Swing Phase Of Walking Research Articles

Gait analysis among patients with quadriceps weakness after anterior cruciate ligament reconstruction post 9 months

Background: One of the most frequent musculoskeletal injuries in young adults is anterior cruciate ligament (ACL) damage. Following ACL reconstruction, there have been reports of changes in the lower extremity joints' kinematics and kinetics, including decreased knee ROM during the stance and swing phases of walking and weakened knee joint flexor and extensor muscles. Objective: To analyze the gait parameter among patients with Quadriceps weakness after Anterior Cruciate Ligament Reconstruction (ACLR) post 9 months. Methods: A descriptive cross-sectional study was carried out on 143 soccer players with age range of 18-39 years, who had unilateral ACL rupture managed through arthroscopic-assisted ACLR Endo-button procedure post 9 months. Written informed consent from the participants was taken before data collection. Observational gait analysis (OGA) with 66 check-off option is used to identify the gait deviations among the patients. Results: In ankle during the weight acceptance phase, inadequate dorsiflexion (36.4%) and plantar flexion (23.8%) were reported; during single limb support, early heel off was (4.2%) and inadequate dorsiflexion (44.1%) and during single limb advancement, toe drag was (18.2%) and inadequate dorsiflexion (65%). In knee during the weight acceptance phase, inadequate extension (59.4%) and flexion (16.1%) were reported; during single limb support. Conclusion: OGA revealed gait deviations as inadequate dorsiflexion, inadequate extension, and inadequate flexion due to eccentric loss of quadriceps widely after ACL reconstruction post 9 months.

Intramuscular coherence enables robust assessment of modulated supra-spinal input in human gait: an inter-dependence study of visual task and walking speed

Intramuscular high-frequency coherence is increased during visually guided treadmill walking as a consequence of increased supra-spinal input. The influence of walking speed on intramuscular coherence and its inter-trial reproducibility need to be established before adoption as a functional gait assessment tool in clinical settings. Here, fifteen healthy controls performed a normal and a target walking task on a treadmill at various speeds (0.3 m/s, 0.5 m/s, 0.9 m/s, and preferred) during two sessions. Intramuscular coherence was calculated between two surface EMG recordings sites of the Tibialis anterior muscle during the swing phase of walking. The results were averaged across low-frequency (5–14 Hz) and high-frequency (15–55 Hz) bands. The effect of speed, task, and time on mean coherence was assessed using three-way repeated measures ANOVA. Reliability and agreement were calculated with the intra-class correlation coefficient and Bland–Altman method, respectively. Intramuscular coherence during target walking was significantly higher than during normal walking across all walking speeds in the high-frequency band as obtained by the three-way repeated measures ANOVA. Interaction effects between task and speed were found for the low- and high-frequency bands, suggesting that task-dependent differences increase at higher walking speeds. Reliability of intramuscular coherence was moderate to excellent for most normal and target walking tasks in all frequency bands. This study confirms previous reports of increased intramuscular coherence during target walking, while providing first evidence for reproducibility and robustness of this measure as a requirement to investigate supra-spinal input.Trial registration Registry number/ClinicalTrials.gov Identifier: NCT03343132, date of registration 2017/11/17.

Assessment of Dorsiflexion Ability across Tasks in Persons with Subacute SCI after Combined Locomotor Training and Transcutaneous Spinal Stimulation.

In people with spinal cord injury (SCI), transcutaneous spinal stimulation (TSS) has an immediate effect on the ability to dorsiflex the ankle, but persistent effects are not known. Furthermore, TSS has been associated with improved walking, increased volitional muscle activation, and decreased spasticity when combined with locomotor training (LT). In this study, the persistent impact of combined LT and TSS on dorsiflexion during the swing phase of walking and a volitional task in participants with SCI is determined. Ten participants with subacute motor-incomplete SCI received 2 weeks of LT alone (wash-in phase), followed by 2 weeks of either LT + TSS (TSS at 50 Hz) or LT + TSSSham (intervention phase). There was no persistent effect of TSS on dorsiflexion during walking and inconsistent effects on the volitional task. There was a strong positive correlation between the dorsiflexor ability for both tasks. There was a moderate effect of 4 weeks of LT on increased dorsiflexion during the task (d = 0.33) and walking (d = 0.34) and a small effect on spasticity (d = -0.2). Combined LT + TSS did not show persistent effects on dorsiflexion ability in people with SCI. Four weeks of locomotor training was associated with increased dorsiflexion across tasks. Improvements in walking observed with TSS may be due to factors other than improved ankle dorsiflexion.

