The sit-up is a strength training exercise commonly performed with the aim of strengthening the hip flexors and abdominal muscles. It begins with lying with the back on the floor, typically with the arms across the chest or hands behind the head and the knees bent in an attempt to reduce stress on the back muscles and spine, and then elevating both the upper and lower vertebrae from the floor until everything superior to the buttocks is not touching the ground. Some argue that situps can be dangerous due to high compressive lumbar load[1] and may be replaced with the crunch in exercise programs.[2]