【Bend your knees and sit ups】mainly exercises the abdominal muscles. Lie flat on your back, cross your hands on your chest, bend your legs to 90°C, and place the soles of your feet flat on the ground. Use the strength of your abdomen to roll up your shoulders, upper back, lower back and other parts one by one until your body is raised about 45°C, against gravity, and hold for half a second. In reverse order, slowly lower the above parts back to the ground and return to the lying position. It is recommended to repeat it 12 to 15 times. The number of times can be increased or decreased according to personal physical condition.
