This study is being done to answer the question: What are the effects of electrical stimulation and stepping practice on connections between the brain and muscles? The long-term goal of this project is to develop novel, effective, and personalized rehabilitation protocols founded on an understanding of neurobiological mechanisms that combine electrical stimulation with gait training to improve gait performance in older adults and stroke survivors. The rationale of this project is to explore and generate preliminary data regarding how electrical stimulation-based strategies modulate cortical and spinal circuits in able-bodied individuals. The researchers will evaluate the effects of short treadmill walking bouts or single gait training sessions with and without electrical stimulation on somatosensory, spinal-reflex, corticospinal circuit neurophysiology, and/or gait performance. The study will provide important preliminary and normative data that can explain how brain circuits change with stimulation or stepping practice and inform future rehabilitation studies on patients. The study population is able-bodied individuals.