Interlimb coordination during the stance phase of gait in subjects with stroke

Objective: To analyze the relation between contralesional and ipsilesional limbs in subjects with stroke during step-to-step transition of walking. Design: Observational, transversal, analytical study with a convenience sample. Setting: Physical medicine and rehabilitation clinic. Participants: Subjects (nZ16) with poststroke hemiparesis with the ability to walk independently and healthy controls (nZ22). Interventions: Not applicable. Main Outcome Measures: Bilateral lower limbs electromyographic activity of the soleus (SOL), gastrocnemius medialis, tibialis anterior, biceps femoris, rectus femoris, and vastus medialis (VM) muscles and the ground reaction force were analyzed during double-support and terminal stance phases of gait. Results: The propulsive impulse of the contralesional trailing limb was negatively correlated with the braking impulse of the leading limb during double support (rZ .639, PZ.01). A moderate functional relation was observed between thigh muscles (rZ .529, PZ.035), and a strong and moderate dysfunctional relation was found between the plantar flexors of the ipsilesional limb and the vastus medialis of the contralesional limb, respectively (SOL-VM, rZ .80, P<.001; gastrocnemius medialis-VM, rZ .655, PZ.002). Also, a functional moderate negative correlation was found between the SOL and rectus femoris muscles of the ipsilesional limb during terminal stance and between the SOL (rZ .506, PZ.046) and VM (rZ .518, PZ.04) muscles of the contralesional limb during loading response, respectively. The trailing limb relative impulse contribution of the contralesional limb was lower than the ipsilesional limb of subjects with stroke (PZ.02) and lower than the relative impulse contribution of the healthy limb (PZ.008) during double support. Conclusions: The findings obtained suggest that the lower performance of the contralesional limb in forward propulsion during gait is related not only to contralateral supraspinal damage but also to a dysfunctional influence of the ipsilesional limb.

Interlimb relation during the double support phase of gait: an electromyographic, mechanical and energy based analysis

The purpose of this study is to analyse the interlimb relation and the influence of mechanical energy on metabolic energy expenditure during gait. In total, 22 subjects were monitored as to electromyographic activity, ground reaction forces and VO2 consumption (metabolic power) during gait. The results demonstrate a moderate negative correlation between the activity of tibialis anterior, biceps femoris and vastus medialis of the trailing limb during the transition between midstance and double support and that of the leading limb during double support for the same muscles, and between these and gastrocnemius medialis and soleus of the trailing limb during double support. Trailing limb soleus during the transition between mid-stance and double support was positively correlated to leading limb tibialis anterior, vastus medialis and biceps femoris during double support. Also, the trailing limb centre of mass mechanical work was strongly influenced by the leading limbs, although only the mechanical power related to forward progression of both limbs was correlated to metabolic power. These findings demonstrate a consistent interlimb relation in terms of electromyographic activity and centre of mass mechanical work, being the relations occurred in the plane of forward progression the more important to gait energy expenditure.

Reliability of Two Methods for Identifying the Postural Phase of Gait Initiation in Healthy and Post-stroke Subjects

This study aims to compare two methods of assessing the postural phase of gait initiation as to intrasession reliability, in healthy and post-stroke subjects. As a secondary aim, this study aims to analyse anticipatory postural adjustments during gait initiation based on the centre of pressure (CoP) displacements in post-stroke participants. The CoP signal was acquired during gait initiation in fifteen post-stroke subjects and twenty-three healthy controls. Postural phase was identified through a baseline-based method and a maximal displacement based method. In both healthy and post-stroke participants higher intra-class correlation coefficient and lower coefficient of variation values were obtained with the baseline-based method when compared to the maximal displacement based method. Post-stroke participants presented decreased CoP displacement backward and toward the first swing limb compared to controls when the baseline-based method was used. With the maximal displacement based method, there were differences between groups only regarding backward CoP displacement. Postural phase duration in medial-lateral direction was also increased in post-stroke participants when using the maximal displacement based method. The findings obtained indicate that the baseline-based method is more reliable detecting the onset of gait initiation in both groups, while the maximal displacement based method presents greater sensitivity for post-stroke participants.

