2. Old shoes are casual shoes and are not suitable for running. Casual shoes, after all, are just for leisure. Besides, the soles of old shoes are generally 4-6 cm high, and the soles are high and thick, which makes it easy to sprain your feet when climbing mountains or doing speed sports. The anti-slip shading of soles is not as deep as professional sports shoes, and it is easy to slip during high-intensity exercise, so wearing old shoes is not suitable for running.