Often the best way to pick out a running shoe is to go to a store and try them on. You might also want to pick up the shoe and bend it to see how sturdy the shank of the shoe is. "You shouldn't be able to [bend it], because the shank is the actual structure of the shoe, and should be rigid to hold up and support the arch," Dr. Cunha says. Squeezing the heel of the shoe will tell you how firm it is. "You shouldn't be able to compress it, so when you're running it supports the heel," he adds. As we said, be sure that the shoe is wide enough in the forefoot to prevent toe and toenail problems such as bunions and ingrown toenails.