## 1 Introduction  
Stroke is a leading cause of long-term disability in the United States [1], often resulting in persistent motor impairments that compromise functional independence, especially during walking and balance tasks. These deficits are particularly pronounced in the lower limbs, where impairments in strength, motor control, and coordination can significantly limit mobility [2, 3]. Although conventional rehabilitation strategies can yield modest improvements, many individuals experience a plateau in recovery, underscoring the need for adjunct interventions that promote neuroplasticity and target functional motor skills [4].  
Neuroplasticity--the brain's capacity to reorganize neural pathways in response to injury, experience, or training--is central to recovery after stroke [5]. Greater engagement of adaptive neuroplastic mechanisms has been linked to improved motor outcomes [6]. As a result, there is growing interest in interventions that might modulate the nervous system in ways that facilitate more effective motor learning. One area of exploration involves the use of \"priming\" strategies, which aim to transiently influence cortical or subcortical excitability before task-specific training [7, 8]. These techniques are still under investigation, and while promising, their clinical utility and optimal parameters remain to be clearly defined.  
Among various priming approaches, sensory-based priming has emerged as a promising strategy to enhance motor learning by modulating sensorimotor networks prior to task-specific training [9]. Across a range of sensory modalities, repetitive peripheral magnetic stimulation (rPMS) stands out for its non-invasive application and ability to stimulate deep neuromuscular structures. Previous studies have shown that a single session of rPMS can enhance cortical excitability and improve motor outcomes, particularly in the upper limbs [10, 11, 12, 13]. While modalities such as electrical stimulation and vibration have been extensively explored in this context, the role of rPMS--particularly in lower-limb motor skill performance--remains underexamined. Most rPMS studies have focused on isolated motor outcomes such as strength, spasticity, or range of motion [14, 15, 16]. These outcomes, although clinically useful, do not reflect the demands of everyday motor behavior, which often requires visuomotor integration, sensorimotor coordination, and cognitive control.  
Despite promising evidence that a single session of rPMS can modulate basic motor parameters such as strength and spasticity, its ability to enhance integrated, higher-order motor skills remains uncertain. Given the complexity of sensorimotor coordination required for functional tasks, the immediate effects observed in simpler paradigms may not translate to improvements in more demanding motor behaviors. Understanding whether rPMS can influence complex, functional performance--and whether such effects vary over time--is critical for determining its potential utility as a sensory-based priming tool. Insights into these temporal dynamics may help guide the timing and application of rPMS alongside functional training in stroke rehabilitation.  
To address this gap, the present study investigated the temporal effectiveness of rPMS on lower-limb motor skill performance in individuals with chronic stroke. Using a visuomotor ankle-tracking task, we assessed motor performance at baseline and at 0, 30, and 60 min following stimulation. rPMS was delivered at 20 Hz and 10% above motor threshold for 15 min, consistent with protocols shown to enhance corticomotor excitability in prior studies [16]. These parameters were selected to allow comparison with previous findings while ensuring feasibility and tolerability in a clinical population. This approach enabled us to evaluate whether a single session of rPMS could acutely influence integrated motor performance and whether such effects vary across post-stimulation time points.