The plantar fascia is a thick layer of tissue stretching from the calcaneus (heel bone) to the toes. It is in three segments:

1. Central portion: the most important. A thick portion of tissue running down the middle of the foot from the heel to the toes, forming the longitudinal arch of the foot.
2. Medial portion (inside of the foot).
3. Lateral portion (outside of foot).

What does it do?

It is an important structure providing us with a stable base to stand on and allowing us to propel ourselves forwards, absorbing shock while doing so. 

When we are standing the plantar fascia provides support to the arch of our foot. 

When moving forward, such as when walking or running, our foot becomes flat at mid-stance and the plantar fascia relaxes. This allows our foot to pronate (roll-in) and absorb shock. 
As we raise on to our toes to push off the ground the plantar fascia shortens, pulling up the arch of the foot allowing it to supinate (roll back out). This provides us with a stable base to push-off from. 

There is a link between the plantar fascia and the achilles tendon. As we raise on to our toes both of these structures contract, allowing the force generated from the calf to be transmitted to the foot to propel us forwards. 

How does it become injured?

Increased stress on the plantar fascia, or ‘overload’, can result in it becoming injured. The factors that can contribute to overload include:

• low arches (flat foot) or high arches
• Activities such as running or dancing 
• Increased Body Mass Index (BMI) in a sedentary population
• Incorrect or poorly fitting footwear
• Increased age
• Reduced ankle dorsiflexion
• Reduced 1st MTP (big toe) extension
• Prolonged standing in daily living
• Tightness in calf, hamstring and gluteal regions
• Imbalances in hip muscle strength

Stuart McKay
APA Physiotherapist