As Martial Arts students, we frequently learn falling, rolling, and other ground techniques, they are crucial to a well-rounded self-defense curriculum. In this video, Wing Chun Sifu Leo Au Yeung travels to Russia to learn Systema and train in low acrobatics and locks and holds.
Both styles utilize sensitivity and relaxation training.
https://www.youtube.com/watch?v=ZqVeYQYvPYk