The immune system is a fighter. Every single minute it is hard at work locating, hunting, and attacking foreign invaders that come into the body. There are various factors that affect the health of the immune system and can lead to increases or suppressions of certain lymphocytes. Some of these factors include but are not limited to: exercise, nutrition, environment, stress, sleep, drugs, alcohol, and disease. With the focus being placed on exercise here, yes, to a point, exercise is great at increasing the efficiency and healthiness of the immune system4. However, with the increase in popularity of certain marathon sports, intense endurance exercise, and exhaustive training, questions are being raised about how well the immune system is adapting to such an extreme factor. Taking a look at many of the components of the immune system, low and moderate exercise can be contrasted with prolonged intense exercise in the ways that each affects immunity.

VERY BRIEF OVERVIEW OF THE IMMUNE SYSTEM
Each healthy individual is equipped with two branches of the immune system: innate and adaptive. The innate system is present at birth, works very quickly, develops no long-lasting immunity, and consists of the skin, mucous membranes, stomach acid, and phagocytic cells3. Phagocytic cells participate in the direct killing of b…

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