Exercise and your immune system: What you need to know
With the current lockdown Australians are facing, many are trying to figure out a means to keep healthy that is safe, responsible, and doesn’t expose themselves or others to COVID-19. This has become a hot topic for discussion in the news and media and many mixed messages have been flying around. These mixed messages muddy the waters and confuse people: Will exercise make my immune system less effective? Will it improve my immune system? Are the two even related?!
Fear not, in this blog post we’ll be looking at a 2019 review published in the Journal of Sport and Health Science, outlining the link between exercise and the body’s immune system.
The compelling link between physical activity and the body’s defense system
The human body is fantastically complex and there’s a whole lot about it that we don’t understand. Thankfully, the authors of this review collected information from four of the hottest areas in immune research to see what effect, if any, exercise has. We outline the results (and their implications for you) below! First off we’ll look at the benefits your immune system can gain from exercise, and what amount of exercise provides the most benefit. Then, we’ll address the talking point that some exercise can weaken your immune system.
Short(ish) bouts of exercise are GREAT for your immune system
The researchers from this review found that short (defined as less than 60 minutes) of exercise have an interesting effect on your body’s defenses. Moderate to vigorous intensity exercise within this shorter timeframe increases the ‘alertness’ of many of the components of your immune system without releasing an excessive amount of stress hormones. To understand this, it’s good to have a picture of what stress hormones do in your body. Stress hormones are released when your body is working very hard (or anticipating that it will have to work very hard) and actually suppress immune cell function, while increasing the amount of inflammation in your body. Meanwhile, the increased ‘immunosurveilance’ (alertness) your immune system gains from exercise helps you detect disease-causing agents earlier, before they have a chance to settle or spread.
So basically, short bouts of exercise increase the sensitivity of your body’s natural surveillance system – how cool!
Regular exercise can reduce bodily inflammation
Another benefit of exercise that has been reported is that regular exercise lowers levels of systemic inflammation. Despite moderate to intense exercise increasing your inflammation levels for a brief period after exercise, people who exercise on the regular have been found to have lower resting inflammation levels than their peers. Inflammation is a regular part of the immune response, however the process of inflammation (and managing it) is quite intensive for your body. Thus, having a lower amount of baseline inflammation can help your body allocate more energy to fighting diseases and illnesses that require an immune response. In essence, regular exercise leaves you with an increased reserve to fight illness should that situation arise.
Oldies take note: Exercise decreases immunosenescence
As we get older, we inevitably start to see things slow down. Touch footy becomes bingo, and a walk to the shops starts looking like a half marathon. Don’t give up just yet though! More and more evidence in many different faculties studying the human body is revealing that we may have some control over this!
As everything else slows down, there’s a potential for the immune system to slow down and it’s function to weaken. This is called immunosenescence (in some circles, this is also known as ‘that word that’s near impossible to play in scrabble). Immunosenescence affects some parts of your immune system more than others, but the overall result is a bit of a slowdown. Thankfully it looks like exercise can slow and even delay the development of immunosenescence, giving your body enhanced responses to vaccines, as well as increased numbers of a whole host of the bug-killing immuno-good-guys in your blood, and (again) decreased levels of inflammatory markers.
So is exercise ever bad for my immune system?
Like the strawberry in neopolitan ice cream, every good thing usually has a little bit of bad to come with it. The same is true with exercise, but it’s probably not as bad as you think…
As it turns out, when you exercise at a very high intensity, it can have a short term effect of suppressing your immune system. To give you a picture of the intensity of exercise we’re talking about here – in a study of 2361 marathon runners, 13% reported feeling unwell at some point in the week after their big race, vs only 2.2% of people the same age who didn’t run a marathon.
This is because of the increased stress and demands that intense exercise puts on your body – it redirects some energy away from your immune system to make sure you don’t completely collapse. The good news is that you recover fairly quickly, however in the midst of a pandemic such as COVID-19, it stands as good advice to keep your workouts to a more moderate / vigorous tone, and limit the high intensity stuff.
Sure vigorous is a cool word… but what does moderate to vigorous exercise look like?!
For a bit of guidance here, we can turn to the Australian Government’s physical fitness guidelines as well as recommendations from Exercise and Sports Science Australia (ESSA). The ESSA defines moderate activity as exercise that rates between 2 and 4 out of 10 in difficulty (where 10 means you are working as hard as you possibly could) – or 55-70% of HR max for those nerds out there with heart rate monitors. Vigorous exercise is that from 70-90% of HR max, or 5-6 out of 10.
The government has given out a guideline of how much of each type of activity you should be doing: Adults are recommended to do 75-150 minutes (2.5hrs) of vigorous activity per week, or 150 to 300 minutes (5hrs) of moderate exercise per week, or a mix of the two.
So our recommendation, out of that, is thus:
If you’re looking to exercise in a manner that maximally boosts your immune system, aim to exercise 4-5x per week, for between 40 to 60 minutes, at a difficulty between 3 and 6 out of 10 (where 10 is the hardest you could possibly work).
Stuck for how to put this all to action?
If you want any help designing a program that fits this bill, or have an injury or condition that you’re worried might affect your response to exercise, give us a call on (02) 8411 2050. We’ll be more than happy to help you figure out an exercise program that works with your body and your schedule to achieve your goals. We are conveniently located near Beecroft, Cherrybrook, Hornsby, Normanhurst, Pennant Hills, Waitara, Wahroonga, Westleigh, West Pennant Hills, and West Pymble. We are also offering online consults so that you can benefit from our physiotherapists from the benefit of your own home.
Many thanks,
Pearce, Tina, Emilie, Debbie, Dan, and Henry
The Team at Thornleigh Performance Physiotherapy
11/2-4 Central Avenue
Thornleigh, NSW 2120
(02) 8411 2050
W: www.thornleighphysio.com.au
E: hello@thornleighphysio.com.au
References:
Brown W, Bauman A, Bull F, Burton N. Development of Evidence Based Physical Activity Recommendations for Adults (18-64 years). Health.gov. (2012). https://www1.health.gov.au/internet/main/publishing.nsf/Content/3768EA4DC0BF11D0CA257BF0001ED77E/$File/DEBPA%20Adults.PDF
Nieman DC, Wentz LM. The compelling link between physical activity and the body's defense system. J Sport Health Sci. 2019;8(3):201–217. doi:10.1016/j.jshs.2018.09.009
Norton K, Norton L, Sadgrove D. Position statement on physical activity and exercise intensity terminology. J. Science and Medicine in Sport. 2009; 10.1016/j.jsams.2009.09.008