Reorganização dos componentes neuro-motores com influência na marcha em indivíduos com lesão do sistema nervoso central - impacto funcional

Objectivo: Avaliar o impacto qualitativo de um programa de intervenção em fisioterapia, segundo o Conceito de Bobath, nas actividades e participação de dois indivíduos com lesão do Sistema Nervoso Central. Avaliar as modificações no comportamento da actividade muscular ao longo da fase de apoio do ciclo da marcha, na força de reacção ao solo e respectiva contribuição muscular. Metodologia: A avaliação realizou-se antes e após um programa de intervenção, segundo a abordagem do Conceito de Bobath, através da Classificação Internacional de Funcionalidade, Incapacidade e Saúde, electromiografia, plataforma de forças e máquina fotográfica. Resultados: Obteve-se melhorias na restrição da participação e na limitação da actividade. Verifica-se uma tendência de modificação do comportamento muscular ao longo da fase de apoio e na componente antero-posterior (Fy), mais evidente no mecanismo de aceleração. A mudança na contribuição muscular para a este mecanismo é mais evidente. Conclusão: O programa de intervenção, segundo o Conceito de Bobath, induziu mudanças positivas quanto à funcionalidade dos indivíduos, reflectindo-se na possibilidade de reorganização dos componentes neuro-motores em indivíduos com lesão do Sistema Nervoso Central.

Ankle dynamic in stroke patients: agonist vs. antagonist muscle relations

O documento em anexo encontra-se na versão post-print (versão corrigida pelo editor).

Comparative analysis of the ground reaction forces, during the support phase, in a group of pregnant women on their 3rd trimester of pregnancy and in a group of not pregnant women

PURPOSE: To analyze and compare the Ground Reaction Forces (GRF), during the stance phase of walking in pregnant women in the 3rd trimester of pregnancy, and non pregnant women. METHODS: 20 women, 10 pregnant and 10 non pregnant, voluntarily took part in this study. GRF were measured (1000 Hz) using a force platform (BERTEC 4060-15), an amplifier (BERTEC AM 6300) and an analogical-digital converter of 16 Bits (Biopac). RESULTS: The study showed that there were significant differences among the two groups concerning absolute values of time of the stance phase. In what concerns to the normalized values the most significant differences were verified in the maximums values of vertical force (Fz3, Fz1) and in the impulse of the antero-posterior force (Fy2), taxes of growth of the vertical force, and in the period of time for the antero-posterior force (Fy) be null. CONCLUSIONS: It is easier for the pregnant to continue forward movement (push-off phase). O smaller growth rates in what concerns to the maximum of the vertical force (Fz1) for the pregnant, can be associated with a slower speed of gait, as an adaptation strategy to maintain the balance, to compensate the alterations in the position of her center of gravity due to the load increase. The data related to the antero-posterior component of the force (Fy), shows that there is a significant difference between the pregnant woman’s left foot and right foot, which accuses a different functional behavior in each one of the feet, during the propulsion phase (TS).

Localization system for pedestrians based on sensor and information fusion

Nowadays there is an increase of location-aware mobile applications. However, these applications only retrieve location with a mobile device's GPS chip. This means that in indoor or in more dense environments these applications don't work properly. To provide location information everywhere a pedestrian Inertial Navigation System (INS) is typically used, but these systems can have a large estimation error since, in order to turn the system wearable, they use low-cost and low-power sensors. In this work a pedestrian INS is proposed, where force sensors were included to combine with the accelerometer data in order to have a better detection of the stance phase of the human gait cycle, which leads to improvements in location estimation. Besides sensor fusion an information fusion architecture is proposed, based on the information from GPS and several inertial units placed on the pedestrian body, that will be used to learn the pedestrian gait behavior to correct, in real-time, the inertial sensors errors, thus improving location estimation.

Ankle anticipatory postural adjustments during gait initiation in healthy and post-stroke subjects

