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- Antagonist coativation in stroke vs healthy subjects during sit-to-standPublication . Silva, Augusta; Sousa, Andreia S. P.; Silva, Cláudia; Santos, Rubim; Tavares, João Manuel R. S.; Calheno, Teresa; Sousa, FilipaHigh levels og antagonista coativation is frequently found in post stroke subjects, related with postural control impairments. The bilateral postural control dysfunction expected in post-stroke subjects is due to the bilateral disposal of reticulospinal system.
- Atividade do músculo solear nos dois membros inferiores em sujeitos com acidente vascular encefálico-sub-fase média de apoio da marchaPublication . Silva, Augusta; Santos, Rubim; Sousa, FilipaO objetivo da presente investigação foi estudar as diferenças de magnitude da atividade electromiográfica do músculo solear, durante a sub-fase média de apoio da marcha, entre os dois membros inferiores em indivíduos com acidente vascular encefálico. Foi constituída uma amostra, de forma não probabilística voluntária de cinco indivíduos com alterações neuro-motoras por AVE. O sinal electromiográfico foi recolhido e tratado pelo sistema Biopac MP 150 Worksation, e o software de apoio Acqknowledge® versão 3.9. foi utilizada uma Plataforma de forças e respectivo amplificador Bertec AM6300. Foi utilizada a versão adaptada para a população portuguesa da Fugl-Meyer AssessmentfsensorimotorRecoveryafterStroke. Para determinar o onset do sinal electromiográfico foi identificado o seu valor de atividade basal. O sinal da plataforma de forças foi normalizado ao peso e à velocidade da marcha dos sujeitos. Para a análise estatística das variáveis em estudo foi utilizado o software SPPS®. O intervalo de confiança utilizado foi de 95%, com um nível de significância de 0,05. Os resultados permitem-nos verificar uma tendência para uma diminuição da atividade electromiográfica do músculo solear no membro inferior menos comprometido. Não foram encontradas diferenças estatisticamente significativas para a atividade eletromiográfica do músculo solear entre os dois membros inferiores na sub-fase média de apoio da marcha nos sujeitos com AVE.
- Interlimb coordination during the stance phase of gait in subjects with strokePublication . Sousa, Andreia S. P.; Silva, Augusta; Santos, Rubim; Sousa, Filipa; Tavares, João ManuelTo analyze the relation between contralesional and ipsilesional limbs in subjects with stroke during step-to-step transition of walking. Observational, transversal, analytical study with a convenience sample. 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. 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. 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.
- Co-activation of upper limb muscles during reaching in post-stroke subjects: An analysis of the contralesional and ipsilesional limbsPublication . Silva, Cláudia; Silva, Augusta; Pinheiro De Sousa, Andreia Sofia; Pinheiro, Ana Rita; Bourlinova, Catarina; Silva, Ana; Salazar, António; Borges, Carla; Crasto, Carlos; Correia, Miguel Velhote; Vilas-Boas, João Paulo; Santos, RubimThe purpose of this study was to analyze the change in antagonist co-activation ratio of upper-limb muscle pairs, during the reaching movement, of both ipsilesional and contralesional limbs of post-stroke subjects. Nine healthy and nine post-stroke subjects were instructed to reach and grasp a target, placed in the sagittal and scapular planes of movement. Surface EMG was recorded from postural control and movement related muscles. Reaching movement was divided in two sub-phases, according to proximal postural control versus movement control demands, during which antagonist co-activation ratios were calculated for the muscle pairs LD/PM, PD/AD, TRIlat/BB and TRIlat/BR. Post-stroke's ipsilesional limb presented lower co-activation in muscles with an important role in postural control (LD/PM), comparing to the healthy subjects during the first sub-phase, when the movement was performed in the sagittal plane (p<0.05). Conversely, the post-stroke's contralesional limb showed in general an increased co-activation ratio in muscles related to movement control, comparing to the healthy subjects. Our findings demonstrate that, in post-stroke subjects, the reaching movement performed with the ipsilesional upper limb seems to show co-activation impairments in muscle pairs associated to postural control, whereas the contralesional upper limb seems to have signs of impairment of muscle pairs related to movement.
