I suspect exercise is a great way to oxygenate the body and giving blood cells and immune system a boost to kill some of them, but definately not all of them. When looking under the microscope some are just too large for the immunesystem to even try to kill it's virtually immpossible as long as they are dead, and some are so threatening to the body, that the immunesystem backs off and avoids them according to one microscope researcher. She actually observed this under her microscope.