What Are the Reasons for an Enlarged Buttocks Immediately After Sitting Down Post-Running?

Generally, sitting immediately after running and noticing an enlarged buttock may be caused by factors such as local poor blood circulation, accelerated fat accumulation, muscle relaxation without tightening, temporarily reduced metabolic rate, and obstructed lymphatic return. Detailed explanations are as follows:

1. Poor local blood circulation: After running, the blood vessels in the buttocks dilate, and sitting immediately compresses the blood vessels, causing slowed blood flow and accumulation of metabolic waste. Long-term effects may lead to swelling of the buttock tissues, making them appear larger visually. After running, it is advisable to walk slowly for 5–10 minutes and perform leg-stretching exercises such as lunges to promote blood circulation and avoid prolonged sitting that hinders blood flow.

2. Accelerated fat accumulation: Calories are burned during running, but sitting immediately afterward without continuing to expend energy may cause excess calories to convert into fat stored in the buttocks, especially noticeable when consuming high-calorie foods frequently. It is important to control total daily calorie intake. After running, choose low-calorie fruits such as apples and strawberries to replenish energy, and avoid high-fat foods such as cakes and potato chips.

3. Muscle relaxation without tightening: During running, the gluteal muscles contract. Sitting immediately afterward causes sudden muscle relaxation without timely stretching, potentially leading to loose muscle tone and an enlarged, saggy appearance over time. After running, perform gluteal tightening exercises such as glute bridges and side leg lifts, 15 repetitions per set, to help restore muscle firmness and improve buttock contours.

4. Temporarily reduced metabolic rate: After running, the body's metabolism remains elevated. Sitting immediately causes a rapid decline in metabolic activity and reduced calorie consumption, which may lead to fat accumulation in the buttocks. After running, engage in low-intensity activities such as walking or tidying up to maintain metabolic activity for more than 30 minutes before sitting down to rest.

5. Obstructed lymphatic return: Lymphatic circulation becomes active after running. Sitting immediately compresses the lymphatic tissues in the buttocks, impairing lymphatic fluid drainage and causing localized swelling. This makes the buttocks appear larger and may be accompanied by mild soreness or tightness. To promote lymphatic drainage, massage the buttocks using the palm in a clockwise direction for 5–10 minutes.

In daily life, avoid sitting or hunching over immediately after running. Maintain proper sitting posture to reduce pressure on the buttocks. Combine 2–3 weekly glute-strengthening exercises such as squats and lunges to enhance muscle strength, prevent fat accumulation, and maintain a normal buttock shape.