Run long enough and far enough, and something will start to chafe. Maybe your thighs, maybe your bra straps, maybe some random spot that was never a problem on 10-mile runs but kills on a 12-miler.

Chafing is when skin becomes red, sore, and painful due to repeated rubbing of the same spot. To prevent chafing, lubricate the area, wear loose-fitting clothes, or try an anti-chafing stick. To heal ...