Sitting abdominal muscle exerciser is a common fitness equipment, which can help to exercise abdominal muscles. The use of the sitting abdominal muscle exerciser is as follows:

1. Adjust the seat: sit in a chair with your feet flat on the ground, your back straight, and hold the handle with both hands.

2. Adjust the counterweight: adjust the weight of the counterweight according to your physical condition and exercise purpose.

3. Start practicing: sit in a chair with your feet flat on the ground, your back straight and your hands holding the handle. Then slowly lean back until your body makes a 90-degree angle with the ground. Hold this position for a few seconds, and then slowly return to the starting position. Repeat this action several times.