If the pain in the heel occurs when the big toe hits the ground, it may be caused by tenosynovitis, foot fracture, plantar fasciitis and heel bursitis. 1. Tendovaginitis: In ordinary sports, tendons and tendon sheaths repeatedly rub together, causing accumulated fatigue injury to the tendon sheaths, and prolonged injury will eventually lead to aseptic inflammation of the tendon sheaths, such as hyperplasia and degeneration, causing pain, swelling and other discomfort. When the big toe falls to the ground, it will cause irritation of the heel tendon sheath and painful symptoms. 2. Foot fracture: when the toe bone, heel bone and other bones of the foot are fractured, exercise will aggravate the degree of damage of the fracture, and cause pain and bruising to the surrounding soft tissues and nerves due to irritation. Thus, the big toe landing will cause pain in the heel. 3. Plantar fasciitis: long-term jogging, mountain climbing and other strenuous exercise will make the plantar fascia to withstand greater pressure and fatigue injury, resulting in aseptic inflammation and lead to pain. When the big toe falls on the unbalanced ground, it will enhance the inflammatory reaction of plantar fasciitis and cause heel pain. 4. Heel bursitis: due to repeated, long-term, continuous pressure when walking with the foot on the ground, causing inflammation of the heel bursa, when the big toe lands on the ground, it will cause the heel bursa inflammation symptoms to worsen, and feel the pain below the heel bone. There are many causes of heel pain when the big toe hits the ground, so it is recommended to go to the orthopedic department of the hospital for examination to clarify the cause.