Bart Ninja Performance on Instagram: "A lot of people overlook spine extension, but it is a powerful position that allows you to generate a lot of force and keep your lower back mobile, strong, and resilient, which carries into everything you do in your sport and everyday life. #spineextension #backextension #strongback #sportperformance #performancetraining #strengthandconditioning #suplex #suplexcity #combatsports #antifragile #resilientsf"