Background: Anticipatory postural adjustments during gait initiation have an important role in postural stability but also in gait performance. However, these first phase mechanisms of gait initiation have received little attention, particularly in subcortical post-stroke subjects, where bilateral postural control pathways can be impaired. This study aims to evaluate ankle anticipatory postural adjustments during gait initiation in chronic post-stroke subjects with lesion in the territory of middle cerebral artery. Methods: Eleven subjects with post-stroke hemiparesis with the ability to walk independently and twelve healthy controls participated in this study. Bilateral electromyographic activity of tibialis anterior, soleus and medial gastrocnemius was collected during gait initiation to assess the muscle onset timing, period of activation/deactivation and magnitude of muscle activity during postural phase of gait initiation. This phase was identified through centre of pressure signal. Findings: Post-stroke group presented only half of the tibialis anterior relative magnitude observed in healthy subjects in contralesional limb (t=2.38, p=0.027) and decreased soleus deactivation period (contralesional limb, t=2.25, p=0.04; ipsilesional limb, t=3.67, p=0.003) as well its onset timing (contralesional limb, t=3.2. p=0.005; ipsilesional limb, t=2.88, p=0.033) in both limbs. A decreased centre of pressure displacement backward (t=3.45, p=0.002) and toward the first swing limb (t=3.29, p=0.004) was observed in post-stroke subjects. Interpretation: These findings indicate that chronic post-stroke subjects with lesion at middle cerebral artery territory present dysfunction in ankle anticipatory postural adjustments in both limbs during gait initiation.

The influence of gait cadence on the ground reaction forces and plantar pressures during load carriage of young adults

Biomechanical gait parameters—ground reaction forces (GRFs) and plantar pressures—during load carriage of young adults were compared at a low gait cadence and a high gait cadence. Differences between load carriage and normal walking during both gait cadences were also assessed. A force plate and an in-shoe plantar pressure system were used to assess 60 adults while they were walking either normally (unloaded condition) or wearing a backpack (loaded condition) at low (70 steps per minute) and high gait cadences (120 steps per minute). GRF and plantar pressure peaks were scaled to body weight (or body weight plus backpack weight). With medium to high effect sizes we found greater anterior-posterior and vertical GRFs and greater plantar pressure peaks in the rearfoot, forefoot and hallux when the participants walked carrying a backpack at high gait cadences compared to walking at low gait cadences. Differences between loaded and unloaded conditions in both gait cadences were also observed.

Ankle antagonist coactivation in the double-support phase of walking: Stroke vs. healthy subjects

Introduction: Lesions at ipsilateral systems related to postural control at ipsilesional side, may justify the lower performance of stroke subjects during walking. Purpose: To analyse bilateral ankle antagonist coactivation during double-support in stroke subjects. Methods: Sixteen (8 females; 8 males) subjects with a first isquemic stroke, and twenty two controls (12 females; 10 males) participated in this study. The double support phase was assessed through ground reaction forces and electromyography of ankle muscles was assessed in both limbs. Results: Ipsilesional limb presented statistical significant differences from control when assuming specific roles during double support, being the tibialis anterior and soleus pair the one in which this atypical behavior was more pronounced. Conclusion: The ipsilesional limb presents a dysfunctional behavior when a higher postural control activity was demanded.

Iniciação da marcha em indivíduos com AVE. Sequência de ativação muscular do tibial anterior e solear

Introdução: A iniciação da marcha, enquanto tarefa motora complexa que consiste na transição de uma postura mantida pelo apoio simultâneo dos dois membros inferiores para um equilíbrio dinâmico, permitindo a progressão anterior do corpo, constitui um exemplo que implica uma correta sequência de ativação muscular. Objetivos: Verificar a modificação da fase de iniciação da marcha face à aplicação de um programa de recuperação funcional, analisando a sequência de ativação dos músculos tibial anterior e solear. Registar as repercussões funcionais na participação nas diferentes atividades da vida diária, em contexto padronizado e social. Metodologia: Nos dois participantes em estudo foi realizada uma avaliação antes e após um programa de intervenção, segundo a abordagem do Conceito de Bobath, através da Classificação Internacional de Funcionalidade, Incapacidade e Saúde, da Fugl Meyer Assessment of Sensorymotor Recovery After Stroke, electromiografia e plataforma de forças. Resultados: Após a aplicação do programa de recuperação funcional, verificaram-se alterações na sequência de ativação do tibial anterior e solear. O músculo tibial anterior passou a ser o primeiro a ser recrutado nesta sequência. Conclusão: Foi possível verificar modificações durante a fase de iniciação da marcha, face a um programa de recuperação funcional, em que a sequência de ativação do tibial anterior e solear, tendencialmente, se assemelharam ao comportamento em indivíduos saudáveis, repercutindo-se numa melhoria funcional na participação nas atividades da vida diária.

