Is the 300 to 500 mile rule for replacing running shoes founded on research? Do you really need to replace your shoes that often? Yes, says podiatrist Dan Michaels, DPM, who works with walkers and runners. “The midsole, found between the insole and the outsole, breaks down and wears out in this range,” he explains.
He says that the midsole of sneakers is usually composed of ethylene-vinyl acetate (EVA) or polyethylene-vinyl acetate (PEVA), and the material serves as a shock absorber. However, the rebound effectiveness decreases over time. “Running or walking without this shock-absorbing material fully intact could possibly lead to injuries,” cautions Dr. Michaels. That could mean stress fractures, shin splints, plantar fasciitis, or runner’s knee.