What are the Effects of Exercise on the Immune System?
The COVID-19 pandemic has left many of us feeling vulnerable.
We know the benefits of regular hand washing, the use of antibacterial sanitizer, social distancing and isolation, and of wearing masks and gloves but is there anything else we can do to help protect ourselves against this potentially deadly virus?
Exercise can’t prevent or cure COVID-19 but exercise can have a positive impact on the immune system and our body’s ability to resist and beat illness like Coronavirus.
And of course, supporting your exercise regime with good diet habits will help you to maintain a healthy immune system, too.
Exercise and the Immune System
David Nieman, a professor of public health and director of the Human Performance Lab at Appalachian State University, told TIME Magazine that being physically active is the best thing you can do to ‘decrease the number of days you suffer from a common cold’
We know that if you take part in moderate exercise, you’re less likely to develop an upper respiratory tract infection (URTI) than someone who doesn’t regularly exercise.
URTIs are illnesses like the common cold and tonsillitis.
The average American adult, for example, can expect to contract between 2 and 3 URTIs each year.
Researchers found that 1-2 hours of moderate exercise a day, reduced the risk of getting a URTI by a third.
Which is a pretty big reduction.
How Does Exercise Effect the Immune System?
There are a lot of theories into how exercise helps boost the immune system, but there’s not one single answer.
Medline Plus on the US National Library of Health Website reports that: It could be that physical activity flushes bacteria away and out of the lungs, reducing your chance of developing an illness.
Exercise causes white blood cells to circulate more quickly in the body, so it could mean they’re able to find illnesses earlier than might otherwise have been the case.
A rise in body temperature could help the body fight the infection more efficiently.
Exercise slows the body’s release of stress hormones and we know stress weakens the immune response.
It could also be that exercise encourages good sleeping practices which has an impact on immunity.
Equally, people who exercise are more likely to have a healthier lifestyle and diet. Poor nutrition, smoking and drinking alcohol, for example, are known to impact the immune system.
How Long to Boost Immunity?
One study published in 2017 in Brain, Behaviour and Immunity, found that just 20 minutes of exercise could have an impact on the immune system.
Blood samples taken from participants found a decrease in immune cells called tumour necrosis factor (TNF).
Healthy.com explains why this is important: exercise releases hormones into the bloodstream that suppresses TNF and whilst TNF can benefit the body, it also has inflammatory properties which can lead to autoimmune diseases like arthritis and multiple sclerosis.
What’s the Best Exercise for the Immune System?
Professor David Nieman also told TIME that brisk walking, cycling and ‘easy running’, are amongst the best things you can do. At the moment, there’s not enough research on weightlifting but it could be equally effective.
To maintain good health, the NHS recommends either 150 minutes each week of moderate activity (walking, gardening, hiking, etc) or 70 minutes of intense activity (running, aerobics, etc).
Short intense bouts of exercise appear to be good for our immune system, but there’s evidence that overtraining or intensive training (the sort undertaken pre-marathon or by athletes in the run-up to a competition) can reduce immune function.
Overtraining and the Immune System
Research has shown that following intense bouts of exercise, immune function could drop for up to 72-hours afterwards. The body appears to release certain hormones that cause a temporary drop in the immune system.
Intense exercise is stressful on the body. We all know we’re supposed to incorporate recovery and rest days into our schedules, but sometimes that’s not possible in the run-up to a big event or race.
One study after the Los Angeles Marathon showed that post-event, 1 in 7 runners got sick. It also found that those running 60+ miles a week in the two-month run-up to the race were twice as likely to get ill as those only running 20+.
It’s believed that for between 48 and 72 hours after an intense period of exercise, the release of stress hormones like cortisol and adrenaline leads to a decrease in T-cell production. T-cells are white blood cells that fight off infection. Fewer T-cells mean that infections have a greater chance of taking root in the body.
But research published in 2018, suggests that overtraining and a drop in immune function might not be connected at all. The authors argue that the benefits of endurance exercise outweigh the risks and they point to other factors that could explain why intense exercisers are more prone to respiratory infections, believing that events where large groups of people are near one another, sleep disruption, inadequate diet, getting cold and wet, and psychological stress could all explain why infection is more prevalent.
Exercise and the Coronavirus
Exercise is key to maintaining our physical health and wellbeing. During the current COVID-19 pandemic, it’s more important than ever. Taking advantage of Government advice on exercise during the lockdown and by exercising once each day, should be something we’re all taking seriously.
Fit and healthy people can catch Coronavirus. Runners, weightlifters, cyclists, athletes have died from it, too. Don’t assume that because you used to hit the gym every day or that you run 10 miles on the weekends means you can’t catch it, spread it or die from it. You can.
Exercise is an immune booster but it’s not a magic bullet.
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