Being based in the South West of England, the coldest we ever really have to contemplate is single-figure temps below zero. Of course, this is not the case everywhere, and for a large number of our US/Canadian/Scandinavian-based audience, the temperatures can get lower – much lower. Even before typing this, I saw a Facebook comment saying it was -39 C in Montana. Definitely a stay-at-home kind of day! If that happened in the UK it would be declared a national emergency and the nation would grind to a halt. With this in mind, we wanted to know how cold is considered too cold to run and when you really should stay at home and hit the ‘dread mill’ instead! If you are going to run, what precautions can you take and what is the best gear for running in winter?

Of course, we do have to add here that we are not scientists, nor have we ever really experienced the kind of temperatures that some will have so we would be interested to hear your thoughts and comments on what you consider is too cold to run in. In the meantime, the following information is based on our research and findings.

When it is a Threat to the Respiratory System

You may have visions of getting frostbite on your fingers and toes when running outside in extreme temperatures however, there is something far worse you need to consider and this is the potential damage to your respiratory system.

For anyone who has ever run in freezing temps, you will be fully aware of that feeling of the cold air getting into your lungs and how difficult it can be to catch your breath, especially in freezing winds. We have probably never experienced anything below -5/6 C however, even in these temperatures it can often feel too cold to run.

But what is considered a threat to health? Experts suggest that running in anything below -15 C is not advisable. This is because the colder the air gets, the drier it gets. Air that is -20 C holds 99% less water than air that is 10 C. Inhaling such cold, dry air can be an acute physiological stressor to the surfaces of your airway. As the airway lining is a liquid surface, when you breathe this liquid naturally evaporates a little. The cold dry air increases the evaporation rate quicker than your body can cope with. 

The lungs respond to significant stress by re-modeling in a way that affects lung function. Over time, this can lead to a chronic airway dysfunction known as exercise-induced bronchoconstriction (EIB). Repeated instances of running outside in extreme freezing temperatures will increase your chances of developing EIB.

exercise induced bronchoconstriction

Airways become inflamed and constricted, and can produce more mucous.(Freepik)

Obviously the objective of exercise is to improve our health not sabotage it so, if you are determined to get out there and complete that run, you are going to need to cover your mouth with a buff or mask. You also need to consider the intensity of your exercise. Intervals and tempo runs are going to force you to inhale more cold dry air than gentle miles. Run easy enough to be able to breathe through your nose to reduce the pressure on your lungs. 

Warm Up Properly Indoors

You should aim to do an indoor warmup of 15 to 20 minutes first. This will help dilate the bronchioles and reduce the effects of cold air once outside. It also warms up the muscles and joints and means that your muscles won’t be so tight when you venture outside You should warm the body to a level where you experience a light sweat. 

Wear the Right Clothing

When it comes to other negative effects of the cold, be sure to dress appropriately – layer up, wear gloves, wear a hat – dress for the weather. Wear layers made of wicking material to wick the moisture away from your skin. If there are any exposed areas of skin, you could use Bodyglide to protect them. While you may be tempted to overdress, you actually need to dress for a temperature that is warmer than the actual temperature. This way you won’t overheat. If you are wearing a hat and you worry that you might get too hot, take a backpack or make sure you have a pocket in case you need to take it off. 

Best Trail Shoes for Winter?

The shoes you choose will depend on the conditions. Is there heavy snow or a light dusting? Is it icy and are the paths safe to run? When running through thick snow and ice,  you are going to need shoes that provide great traction. If you can, you should keep clear of snow and ice where possible and stick to clear paths and trails but you are sure to still encounter some patches that are unavoidable.

If you are running in ice, you need shoes that are designed for the job. While longer lugs will do the job, spikes are the only way to get foolproof traction. You also need to consider how often you will run in ice. If it’s an extreme case and you only experience icy conditions sporadically, do you need to spend money on spikes? Perhaps choose a pair of trail shoes that are suitable for more than just icy conditions.

Salmon do a great shoe designed for either snow or ice – the Salomon Spikecross 5 GTX and the Snowspike. The Salomon SpikeCross 5 GTX combines spikes with contragrip outsole.

Waterproof Trail Shoes

Whether running through snow, ice or just really wet conditions, the main consideration is keeping your feet dry. Wet feet will just make it more miserable, especially if it’s already feeling too cold to run in. Choose wicking socks and a gore-tex shoe that will keep the water out. We have written a great guide to waterproof trail shoes which you can find here. 

Stay Safe

If you are running in snow-covered terrain, be mindful of the conditions, the weather forecast, and your surroundings. Are there severe weather warnings or is there a risk of falling snow (avalanche)? Are you likely to be out when it gets dark – what would happen if you ran into trouble? Consider all the relevant safety precautions and be sure to carry the following:

  • Mobile phone
  • Snack
  • Extra layers/foil blanket
  • Water (if it doesn’t freeze)
  • You may also consider other precautions such as an emergency flare or whistle

Stick to roads, paths, and trails that are frequented by others. Some main routes will be gritted however, for trail runners running off the beaten track this is very unlikely. Don’t venture off into the wilderness. Tell someone where you are going, let them know your route and don’t deviate from it. Also, be mindful of your local wildlife – are you likely to encounter bears or wolves for example?

Be Visible

When running in winter, you have much shorter days – the mornings and the evenings are darker and for those that work during the day, sometimes the only time to get out is before or after when it is dark. It’s really important to make sure you can be seen so make sure you have one or more of the following:

  • Hi-vis gear
  • Head torch
  • Body lights 
  • Reflective clothing
  • Shoe lights

Consider the Wind Direction

Start your run into the wind and then you will have it on your back in the second half of your run. This means you won’t be turning your sweat to ice once you’ve broken it. it’s also much nicer to get the windy stretch of your run out of the way first.

Post Run  

When you have finished your run you must change out of your clothes ASAP! Your body temperature will drop quite quickly so you need to get out of those damp clothes. Pop on some warm clothes, and a warm dry beanie, grab a hot drink (take a flask if driving to a run) and warm yourself up. Some of you may suffer with Raynauds – it is especially exacerbated in cold conditions so it is important that you get yourself back to normal temperature ASAP. 

Deciding when it is too cold to run will largely decide on your desire, your motivation, how important the run is in your plan, and whether you can adjust your training scheduled to run easy miles to reduce the stress on your lungs. Remember though, in the grand scheme of things, it’s just a run and your health is far more important!