I stretch before running. When I first start running the fronts of my calves (I suppose that would be the shin area) aches. After I warm up, they are fine. After I get more tired, they ache again. What do you suppose the deal is? They do not hurt at any other time. What are the proper stretches to do for this front calf/shin area...maybe I am not doing them right or not enough. Thanks for your input.