Running shoes are an ongoing investment for runners. Wearing worn- Not wearing running shoes makes it easier for runners to get hurt. According to a report from the American Journal of Sports Medicine 1985, running shoes lose about 60% of their shock absorption ability after using 250 to 500 miles of running. According to The Wall Street Journal, all brands wear similar running shoes. With this knowledge, running shoes should be retired after running about 300 miles. Depending on the shoes, terrain and individual runners, the running shoes will be worn differently. Check the shoes regularly for wear to determine when to buy new running shoes. Teaching difficulties: pay attention to the feeling of the body when running. Running shoes usually need to be replaced before any signs of wear appear. If the shoes don\'t feel as comfortable as before, it\'s time to change. The best sign that your shoes should retire is pain in the joints or bones after running. Pain symptoms include foot pain, knee pain, and leg pain. These pain symptoms suggest that your running shoes no longer provide shock absorption as before. Look at the condition of your running shoes. If the upper looks shabby or is about to be separated, it is time to return the shoes. Shoes should be retired if the upper is separated from the sole. Wearing in any part of the shoe means that they do not provide foot support or a suitable fit as before. Feel the inside of your running shoes. Is the insole obviously worn out, or is it lost and looks flat? If you answer yes, now is the time to retire your shoes as they do not provide adequate shock absorption. Check the soles of your running shoes. Does the sole look worn out? If they do, it\'s time to replace them. The worn sole does not provide proper traction. To make matters worse, uneven wear on the sole can cause incorrect position of the foot, which can cause back injury. To check if the sole of your running shoe is worn out evenly, place the shoes on the table. Kneel down and keep the shoes at the height of the eyes. If the shoes are tilted, the sole is worn out evenly. Tap the shoes with your hands and see if they shake. If the shoes shake, they will wear out evenly. The Tips & warningssources article by Rose KiviRose Kivi has been written for more than 10 years. She has a background in the area of care, wildlife restoration and habitat protection. Kivi has written educational textbooks, patient care brochures, animal husbandry guides, outdoor survival manuals, and has written contributors to two books in Uncle John\'s Bathroom Reader series.