Running shoes provide important shock absorption and motion control for the wearer. A study investigating the change in shock-absorption properties of various models of running shoes in wear has shown shock absorption is a function of the number of miles run, with the energy absorption of running shoes, determined by the area under a load vs. deformation curve, steadily worsening over time in laboratory simulations equivalent to running up to 500 miles. The energy absorption properties of running shoes worn by volunteers were also measured during the course of normal training, for comparison. In general, the mechanically tested shoes retained 75% of their initial shock absorption capability after 50 miles, 67% after 100 to 150 miles and less than 60% of their initial shock-absorption capacity after a simulated 250-500 miles. By comparison, the shoes worn by volunteers retained a slightly higher 70% of their initial shock absorption characteristics by the end of the 500 mile trial. Some running shoes with superior initial shock absorption capability were found to degrade more rapidly in these trials, so initial comfort properties are not necessarily a good measure of performance in wear
LASRA has developed a test to plot this reduction in shock absorption performance in simulated wear, which is suitable for any kind of footwear. This technique has been successfully applied to footwear supplied in to the sports industry, and also trialled on safety footwear to simulate conditions of wear for people who are on their feet all day, where shock absorption is an important comfort feature.
Feel free to contact LASRA about this test if this topic interests you