Lower leg fatigue may be induced through foot pronation. Pronation of the foot causes a general muscle imbalance to occur. As your feet pronate, your leg is no longer aligned properly, so your leg and foot muscles must work harder to give you the support usually provided by your bones. The muscles fatigue, causing pain and discomfort. Your feet are your foundation. Without a good foundation, the other joints and muscle groups in your body suffer. Therefore, leg fatigue may be directly related to pronated feet.