The upper limbs play an essential role for safe and efficient walking in healthy persons and persons post-stroke. Nevertheless, in current post-stroke gait rehabilitation (research) the upper limbs are barely targeted. To address this gap, my project aims to investigate the selective motor control of the upper limbs during walking and the contribution of the cortical activity to the arm swing in independent walkers after stroke. To gain insight in the direct effects of stroke on the arm swing, the primary motor control of the arm swing will be evaluated by determining muscle synergies (i.e group of muscles working together as a task-specific functional unit). Additionally, the cortical activity (EEG-analysis) during walking of persons post-stroke will be compared to healthy controls and the relationship between stroke-induced changes in cortical activity and arm swing deviations will be assessed. Furthermore, I will evaluate whether improvements in cortical activity relate to improvements in primary motor control of the arm swing. This innovative project will be the first to investigate the direct coupling between the cortex and the muscle synergies in persons post-stroke during independent walking to investigate the arm swing. These fundamental insights in the primary motor control of the arm swing and the contribution of the cortical activity will allow to develop targeted interventions aiming to improve arm swing and as such optimize post-stroke gait rehabilitation. Research questions: 1. How can muscle synergies explain arm swing alterations in independent walkers after stroke? 2. How do stroke-induced changes in cortical activity relate to arm swing deviations in persons after stroke? 3. Are changes in primary motor control of the upper limb during walking related to normalization of brain activity in independent walkers after stroke?