Any sensible hardcore long-distance runner does this eventually. (Male runners, at least; sports brassiere probably grants invulnerability.) As all but the gentlest garments tend to chafe after a while, especially during cool weather, taping provides both a suitable prevention and cure for this painful condition. Nothing is more unpleasant than a raw and bloodied nipple with seven more miles to go (a condition I was in earlier today during a seventeen-mile harbor run. My nipples are taped now.)