In sporting events, it is not uncommon for athletes to accidentally break their feet while moving and lose their trophies. From a medical point of view, a broken foot can be avoided if some preventive measures are taken. One of the reasons is that the outer ankle is long and blocks the external rotation, but the main reason is that the ankle is subjected to inward horizontal shear force when the sport stops sharply. This force is proportional to speed and weight, often exceeding it. When the outer side of the shoe wears off, the foot is already in a state of mild inversion, making it more likely to invert and break the injury. From a biomechanical point of view, if the outer side of the shoe is thickened so that the ankle joint is in a neutral or mildly valgus position, the chances of inversion injury will be greatly reduced. If the width of the heel is 5cm, the outer side of the shoe will be padded 1cm, according to the principle of mechanics, 1/5 of the horizontal shear force will be decomposed into the longitudinal force, and the possibility of foot fracture will be greatly reduced. If the height of the shoe top exceeds the ankle joint, the broken foot will be even less likely to happen. However, high-top shoes may not feel flexible, so it is recommended that tennis players wear anti-fracture shoes with high soles and low soles. These shoes are not yet available on the market, but can be replaced by thicker insoles on the outside, and I believe there will be manufacturers producing these shoes in the near future.