Aerobic exercises encompass those that cause your heart and lungs to work harder than in a resting state, and include swimming. A study reported in 2007 in the "Pakistani Journal of Physiology" showed that white blood cell count, or WBC count, is affected by aerobic exercises. Your WBCs help your body to fight infections, and a WBC count measures the amount of white blood cells found in a blood test.
White Blood Cells
White blood cells, also called leukocytes, are produced by your body in response to infections, allergic reactions or sometimes general stress. There are five main types of WBCs: lymphocytes, or B and T cells; monocytes; basophils; eosinophils and neutrophils. The National Institute of Health considers a WBC count of 4,500 to 10,000 WBC per microliter of blood to be normal. Your risk of infection increases when your white blood cell count is low.
Exercise and Immunity
According to the National Institute of Health, exercise helps your immune system to fight off bacterial and viral infections. One theory proposed for this effect is that exercises such as swimming increase the rate at which WBCs move through the body. This increased pace allows the possibility of earlier detection of infections by your body.
Aerobic Exercises
A 2007 study published in the "Pakistani Journal of Physiology" looked at the effect of exercise on different blood parameters, including WBC count. The researchers reported an almost two-fold increase in total WBC count after exercise in both male and female subjects. They concluded that exercise causes physiological stress on the body, which induces a significant increase in WBC count. This study supports the theory that swimming, an aerobic exercise, should have a similar effect on WBC count.
Conflicting Evidence
Six months of moderate aerobic exercise was found to have no effect on total WBC count, reported the journal "Mechianism of Aging and Development." Elderly subjects were asked to engage in moderate aerobic exercise three times per week for six months. Researchers found a small increase in T-cell proliferative response, but no change in total WBC count, leading to the conclusion that moderate exercise affects some immune responses in the body, but not others. This study suggests that exercises such as swimming may not increase your total WBC count over the long term, but will have an effect on your T-cell proliferation.
Consideration
Scientific evidence supports the concept that swimming and other exercises will improve your immune response. Whether it is a transient increase in total WBC count or an increase in the pace at which the WBCs move through your body, the positive effect cannot be discounted. Increase your physical activity to give your immune system a boost. But consult your doctor before doing so.
References
- Georgia State University: Exercise and Physical Fitness Page
- "Pakistani Journal of Physiology": The Effect of Exercise on Blood Parameters
- MedlinePlus: WBC Count
- Chemocare.com: Side Effects -- Symptoms and Solutions
- PubMed.gov: Effects of 6 Months of Moderate Aerobic Exercise on Immune Function in the Elderly