- Ankle dynamic in stroke patients: agonist vs. antagonist muscle relationsPublication . Silva, Augusta; Sousa, Andreia S. P.; Tavares, João Manuel; Tinoco, Ana; Santos, Rubim; Sousa, FilipaAtypical ankle patterns of muscle activity during gait are commonly reported in patients with stroke. These findings can be due to changes between tibialis anterior (TA) and soleus (SOL) coactivation mechanisms. To compare the electromyographic activity (EMGa) of SOL and TA muscles and antagonist coactivation (C) level in the contralateral (CONTRA) and ipsilateral (IPSI) limbs to the side of the stroke lesion during stance phase of the gait cycle. Twelve subjects with a stroke episode participated in this study. The electromyographic signal of TA and SOL and ground reaction forces were acquired while subjects walked at their self-selected speed. Values of ground reaction forces were used to divide the stance phase of gait into initial contact, midstance and terminal stance. In each subphase the magnitude of TA and SOL was calculated as well as the level of the antagonist C. Although no statistical differences were found, mean values of SOL EMGa were lower in the IPSI in all stance phases in relation to the CONTRA limb, and the opposite was observed in the TA EMGa. Moreover, higher mean levels of antagonist C were only found during initial contact sub-phase in CONTRA limb and in the other sub-phases in the IPSI limb. Besides, statistical differences were observed only during midstance. Conclusion: In stroke subjects the antagonist C level during midstance of gait my reflected the dysfunction of the neuronal system over the IPSI limb.
- Early postural adjustments in gait initiation in post-stroke subjectsPublication . Bento, Daniela; Sousa, Andreia; Santos, Rubim; Silva, AugustaThe success of gait initiation dependes of the ability on the central nervous system (CNS) to anticipate the perturbation related to the voluntary action through of postural adjustments: early postural adjustments (EPAs) and the antecipatory postural adjustments (APAs).
- Reliability of two methods for identifying the postural phase of gait initiation in healthy and post-stroke subjectsPublication . Sousa, Andreia S. P.; Silva, Augusta; Santos, RubimThis 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.
- Antagonist coactivation of muscles of ankle and thigh in post-stroke vs. healthy subjects during sit-to-stand taskPublication . Pinho, Liliana; Sousa, Andreia S. P.; Silva, Cláudia; Cunha, Christine; Santos, Rubim; Tavares, João Manuel R. S.; Pereira, Soraia; Pinheiro, Ana Rita; Félix, José; Pinho, Francisco; Sousa, Filipa; Silva, AugustaThis study aims to analyse the coactivation of antagonist muscles of the thigh and ankle during the sit-to-stand task in post-stroke subjects, specifically during forward and antigravity sub-phases. A group of 18 healthy subjects and another with 18 subjects with a history of stroke participated voluntarily in this study. Bilateral surface electromyography (EMGs) of the soleus, gastrocnemius medialis, tibialis anterior, rectus femoris and biceps femoris muscles were collected synchronously with ground reaction forces (GRF) during the sit-to-stand task. The magnitude of electromyographic (EMG) activity was analysed during forward translation and antigravity sub-phases which were determined through GRF signals. The coactivation was calculated to quantify the degree of antagonist coactivation according to the role of the muscles during the task. Statistically significant values were found between antagonist coactivation on both sub-phases of the sit-to-stand task when comparing healthy and post-stroke subjects (healthy with ipsilesional (IPSI); healthy with contralesional (CONTRA); and healthy with IPSI and with CONTRA limbs) in all muscle pairs analysed (p < 0.01), except on thigh muscles (p > 0.05), in the antigravity sub-phase. When comparing IPSI with CONTRA sides in post-stroke subjects, no statistically significant differences were found. Increased values of antagonist coactivation were observed in post-stroke subjects compared to healthy subjects (both IPSI and CONTRA limb) in the two sub-phases analysed. The forward sub-phase CONTRA limb showed higher antagonist coactivation compared to IPSI, while in the antigravity sub-phase, IPSI antagonist coactivation was higher than in the CONTRA. In conclusion, post-stroke subjects presented an antagonist coactivation more dysfunctional at the ankle joint muscles compared to the thigh segment. So, it seems that the distal segment could express more accurately the central nervous system dysfunction in post-stroke subjects, despite the need for further studies to achieve a better spatiotemporal understanding of the variability on coactivation levels.
- A marcha humana: circuitos neuronais entre estruturas corticais vs sub-corticaisPublication . Silva, AugustaAs conexões entre os níveis corticais e sub-corticais na activação da marcha Humana carecem de discussão. As alterações da marcha por lesão no território da Artéria Cerebral Média (ACM) podem ser explicadas pela disfunção de circuitos neuronais dos Núcleos da Base ao córtex e Núcleos Pedúnculo-Pontino. Este trabalho tem como objectivo identificar os percursos anatómicos das principais conexões entre as estruturas encefálicas referidas no território da ACM. Com base na topografia das conexões neuronais, é aceitável que as alterações da marcha sejam explicadas por alterações na função dos Núcleos da Base, através das suas conexões, enquanto moduladores da actividade motora.
- The use of FES as a strategy to improve upper limb function in stroke. What is missing?Publication . Sousa, Andreia; Silva, Cláudia; Mesquita, Inês; Silva, Augusta; Macedo, Rui; Santos, RubimStroke is the main cause of adult disability that leads to significant impairment of upper limb (UL) function. However, despite the various rehabilitation strategies, only 5-20% recover completely. This data point to the need of improving stroke intervention methods.