How to acclimatize to changing seasons: The science

Running in the dead of winter could not be more different than in the heat of the summer. Almost everything about it is different from what you wear, your top safety concerns to what you feel like when you’re giving it your all. But this doesn’t just relate to exercising in the great outdoors it can apply to working outside too. I live in Nova Scotia on the Atlantic Coast of Canada and our season changes (particularly spring/summer) can feel a lot like someone flipping a light switch. One day it’s 10 c and feels almost like winter and the next day you’re into the 20’s. Whether you’re working outdoors or working out outdoors the considerations are very similar but it’s always a little tougher when the seasons are actively changing. In November those first few days around 5 degrees are pretty tough but fast forward to February and people are wearing T-shirts at that temperature. If you’ve ever wondered about how your body copes with these big swings in temperature I have too! Let’s go ahead and jump into the science of how your body adapts throughout the year.

This time I’ve decided to incorporate the peer reviewed scientific literature a little differently. Since in line citations can break up the flow for some I’ve included citations and links to the articles referenced at the end of this post only.

Be consistent throughout the year

One of the best ways to minimize the discomfort of the changing season is to stay consistent in your outdoor activities. Depending on where you live a few weeks off running might mean the weather is substantially different when you return. If on the other hand you’re out there every week, or multiple times a week, you just adapt and change along with the weather. That doesn’t mean you’ll be perfectly suited to the weather on every workout though. Cold fall days and hot as hell spring days do pop up unexpectedly from time to time. 

Give yourself some time 

It’s kind of a weird combination of points here. One is that basically the only way to acclimatize to changing weather is to get out there in it. The other is to take it really easy for a period of time when it does. There has been a lot of scientific study done on how athletes and workers get used to and preform in changing weather conditions so we can confidently know what we should do. There is some variability from person to person but people mostly acclimatize in 7-14 days and continue to adapt more slowly for 30 days. For that period of time get out there at the time you would normally work out but lower the intensity and maybe the duration. For me when it comes to running I’ll normally either jog that week really, really slowly and take an unlimited number of walk breaks too with absolutely zero guilt. You also don’t have to workout for as long as you normally would. 

We also know that every hot or cold workout contributes to acclimatization even if those conditions don’t last because athletes that exercise one every three days in the heat acclimatize to a similar degree to those that are heat stressed every day. That means getting out there those few hot days in May or June are setting you up well for July and August.

Since we also work outdoors and are responsible for the safety of others that first week when the heat hits we make sure to dial way back what we expect people to get done in a day. We make sure people take lots of breaks in the shade and have lots of cold drinks on hand. We will also try to tackle ‘easy’ tasks and maybe even call the day short too. There’s more specific information below on hot and cold acclimatization.

Recognize the limitations of the weather

It should be noted that either a hot spell in the summer or a cold snap in the winter can lead to another alcimitiztion period. Whether hot or cold there comes a point where you just shouldn’t be outdoors. There is no real way to say how hot or cold is too hot for anyone to be outside exercising. It depends on a lot of factors like:

  • How extreme your regular temperatures are (think Alaska vs Arizona)
  • Whether you tolerate hot or cold better in general
  • The gear you have access to
  • How effectively your body cools or keeps warm
  • How healthy you are generally (healthier people adapt faster and to a greater degree)

Personally I can tolerate the heat a lot better than I can handle the cold though neither get to really universally dangerous levels here. The point I’m getting at is it can be too hot or too cold for you on a given day but someone else is out there that’s totally okay. Even though I run long distances in heat warnings pretty regularly in training there are days I just have to turn a speed workout into an easy run. On the other hand lots of runners dp finish and and complete the hypothermic half but in the cold of winter I just can’t bring myself to run past the hour point and that’s totally okay.

