Walking on different inclines affects gait symmetry differently in the anterior-posterior and vertical directions: implication for future sensorimotor training.

A symmetric gait pattern in humans reflects near-identical movement in bilateral limbs during walking. However, little is known about how gait symmetry changes on different inclines. This study aimed to address this knowledge gap using the central pattern generator and internal model hypotheses. Eighteen healthy young adults underwent five 2-minute walking trials (inclines of +15%, +8%, 0%, -8%, and -15%). Dependent variables included step time, step length, step width, maximum heel clearance, time to peaks of maximum heel clearance, their corresponding coefficients of variation (CV), and respective symmetry indices (SI). Significant differences were observed in SI of step length (p = .022), step length variability (p < .001), step width variability (p =.001), maximum heel clearance (p < .001), and maximum heel clearance variability (p = .049). Compared to level walking, walking at -8% and -15% inclines increased SI of step length (p = .011, p = .039 respectively) but decreased SI of maximum heel clearance (p = .025, p = .019 respectively). These observations suggested that incline walking affected gait symmetry differently, possibly due to varied internal models used in locomotion. Downhill walking improved vertical gait symmetry but reduced anterior-posterior symmetry compared to level walking. Downhill walking may be a preferable rehabilitation protocol for enhancing gait symmetry, as it activates internal model controls. Even slight downhill inclines could increase active control loading, beneficial for the elderly and those with impaired gait.

Cross-step detection using center-of-pressure based algorithm for real-time applications.

BACKGROUND: Gait event detection is crucial for assessment, evaluation and provision of biofeedback during rehabilitation of walking. Existing online gait event detection algorithms mostly rely on add-on sensors, limiting their practicality. Instrumented treadmills offer a promising alternative by utilizing the Center of Pressure (CoP) signal for real-time gait event detection. However, current methods have limitations, particularly in detecting cross-step events during perturbed walking conditions. METHODS: We present and validate a CoP-based algorithm to detect gait events and cross-steps in real-time, which combines thresholding and logic techniques. The algorithm was evaluated on CoP datasets from healthy participants (age range 21-61 years), stroke survivors (age range 20-67 years), and people with unilateral transtibial amputation (age range 28-63 years) that underwent perturbation-based balance assessments, encompassing different walking speeds. Detected gait events from a simulated real-time processing operation were compared to offline identified counterparts in order to present related temporal absolute mean errors (AME) and success rate. RESULTS: The proposed algorithm demonstrated high accuracy in detecting gait events during native gait, as well as cross-step events during perturbed walking conditions. It successfully recognized the majority of cross-steps, with a detection success rate of 94%. However, some misclassifications or missed events occurred, mainly due to the complexity of cross-step events. AME for heel strikes (HS) during native gait and cross-step events averaged at 78 ms and 64 ms respectively, while toe off (TO) AME were 126 ms and 111 ms respectively. A statistically significant difference in the algorithm's success rate score in detecting gait events during cross-step intervals was observed across various walking speeds in a sample of 12 healthy participants, while there was no significant difference among groups. CONCLUSION: The proposed algorithm represents an advancement in gait event detection on instrumented treadmills. By leveraging the CoP signal, it successfully identifies gait events and cross-steps in the simulated real-time processing operation, providing valuable insights into human locomotion. The algorithm's ability to accommodate diverse CoP patterns enhance its applicability to a wide range of individuals and gait characteristics. The algorithm's performance was consistent across different populations, suggesting its potential for diverse clinical and research settings, particularly in the domains of gait analysis and rehabilitation practices.

Exploratory study of the lateral body sway predictability as frame of reference for gait rehabilitation following a total knee arthroplasty.

