What is the starting position for performing crunches?

The starting position for performing crunches involves lying on your back with your knees bent and your feet flat on the ground, while your hands are typically placed across your chest or behind your head. This position stabilizes the lower back and allows for effective engagement of the abdominal muscles during the exercise.

When the knees are bent, the pelvis is tilted slightly backward, which helps to reduce strain on the lower back and encourages a more controlled movement as you lift your shoulders off the ground. This position is essential for optimal form during crunches, ensuring that the focus remains on strengthening the core muscles while minimizing the risk of injury.

In contrast, the other options do not provide the suitable setup for performing crunches effectively. For example, lying flat with legs straight may lack the necessary engagement of the core and can place undue stress on the lower back. Similarly, being on your stomach or sitting upright does not facilitate the specific motion required for crunches.