Exercise has long been recommended as a way to improve the health of the immune system. Many theories exist as to why the increase in physical activity has a positive impact on immunity, some of which involve the production and movement of white blood cells. It appears that regular exercise, such as swimming, affects the number and speed of these disease-fighting cells.
Count
One way in which swimming improves white blood cells is its effect on their count. A study reported in 2007 by the Department of Physiology at the University of Sindh in Pakistan showed that 30 minutes of strenuous exercise -- in this case, jogging -- almost doubled the number of white blood cells in both men and women. As percentages go, women saw a greater benefit than men, coming in at a 196 percent increase as opposed to 193 percent. But it's the intensity, not the activity, of the exercise that affects this number, so you could see a similar increase in your white blood cell count when swimming at strenuous levels.
Movement
Another way in which swimming improves white blood cells is its effect on their movement. Like any physical activity, swimming causes an increase in heart rate to meet the need for oxygen within your skeletal muscles. This causes blood to move throughout the body at a faster rate than normal, and thereby does the same to white blood cells. The increased movement may help the immune system respond to pathogens earlier than normal, the National Institutes of Health suggests.
Benefits
The increased number and movement of white blood cells have the obvious benefit of improving the health of your immune system. A healthy immune system often means you're better able to fight off infections and illnesses. It may also decrease your risks of developing certain medical conditions, such as heart disease or cancer.
Recommendation
Before making changes to your level of physical activity, talk to your doctor. Even if you currently have a low white blood cell count, it's essential to talk to a medical professional prior to swimming for prolonged periods of time. He may have other recommendations for physical activities that better match your health and fitness level.