AIMS: The aim of the present study was to investigate whether the predictability of fronto-parallel trunk rotations (lateral body sway) could serve as a frame of reference to monitor recovery after total knee arthroplasty (TKA). METHODS: Before surgery, 11 TKA patients were asked to perform a treadmill walking task at three different speeds. In addition, their gait abilities were scored on three standard clinical walking tests. The treadmill walking task was repeated at three different timepoints following surgery, i.e., at 3, 6 and 12 months post-TKA. The movements of the trunk were digitized with an inertial sensor to capture the amplitude and the sample entropy (SEn) of the lateral body sway that were evaluated in separate ANOVAs. RESULTS: Before surgery the TKA group showed larger body sway (P = 0.025) with smaller SEn values (P = 0.038), which both restored to levels of healthy adults in the 12 months following surgery. Systematic correlations between the SEn values and the clinical test scores were found. CONCLUSIONS: The current findings show that movement behavior of the trunk in the fronto-parallel plane was affected by knee osteoarthritis and suggest that the predictability of the lateral body sway may serve as an index of recovery after TKA.

Effect of Oleuropein on Anti-Obesity and Uncoupling Protein 1 Level in Brown Adipose Tissue in Mild Treadmill Walking Rats with Diet-Induced Obesity.

Oleuropein aglycone (OA), which is the absorbed form of oleuropein, is a major phenolic compound in extra virgin olive oil. We analyzed the anti-obesity effect of OA intake combined with mild treadmill walking (MTW, 4 m/min for 20 min/d, 5-6 d/wk, without electric shocks and slope) in rats under a high-fat diet (HF). Four-week-old male Sprague-Dawley rats (n=28) were equally divided into four groups: control (HF), 0.08% oleuropein-supplemented HF (HFO), HF with MTW (HF+W), and HFO with MTW (HFO+W) groups. After 28 d, the inguinal subcutaneous fat content and weight gain were significantly lower in the HFO+W group than in the control group. The HFO+W group also had significantly higher levels of urinary noradrenaline secretion, interscapular brown adipose tissue, uncoupling protein 1, brain transient receptor potential ankyrin subtype 1 (TRPA1), vanilloid subtype 1 (TRPV1), and brain-derived neurotrophic factor (BDNF) than the control group. Especially, the HFO+W group showed a synergistic effect on noradrenaline secretion. Therefore, OA combined with MTW may accelerate the enhancement of UCP1 and BDNF levels in rats with HF-induced obesity by increasing noradrenaline secretion after TRPA1 and TRPV1 activation.

Feasibility of performing treadmill walking test for patients with peripheral arterial occlusive disease by the advanced practice nurses.

AIM: The treadmill walking test with post-exercise pressure measurement can be used as a diagnostic test and could classify peripheral arterial disease of the lower limbs. It can also exclude the diagnosis allowing to raise the possibility of differential diagnoses. In this study, we assessed the feasibility of performing treadmill test by advanced practice nurse to assess suspected lower extremity peripheral artery disease patients. DESIGN AND METHOD: This is a longitudinal monocentric study to assess the feasibility of a treadmill walking test performed by an advanced practice nurse. The primary endpoint was the number of tests performed during this period. The secondary objectives were to evaluate the reasons for requesting the test, the main results obtained in terms of the test's contribution and diagnoses, and patients' clinical characteristics. RESULTS: From February to May 2023, amongst 31 patients who underwent the treadmill walking test, 4 tests were able to rule out peripheral arterial disease and to detect differential diagnoses. For the remaining 27 patients, 4 had stage IIa of the Leriche classification, 23 had stage IIb, 2 of which were associated with a narrow lumbar spine. In contrast to the usual report, the APN's report on the walking test included an identification of cardiovascular risk factors, as well as a possible medical reorientation linked to the correction of a detected cardiovascular risk factor. CONCLUSION: The treadmill walking test can be performed by an advanced practice nurse. He/She added a comprehensive/global patient management, with the detection of cardiovascular risk factors. This new profession led to an increase in the number of tests performed of more than 50% over the period and reduced the time to access the test.

