Regular Exercise Benefits Immunity – Even in Isolation

Over the last four decades, many studies have investigated how exercise affects the immune system. It is widely agreed that regular moderate intensity exercise is beneficial for immunity, but a view held by some is that more arduous exercise can suppress immune function, leading to an ‘open-window’ of heightened infection risk in the hours and days following exercise.

In a benchmark study in 2018, this ‘open window’ hypothesis was challenged by Dr Campbell and Dr Turner. They reported in a review article that the theory was not well supported by scientific evidence, summarizing that there is limited reliable evidence that exercise suppresses immunity, concluding instead that exercise is beneficial for immune function.

They say that, in the short term, exercise can help the immune system find and deal with pathogens, and in the long term, regular exercise slows down changes that happen to the immune system with ageing, therefore reducing the risk of infections.

In a new article, published this month, leading experts, including Dr Turner and Dr Campbell, debated whether the immune system can change in a negative or positive way after exercise, and whether or not athletes get more infections than the general population. The article concludes that infections are more likely to be linked to inadequate diet, psychological stress, insufficient sleep, travel and importantly, pathogen exposure at social gathering events like marathons – rather than the act of exercising itself.

Author Dr James Turner from our Department for Health explains: “Our work has concluded that there is very limited evidence for exercise directly increasing the risk of becoming infected with viruses. In the context of coronavirus and the conditions we find ourselves in today, the most important consideration is reducing your exposure from other people who may be carrying the virus. But people should not overlook the importance of staying fit, active and healthy during this period. Provided it is carried out in isolation – away from others – then regular, daily exercise will help better maintain the way the immune system works – not suppress it.”

Co-author, Dr John Campbell added: “People should not fear that their immune system will be suppressed by exercise placing them at increased risk of Coronavirus. Provided exercise is carried out according to latest government guidance on social distancing, regular exercise will have a tremendously positive effect on our health and wellbeing, both today and for the future.”

Regular moderate intensity aerobic exercise, such as walking, running or cycling is recommended, with the aim of achieving 150 minutes per week. Longer, more vigorous exercise would not be harmful, but if capacity to exercise is restricted due to a health condition or disability, the message is to ‘move more’ and that ‘something is better than nothing’. Resistance exercise has clear benefits for maintaining muscles, which also helps movement.

At this current time in particular, the researchers underline the importance of maintaining good personal hygiene when exercising, including thoroughly washing hands following exercise. To give the body its best chance at fighting off infections, they suggest in addition to doing regular exercise, people need to pay attention to the amount of sleep they get and maintain a healthy diet, that is energy balanced to account for energy that is used during exercise. They hope that this debate article will lead to a wave of new research exploring the beneficial effects of exercise on immune function.

Contacts and sources:
Andy Dunne

University of Bath

Publication: Can Exercise Affect Immune Function to Increase Susceptibility to Infection? Richard J Simpson, John P Campbell, Maree Gleeson, Karsten Krüger, David C Nieman, David B Pyne, James E Turner, Neil P Walsh. Exerc Immunol Rev, 2020