The foot sometimes hurts and sometimes does not hurt mainly due to three reasons: First, the local osteophytes or calcification of the place, activities may lead to local stimulation of the surrounding soft tissues is more obvious, so the symptoms of pain is more obvious, in the state of rest without the stimulation of the pain symptoms will be significantly improved. Second, the local formation of chronic inflammatory foci, such as plantar fasciitis, strenuous exercise and activities often occur when the symptoms of pain, generally after bed rest and the position of the lower limbs will be elevated, edema gradually subside, the symptoms can be significantly improved. Third, strain with cold, usually in the activities of the local blood circulation is better, the lactic acid and inflammation and other metabolites can be metabolized in a timely manner, so the symptoms are not obvious, but in the rest and cold easily lead to a decline in blood circulation, vasoconstriction, which leads to metabolite buildup, and therefore there will be a more obvious pain.