Improving walking via real-time visual feedback after stroke in treadmill training (RE-VISIT): a protocol for randomized controlled trial / Melhorando a caminhada por meio de feedback visual em tempo real após acidente vascular cerebral em treinamento em esteira (RE-VISIT): um protocolo para ensaio clínico randomizado

BACKGROUND: After a stroke, most patients often suffer reduced walking ability and balance. Restoring walking ability and improving balance are major goals of stroke rehabilitation. Treadmills are often used in clinical setups to achieve these goals. Adding dimensions to the visual feedback in addition to the mirror for real-time frontal view is proven to enhance the gait. It is, therefore, important to design additional real-time visual feedback in treadmill training, in particular for the sagittal view involved side. OBJECTIVE: The objective of this study is to test if the real-time sagittal visual feedback during treadmill training is superior to the conventional mirror feedback treadmill training program of equivalent intensity in improving walking speed and balance after stroke. METHODS/DESIGN: The RE-VISIT trial (Real-time Visual feedback after Stroke in Treadmill training) is registered in the Clinical Trial Registry of India (CTRI/2023/10/058299). In this two-arm randomized control trial, which will be a single-blinded study, 42 eligible stroke survivors undergoing rehabilitation will be randomly allocated (1:1 ratio) to either real-time visual sagittal feedback along with front mirror (experimental) group or only front mirror treadmill training (control) group, all the participants will receive 15 sessions of treadmill training for up to 15 min at a safe self-selected speed over 5-6 weeks. The RE-VISIT (experimental) group will receive real-time, visual sagittal view feedback of the involved lower limb trajectory along with the routine front mirror view during treadmill training and will be asked to modify their gait pattern. The control group will receive treadmill walking training only with the routine front mirror view feedback. Clinical and gait assessments will be conducted at the baseline, immediately following the final session of training, and at the 9th week during follow-up. The outcome measures of interest are walking speed (primary) and balance (secondary), which will be measured prior to baseline, post 15 sessions of training, and at the 9th week following training. DISCUSSION: This REVISIT trial will provide insight and contribute to the existing innovation and modifications of incorporating realtime visual feedback during treadmill training in post-stroke gait rehabilitation. The findings will help the better designing of a gait rehabilitation program with a treadmill for post-stroke subjects to improve walking speed, and balance for those who have greater difficulties in community ambulation. We anticipate that those in the REVISIT training will demonstrate improved walking ability.

CONTEXTO: Após o acidente vascular cerebral, a maioria dos pacientes frequentemente sofre redução da capacidade de caminhar e do equilíbrio. Restaurar a capacidade de caminhar e melhorar o equilíbrio são os principais objetivos da reabilitação do AVC. As esteiras são frequentemente usadas em ambientes clínicos para atingir esses objetivos. Está comprovado que adicionar dimensões ao feedback visual, além do espelho para visão frontal em tempo real, melhora a marcha. É, portanto, importante projetar feedbacks visuais adicionais em tempo real no treinamento em esteira, em particular para o lado envolvido na visão sagital. OBJETIVO: O objetivo deste estudo é testar se o feedback visual sagital em tempo real durante o treinamento em esteira é superior ao programa de treinamento em esteira com feedback de espelho convencional de intensidade equivalente na melhoria da velocidade de caminhada e equilíbrio após acidente vascular cerebral. MÉTODOS/ DESENHO: O ensaio RE-VISIT (feedback visual em tempo real após acidente vascular cerebral no treinamento em esteira) está registrado no Registro de Ensaios Clínicos da Índia (CTRI/2023/10/058299). Neste ensaio de controle randomizado de dois braços, que será um estudo cego, 42 sobreviventes de AVC elegíveis em reabilitação serão alocados aleatoriamente (proporção de 1:1) para feedback sagital visual em tempo real junto com grupo de espelho frontal (experimental) ou apenas Grupo de treinamento em esteira com espelho frontal (controle), todos os participantes receberão 15 sessões de treinamento em esteira por até 15 minutos em uma velocidade segura e autosselecionada durante 5-6 semanas. O grupo RE-VISIT (experimental) receberá feedback visual em tempo real da visão sagital da trajetória dos membros inferiores envolvidos, juntamente com a visão rotineira do espelho frontal durante o treinamento em esteira e será solicitado a modificar seu padrão de marcha. O grupo de controle receberá treinamento de caminhada em esteira apenas com o feedback rotineiro da visão do espelho frontal. Avaliações clínicas e de marcha serão realizadas no início do estudo, imediatamente após a sessão final de treinamento e na 9ª semana durante o acompanhamento. As medidas de resultados de interesse são a velocidade de caminhada (primária) e o equilíbrio (secundário), que serão medidos antes da linha de base, após a 15ª sessão de treinamento e na 9ª semana após o treinamento. DISCUSSÃO: este ensaio REVISIT fornecerá insights e contribuirá para a inovação e modificações existentes na incorporação de feedbacks visuais em tempo real durante o treinamento em esteira na reabilitação da marcha pós-AVC. As descobertas ajudarão no melhor desenho de um programa de reabilitação da marcha com esteira para indivíduos pós-AVC para melhorar a velocidade de caminhada e o equilíbrio para aqueles que têm maiores dificuldades na deambulação comunitária. Prevemos que aqueles no treinamento REVISIT demonstrarão melhor capacidade de caminhada.

