Itching in the legs after running may be caused by seasonal pruritus, blocked qi and blood, dry skin, capillary congestion, and other reasons. Here are the possible causes:

1. Seasonal Pruritus

Seasonal itching of the legs caused by dryness often exhibits distinct seasonal patterns, such as occurring during autumn and winter. However, if it occurs out of season, such as in spring or summer, it is advisable to consult a doctor for further examination. Certain internal organ diseases, such as diabetes, hyperthyroidism, uremia, and malignant tumors, can also cause itching in the legs, and such cases require prompt medical attention. Additionally, some itching may be caused by certain medications, including those used to treat diabetes, chronic kidney disease, chronic liver and gallbladder diseases, and blood-related conditions.

2. Blocked Qi and Blood

During running, the blood circulation accelerates and the body begins to sweat. However, for some people, their subcutaneous capillaries may be narrow, and their skin pores may be tightened, preventing the capillaries from tolerating the pressure caused by the accelerated blood flow. Additionally, the pores may be unable to eliminate sweat, resulting in itching sensations in the legs.

3. Dry Skin

Dry skin is a common cause of itching, and it can be triggered by various factors. As the air becomes drier in autumn and winter, more water is lost through breathing during running. Additionally, people may have less desire to drink water in cold weather, leading to a lack of moisture in the skin of the legs and triggering itching. Furthermore, many people prefer to take hot showers in cold weather and may use alkaline soaps or medicinal soaps, which can strip away the natural oils that help keep the skin moisturized, thereby exacerbating itching in the legs.

4. Capillary Congestion

Some people may notice that their legs become itchy after jogging. This is because the capillaries of those who do not exercise regularly are unused. When they become congested irregularly, they may expand, stimulating nearby nerve endings and sending a sensation of itching to the brain.