I’ve heard this one time and time, again.

“Ah, I better not go outside to exercise today, I might catch a cold.”

or

“You could get sick if you exercise in the cold!”

NO.

These are statements which are not true.

Before I get into why, let’s talk about how I suspect this myth started: someone who was exercising outside on a regular basis experienced a sudden drop in temperature or change in weather from dry to wet, perhaps during their activity, or in day-to-day variability. For example, they rode their bike outside on Monday which was warm, and then on Tuesday which was cold, and on Wednesday they started to feel a sore throat and so thought “Ah, I shouldn’t have ridden my bike outside on Tuesday!” Wrong. Our immune systems don’t work like that and that line of thinking follows a confirmation bias and is not a valid argument.

Now, let’s talk about things that are bad for the immune system. In other words, all of the things on the list below are things that are going to weaken one’s immune system or, increase one’s susceptibility to illness.

• inadequate sleep/insomnia
• emotional stress
• inadequate nutrition (macro and micronutrients are both important)
• heavy alcohol consumption
• smoking
• improper use/abuse of prescription drugs
• abuse of psychoactive drugs
• physical stress (recovering from an injury, labour-intensive employment, or exercising beyond a level which one has been trained for)

Given all the factors listed above which can increase one’s susceptibility to illness, a lot of people could be dealing with a sum of many factors, leading to a weakened immune system. These factors do not need to be present together for very much time. For example, let’s say you are having a really busy week at work. This will likely cause some fatigue and stress. Chances are, your nutrition has also gone out the window, because if you are eating the majority of your meals “on the go”, you have less control over nutritional content, and decisions are being made in desperation given the limited parameters. Fatigue also brings on more food being consumed, because something has to keep you awake, and research shows we tend to choose to eat more sugar and caffeine under stress. There is a wealth of research showing that a majority of people living with obesity are getting less sleep than average.

After this busy week of work is done, let’s say you got really ambitious on Friday and you rode your bike to work. After all, you’ve been trying to “get into exercise” and you are working too much to attend any structured exercise program. Looking at the events which preceded Friday however, does it seem like adding more stress to the system (in this case, your body) is going to

a) accomplish the goal of adopting a more active lifestyle,

b) allow for adequate rest, or

c) allow you more time to choose nutritionally sound meals on the go?

Chances are, that one additional stress to the system (in this case, exercise) might be enough to put your immune system over the edge and allow a cold virus already living inside your nose to replicate. Even if the habit of cycle commuting is well-established, it can still be something that causes physiological stress. Certainly, too much rest can also bring on feelings of fatigue and lethargy, and some amount of activity keeps the mind agile and can provide some emotional stress relief. If the activity is too demanding however, it can have a detrimental effect.

While exercise, in general, is a very good thing, it’s best to make changes to it (adding it to your life, changing the intensity/duration/type/load) when your life is already feeling relatively stable. Since we seldom have a say in when our lives are stable or not, all we can do is modify our reactions accordingly. We humans are an ambitious bunch! Sometimes, our ambitions are far bigger than our current reality or ability to plan ahead. We treat exercise like it’s something that we should all be able to wake up and do without much thought into how or for what purpose. Yet, when executed with little precision, it can lead to much illness. Similar to learning how to drive a car – one is not just handed a license off the bat, one has to prove they have learned the rules of the road and how to safely operate a motorized vehicle. Exercise is a type of stress, complete with its own set of physiological effects. Take that into consideration when contemplating if exercising outside in the cold is really what made you catch a cold. What other stress factors could be present to consider?