Chafing is one of the most preventable marathon mistakes. With the right prep and a bit of skin‑care know‑how, you can keep friction from becoming a Finish-Line nightmare. Drawing on skin‑science expertise, Katherine Frizoni outlines how strategic use of Vaseline before, during and after a run can protect the skin in all weather conditions and even support recovery. We even have extra tips for those of you with sensitive skin.