Contribution of Different Impairments to Restricted Knee Flexion during Gait in Individuals with Cerebral Palsy.

The coexistence of overlapping impairments modulates the knee pattern in the swing phase of walking in children with cerebral palsy (CP). The impact and contribution of each impairment to the reduction of knee range-of-motion is unknown. The aim of the study was to establish the gradation of the impact of individual coexisting impairments on the knee flexion range-of-motion. Passive range-of-motion, selective motor control, strength, and spasticity from 132 patients (Male = 76, Female = 56, age:11 ± 4 years) with spastic CP were tested with clinical tools. Knee flexion range-of-motion at terminal stance, pre-swing, and initial swing phases were assessed by gait analysis. Hypertonia (β = −5.75) and weakness (β = 2.76) of knee extensors were associated with lower range of knee flexion (R2 = 0.0801, F = 11.0963, p < 0.0001). The predictive factors (R2 = 0.0744, F = 7.2135, p < 0.0001) were strength (β = 4.04) and spasticity (β = −2.74) of knee extensors and strength of hip flexors (β = −2.01); in swing those were knee extensors hypertonia (β = −2.55) and passive range of flexion (β = 0.16) (R2 = 0.0398, F = 3.4010, p = 0.01). Hypertonia of knee extensors has the strongest impact on knee flexion range-of-motion; secondary is the strength of knee extensors. The knee extensors strength with knee extensors hypertonia and strength of hip flexors contributes in stance. Knee extensors hypertonia with passive knee flexion range-of-motion contributes in swing.

Effect of External Damping on Ankle Motion During the Swing Phase of Walking

Manipulation of human ankle dynamics during walking is essential for a smooth gait cycle. Ankle exoskeletons have generally proven positive for rehabilitation and restoration purposes. With the focus on prolonged use of such exoskeletons, there is a need to study the effect of exoskeletons’ residual dynamics on gait adaptation. Understanding such inadvertent interaction can help future intervention paradigm decisions and exoskeleton design. The current work investigates the effect of residual damping on the ankle joint during the swing phase of walking, typically the non-targeted phase of a rehabilitation paradigm. A gait adaptation study was conducted using a cable-driven ankle exoskeleton that applied external damping, both positive and negative, on nine healthy individuals. The interventions resulted in varied perturbed ankle kinematics during the swing phase showing significant reduction and amplification of ankle motion due to the applied positive and negative damping, respectively. The current study demonstrates that healthy individuals can alter their ankle impedance during the swing phase of walking without limiting the overall gait performance.

Development and deployment of cyclical focal muscle vibration system to improve walking performance in multiple sclerosis

Vibration, a potent mechanical stimulus for activating muscle spindle primary afferents, may improve gait performance in persons with multiple sclerosis (MS), but has yet to be developed and deployed for multiple leg muscles with application during walking training. This study explored the development of a cyclic focal muscle vibration (FMV) system, and the deployment feasibility to correct MS walking swing phase deficits in order to determine whether this intervention warrants comprehensive study. The system was deployed during twelve, two-hour sessions of walking with cyclic FMV over six weeks. Participants served as their own control. Blood pressure, heart rate, walking speed, kinematics (peak hip, knee and ankle angles during swing), toe clearance, and step length were measured before and after deployment with blood pressure and heart rate monitored during deployment. During system deployment, there were no untoward sensations and physiological changes in blood pressure and heart rate, and volitional improvements were found in walking speed, improved swing phase kinematics, toe clearance and step length. This FMV training system was developed and deployed to improve joint flexion during walking in those with MS, and it demonstrated feasibility and benefits. Further study will determine the most effective vibration frequency and dose, carryover effects, and those most likely to benefit from this intervention.

