Developed by biomechanists at the Center for Human Performance at London’s Southbank University, FitFlops have been scientifically proven in independent studies to boost overall leg and calf muscle activity as you walk while reducing strain on your feet, knees and back. The secret is the varying density of EVA foam in the midsole that generates a “micro-wobbleboard™” effect to significantly increase muscular tension. The result: your legs work harder than they do in standard sneakers or shoes and you burn more calories.