Updated: Mar 24
Typically plantar fasciitis is described as pain in the heel that progressively worsens with time, sometimes spreading to the arch of the foot. It often comes and goes and is of varying intensities. These symptoms are considered chronic if they persist for longer than 3 months and recurrent if they come and go. It is possible to have both chronic and recurrent pain with bouts of pain lasting longer than 3 months at a time. A large contributor to this is the inflammatory process of the body.
There are two main types of inflammation: that from the immune system in response to injury or emotional stress, and that which is directly driven by the nervous system - neurogenic inflammation. When a nerve is sensitive, lots of signals get sent to the spinal cord, which then transfers the message to the brain where it is interpreted. The brain then "decides" how to respond. If it is stressed, it will often default to "protection mode" and cause longer-lasting pain.
Muscles respond to pain by contracting, placing pressure on a nerve that travels along the back of the leg (tibial nerve) and its branches (medial and lateral plantar nerves) on the bottom of the foot. One branch of the lateral plantar nerve travels to the front of the heel bone and is often the first site of discomfort in this condition (the same area the plantar fascia attaches). The medial plantar nerve travels along the arch of the foot, where pain is often felt in chronic plantar fasciitis. That's an interesting phenomenon that happens with nerves: the more sensitive they become, the further down the extremity symptoms are felt. Pressure on the sensitized nerves of the bottom of the foot causes inflammation, increasing pressure in this area and making your first steps in the morning very uncomfortable. When you sit or lie down, inflammation from the irritated nerves may settle between the cells of the soft tissues and the next time you stand you will feel pain.
After striking my heel directly on a rock at scout camp, I had recurrent pain in my heel for about a year and a half. This pain was initially due to tissue damage and irritation of the fat pad at the bottom of my heel, but I knew the tissue would heal in 3 months or less. It didn't make any sense to me that it would keep hurting when I knew there was no longer damage to that area. It would become irritated when I exercised or when I ran, and it would stay sensitive for a couple days after doing those activities. Why did the tissue repetitively become irritated? The nerves in the area were continuing to produce inflammation long after the healing had occurred. I'm not sure why this happens and there's no predicting when it will happen. It was annoying, but I knew eventually it would go away, and it did.
An important question to address here is: What causes inflammation? Inflammation is a key part of the body's natural healing process and happens immediately following most injuries. Inflammation helps protect the area and fights infection. The inflammation releases chemicals that make nerves more sensitive, increases pressure on the tissues in the area around the injury, and ultimately slows us down so the structures aren't injured further. The inflammation shouldn't stay present after healing has occurred and the threat of infection is gone.
Chronic inflammation is when the swelling hangs around for longer than it is needed. It's like those visitors that overstay their welcome. They're not wanted or needed and can be annoying. Joint and muscle stiffness is most likely because of inflammation that has settled into the area. Systemic inflammation is a little different. It doesn't require an injury to be present; it can be present throughout the body (system) for prolonged periods of time. This inflammation (present in both rheumatoid arthritis and osteoarthritis) can be very limiting and of great concern. Several things affect the levels of inflammation in the body. Stress (psychological and physical) is a major driver of the body's inflammatory response. Frequent exercise, dietary changes, and decreasing stress may have a very positive effect on nerve sensitivity because these habits can alter the inflammatory response. Understanding pain can help reduce the inflammatory response by decreasing the psychological impact of pain and the fear associated with it. Early understanding and confrontation of pain-related issues leads to quicker recovery and reduced likelihood of developing chronic pain.