Plantar fasciitis, the most common culprit for heel pain in adults, is caused by over-stretching and irritation in the plantar fascia band. This ligament attaches to the underside of your heel bone and runs the length of your sole to attach to your toes. It supports the arch and helps your foot absorb shock by stretching slightly when you take a step. However, too much pressure, repetitive impacts, and general overuse can strain the plantar fascia and contribute to micro-tears in the tissue. The ligament grows inflamed, irritated, and swollen, thickening and stiffening as a result.