Design of a control framework for lower limb exoskeleton rehabilitation robot based on predictive assessment

BackgroundPatients suffering from lower limb dyskinesia, especially in early stages of rehabilitation, have weak residual muscle strength in affected limb and require passive training by the lower limb rehabilitation robot. Anatomy indicates that the biceps femoris short head muscle has a strong influence on knee motion at the swing phase of walking. We sought to explore how it would influence on gait cycle in optimization framework. However, the training trajectory of conventional rehabilitation robots performing passive training usually follows gait planning based on general human gait data, which cannot simultaneously ensure both effective rehabilitation of affected limbs with varying severity pathological gait and comfort of the wearer within a safe motion trajectory. MethodsTo elucidate the effects of weakness and contracture, we systematically introduced isolated defects into the musculoskeletal model and generated walking simulations to predict the gait adaptation due to these defects. An impedance control model of the rehabilitation robot is developed. Knee joint parameters optimized by predictive forward dynamics simulation are adopted as the expected values for the robot controller to achieve customized adjustment of the robot motion trajectory. FindingsSevere muscle contracture leads to severe knee flexion; severe muscle weakness induces a significant posterior tilt of the upper trunk, which hinders walking speed. InterpretationOur simulation results attempt to reveal pathological gait features, which may help to reproduce the simulation of pathological gait. Furthermore, the robot simulation results show that the robot system achieves a speedy tracking by setting a larger stiffness value. The model also allows the implementation of different levels of damping or elasticity effects.Trial registration: The method proposed in this paper is an initial basic study that did not reach clinical trials and therefore retains retrospectively registered.

Effect of Knee Brace on the Electric Activity of Selected Lower Limb Muscles during Walking in Older Adults

Background and Aims One of the treatment methods in the old age is to strengthen the sensory inputs. This study aims to evaluate the effect of knee brace on the electric activity of selected lower limb muscles during walking in older adults. Methods The is a quasi-experimental and laboratory study. Participants were 30 older adults, 15 females (Mean age=62.66±3.84 years, mean height= 159.93±0.02 cm, mean weight= 73.86±11.56 kg, body mass index=28.82±4.17 kg/m2) and 15 males (Mean age= 68.93±5.88 years, mean height=175.07±0.03 cm, mean weight= 81.20±11.07 kg, body mass index= 26.44±3.19 kg/m2). The intervention was the use of a type of brace by restricting knee flexion and extension movements or knee support. Electromyography (EMG) data were analyzed in DataLITE and MATLAB applications using two-way ANOVA with repeated measures, and considering the significance level at P&lt;0.05. Results The effects of braces on the electric activity of tibialis anterior, semitendinosus and erector spinae muscles were significantly different in the loading response, mid-stance, push-off and swing phases of walking. The effect of group on the electric activity of anterior tibialis and biceps femoris muscles in the loading response phase and for gastrocnemius medialis and biceps femoris muscles in the push-off and swing phases were significantly different. The interaction effect of group and brace was significant on the electric activity of the gastrocnemius and vastus medialis muscles in the push-off phase, and on the electric activity of the vastus lateralis and semitendinosus muscles in the swing phase. Conclusion The knee brace improves the electric activity of selected muscles during walking in older adults. However, further studies are needed to prove this claim.

Identification of Hip and Knee Joint Impedance During the Swing Phase of Walking.

Knowledge on joint impedance during walking in various conditions is relevant for clinical decision-making and the development of robotic gait trainers, leg prostheses, leg orthotics and wearable exoskeletons. Whereas ankle impedance during walking has been experimentally assessed, knee and hip joint impedance during walking have not been identified yet. Here we developed and evaluated a lower limb perturbator to identify hip, knee and ankle joint impedance during treadmill walking. The lower limb perturbator (LOPER) consists of an actuator connected to the thigh via rods. The LOPER allows to apply force perturbations to a free-hanging leg, while standing on the contralateral leg, with a bandwidth of up to 39 Hz. While walking in minimal impedance mode, the interaction forces between LOPER and the thigh were low (<5N) and the effect on the walking pattern was smaller than the within-subject variability during normal walking. Using a non-linear multibody dynamical model of swing leg dynamics, the hip, knee and ankle joint impedance were estimated at three time points during the swing phase for nine subjects walking at a speed of 0.5 m/s. The identified model was well able to predict the experimental responses for the hip and knee, since the mean variance accounted (VAF) for was 99% and 96%, respectively. The ankle lacked a consistent response and the mean VAF of the model fit was only 77%, and therefore the estimated ankle impedance was not reliable. The averaged across-subjects stiffness varied between the three time points within 34-66 and 0-3.5 Nm/rad Nm/rad for the hip and knee joint respectively. The damping varied between 1.9-4.6 and 0.02-0.14 Nms/rad Nms/rad for hip and knee respectively. The developed LOPER has a negligible effect on the unperturbed walking pattern and allows to identify hip and knee impedance during the swing phase.

