Running: Overtraining & Immunity

You should be convinced by now that overtraining has significant health consequences as a result of hormone shifts. Another question that arises is the effects on immunity.

Overtraining is associated with compromised mucosal immunity. This means that you are more prone to infection. It is clear that overtrained athletes have a decrease in salivary IgA. This is an immunoglobulin that serves to protect mucous linings. That means that when viruses or bacteria get into your nasal cavity or gut, you are more likely to suffer an infection because you have fewer antibodies in the area to defend you. Exercise Immunology Review 2004;10:107-28.

The immune system falls out of balance. Many of us have a general idea that people can have weak or strong immune systems. This black or white approach toward physiology is not accurate. Although I mentioned in the previous paragraph that mucosal immunity is compromised, we should understand this to mean that one component of immunity is compromised. It's not fair to say you have a globally weak immune system. One paper that speak to this point states:

" It is concluded that an increased incidence of illness associated with overtraining syndrome and in response to excessive exercise is not due to immunosuppression per se, but rather to an altered focus of immune function, with an up-regulation of humoral immunity and suppression of cell mediated immunity." Sports Medicine 2003;33(5):347-64.

This is the equivalent of our armed forces failing to cooperate during a time of war. While each branch may be powerful alone, there must be central coordination for success.

Another group of researchers echo this sentiment and states:
" Whereas athletes are not clinically immune deficient, it is possible that the combined effects of small changes in several immune parameters may compromise resistance to minor illnesses such as upper respiratory tract infection." Medicine and Science in Sports and Exercise 2000 Jul;32(7 Suppl):S369-76.

You can see that overtraining has major negative impact on the immune system.