The Bulgarian Split Squat may sound like something reserved solely for military officials with a high ranking, but as InStyle’s Kim Peiffer recently learned, the tried and true workout move is the reason Khloé Kardashianmaintains her rock-hard booty. In the video above, Peiffer heads to L.A. to join celebrity fitness trainer Gunnar Peterson, Khloé’s go-to, inside the space where Kardashian-Jenner #fitspo dreams are made of. Together, the duo breaks down the step-by-step process to achieving a sculpted derrière cheek to cheek. Peterson’s suggested number of reps for max results? “Anywhere between 8 and 15, per side,” he tells Peiffer, moving on to zero-in on how many sets you should do per week.