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Onetrack Paper

Keeping Our Immune System Strong During Winter Training

Updated: Dec 21, 2021

We speak to Functional Medicine expert, Peter Williams, about how to keep our immune system strong while training in the cold weather.

As we come to the end of the year and Christmas is fast approaching, our daily runs will be featuring – more often than not – clouds, rain and temperatures below 10 degrees. The signs that it’s (regrettably) winter training time.

Winter training is dreaded by most runners, not just because of its unfriendly weather but also because of the impact it could have on our health. And so, we spoke to Functional Medicine expert, Peter Williams, to understand how our immune system works and how to stay healthy while training during the winter months.

Understanding our immune system

First of all, it is important that we understand our immune system for what it is and how it works.

“Our immune system represents our defence forces – our army, navy and air forces that defend us from the outside world,” Peter explains. “And it has two main components to it: the innate immunity, which is almost like the frontline soldiers patrolling the borders as a first line of defence.”

“And then it has this acquired immunity, which is the immunity that our body has developed after experiencing certain illnesses and it has fought it back,” he continues. "It’s the sort of immunity that vaccines are designed to develop in our bodies."

"The immune system’s job is to identify friends and enemies, letting in friends and protecting our bodies from enemies. The way in which our immune system protects us from viruses and bacteria is by triggering an immune reaction – which manifests itself with symptoms such as a cold, coughing and fever."

“So, when we are talking about strengthening our immune system, we might be using the wrong terminology because for some people you don’t want a more aggressive fight, you want a more efficient and balanced reaction that knows when to turn off, and that only really gets excited when real threats are present” Peter explains.

So, is our immune system weaker during winter?

Peter explains that there are two important factors as to why we tend to get more ill during the winter months. “First of all, the heat and sunshine of the summer tends to kill more viruses and infections – which means less opportunities to fall ill,” he says.

He also explains that there’s a direct connection between how much vitamin D (which we primarily receive from sunshine) we have in our body and how balanced and effective our immune system is. “There are vitamin D receptors on pretty much every cell in our body, so that shows it does a lot for us. The key thing is, we have to stock up on vitamin D during the summer months (for UK residents),” Pete explains. “By the time we get to October, where the sun is in the sky, it’s not high enough to give you any vitamin D at all, by November if you want effective sunshine you have to travel south past Lisbon. So if you want vitamin D in the winter in places like the UK, you can only gain it through diet (which he suggests is poor) or from supplements.”

This is true about the COVID-19 pandemic as well. A study published in the Irish Medical Journal has found “strong circumstantial evidence” that a lack of Vitamin D could be linked to the severity of our immune response to COVID-19.

How does exercise impact our immune system?

"Exercising, particularly during winter, is essential to help our immune system do its job effectively," Peter says. “When you exercise, you increase your blood flow, and that allows you to mobilise your ‘army’, which gets shipped off to where it needs to go, so that it can be more effective, known as immunosurveillance.”

He says that exercise also increases recruitment of immune cells and trains them to be more cytotoxic – which means that these cells are more easily taken around the body to patrol, and they will also be more effective at their job. Active populations can have a reduction in upper respiratory tract infections (URTI) by up to 50% compared to sedentary populations, but this is dependent on being consistent with the exercise.

Peter also explains that another caveat to this decreased risk of URTI is moderate, consistent, daily exercise rather than going all-out every so often. “The importance of exercising for our health is undeniable, but there can be sometimes a mismatch of the way we read research – in the case of exercising too often and too intensively, there is a potential risk of the immune system getting suppressed that we need to be aware of. However, this might be just the way the data is presented, and actually, due to the immune system being spread out all over the body the samples taken had less density of immune cells in them.” So potentially, a case of divide and conquer.

He explains that a lot people exercise nowadays but might not benefit from an immune system point of view because they don’t have a fundamental good enough grasp of how to exercise for their health.

He added: “I think this is why joining running groups such as Onetrack is essential because it helps people understand the fundamentals of periodisation and training load. Learning to listen to the body and assess how things are feeling is an essential part of training and not just about sticking to a plan.”

Members can now listen to the full conversation featuring Peter Williams, Anthony Fletcher & Andrea Gaini in RUN TALKS in the On Demand area here.

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