How to breathe when you run in cold air.

Quick answer. Breathe through your nose for as long as the pace allows, then through nose and mouth together, and pull a buff or neck tube up over your mouth when the air is very cold. Warm up for at least 6 minutes before you set off and build the pace gradually. Your lungs do not freeze: the nose and airways warm and moisten the air on the way in, although research suggests they cannot do it fully during hard running at sub-zero temperatures. That shortfall is the dry, burning feeling.

How do you breathe when running in the cold?

Four habits do most of the work.

• Use your nose on easy runs. A 2020 review in Frontiers in Sports and Active Living describes the nose as "an important structure which serves to condition inspired air", and says nasal breathing "appears to defend against airway cooling when inhaling sub-zero air." At a conversational pace, try to breathe in through your nose.
• Switch to nose and mouth when you need to. The same review notes that during exercise most people switch to breathing through nose and mouth at around 35 litres of air a minute. Forcing nose-only breathing at a hard pace is not the aim. Let the mouth join in when the effort rises.
• Cover your mouth and nose with a buff. A thin neck tube pulled up over your mouth and nose traps some of the warmth and moisture of each out-breath, so the next breath in is a little less cold and dry. Pull it down again once you warm up or if it gets damp.
• Start slowly. The harder you breathe, the less time the airways have to warm each breath. Let the first mile be easy and build from there.

Can running in the cold hurt your lungs?

For a healthy runner on an ordinary cold morning, the short answer from the research is that the airways cope, with a small measurable effect at the extremes. The body warms and moistens every breath before it reaches the lungs. The Frontiers review cites airway mapping showing that even air breathed in at -18°C reached about 23°C by the point where the windpipe divides. That is warm, but short of body temperature, and the review concludes that "below certain sub-zero temperatures, the airways are unable to fully warm and humidify inspired air", especially at the breathing rates of hard exercise.

A 2022 study in the European Journal of Applied Physiology tested this directly. Twenty-three healthy, trained adults ran a 4-minute all-out time trial at -15°C in a climate chamber, once with a breathing mask that warms and moistens the air and once without. Without the mask, the amount of air they could blow out in one second fell by 2.7% on average; with it, by 0.5%. No participant had a fall of 10% or more, the level the authors used to define a significant response.

Those are lab conditions, colder and harder than most UK runs. The dry, raw feeling in your throat on a frosty morning is the airways losing heat and moisture as they warm the air, and it usually fades as you settle into the run.

If cold air leaves you wheezing, coughing for days afterwards or short of breath in a way that is new for you, see a GP.

Should I wear a buff or mask to run in the cold?

A buff is not the same as the breathing devices tested in research, which use a filter designed to hold heat and moisture. The idea behind them is similar, though: the inside of the device is warmed and moistened by each breath out, so the next breath in is partly warmed before it reaches the airways. The study above used a light mask of this kind over the nose and mouth, and found it reduced the airway response to all-out running at -15°C. The authors note that devices vary, so results from one mask do not carry over to every product.

The review also reports that studies have found the airway response to cold air is greater when the face itself is exposed to the cold. A buff, a hat and a high collar all keep the face warmer. In practice:

• Choose a thin, breathable fabric that you can still breathe through at your easy pace.
• Wear it over the mouth and nose for the first ten minutes, or for the whole run in a biting wind.
• Carry a spare on long runs: a buff soaked with breath turns cold quickly.

Our guide to what to wear running in the cold covers the rest of the kit, layer by layer.

Why does cold air hurt to breathe when I run?

Cold winter air holds very little water. Your airways bring every breath up towards body temperature and full humidity, and the moisture for that comes from the lining of the airways. The Frontiers review explains that this water loss cools the lining, and that breathing through the mouth is "less efficient at conditioning inspired air", which leads to cooler air further down and a drier upper airway. That is the scratchy, burning feeling, and it is why the first few minutes feel worst.

How should I warm up for running in cold weather?

A warm-up gets the breathing rate up gradually, rather than going from a warm kitchen to hard breathing in one step. The NHS suggests a routine that "should take at least 6 minutes", built from marching on the spot, heel digs, knee lifts, shoulder rolls and knee bends (NHS: how to warm up). Do it indoors before you open the door, then run the first mile easy.

• Keep hard sessions for milder days. Intervals push your breathing rate highest, which is when cold air is hardest on the airways. On very cold days, swap them for an easy run and move the hard session.
• Run with the wind on the way home. Start into the wind while you are fresh and dry, so you are not breathing into it when you are sweaty and tired.
• Change straight after. Damp kit and a chilled, damp buff cool you quickly once you stop.

For the dark and the frost, our guide to running through a UK winter covers lights, routes and footing.

Where Immufix fits.

Good breathing habits come from practice, not from a pouch. Immufix is one 25g scoop in around 200ml of water, once a day, with breakfast before or after a run. Magnesium contributes to normal muscle function and to electrolyte balance, and vitamin D contributes to the maintenance of normal muscle function. Riboflavin, niacin and vitamin B6 contribute to the reduction of tiredness and fatigue. Every amount is on the science page.

The short version.

• Breathe through your nose at easy pace, and let your mouth join in as the effort rises.
• Pull a thin buff over your mouth and nose in very cold or windy weather.
• Warm up indoors for at least 6 minutes and keep the first mile easy.
• Your airways warm the air before it reaches the lungs. In lab tests at -15°C, healthy runners showed only a small dip in airflow.
• Wheezing, a lasting cough or new breathlessness after cold runs is a reason to see a GP.

Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. If you have a medical condition, are pregnant, breastfeeding or taking medication, speak to your GP or pharmacist before taking any food supplement.