When the four plantar muscles underneath it become weak or deconditioned, the plantar fascia sustains more stress with each step, triggering inflammation. Indeed, many cases involve a stabbing, stepped-on-a-nail sensation near the back of the foot, especially first thing in the morning.īut the plantar fascia is a thick band of tissue that runs all the way from your heel to the base of your toes. If runners know the term, they probably associate it with heel pain, Conenello says. In some cases, arch pain when running signals plantar fasciitis.
