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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.
- 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.
- Postural control during turn on the light task assisted by functional electrical stimulation in post stroke subjectsPublication . Sousa, Andreia S. P.; Moreira, Juliana; Silva, Cláudia; Mesquita, Inês; Silva, Augusta; Macedo, Rui; Santos, RubimPostural control mechanisms have a determinant role in reaching tasks and are typically impaired in post-stroke patients. Functional electrical stimulation (FES) has been demonstrated to be a promising therapy for improving upper limb (UL) function. However, according to our knowledge, no study has evaluated FES infuence on postural control. This study aims to evaluate the infuence of FES UL assistance, during turning on the light task, in the related postural control mechanisms. An observational study involving ten post-stroke subjects with UL dysfunction was performed. Early and anticipatory postural adjustments (EPAs and APAs, respectively), the weight shift, the center of pressure and the center of mass (CoM) displacement were analyzed during the turning on the light task with and without the FES assistance. FES parameters were adjusted to improve UL function according to a consensus between physiotherapists’ and patients’ perspectives. The ANOVA repeated measures, Paired sample t and McNemar tests were used to compare postural control between the assisted and non-assisted conditions. When the task was assisted by FES, the number of participants that presented APAs increased (p= 0.031). UL FES assistance during turning on the light task can improve postural control in neurological patients with UL impairments.