The “open-window” hypothesis
If you’ve ever heard that a bout of exercise can suppress your immunity, it was probably because of the “Open-Window” hypothesis. It says that the immune system is compromised in the hours after vigorous exercise, leading to an increased risk of opportunistic infections in the days thereafter. The problem is that this theory is based on very old evidence and hasn’t been revisited until recently.
A recent review tells a different story
Authors John P. Campbell and James E. Turner decided to investigate this hypothesis and published their findings in the journal Frontiers in Immunology in 2018. The title of their review speaks for itself – “Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan.”
They looked at the key pillars of the open-window hypothesis and found problems with all of them. They say that there’s limited reliable evidence to support the claim that vigorous exercise heightens the risk of opportunistic infections. They’ve also shown that changes to mucosal immunity after exercise do not signify a period of immune suppression. And they point out that the dramatic reductions of lymphocyte numbers and function 1–2 hours 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.
Regular exercise is beneficial for your immunity
This review also says epidemiological evidence indicates that frequent, structured exercise reduces the incidence of many chronic diseases in older age including communicable diseases such as viral and bacterial infections as well as non-communicable diseases such as cancer and chronic inflammatory disorders. Regular physical activity might even limit or delay ageing of the immune system.
Long rides are likely not a danger to your immunity
This new review of current research shows that the evidence for the claim that hard exercise suppresses immunity and makes people more susceptible to disease is weak. Plus, it also reconfirms the vast benefits regular exercise has on health and immunity in the long term. So, it seems like we don’t need to worry too much about long rides as long as we keep riding regularly.