[Crunches to train abdominal muscles] In fact, the most commonly used sit-ups are not very effective in abdominal training. In comparison, crunches are more scientific and practical.

Action essentials:

1. Lie on your back on the floor mat, bend your knees to about 90 degrees, relax your back muscles and spine, and keep your legs together. Straighten with your feet flat on the ground.

2. Lift your body, keeping your lower back from the ground, stretch your hands to reach your calves, then return to the original position and repeat.