Assessing the role of ankle and hip joint proprioceptive information in balance recovery using vibratory stimulation.

Background: Previous work suggests that proprioceptive information from ankle and hip are crucial in maintaining balance during upright standing; however, the contribution of these proprioceptive information during stepping balance recovery in not clear. The goal of the current study was to assess the role of ankle and hip proprioceptive information on balance recovery performance by manipulating type 1a afferent in muscle spindles using vibratory stimulation. Methods: Twenty healthy young participants were recruited (age = 22.2 ± 2.7 years) and were randomly assigned to balance recovery sessions with either ankle or hip stimulation. Trip-like perturbations were imposed using a modified treadmill setup with a protecting harness. Vibratory stimulation was imposed bilaterally on ankle and hip muscles to expose participants to three condition of no-vibration, 40Hz vibration, and 80Hz vibration. Kinematics of the trunk and lower-extremities were measured using wearable sensors to characterize balance recovery performance. Outcomes were response time, recovery step length, trunk angle during toe-off and heel-strike of recovery stepping, and required time for full recovery. Findings: Ankle vibratory stimulation elicited main effects on reaction time and recovery step length (p < 0.002); reaction time and recovery step length increased by 23.0% and 21.2%, respectively, on average across the conditions. Hip vibratory stimulation elicited significant increase in the full recovery time (p = 0.019), with 55.3% increase on average across the conditions. Interpretation: Current findings provided evidence that vibratory stimulation can affect the balance recovery performance, causing a delayed recovery initiation and an impaired balance refinement after the recovery stepping when applied to ankle and hip muscles, respectively.

Change in Achilles Tendon Length after Walking on Treadmill with Gradient.

Objectives: Improving ankle joint contracture is important because stiffness in ankle dorsiflexion can lead to pain, especially when weight-bearing during walking, which tends to concentrate on the forefoot. We hypothesized that the contraction of the gastrocnemius muscle in ankle dorsiflexion would increase the Achilles tendon length and improve the dorsiflexion range of motion. We evaluated the effects of walking with and without a gradient on Achilles tendon length. Methods: This study included 23 men who underwent ultrasound imaging to measure the Achilles tendon length while they stood on an inclined table adjusted according to the dorsiflexion angle. Treadmill walking was performed for 10 min with a 10° incline (gradient condition) or without gradient (level condition). The measurements were compared using a paired t-test. Results: In the gradient condition, the range of motion for ankle dorsiflexion was significantly increased after the intervention. In the gradient condition, the Achilles tendon length while standing on an inclined surface was significantly increased after the intervention. Conclusions: Walking under gradient conditions led to the extension of the Achilles tendon in the ankle dorsiflexion position. This was accompanied by contraction of the gastrocnemius muscle, resulting in lengthening of the Achilles tendon. This finding suggests that such interventions may have clinical applications.

Commingling Effects of Anterior Load and Walking Surface on Dynamic Gait Stability in Young Adults.

Treadmill walking has been used as a surrogate for overground walking to examine how load carriage affects gait. The validity of using treadmill walking to investigate load carriage's effects on stability has not been established. Thirty young adults were randomized into 3 front-loaded groups (group 1: 0%, 2: 10%, or 3: 20% of bodyweight). Participants carried their load during overground and treadmill walking. Dynamic gait stability (primary outcome) was determined for 2 gait events (touchdown and liftoff). Secondary variables included step length, gait speed, and trunk angle. Groups 1 and 2 demonstrated similar stability between walking surfaces. Group 3 was less stable during treadmill walking than overground (P ≤ .005). Besides trunk angle, all secondary outcomes were similar between groups (P > .272) but different between surfaces (P ≤ .001). The trunk angle at both events showed significant group- and surface-related differences (P ≤ .046). Results suggested that walking with an anterior load of up to 10% bodyweight causes comparable stability between surfaces. A 20% bodyweight front load could render participants less stable on the treadmill than overground. This indicates that anteriorly loaded treadmill walking may not be interchangeable with overground walking concerning stability for anterior loads of 20% bodyweight.

