Exercise - a little known way to optimise immunity!
If you want to stay healthy this winter, don't forget about exercise - did you know it can cut your chances of catching a cold by up to 40%?!!!
While many people are aware of the role of nutrition and sleep in helping this immune system function, exercise is less commonly discussed. Yet its a vital part of a healthy immune system.
When we exercise, this helps our immune system in several ways
It directly improves immunity by:
improving blood and lymphtic circulation - this helps white blood cells move around our body and detect invader
helps to recruit highly specialized immune cells (such as natural killer cells and T cells) to find pathogens and fight them. Even a 45 min brisk walk boosts immune cells for up to three hours afterwards!
creating a rise in body temperature that may help fight off bugs
increasing the numbers of antibodies and white blood cells (which fight infection) and helping them work better
reducing chronic inflammation (which can suppress immunity)
boosting cytokines (inflammatory molecules) that fight infection
Exercise also helps immunity in other ways
It:
reduces stress levels and stress hormones (stress suppresses immunity). Exercise in nature reduces stress even more
improves sleep (lack of sleep reduces immune function)
boosts mood and neurotransmitters, which mean we are more likely make healthy lifestyle choices (reducing stress and improving sleep also helps this)
reduces the risk of health issues which affect immunity or make us more likely to get severe illness (ie diabetes, obesity, heart disease)
Regular (daily) moderate exercise of even 45min/day can reduce the number of viral respiratory infections by up to 50 %. Ie can halve the number of times you get sick over a year!!
This effect seems to be even more pronounced in previously sedentary people, or people who are overweight (ie it's never too late to start!). There is also some evidence that it can reduce risk of pneumonia and influenza
When we exercise at a moderate rate (ie enough to make you puffed when talking to someone, but not so much that you are breathless):
Our immune system instantly starts to work better, by sending immunoglobulin, white blood cells, and anti-inflammatory cytokines into our blood stream (all vital parts of immune functioning). It also temporarily increases the numbers of white blood cells
With repeated moderate excerise our body's ability to detect both pathogens (harmful bugs) and even cancer cells, is improved. It also reduces inflammation in the body
The physical act of excerise helps to 'flush' viruses and bacteria out of your airways
The rise in body temperature from excerise may also help stop bad bacteria from multiplying and causing infection
Exercise reduces stress hormones (cortisol), high cortisol can reduce immunity.
Exercise also boosts gut health (an important factor in immune function), by stimulating a bigger variety of healthy gut bacteria, and increasing levels of 'good' bacteria. See post on exercise and gut health for more details
It’s worth noting that intense prolonged excerise (ie running a marathon) may cause a transient reduction in immunity however, especially if adequate rest breaks aren’t taken.
Multiple studies in the past have shown that elite athletes, or endurance athletes, are more prone to infections while training heavily or competing. This is especially relevant if intense prolonged exercise is done during or just before infection (in particular with infections like covid - 19)
The drop in immunity with intense exercise is thought to be due to a temporary increase in inflammation (Th2 anti-inflammatory cytokines that reduce muscle tissue damage, but can get high enough to suppress the immune system), as well as a rise in stress hormones, and a temporary reduction in white blood cells.
There is some evidence that high dose vitamin C can help reduce the risk of viral infections with intense exercise, and also that increasing carbohydrates and polyphenol consumption with intense prolonged exercise, can help reduce this immune effect.
Managing other risk factors such as sleep and stress levels also can help.
It can be worth getting the advice of a sports medicine specialist if this is an issue for you
Did you know, the benefits of regular moderate excerise far outweigh any supplements you can take?!!
Exercise also becomes even more important the older we get!
As we age the immune system can become less effective and less active, leading to more frequent or severe infections
Exercise can also help to boost immune function in the elderly by:
Improving how well vaccines work
Increasing white blood cell levels
Reducing the number of 'worn out' t cells (a type of white blood cell that is affected by ageing)
Increasing anti-inflammatory cytokinesReducing 'inflammatory responses' to bacteria (ie reducing illness severity)
Improving the size and function of the thymus gland (which plays a key role in immunity)
Preventing sarcopenia (age related muscle loss) - muscle actually helps immune function
One study found that active 70 year olds had better immunity than sedentary 20 year olds!
And these are just the direct benefits to immunity - exercise in fresh air also helps mood, vitamin D levels, and literally gives you a breath of fresh air
In general, recommendations are for daily cardio at a moderate to vigorous intensity for 60 minutes or less, and if you do intense exercise ensure you get enough rest periods, and avoid doing while unwell.
What better reason do you need to get moving !
https://www.sciencedirect.com/.../pii/S2095254618301005
https://medlineplus.gov/ency/article/007165.htm
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7387807/