You peel off your running sock and – alas! – there it is: your first bruised toenail. Many runners view bruised toenails as a right of passage, but you are no less of a runner if you never get one. In ...

When Maria Delgado noticed a dark streak under her big toenail, she assumed it was from dropping her gym bag on her foot. Six months later, that seemingly innocent mark led to a diagnosis that saved ...