Your white blood cells are components in your immune system that actively seek out and fight various forms of infection. When you exercise, these cells increase their numbers and circulate more quickly through your body. If you don't exercise too much or too heavily, increased activity by your white blood cells can improve your ability to fight off viral and bacterial infections.
Your white blood cells are also called leukocytes. Along with your red blood cells, leukocytes form inside a spongy material called bone marrow, which forms part of the interior of large bones such as femurs and hip bones. While your leukocytes are commonly referred to simply as white blood cells, your immune system actually contains five major types of leukocytes, including monocytes, neutrophils, basophils and eosinophils, as well as lymphocytes, which are also called T cells and B cells.
Immune System Effects
When you exercise, elevations in the activity of your white blood cells may allow your body to identify disease-causing organisms more quickly than they would under normal circumstances, according to MedlinePlus. This effect may also result from the presence of other parts of your immune system, called antibodies, which also accelerate their activity level when you exercise. In addition to elevating your white blood cell count, exercise promotes other changes that can boost your health, including reduced production of stress hormones, a temporary increase in your body temperature and a flushing of potentially harmful bacteria from your lungs.
Typically, the intensity and duration of exercise required to boost your white blood cells are less than those required by a rigorous aerobic exercise routine. Even individuals who are new to exercise or only exercise moderately can enjoy the immune-boosting benefits of their activity. You can optimize physical activity's effects on your immune system if you get 20 to 30 minutes of exercise five days a week. Potential exercise options include brisk walking, bicycling and participation in relatively slow-paced games like golf.
Too Much Exercise
As far as your immune system goes, there is such a thing as too much exercise. While moderate exercise boosts your white blood cells, regular participation in physically challenging activities such as heavy weightlifting or marathon running can lead to significant decreases in your body's white blood cell count. Participation in this type of exercise can also increase your body's levels of harmful stress hormones. If you're a heavy exerciser, you can help avoid any potential for overtaxing your immune system by reviewing your current exercise routine with your doctor.