Heat rash and cholinergic urticaria are both causes of itchy legs while exercising. Treatment for these skin conditions is typically unnecessary; however, if you're itching does not lessen shortly after discontinuing exercising or your symptoms become worse, contact your family physician or a dermatologist.
Identification
Heat rashes often occur in skin folds and where your clothes rub against the skin. The skin will have small red bumps that itch or feel prickly. Once your skin cools, the bumps tend to disappear on their own. Cholinergic urticaria looks similar to a heat rash. With cholinergic urticaria, very small red welts appear on the legs or other areas of the body followed by an intense itch. The skin may also feel warm to the touch. The area of your legs affected will occasionally appear swollen if the welts form together, according to DermNet NZ.
Cause
Heat rashes and cholinergic urticaria are both caused by sweating. Heat rashes develop when sweat ducts become blocked and perspiration is unable to leave the skin. Wearing clothing while exercising that does not transfer perspiration away from the skin can trigger a heat rash. Cholinergic urticaria is also caused by sweating after your body temperature rises. Histamine is released by mast cells which cause the symptoms of urticaria. This histamine is the same chemical released if you experience an allergic reaction to foods, medications or other substances.
Treatment
Going to an air-conditioned room or standing in front of a fan until your body cools down is typically the only treatment you will need for both conditions. However, calamine lotion or cool compresses can soothe stubborn itching. Keeping your skin cool will clear a heat rash in seven to 10 days. The symptoms from cholinergic urticaria will typically disappear within 80 minutes, according to DermNet NZ.
Prevention
Avoid exercising outdoors during hot, humid days. Exercise in air-conditioned areas, decrease the intensity of your workout or try swimming for a full-body exercise that keeps your skin cool. Oral antihistamines or beta-blockers can be helpful at preventing hives associated with sweating while exercising. Wear loose cotton clothing and dress in layers so you're able to peal layers of clothing off if you begin sweating. Avoid lotions or ointments which block your pores and worsen the effects of perspiration becoming trapped under your skin.
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