Overview: what straight-leg sit-ups train and when to use them
Straight leg sit ups target your rectus abdominis while heavily recruiting the hip flexors—especially the iliopsoas. Since your legs stay extended throughout, the hip flexors contribute significantly to each rep, placing extra demand on the lower back and anterior hips compared to bent-knee variations. Your lower abs work to stabilize the movement, while deeper core muscles like the transverse abdominis and even parts of the quads assist along the way.
