The impact of exercise on immune function
Lifelong physical activity is a potent means of reducing the risk of non-communicable diseases including cancer, cardiovascular disease, and other chronic inflammatory disorders.
Evidence also shows that a physically active lifestyle diminishes the risk of contracting a range of communicable diseases including viral and bacterial infections, implying that immune competency is enhanced by regular exercise bouts.
However, to this day, research practice, academic teaching, and even physical activity promotion and prescription continues to consider a prevailing myth that vigorous exercise can temporarily suppress immune function.
In the first part of this review, the authors (both working in the complex field of immunology) deconstruct the key pillars which lay the foundation to this theory - referred to as the “open window” hypothesis - and highlight that:
- Limited reliable evidence exists to support the claim that vigorous exercise heightens risk of opportunistic infections;
- Purported changes to mucosal immunity, namely salivary IgA levels, after exercise do not signpost a period of immune suppression; and
- The dramatic reductions to lymphocyte numbers and function 1–2h after exercise reflects a transient and time-dependent redistribution of immune cells to peripheral tissues, resulting in a heightened state of immune surveillance and immune regulation, as opposed to immune suppression.
In the second part of this review, they provide evidence that frequent exercise enhances—rather than suppresses—immune competency, and highlight key findings from human vaccination studies which show heightened responses to bacterial and viral antigens following bouts of exercise.
Finally, in the third part of this review, it is highlighted that regular physical activity and frequent exercise might limit or delay aging of the immune system, providing further evidence that exercise is beneficial for immunological health.
The authors conclude that leading an active lifestyle is likely to be beneficial, rather than detrimental, to immune function, which may have implications for health and disease in older age.
> From: Campbell et al., Front Immunol 9 (2018) 648. All rights reserved to The Author(s). Click here for the online summary.