Your core is way more than your abs—just like the best core exercises go beyond sit-ups, crunches, and planks. The thing is, people tend to think of the core as solely the abdominal muscles, including the rectus abdominis (frontside abs), transverse abdominis (deep trunk muscles that wrap around your spine and sides), and obliques (muscles on the sides of your torso). So whether you realize it or not, really “every single exercise we do involves the core,” Kat Paslé-Green, CPT, a certified personal trainer and coach at Bay Club in the San Francisco area, tells SELF.