[duncanj]

This is actually a little paradoxical, because numerous reports have shown that strenuous exercise depresses the immune system by increasing glucocorticoid levels. The odd thing is that glucocorticoids cause an increase in circulating neutrophils, but some think that they are actually less available to fight infection, because usable neutrophils are found lining the postcapillary venules. All told, studies of the cold paint a complicated picture.