[sit-uhp] 
| an exercise in which a person lies flat on the back, lifts the torso to a sitting position, and then lies flat again without changing the position of the legs: formerly done with the legs straight but now usually done with the knees bent. |
| sit-up (sĭt'ŭp') n. A physical exercise in which one uses the abdominal muscles to raise the torso from a supine to a sitting position and then lies back down again without moving the legs. |