2. Although the method of "neck-hanging fitness" adopts the principle of clinical traction, it should not be operated blindly, because the maximum weight that a person's cervical vertebra can bear is about 25 kg, and "neck-hanging fitness" may directly damage nerves and spinal cord.

3. "Hanging the neck" has great hidden dangers for middle-aged and elderly people. The neck is the sensitive and central part of our body, and it is a high-risk part. Improper "hanging neck" may lead to a series of diseases, even fatal, such as high paraplegia. In addition, some middle-aged and elderly people have cervical diseases themselves, and many middle-aged and elderly people don't know the physiological curvature of their cervical vertebrae. Improper "hanging neck" will cause the change of physiological curvature, but it will cause nerve, blood vessel and even spinal cord injury near cervical vertebra. Medical cervical traction also needs to adjust the appropriate angle for treatment, so we must be cautious in doing this action and never imitate it blindly.