Switched Adaptive Concurrent Learning Control using a Stance Foot Model for Gait Rehabilitation using a Hybrid Exoskeleton

Lower-limb hybrid exoskeletons integrate powered mechanisms and functional electrical stimulation (FES) to provide assistive forces and activate muscles for restoring gait function after a neurological injury. Particularly, improving the load-bearing ability is a primary rehabilitation goal. Hence, the control of the exoskeleton and FES is critical within the stance phase of walking to ensure smooth weight transfer between limbs, and achieve a sound loading response and leg propulsion. This paper develops a concurrent learning adaptive control technique to provide torque assistance about the hip and knee joints using a cable-driven exoskeleton, and activate the quadriceps and hamstrings muscle groups via FES for treadmill walking. The human-exoskeleton dynamics are modeled with phase-dependent switching dynamics to strategically update the concurrent learning controller at early stance (heel strike), late stance (toe-off), and the swing phases of walking. Thus, the adaptive switching controller compensates for the dynamic changes within the stance phase and its transition to swing, while achieving joint kinematic tracking and estimating a subset of the leg's uncertain parameters. A multiple Lyapunov function analysis is developed to demonstrate stability of the overall phase-dependent switched system requiring a dwell-time condition that guarantees exponential tracking and parameter estimation convergence.

Muscle co-contractions are greater in older adults during walking at self-selected speeds over uneven compared to even surfaces

Falls in the aging population are a major public health concern. Outdoor falls in community-dwelling older adults are often triggered by uneven pedestrian walkways. Our understanding of the motor control adaptations to walk over an uneven surface, and the effects of aging on these adaptations is sparse. Here, we study changes in muscle co-contraction, a clinically accepted measure of motor control, due to changes in walking surfaces typically encountered in the outdoor built environment. We address the following research questions: 1) are there walking surface and sex-based differences in muscle co-contractions between young and older adults? and 2) is muscle co-contraction associated with age? We calculated muscle co-contractions from 13 young and 17 older adults during walking at self-selected speeds over even and uneven brick walkways. Muscle co-contraction at the ankle joint was determined from the tibialis anterior and lateral gastrocnemius muscle pair, and at the knee joint from the rectus femoris and semitendinosus muscle pair. Older adults displayed 8–13% greater ankle muscle co-contractions during walking over uneven compared to even surfaces. We found 55–61% (entire gait) and 73–75% (stance phase) greater ankle muscle co-contractions in older females compared to older males during walking over even and uneven surfaces. We found 31–43% greater knee muscle co-contractions in older females compared to older males during the swing phase of walking over even and uneven surfaces. This study underscores the need for determining muscle co-contractions from even and uneven surfaces for quantifying motor control deficits due to aging or neuromuscular disorders.

The Effects of Polycentric Knee Design and Alignment on Swing Phase Gait Parameters: A Simulation Approach

