times and whole-body kinematics were recorded throughout practice. Gradual training resulted in significantly lower reaction times during much of training, suggesting that gradual training is less cognitively demanding than sudden training, possibly due to a reduction in error feedback or movement planning demands. [ABSTRACT FROM PUBLISHER]