They challenge hard to reach muscles more. FitFlops are engineered with a multi-density midsole that stimulates your muscles more while you're wearing them. In independent University testing, FitFlops have been shown to trigger increase gluteal muscle response, increased hamstring response, increase rectus femoris (thigh) response and increased calf muscle response .
Every step you take in your FitFlops helps tone and trim your legs: Studies at Salford University by Dr. Philip Graham-Smith and Richard Jones have shown that the FitFlop midsole extends the amount of time that the slow twitch* muscles are engaged during each step (by approximately 10-12%). So just by wearing a pair of FitFlops you'll get more exercise while doing just exactly what you're normally doing. (*slow twitch muscles produce energy by converting fats into energy aerobically)
FitFlops work your bum muscles more. FitFlops have been proven to increase the amount of time that the gluteus maximus muscle is 'activated' during every single step.
FitFlops have been shown to have a significant effect on the toning muscles of your thighs: The rectus femoris muscle (one of the large muscles in the group of muscles in your thigh) is activated for a longer period of time while walking in FitFlops than while normally shod or barefoot .
Walking in FitFlops is like walking barefoot, but a little bit better. According to a study done at the University of Salford in Manchester, UK, the FitFlop wearer's gait is very similar to that of a barefoot walker, but the added cushion provided by the EVA midsole helps reduce joint strain and absorb shock. In fact, several FitFlop wearers have already reported relief from back pain after a few days of wearing them.
FitFlops make it easier to stay in shape. Just throw them on while you're running errands, walking to work, or working around your house. Most first-time FitFlop wearers report feeling their muscles working more, while 'fitter' wearers feedback has been more toward great comfort and cushion. One woman reported feeling like she'd had a 'bum-blasting' workout after a half an hour of FitFlop-shod walking.