Hot weather acclimatization

Let’s go ahead and get into the nerdy science stuff then shall we? Most of the issues we experience when those summer vibes hit is actually due to Newton’s law of cooling. Since there is a lower difference between body temperature and the air heat is disputed more slowly at higher temperatures keeping you feeling steamy. Humidity makes this worse by limiting evaporative cooling.

During this acclimatization period getting dehydrated or overheated are the most pressing issues. After you acclimatize in a week or two your sweat production will actually go up in volume and area and you might even start sweating sooner. While this change is getting established you won’t be sweating as much as you should for the temperature and you are at risk for heat stroke. In your acclimatization period you’ll want to drastically reduce and then slowly reintroduce shorter bursts of high intensity training. In practice what I do is just run with no expectations when that hot weather switch is flipped. If I’m feeling really terrible for one or two of those runs I’m also okay with calling it early.

The cool thing though is after those couple of weeks of potentially terrible workouts your body will actually change in measurable ways to deal with the heat. You will have higher blood lactate levels and maybe faster muscle glycogen depletion along with an increase in blood volume. These changes make you more resistant to dehydration which is really important but should also make your hot weather workouts suck a lot less.

Cold weather acclimatization

Cold weather adaptation is actually harder on the body and being a summer girl at heart I believe it! It takes about the same time but we do it every year none the less. Think about how you feel about a 10 c day in August and compare that with February. Personally I work outdoors year round and I find it so much harder to run in the winter than to stand in it at work. But quilted work onesies are a thing at my house so that helps too.

Acclimatizing to the cold though does have some pretty cool (get it) effects on the body. Your resting metabolism goes up, presumably to generate more body heat. You also acclimatize by having your body temperature fall more slowly in the same conditions over time. This leads to a lower jump in temperature when you do get moving and a decrease in shivering. Of course these changes (hot or cold) do have their limits. I find there are two important things for me with winter running. One is that after a few weeks it really isn’t as bad as I thought it was going to be, so no excuse not to get out there. The other is that I just can’t go for as long. Somewhere just short of the hour mark it does just start to suck. I interpolate that as finding the limit of my cold adaptation and my lack of love of cold weather overall.

The reason that many experts think that cold weather adaptation and exercise is harder in the body is how it affects out respiratory tract. In cold weather there is a much higher degree of heat loss from the respiratory tract which could result in cold injury. This causes changes in your breath which means you need a larger oxygen supply and leads to some degree of hyperventilation. It’s pretty easy to see how this is made worse by exercise in the cold. More people tend to succumb to cold injury than heat injury in any given year. 

Practically speaking we can’t just walk or take it easy for a while to deal with the cold the way we can with the heat. It’s a good idea to take an extra layer with you in case you get cold or the wind picks up. I love a not that breathable wind breaker or cozy hat with you even if you don’t think you’ll need it. It’s also a good idea to keep a close watch on how your extremities are feeling. Since one of the first things that happens in the cold is that warm blood gets drawn towards your core. So if your fingers feel like popsicles or your feet start feeling like hard rocks it’s time to return to the indoors. Last but not lest dress or push yourself only so hard that you’re not sweating a whole lot. If you are sweating a lot you now have a whole lot of evaporative cooling making the situation worse.

Hot or cold, the weather does affect our performance throughout the year but special care must be taken in the transition. We must also remember that we don’t only experience temperature stress once and then we are good for the season. A hot or cold snap means we must readjust again. It’s important to take it easy when the weather changes and be aware that acclimatizing does take time. Which do you find harder adjusting to the hot or the cold each year? Do you have any practical tips to make it easier? Leave it in the comments below!

Read what I read:

Freitas and Grigorieva. 2014 The impact of acclimatization on thermophysiological strain for contrasting regional climates. International journal of Biometerology.

Maughan. 1997 Preparing athletes for competition in the heat: Developing an effective acclimatization strategy. Sports science exchange. 

Anderson and Bell 2009 Weather related mortality: How heat, cold and heat waves affect mortality in the united states. Epidemiology.

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