Running in old or worn-out running shoes can lead to running injuries. Over time, your running shoes lose shock absorption, cushioning and stability. When you run in worn-out shoes, it increases the stress and impact on your legs and joints, which can cause overuse injuries. One of the best things you can do to prevent running injuries is to replace your shoes at the right time. Here's how you know that you need new running shoes:
1. The mileage on your shoes is high.
A good rule of thumb is to replace your running shoes every 300-400 miles, depending on your running style, body weight, and the surface on which you run. Smaller runners can get new shoes at the upper end of the recommendation while heavier runners should consider replacement shoes closer to 300 miles. If you run on rough roads, you’ll need to replace your shoes sooner than if you do primarily treadmill running. If you take good care of your running shoes, you may be able to get away with the higher end of that range.2. You're feeling pain.
If you've been feeling muscle fatigue, shin splints, or some pain in your joints -- especially your knees -- you may be wearing shoes that have lost their cushioning.3. Your shoes fail the twist test.
If you hold your running shoes at both ends and twist the shoe, it should feel firm. An old shoe or one that doesn't have proper support will twist easily (as in this photo).

