Over time running shoes lose stability and shock absorption capacity. Continuing to run in shoes well beyond their prime can increase the stress transferred to the feet and legs while running, particularly on hard pavement. Over time this added stress can lead to an overuse injury. A simple prevention strategy includes replacing running shoes when they wear out. While experts disagree on the specifics regarding the lifespan of a running shoe, there are some general recommendations that seem to be correlated with a reduced risk of injury to runners.