What’s wrong with situps?
Traditional situps emphasize sitting up rather than merely pulling your sternum down to meet your pelvis. The action of the psoas muscles, which run from the lower back around to the front of the thighs, is to pull the thighs closer to the torso. This action is the major component in sitting up. Because of this, situps primarily engage the psoas making them inefficient at exercising your abs. More importantly, they also grind the vertebrae in your lower back. They’re inefficient because the psoas work best when the legs are close to straight (as they are when doing situps), so for most of the situp the psoas are doing most of the work and the abs are just stabilising. Putting the thighs at a right angle to the torso to begin with means that the psoas can’t pull it any further, so all of the stress is placed on the abs. Situps also grind vertebrae in your lower back. This is because to work the abs effectively you are trying to make the lower back round, but tension in the psoas encoura
