If you’ve ever returned from a long walk on a hot day and noticed blotchy, red, or purplish marks on your legs, you might have experienced exercise-induced vasculitis (EIV). While the term sounds alarming, this condition is usually harmless and resolves on its own within a few days. However, its sudden appearance can be startling, as it can sometimes resemble more serious skin or vascular conditions.

Often referred to by nicknames such as “Disney Rash,” “Golfer’s Rash,” “Hiker’s Rash,” or “Golfer’s Vasculitis,” EIV is surprisingly common. Active adults, especially those over 50, are most frequently affected. Even individuals who consider themselves healthy, fit, and free of chronic conditions can develop it after extended periods of walking, standing, or physical activity in warm weather.

This comprehensive guide explores what exercise-induced vasculitis is, why it occurs, who is most at risk, and how to distinguish it from more serious medical conditions.

What Is Exercise-Induced Vasculitis?

Exercise-induced vasculitis is a temporary inflammation of the small blood vessels—capillaries—in the lower legs. The rash generally appears around the ankles, calves, and shins, though in some cases, it may extend toward the thighs.

The condition is closely linked to circulatory changes and heat regulation during physical activity. When you exercise, particularly in hot weather, your body increases blood flow to the skin to release heat. This increased blood flow, combined with gravity and prolonged exertion, can cause blood to pool in the lower legs. When circulation back to the heart is slowed, the small blood vessels may become inflamed, leading to the appearance of the distinctive rash.

The marks can appear red, purplish, or blotchy and sometimes resemble bruises. Because of their appearance, many individuals initially mistake EIV for allergic reactions, insect bites, or skin infections.