ABSTRACT Introduction Typically, polycentric prosthetic knees have been designed with a focus on improved performance during stance. This study analyzes the influence of geometric aspects such as linkage dimensions of the polycentric knees and anterior-posterior (A/P) alignment on the swing phase of walking. Such a study would enable the development of polycentric knees with improved performance during both stance and swing phases. Methods A simulation-based approach was used to analyze the influence of geometric aspects on swing dynamics. A newly developed four-bar knee called IITM polycentric knee (IPK) was used as a baseline prosthesis. First, the swing was simulated with the baseline prosthesis. The IPK in the lower limb was then replaced with the linkage dimensions of four other commercial polycentric knees (Ottobock's 3R36, 3R55, and 3R70 and Ohio Willow Wood's Pendulum knee) for the simulation of swing phase. Effect of A/P alignment was analyzed by translating the socket adapter of the IPK along the A/P axis in the baseline prosthesis, which has the effect of moving the knee and foot in the opposite direction. A maximum of 20 mm translation of the socket adapter was applied on either side of its base location in the lower-limb model. The gait parameters from the simulations and the centrode of different polycentric knees were then analyzed to understand how linkage dimensions and A/P translations of the knee and foot affect the swing dynamics. Results All four-bar knees without extension assists extended to less than 6° before heel contact, which is significantly lower than the 24° obtained for a single-axis knee in a previous study. The swing performances of the different four-bar knees studied here were found to depend on their centrode. The instant centers (ICs) of the 3R55 and IPK, which were comparatively located more superior to the anatomical knee center during swing, enabled better knee extension and foot clearance than other knees. A/P translation of the knee and foot significantly affected the foot clearance. A 20 mm anterior translation increased toe and heel clearance by 1.6 cm and 1.4 cm, respectively, when compared with a 20 mm posterior translation. Conclusions This study shows that polycentric knees, which generally perform better than single-axis knees with improved stance stability and ease of push-off, can also perform well during swing in terms of knee extension before heel contact and foot clearance throughout swing. The extended moment arm for the weight of the shank and foot due to the superior location of the IC in polycentric knees is the reason for the improved swing performance of polycentric knees. Appropriate placement of the socket adapter, which affects A/P alignment, is crucial so that foot clearance during swing is not compromised. The insights obtained from the study would be useful in developing simpler polycentric knees, which can extend completely without any extension assist if proper alignment is used as recommended. Clinical Relevance The study provides better understanding of the effects of polycentric knee placement and the need for an extension assist during the swing phase of walking, which could help clinicians improve the selection of appropriate knees and their alignment for prosthesis users.

Locomotion with a twist: Aquatic beetle walks upside down on the underside of the water's surface

AbstractWhile animals generally move through the aquatic environment by propelling themselves through the water or walking on submerged substrates, some have evolved the unique capacity to move along the water–air interface. This is because cohesive forces between water molecules cause the surface to be in tension, providing a physical substrate that can be used for support and pushed against for horizontal movement. Herein, we report on the use of the underside of the water's surface for locomotion in an unidentified Australian beetle (likely family: Hydrophilidae). Field observations revealed that the beetle was able to rest and move along the surface of an ephemeral pool inverted without penetrating the surface above. The beetle possessed a layer of trapped air along its abdomen and moved forward by walking, with deformations of the water's surface apparent each time a leg made contact. This appears to be the first visual evidence illustrating the ability of aquatic beetles to directly rest and walk on the underside of the water's surface. We propose that the air bubbles located on the abdomen and/or legs may be providing the upward force necessary for the beetle to be pushed against the underside of the water's surface. The water's surface seems to be acting as a support for the beetle, with the force needed for forward movement generated by the beetle's legs as each transition between the stance and swing phases of walking. Our work adds to the small number of observations of animals using the underside of the water's surface to move and highlights the likely importance of surface tension for locomotion on either side of the water–air interface.

The size and echogenicity of the tibialis anterior muscle is preserved in both limbs in young children with unilateral spastic cerebral palsy

Purpose The primary of this study was to compare the volume, length, echo intensity, and growth rate of the medial gastrocnemius (MG) and tibialis anterior (TA) muscle of both limbs (more-involved and less-involved) in children with unilateral spastic cerebral palsy (USCP), with those of an age-matched typically developing (TD) group. A secondary aim in the USCP group was to explore the associations between these muscle parameters and discrete ankle positions during phase of gait. Methods Muscle parameters were assessed using 3D ultrasound. Maximal ankle dorsiflexion in stance and swing during walking were determined from 2D video analysis. Group differences in muscle size and echo intensity were assessed using a two-way analysis of covariance (age-by-group), with the interaction term used to compare muscle growth rates. Associations between muscle parameters and maximal ankle dorsiflexion in stance and swing were assessed using backwards multiple linear regression analyses. Results The MG of both limbs in children with USCP had signs of impaired muscle development (smaller volume and length, higher echo intensity and lower growth rate). There was no evidence of impaired muscle development of TA between limbs or compared the TD children. Tibialis anterior volume, length, echo intensity and MG volume explained 66% and 83% of the variance in maximal ankle dorsiflexion position in the stance and swing phases of walking, respectively. Conclusions Unlike the MG, the TA volume and growth rate in children with USCP are equivalent between limbs and compared to TD children. For the more-involved limb only, TA volume, length, and echo intensity appear associated with maximal ankle dorsiflexion during walking and represent important muscle parameters that could be targeted in with early exercise therapy. Implications for rehabilitation Tibialis anterior (TA) size and echogenicity appear normal in both limbs in young children with unilateral spastic cerebral palsy (USCP); findings that could indicate sufficient mechanical stimulus and muscle anabolism to maintain normal muscle growth. Tibialis anterior size and echogenicity are associated with maximal ankle dorsiflexion in both stance and swing phase of walking in young children with USCP; though such relations appear isolated to the more-involved limb. Early therapeutic interventions that target TA are likely to be successful in maintaining muscle size and may offset the negative effects of medial gastrocnemius atrophy in the development of fixed ankle equinus of the more-involved limb and improve ankle positioning during gait.

