What it feels like: Tenderness or pain around the toenail.
Is it serious? Walkers can encounter various toenail conditions, including blood blisters, thickened toenails, toenails breaking down, and ingrown toenails, where the toenail pushes into the skin. All can be serious if they become infected, so seek treatment if pain persists more than a couple days. However, if you have diabetes or nerve damage, get your feet checked out immediately.
What causes it: Your sneakers are often to blame. If they're the wrong size, your toes repeatedly hit the front of the shoes, causing trauma to nails.
How to prevent it: Find shoes that fit. "Make sure the shoe is not too large so the foot slides with every step, and not too short because then your toes will hit the end," advises Gregory Clark, DPM, head of the Division of Podiatry at Scripps Clinic Medical Group in La Jolla, California. A little grooming also goes a long way: You can avoid these conditions by clipping toenails so just a small amount of nail extends over the skin. Don't trim nails too deep in the corners—this can cause ingrowns.
How to treat it: Stop exercising if nails are inflamed or painful. Ice and elevate the sore toe. Once the nail feels better, cut it to the proper length. A doctor will trim the affected portion of an ingrown toenail. In extreme cases, he may use local anesthesia to remove an entire side of the nail.