The plantar fascia is a band of connective tissue that runs along your sole, from the heel to the ball of your foot, and supports the arch. With continued stress, it, too, may flatten, stretch and tear. Running heads who lapse into funks and fits of guilt when they can't get their daily fix are especially susceptible. They never give the microtears a chance to mend. The penalty is chronic inflammation and pain, and, ultimately, perhaps, a bone spur.
More bone is sent in to beef up the attachment.
But because scar tissue is thick and dense, it heals tight. The pain begins to fade, so after a few days you start running again. But the scar tissue is weaker than normal tissue and more prone to ruptures. So you go out and tear it all over again. They're also vulnerable to such other degenerative diseases as osteoporosis and arteriosclerosis.