Comparison of the Lumbosacral Manipulation Method Versus Knee Exercises Alone in Patients with Patellofemoral Pain Syndrome

Background: Patellofemoral Pain Syndrome (PFPS) is one of the most common diagnoses made for patients referred to physical/rehabilitation and orthopedic clinics. The most common symptom of PFPS is a diffuse pain in front of either one or both knees exacerbated by intense activity, kneeling, squatting, climbing, and weakness of quadriceps muscle. Lumbosacral manipulation and knee exercises are the most commonly used methods in physical medicine with no major side effects. Objectives: The current study aimed to compare the efficacy of the lumbosacral manipulation technique with knee exercises versus sole knee exercises in patients with PFPS. Study Design was Randomized Controlled Clinical Trial. Methods: In this randomized controlled clinical trial, 30 patients (18 females and 12 males) diagnosed with PFPS were divided into two groups of study and control, each with 15 subjects. Those in the intervention group received a single bilateral lumbosacral manipulation after ruling out any contraindication for lumbosacral manipulation by lumbosacral radiography. Quality of life, gait, quadriceps muscle strength, keen pain improvement, and range of motion were evaluated at the beginning and four weeks following the knee strengthening exercises for all participants. Results: The mean age of participants was 34 ± 5 years. The difference between the groups concerning the swing phase of walking and quadriceps muscle strength was in both groups was investigated following providing interventions. Conclusions: The manipulation technique had a greater effect on improving the function of patients with PFPS compared to therapeutic knee exercises.

A Clustering-Based Approach to Identify Joint Impedance During Walking.

Mechanical impedance, which changes with posture and muscle activations, characterizes how the central nervous system regulates the interaction with the environment. Traditional approaches to impedance estimation, based on averaging of movement kinetics, requires a large number of trials and may introduce bias to the estimation due to the high variability in a repeated or periodic movement. Here, we introduce a data-driven modeling technique to estimate joint impedance considering the large gait variability. The proposed method can be used to estimate impedance in both the stance and swing phases of walking. A 2-pass clustering approach is used to extract groups of unperturbed gait data and estimate candidate baselines. Then patterns of perturbed data are matched with the most similar unperturbed baseline. The kinematic and torque deviations from the baselines are regressed locally to compute joint impedance at different gait phases. Simulations using the trajectory data of a subject's gait at different speeds demonstrate a more accurate estimation of ankle stiffness and damping with the proposed clustering-based method when compared with two methods: i) using average unperturbed baselines, and ii) matching shifted and scaled average unperturbed velocity baselines. Furthermore, the proposed method requires fewer trials than methods based on average unperturbed baselines. The experimental results on human hip impedance estimation show the feasibility of clustering-based technique and verifies that it reduces the estimation variability.

Effects of mechanical perturbation gait training on gait and balance function in patients with stroke: A pre-post research study

Patients with stroke (PwS) demonstrate impaired gait and balance, and asymmetric gait, placing them at high risk of falls. We aimed to investigate the effects of a single training session that included mechanical external perturbation which resists forward movement of the paretic leg during its swing phase of walking on gait and balance in PwS. In a pre-post pilot study, gait asymmetry and balance function were assessed in 22 first-event chronic PwS (i.e., unilateral hemiparesis). PwS underwent tests during baseline and one week later, after participating in a single training session that resisted forward stepping during the swing phase of walking with a device secured around the patient's waist and connected diagonally to the patient’s foot by a tension cord. Ground reaction forces and center of pressure were sampled during treadmill gait to assess step length asymmetry. Performance-oriented mobility assessment (POMA), a two-minute walk test (2MWT), and the voluntary step execution test were also measured. We found no significant improvement in step length asymmetry. However, POMA scores, as well as voluntary step execution tests improved with a moderate effect size. It seems that applying diagonal resistance force to the swinging leg resulted in insufficient horizontal force. However, the improvement in the preparation phase, i.e., better weight-bearing abilities during the voluntary stepping, may be due to the compression force applied to the lower limb joints thus providing proprioceptive training. This suggests that proprioceptive training may improve gait performance in stroke patients in a very short training period.