Interleaved configurations of percutaneous epidural stimulation enhanced overground stepping in a person with chronic paraplegia.

Descending motor signals are disrupted after complete spinal cord injury (SCI) resulting in loss of standing and walking. We previously restored standing and trunk control in a person with a T3 complete SCI following implantation of percutaneous spinal cord epidural stimulation (SCES). We, hereby, present a step-by-step procedure on configuring the SCES leads to initiate rhythmic lower limb activation (rhythmic-SCES) resulting in independent overground stepping in parallel bars and using a standard walker. Initially, SCES was examined in supine lying at 2 Hz before initiating stepping-like activity in parallel bars using 20 or 30 Hz; however, single lead configuration (+2, -5) resulted in lower limb adduction and crossing of limbs, impairing the initiation of overground stepping. After 6 months, interleaving the original rhythmic-SCES with an additional configuration (-12, +15) on the opposite lead, resulted in a decrease of the extensive adduction tone and allowed the participant to initiate overground stepping up to 16 consecutive steps. The current paradigm suggests that interleaving two rhythmic-SCES configurations may improve the excitability of the spinal circuitry to better interpret the residual descending supraspinal signals with the ascending proprioceptive inputs, resulting in a stepping-like motor behavior after complete SCI.

Does listening to audiobooks affect gait behavior?

BACKGROUND: The effect of listening to audiobooks, podcasts, and other audio files while walking on gait performance has not been well studied. Although the number of audio users is growing annually. Evidence suggests that a posture-first strategy contributes to gait stability in healthy individuals during dual-task conditions, but this effect may be diminished when the cognitive task is consciously prioritized. OBJECTIVES: To study the effect of listening to an audiobook while walking, as a daily life-like dual-task, on spatiotemporal gait parameters. METHODS: Forty young healthy (24.05 ± 3.66) subjects participated in the study. Spatiotemporal gait parameters were measured for 5 min on a treadmill once without (single-task) and once while listening to an audiobook through over-ear headphones (dual-task). Measured parameters included spatiotemporal parameters, gait phases, maximum pressure, and dual-task cost. Data were statistically analyzed using SPSS software. RESULTS: There were no significant differences in any of the studied parameters between the single- and dual-task conditions, even though the subjective cognitive load of listening to audiobooks while walking was high. However, participants with different habits had significant differences in gait phases and maximum pressure. Rare listeners had a shorter stance phase, a longer swing phase, and a higher maximum pressure on the dominant heel. They also had significant differences in dual-task costs. CONCLUSION: No differences in the spatiotemporal gait parameters for walking with and without listening to audiobooks, as a daily life-like dual-task, were observed. However, the difference between participants who listened rarely and participants who listened often may confirm the "posture first" strategy in young healthy people. TRIAL REGISTRATION: DRKS00025837, retrospectively registered on 23.11.2021.

Mountain Hiking: Prolonged Eccentric Muscle Contraction during Simulated Downhill Walking Perturbs Sensorimotor Control Loops Needed for Safe Dynamic Foot-Ground Interactions.

Safe mountain hiking requires precise control of dynamic foot-ground interactions. In addition to vision and vestibular afferents, limb proprioception, sensorimotor control loops, and reflex responses are used to adapt to the specific nature of the ground contact. Diminished leg dexterity and balance during downhill walking is usually attributed to fatigue. We investigated the supplementary hypothesis that the eccentric contractions inherent to downhill walking can also disrupt muscle proprioception, as well as the sensorimotor control loops and reflex responses that depend on it. In this study, we measured leg dexterity (LD), anterior-posterior (AP) and medio-lateral (ML) bipedal balance, and maximal voluntary leg extension strength in young and healthy participants before and after 30 min of simulated downhill walking at a natural pace on a treadmill at a 20° decline. Post-pre comparisons of LD (p < 0.001) and AP balance (p = 0.001) revealed significant reductions in dynamic foot-ground interactions after eccentric exercise without an accompanying reduction in leg extension strength. We conclude that eccentric contractions during downhill walking can disrupt the control of dynamic foot-ground interactions independently of fatigue. We speculate that mountaineering safety could be improved by increasing conscious attention to compensate for unadjusted proprioception weighting, especially in the descent.

