What does the single straight-leg stretch exercise challenge?

The single straight-leg stretch exercise primarily challenges the abdominal muscles with more extended straight legs. In this exercise, the legs are held in a position that requires significant core engagement to stabilize the pelvis and spine while the legs move. The extended position increases the demands on the abdominal muscles, as they must work harder to maintain alignment and control throughout the movement.

This exercise emphasizes the importance of core strength and stability, as the hip flexors and lower back muscles are also engaged, but the focus remains on the abdominal region. Maintaining proper form while extending the legs requires coordination and strength, making it an effective way to enhance core stability and strength.