We all know there are a multitude of benefits from regular exercise, but did you know this also includes a positive impact on the functioning of the immune function?

Although exercise immunology is considered a relatively new area, some research shows that leading a physically active lifestyle reduces the incidence of communicable (e.g. bacterial and viral infections) and non-communicable diseases (e.g. cancer), indicating that immune competency is boosted by regular exercise bouts. Similar to a healthy varied diet, physical activity supports general good health and that includes a healthy immune system.

Research shows moderate levels of regular exercise at moderate intensity can reduce susceptibility to illness and lowers the risk of upper respiratory tract infections (URTI) like the common cold, compared with a sedentary lifestyle. Results from a group of 1002 adults (aged 18-85 years) studied for 12 weeks with monitoring of URTI symptoms and severity, found the number of days with URTI was 43% lower in subjects engaging in an average of 5 or more days per week of aerobic exercise (20 minute bouts or longer) compared with those who were largely sedentary (≤ 1 day/week).

There is increasing evidence that regular exercises stimulates a recirculation of key immune cells and facilitates an anti-inflammatory and antioxidant state through multiple mechanisms, which plays a critical role in immune defence activity.

In contrast, excessive amounts of exercise particularly by athletes who regularly perform prolonged high-intensity activity and high training volumes have been linked to reduced immune function, higher inflammation and oxidative stress than the rest of the population. This is most likely caused by the exercise triggering ‘stress hormones’. This is best described as a J-shaped curve, where moderate activity may be beneficial, yet sedentary or excessive behaviour has the inverse effect.

With this is mind and supported by a rigorous evidence review process, the Australian Department of Health recommend all adults aged 18 – 64 years to be active on most, preferable all, days of the week and to accumulate 2½ to 5 hours of moderate intensity physical activity or 75 to 150 minutes (1 ¼ to 2 ½ hours) of vigorous intensity physical activity, or an equivalent combination. Doing muscle strengthening activities is also recommended on at least 2 days each week.

Exercise confers multiple health benefits and getting the optimal daily dose of exercise is a critical part of the equation. So for good immune health, aim for the recommended dose: just enough exercise to strengthen your immune system but not too much to weaken it.

References

  1. Campbell JP and Turner JE. Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan. Front Immunol. 2018; 9:648.
  2. Simpson RJ, Campbell JP, Gleeson M et al. Can exercise affect immune function to increase susceptibility to infection? Exerc Immunol Rev. 2020; 26:8-22.
  3. Exercise, immune function and respiratory infection: An update on the influence of training and environmental stress. Immunol Cell Biol. 2016;94(2):132-9.
  4. The Australian Government Department of Health. Australia’s Physical Activity and Sedentary Behaviour Guidelines and the Australian 24-hour movement guidelines. Available at: https://www1.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-phys-act-guidelines
  5. Gleeson M. Immune function in sport and exercise. J Appl Physiol. 2007; 103(2):693-699.
  6. Nieman DC, Henson DA, Austin MD et al. Upper respiratory tract infection is reduced in physically fit and active adults. Br J Sports Med. 2011; 45(11):987-92.
  7. The compelling link between physical activity and the body’s defence system. J Sport Health Sci. 2019;8(3):201-217.