More Predictable and Less Automatized Movements during Walking -not during Repetitive Punching- in Knee Osteoarthritis.

Using the non-affected leg as stable frame of reference for the affected leg in gait assessment in knee osteoarthritis (KO) fails due to compensatory mechanisms. Assessing the cyclical movements of the upper extremities in a frequency-controlled repetitive punching task may provide an alternative frame of reference in gait assessment in patients with KO. Eleven participants with unilateral KO and eleven healthy controls were asked to perform treadmill walking and repetitive punching. The KO group showed more predictable (p = 0.020) and less automatized (p = 0.007) movement behavior than controls during treadmill walking. During repetitive punching, the KO group showed a similar degree of predictability (p = 0.784) but relative more automatized movement behavior (p = 0.013). Thus, the predictability of the movement behavior of the upper extremities during repetitive punching seems unaffected by KO and could provide an alternative frame of reference in gait assessment in patients with KO.

The Soft Prefabricated Orthopedic Insole Decreases Plantar Pressure during Uphill Walking with Heavy Load Carriage.

This study aimed to investigate the effect of varying the hardness of prefabricated orthopedic insoles on plantar pressure and muscle fatigue during uphill walking with a heavy backpack. Fifteen healthy male recreational athletes (age: 20.4 ± 1.0 years, height: 176.9 ± 5.7 cm, weight: 76.5 ± 9.0 kg) wore prefabricated orthopedic insoles with foot arch support; a heel cup with medium (MI), hard (HI), and soft (SI) relative hardnesses; and flat insoles (FI). They performed treadmill walking on uphill gradients with 25 kg backpacks. The plantar pressure and surface electromyographic activity were recorded separately, in 30 s and 6 min uphill treadmill walking trials, respectively. The HI, MI, and SI significantly decreased peak plantar pressure in the lateral heel compared to FI. The MI and SI significantly decreased the peak plantar pressure in the fifth metatarsal compared to FI. The MI significantly reduced the pressure-time integral in the lateral heel compared to FI. The HI significantly increased the peak plantar pressure and pressure-time integral in the toes compared to other insoles, and decreased the contact area in the metatarsal compared to SI. In conclusion, a prefabricated orthopedic insole made of soft material at the fore- and rearfoot, with midfoot arch support and a heel cup, may augment the advantages of plantar pressure distribution during uphill weighted walking.

The influence of wearing an ultrasound device on gait in children with cerebral palsy and typically developing children.

BACKGROUND: Ultrasonography with motion analysis enables dynamic imaging of medial gastrocnemius (MG) muscles and tendons during gait. This revealed pathological muscle-tendon dynamics in children with spastic cerebral palsy (CP) compared to typically developing (TD) children. However, wearing an ultrasound probe on the lower leg could interfere with gait and bias muscle length changes observed with ultrasound. RESEARCH QUESTION: Does wearing an ultrasound probe on the MG influence gait in children with CP and TD children? METHODS: Eighteen children with spastic CP and 16 age-matched TD children walked at comfortable walking speed on an instrumented treadmill. One baseline gait condition (BASE) and two conditions with an ultrasound probe and custom-made probe holder were measured: on the mid-muscle fascicles (FAS) and on the muscle-tendon junction (MTJ). The effect of condition and group on spatiotemporal parameters, hip, knee and ankle kinematics, ankle moment, ankle power, and modeled MG muscle-tendon unit (MTU) length was assessed using two-way repeated measures ANOVA's. Statistical non-parametric mapping was applied for time-series. Post-hoc paired-samples t-tests were conducted, and the root mean square difference was calculated for significant parts. RESULTS: Children took wider steps during FAS (CP, TD) and MTJ (TD) compared to BASE, and during FAS compared to MTJ (CP). Hip extension was lower (2.7°) during terminal stance for MTJ compared to FAS for TD only. There was less swing knee flexion (FAS 4.9°; MTJ 4.0°) and ankle plantarflexion around toe-off (FAS 3.0°; MTJ 2.4°) for both ultrasound placements, with no group effect. Power absorption during loading response was slightly increased for both ultrasound placements (0.12 W/kg), with no group effect. MTU shortened less in swing for both ultrasound placements (FAS 3.6 mm; MTJ 3.7 mm), with no group effect. SIGNIFICANCE: Wearing an ultrasound probe causes minimal lower-limb gait alterations and MTU length changes that are mostly similar in CP and TD.

