Vibram 5 Finger Shoes is unstable, activates the muscles will have a positive impact on the entire body. Vibram Sprint FiveFingers stimulates the muscles of the legs and feet, which not only makes you stronger and healthier, but also improve your balance, flexibility and proprioception. Vibram Five Fingers Sprint improved muscle tone in calves thighs and buttocks. Vibram Treksport FiveFingers also stimulate the muscles of the legs and feet to strengthen and improve flexibility.