The outside of Laurence Socha's foot had been hurting for months. But the veteran marathoner kept running. "The pain would come and go, so I just ignored it," says Socha, 27, a teacher who lives in Washington, D.C. On a run one night, his sore foot rolled, and he had to limp home. Turns out, Socha had been disregarding a hairline fracture, and he had broken his fifth metatarsal. He needed surgery and was on crutches for six weeks.
Bad idea to ignore what your feet are trying to tell you. Obvious pains like Socha's, or merely visible imperfections like black toenails or calluses, often indicate imbalances that can lead to injury. "I like to compare foot care to the foundation of a house," says Roy DeFrancis, D.P.M., president of the New York State Podiatric Medical Association. "A house without a strong foundation is likely to crumble."
The Warning: Black Toenail
Black toenails, or "runners' toes," frequently plague distance runners. A common culprit? Not keeping your toenails closely clipped, says Dr. DeFrancis. If the end of the toenail jams into the shoe, the base of the nail wiggles enough to cause bleeding just below the surface. Shoes that are too tight can also cause the problem; try a half size larger or a higher toebox. The discoloration can also be a warning that you're running too many downhills, so keep your runs confined to flats.
The black part will grow out or fall off in a few months, but if you're in pain, a doctor can relieve the swelling by making a small hole in the nail plate.
The Warning: Calluses
Calluses, areas of thickened skin, form from repetitive pressure. "Calluses are a sign that the feet are getting a lot of force on one spot," says Leslie Campbell, D.P.M., a podiatrist in Dallas.
Overpronators frequently find calluses on the inside of their big toes or at the ends of their toes. Severe overpronators are susceptible to Achilles tendinitis, runner's knee, and shinsplints. Calluses that develop on the fifth toe or anywhere along the outside of the foot indicate outward rolling, or supination. Over time, supinators stress the outside of their feet and ankles, which can lead to sprains, tendinitis, and stress fractures.
A pair of stability shoes are the first treatment option for overpronation; cushioned shoes will support a supinator's high arch. More extreme cases may need an orthotic to correct the foot's motion.
Runners who have one foot that is more callused than the other may have an imbalance, such as leg–length discrepancy, which can often be fixed with a heel lift. Or it may indicate that you're simply stronger on one side. A physical therapist can help you develop a stretching and strengthening regimen to balance your gait—and help your feet evenly absorb the impact of each step.
The Warning: Bunions
When the joint at the base of the big toe faces extra pressure, it can swell and form a bunion: a bony protrusion on the side of the foot that may be painful as the big toe moves out of alignment. In extreme cases, the big toe overlaps the second and third toes. "Bunions tend to happen in runners with flat feet that roll in, because the muscles that stabilize the big toes don't work as well when the foot overpronates," says Stephen Pribut, D.P.M., a sports podiatrist in Washington, D.C.
Bunions don't have to hurt. Make sure your sneakers are wide and deep enough at the toebox, and avoid shoes with seams that rub against the problem joint. If you notice changes to your bunions or feel pain, consult a sports podiatrist. Orthotics can correct the pronation and slow the development of bunions—which require surgery to correct severe cases.
The Warning: Neuroma
A neuroma is an enlarged nerve, which most frequently occurs in the interspace between the third and fourth toes. Though neuromas aren't visible, you can definitely feel them: They can cause toe cramps or a more general pain in the ball of the foot. According to Dr. Campbell, hill running, which puts abnormal pressure on the ball of the foot, is a common cause of neuromas, so stick to the flats until the pain subsides. Your shoes might also be too tight in the toebox. Remove the insert, stand on it, and take a close look: If any portion of your foot is hanging over the insert, your shoes are too small.
The Warning: Plantar Fasciitis
Plantar fasciitis, which causes pain in the heel or arch, occurs when the connective fibers that run along the bottom of the foot become inflamed at the spot where they attach to the heel bone. The pain most often occurs in one foot, not both, says Dr. Pribut, because of a leg–length discrepancy or strength imbalance.
Runners who suffer from plantar fasciitis often have weak muscles in their feet. So try this exercise to strengthen your toes and feet: Keeping your heel on the floor, curl your toes down against a towel and try to drag it closer to you. Plantar fasciitis can also signal tight calf muscles, so Pribut recommends gentle stretching of those muscles to ease the pain and to prevent a recurrence.