Hands: put your hands on your sides, and you can cross your hands and stick them on your chest after you get used to it; After the ability is enhanced, you can open your elbows with your hands, put them on both sides of your head or gently pinch your ears.
Legs: Knees are bent at about 90 degrees, feet are hip width apart, and lie flat on the bed. When doing sit-ups with your hands on your head, in order to make up for the lack of abdominal strength, you often pull your head and neck forward with your arms, driving the whole trunk forward.
Holding your head with both hands will lead to back bending and lumbar disc compression. In addition, subconsciously holding your head with your hands will inevitably increase the pressure on the cervical spine. Don't leave the waist and coccyx (below the sacrum) on the ground, otherwise the coccyx will be forcibly rubbed, causing discomfort or backache of the coccyx, and even piercing the skin at the coccyx.
After doing sit-ups, you can stretch your limbs and lie flat on the bed, use your arms and elbows as support, make your back leave the bed a little, then relax and lie on your back, and repeat for 3~5 times.