Using our hands to release tension in our bodies is something we do instinctively. When you bang your shin it is and automatic reaction to hold your hurt leg or rub it better. You are thus releasing the disturbed energy from the traumatised part of your body through contact with the undisturbed energy of your hands. In effect you are re-balancing the traumatised area to restore it to its natural state of well-being, with harmony between the flow of energy, circulation and muscle tension.
Treatment of the feet and hands and of pressure points has been practised for thousands of years, the earliest known evidence of being a relief in a mastaba (funerary monument) at Saqqara in Egypt dated around 2,500-2,300 BC. The tomb was that of two priests of the royal palace, during the 5th dynasty of the Pharaohs.
The word "reflex" means to reflect. Pressure points on your feet and hands reflect all the parts of your body, both external and internal organs and glands as well as limbs, torso and head. Each point reflects the activity of another part of the body.