Bodyweight support alters the relationship between preferred walking speed and cost of transport.

Humans tend to select a preferred walking speed (PWS) that minimizes the metabolic energy consumed per distance traveled, i.e. the Cost of Transport (CoT). The aims of this study were to: 1. compare PWS overground vs. on a treadmill at 100 and 50% of body weight, and 2. explore whether with body weight support, PWS corresponds to the speed that minimizes CoT. Fifteen healthy adults walked overground and on a lower body positive pressure treadmill with and without bodyweight support. Walking speeds (m.s-1) were recorded for each condition. Rate of energy expenditure (J.kg-1.min-1) and CoT (J.kg-1.m-1) were then determined from 5-min walking trials with 50% bodyweight support at PWS and ± 30% of the self-selected walking speed for that condition. PWS did not differ across conditions. With 50% body weight support, for each 30% increase in walking speed, rates of metabolic energy expenditure increased ∼15% while CoT decreased by ∼14%. Thus, with 50% body weight support, PWS did not correspond with the speed that minimized CoT. Bodyweight support decreases cost of maintaining an upright body but does not decrease the metabolic demand of limb advancement, contributing to the linear yet not proportional changes in rates of energy expenditure and CoT. We conclude that bodyweight support via an AlterG® treadmill disconnects the association between PWS and minimum CoT. These findings have implications for clinical populations (e.g., obese, elderly) who may benefit from walking on a bodyweight supporting treadmill but may select speeds incompatible with their physical activity goals.

Different types of plantar vibration affect gait characteristics differently while walking on different inclines.

Background: Plantar vibration has been widely used to strengthen the sensation of the somatosensory system, further enhancing balance during walking on a level surface in patients with stroke. However, previous studies with plantar vibration only involved the level surface, which neglected the importance of inclined/declined walking in daily life. Thus, combining the plantar vibration and inclined/declined walking might answer a critical research question: whether different types of plantar vibration had different effects on gait characteristics during walking on different inclines. Methods: Eighteen healthy young adults were recruited. Fifteen walking conditions were assigned randomly to these healthy adults (no, sub-, and supra-threshold plantar vibration × five different inclines: +15%, +8%, 0%, -8%, -15% grade). A motion capture system with eight cameras captured 12 retro-reflective markers and measured the stride time, stride length, step width, and respective variabilities. Results: A significant interaction between vibration and inclination was observed in the stride time (p < 0.0001) and step width (p = 0.015). Post hoc comparisons found that supra-threshold vibration significantly decreased the stride time (-8%: p < 0.001; -15%: p < 0.001) while the sub-threshold vibration significantly increased the step width (-8%: p = 0.036) in comparison with no plantar vibration. Conclusions: When walking downhill, any perceivable (supra-threshold) vibration on the plantar area decreased the stride time. Also, the increase in step width was observed by non-perceivable (sub-threshold) plantar vibration while walking uphill. These observations were crucial as follows: (1) applying sub-threshold plantar vibrations during uphill walking could increase the base of support, and (2) for those who may need challenges in locomotor training, applying supra-threshold vibration during downhill walking could reach this specific training goal.

Comparing spatiotemporal gait parameters between overground walking and self-paced treadmill walking in persons after stroke.

