Why are crunches better/safer than situps?
Crunches focus your effort solely on the abdominal muscles, while Sit-Ups involve both the abdominals and the hip flexors (ilio psoas). The purpose of the rectus abdominis (the primary abdominal muscle group) is to bring your sternum closer to your pelvis. This only involves the first 30 degrees of movement from the horizontal position. Anything beyond that engages your hip flexors. The psoas (as their frequently called) attach at the front and top of the thigh, and wrap around to connect at the base of your spine. Whenever you perform a movement where you’re bringing your thigh closer to your torso, you use your psoas. So, if the upper part of your thighs has ever felt sore during Sit-Ups, that’s why. From an injury stand point, Sit-Ups tend to grind the vertebrae in the lower part of the spine. This can aggravate sensitive lower backs. Since we’re focusing on the abdominals rather than our hip flexors anyway, why not avoid potential lower back injury and just do crunches. Crunches ar
