When doing supine cervical gymnastics, how long does it take at a time?
Sit-ups and cervical gymnastics are performed with head pads, also called spine pads, as shown in the figure below. You can do it for about three hours at a time-you do sit-ups and cervical gymnastics on its inclined plane, and put its customized pillow as an ordinary mattress when you don't want to do it. Please refer to!