Kinematic Design and Evaluation of a Six-Bar Knee-Ankle-Foot Orthosis

Abstract This paper presents a new two-step design procedure and preliminary kinematic evaluation of a novel, passive, six-bar knee-ankle-foot orthosis (KAFO). The kinematic design and preliminary kinematic gait analysis of the KAFO are based on motion capture data from a single healthy male subject. Preliminary kinematic evaluation shows that the designed passive KAFO is capable of supporting flexion and extension of the knee joint during stance and swing phases of walking. The two-step design procedure for the KAFO consists of (1) computational synthesis based on user's motion data and (2) performance optimization. In the computational synthesis step, first the lower leg (knee-ankle-foot) of the subject is approximated as a 2R kinematic chain and its target trajectories are specified from motion capture data. Six-bar linkages are synthesized to coordinate the angular movements of knee and ankle joints of the 2R chain at 11 accuracy points. The first step of the design procedure yields 332 six-bar KAFO design candidates. This is followed by a performance optimization step in which the KAFO design candidates are optimally modified to satisfy specified constraints on end-effector trajectory and shape. This two-step process yields an optimally designed passive six-bar KAFO that shows promising kinematic results at the knee joint of the user during walking. The preliminary prototype manufactured is cost effective, easy to operate, and suitably demonstrates the feasibility of the proposed concept.

The effect of wearing insoles with a toe-grip bar on occupational leg swelling and lower limb muscle activity: A randomized cross-over study.

ObjectiveSitting or standing for hours decreases the blood flow in the legs and results in increased pressure on the veins, leading to the development of chronic venous disease. This study aimed to investigate the effects of insoles with a toe‐grip bar on occupational leg swelling and lower limb muscle activity.MethodsThis randomized cross‐over study enrolled 12 healthy men who work in a sitting or standing position. They were randomly divided into groups A (wore shoes with insoles with a toe‐grip bar for 8 hours each) and B (wore shoes with regular insoles for 8 hours each). After 1 week, groups A and B wore shoes with regular insoles and shoes with insoles with a toe‐grip bar, respectively, for 8 hours each. Lower leg volume was measured before and after each intervention, and lower limb muscle activity was measured at the start of each intervention.ResultsOccupational leg swelling was significantly smaller in men wearing insoles with a toe‐grip bar (P < .05). Moreover, the integrated electromyogram value of the tibialis anterior muscle and medial and lateral gastrocnemius muscles during the stance phase of walking, and tibialis anterior muscle during the swing phase of walking was significantly greater in men wearing insoles with a toe‐grip bar (all P < .05).ConclusionInsoles with a toe‐grip bar contribute to increased lower limb muscle activity, attenuating occupational leg swelling.

Effect of aging on H-reflex response to fatigue.

Injury as a result of tripping is relatively common among older people. The risk of falling increases with fatigue and of importance is the ability to dorsiflex the foot through timely activation of the tibialis anterior (TA) muscle to ensure the foot clears the ground, or an obstacle, during the swing phase of walking. We, therefore, questioned whether the muscle spindle input to the motoneurons alters with ongoing fatigue in older people. We electrically stimulated the common peroneal nerve to assess the TA primary afferent efficacy using H-reflex before, immediately following and after a fatiguing maximal isometric contraction. M-response was kept unchanged throughout the experiment to ensure a similar stimulus intensity was delivered across time points. H-reflex increased significantly while the TA muscle was in a state of fatigue for the younger participants but tended to decrease with increasing age. The main contributor to the tonicity of TA muscle, i.e., excitatory synapses of spindle primary endings of motoneurons that innervate TA muscle, tend to lose their efficacy during fatigue in the older individuals but increased efficiency in the majority of the younger people. Since TA muscle is the main dorsiflexor of the foot and it needs to be active during the swing phase of stepping to prevent tripping, older individuals become more susceptible to falling when their muscles are fatigued. This finding may help improve devices/treatments to overcome the problem of tripping among older individuals.