PURPOSE: Since self-paced treadmills enable more natural gait patterns compared to fixed-speed treadmills we examined the use of a self-paced treadmill as a alternative for overground gait analysis in persons after stroke. MATERIAL AND METHODS: Twenty-five persons after stroke (10 males/15 females; 53 ± 12.05 years; 40.72 ± 42.94 months post-stroke) walked at self-selected speed overground (GAITRite, CIR Systems) and on a self-paced treadmill (GRAIL, Motek) in randomized order. Spatiotemporal parameters, variability and symmetry measures were compared using paired-sample t-tests or Wilcoxon Signed Rank tests. Concurrent validity was assessed using intraclass correlation coefficients and Bland-Altman plots. A regression model determined the contribution of the walking velocity to the changes in spatiotemporal parameters. RESULTS: The velocity on the treadmill was significant lower compared to overground (p < 0.001). This difference predicted the significant changes in other spatiotemporal parameters to varying degrees (27.7%-83.8%). Bland-Altman plots showed large percentage of bias and limits of agreement. Variability and symmetry measures were similar between conditions. CONCLUSIONS: When considering gait analysis in persons after stroke a self-paced treadmill may be a valuable alternative for overground analysis. Although a slower walking velocity, and accompanying changes in other spatiotemporal parameters, should be taken into account compared to overground walking.Implications for rehabilitationConsidering the advantages regarding space and time, instrumented treadmills provide opportunities for gait assessment and training in a stroke population.When using self-paced treadmills for clinical gait analysis in persons after stroke, the slower walking velocity and accompanying changes in other spatiotemporal parameters need to be taken into account.Stroke patients seem to preserve their walking pattern on a self-paced treadmill.

Muscle activation and rating of perceived exertion of typically developing children during DRY and aquatic treadmill walking.

Aquatic treadmill gait training is a poorly understood rehabilitation method that alters bodyweight support, increases lower limb resistance, and assists with postural stability. This training could be an attractive tool for clinical populations with balance control issues or limited weight-bearing prescriptions for the lower limb. As a first step, the purpose of this study was to quantify differences in mean muscle activity of the tibialis anterior, rectus femoris, medial gastrocnemius, and semitendinosus, and perceived exertion (RPE) in typically developing children (7:8 M:F, age = 11.3 ± 4.1 years, 1.46 ± 0.18 m, and 44.2 ± 16.8 kg) during dry and aquatic treadmill walking at 75 %, 100 %, and 125 % self-selected speed. We hypothesized that the greatest mean muscle activity, normalized to percent maximum voluntary contraction and averaged across all strides, would be observed during 125 % dry treadmill walking and that aquatic treadmill walking would produce lower RPE. Overall, aquatic treadmill walking reduced mean medial gastrocnemius activity by 50.2 % (padj < 0.001), increased mean rectus femoris activity at least 32.8 % (padj < 0.006), and produced 78.0 % (padj = 0.007) greater RPE compared to dry treadmill walking. This study provides normative pediatric data for future aquatic treadmill walking studies in clinical populations to help inform gait rehabilitation protocols.

Assessing Walking Stability Based on Whole-Body Movement Derived from a Depth-Sensing Camera.

Stability during walking is considered a crucial aspect of assessing gait ability. The current study aimed to assess walking stability by applying principal component analysis (PCA) to decompose three-dimensional (3D) whole-body kinematic data of 104 healthy young adults (21.9 ± 3.5 years, 54 females) derived from a depth-sensing camera into a set of movement components/synergies called "principal movements" (PMs), forming together to achieve the task goal. The effect of sex as the focus area was tested on three PCA-based variables computed for each PM: the relative explained variance (rVAR) as a measure of the composition of movement structures; the largest Lyapunov exponent (LyE) as a measure of variability; and the number of zero-crossings (N) as a measure of the tightness of neuromuscular control. The results show that the sex effects appear in the specific PMs. Specifically, in PM1, resembling the swing-phase movement, females have greater LyE (p = 0.013) and N (p = 0.017) values than males. Moreover, in PM3, representing the mid-stance-phase movement, females have smaller rVAR (p = 0.020) but greater N (p = 0.008) values than males. These empirical findings suggest that the inherent sex differences in walking stability should be considered in assessing and training locomotion.