Ajustes posturais antecipatórios no alcance em crianças com hemiparésia espástica

Objectivos: Verificar o comportamento dos Ajustes Posturais Antecipatórios no alcance, em três crianças com hemiparésia espástica, face à aplicação de uma intervenção em Fisioterapia baseada numa abordagem segundo o conceito de Bobath. Pretendeu-se também perceber as modificações ao nível das actividades e participação, bem como ao nível da capacidade de modificação das componentes neuromotoras. Metodologia: A avaliação foi realizada antes e três meses após a intervenção através da electromiografia de superfície, máquina fotográfica Canon EOS, Classificação Internacional de Funcionalidade para Crianças e Jovens (CIF-CJ) e Sistema de Classificação da Função Motora Global (GMFCS). Resultados: Verificou-se melhorias nos Ajustes Posturais Antecipatórios no alcance com os dois membros superiores, nomeadamente no tempo de activação e na duração da actividade muscular, bem como alterações positivas nas componentes neuromotoras, como na sequência de movimento de sentado para de pé, e de pé para sentado, e marcha mais especificamente na fase pendular com o membro inferior predominantemente comprometido. Também se verificou após a intervenção uma maior funcionalidade nas três crianças, verificando-se alterações positivas nos qualificadores nas actividades e participação. Conclusão: A intervenção com base no conceito de Bobath induziu mudanças positivas quanto à funcionalidade das crianças, reflectindo-se nos Ajustes Posturais Antecipatórios e na reorganização de componentes de movimento.

The influence of differente speeds on backpacker's gait kinectics

This study analyzed the influence of different speeds on ground reaction force’s (GRF), impulses and mean vertical force during gait of people submitted to occasional overload (backpack). A force plate was used to record the GRF data of 60 young adult subjects walking in two different cadences: 69 steps/min (slow gait) and 120 steps/min (fast gait). During the slow gait, the impact and propulsive impulses of vertical GRF, propulsive impulse of anterior-posterior GRF, impulse of medial-lateral GRF and duration of stance phase were larger than during the fast gait; the mean vertical force was the only variable that showed larger values during fast gait. Therefore, slow gait may present a larger possibility of blister development and gait unbalance, while the fast gait, even presenting a small impulse, seems to be more harmful to the musculoskeletal system.

Comfort and functionality of pregnant women's feet study of kinetic parameters with silicon insoles

As gestantes, fruto das suas alterações fisiológicas e biomecânicas, constituem uma população de risco relativamente a dores ou lesões do sistema músculo-esquelético, nomeadamente, nos membros inferiores e coluna. Os objectivos deste estudo consistiram em avaliar: (i) a dor e o conforto dos pés durante a marcha: sem o uso de qualquer palmilha nas gestantes e no grupo de controlo; com a aplicação de uma palmilha de retropé e com a aplicação de uma palmilha completa (nas gestantes); (ii) a distribuição das pressões plantares e, (iii) as forças de reacção do solo nas mesmas condições experimentais. Avaliámos ainda a duração das diferentes fases do ciclo de marcha nas gestantes, com e sem palmilhas, e no grupo de controlo, sem o uso de palmilha. Os nossos resultados mostraram que: (i) as gestantes demoram mais tempo a completar a fase de apoio da marcha, (ii) têm um aumento significativo de dores nos pés, face ao grupo de controlo, (iii) as gestantes sentem menos dor e mais conforto quando realizam marcha, com palmilhas, especialmente com a palmilha completa, (iv) a palmilha completa redistribui as forças, diminui os valores de pressão e aumenta a área de contacto do pé com o solo. Os nossos resultados sugerem que, o uso da palmilha completa de silicone, durante a marcha, pode ser eficaz na melhoria da sintomatologia dolorosa e no aumento do conforto da grávida.

Análise electromiográfica da fase de apoio da marcha com utilização de sapatilhas MBT

As sapatilhas MBT combinam um aumento da actividade muscular dos membros inferiores com a marcha. Objectivo: Analisar influência das MBT na actividade electromiográfica do tibial anterior, gastrocnémio medial, recto femoral e bicípite femoral na fase de apoio. Metodologia: A amostra constitui-se por 30 indivíduos. Utilizou-se electromiografia de superfície e plataforma de forças. Resultados: Foram encontradas diferenças no tempo de início de activação do gastrocnémio medial (p <0,0001) e nas sequências de início de actividade (p =0,007). Conclusão: O uso das MBT diminui o tempo de início da actividade do gastrocnémio medial e altera as sequências de início de actividade.