Running in winter

Winter loses more runners than injuries do. Not because it's dangerous, but because it makes each outing slightly more costly to decide on — and after six weeks of giving up, the base built in autumn has disappeared. Here's what really changes, and what's just a belief.

Cold doesn't burn your lungs

This is the most widespread and least founded fear. Inhaled air is warmed and humidified by the upper airways before reaching the bronchi: even at −10 °C, the air that reaches the lungs is close to body temperature. A healthy adult doesn't "burn" anything.

What does exist, however, is exercise-induced bronchoconstriction, favored by cold, dry air. It manifests as a dry cough, chest tightness, or wheezing during effort or in the minutes that follow. It's not an inevitable burden to endure: breathing through your nose as long as possible, covering your mouth with a neck gaiter at the start, and extending your warm-up significantly reduce the phenomenon. If it persists, it's a medical issue, not a training one.

Dressing: three layers, and one rule

The rule that sums it all up: you should feel a bit cold when leaving home. If you're comfortable at the start, you'll be drenched in sweat after ten minutes — and sweat, in winter, is what really makes you cold.

• First layer: technical, close to the body, never cotton. Its role is to wick away moisture, not to keep you warm. Cotton traps moisture against the skin and turns a cool run into a freezing one.
• Second layer: insulating, lightweight, to be worn only below 5 °C approximately.
• Third layer: windproof, only if wind or rain justify it. Wind does much more damage than temperature: −2 °C without wind is comfortable, +4 °C with 40 km/h wind is not.

The extremities matter more than the torso. A hat and gloves transform a run, because that's where heat escapes and it's your fingers and ears that make a run unpleasant, not your thighs.

The real danger: the ground, not the cold

Winter injuries come overwhelmingly from the ground. Black ice, frozen dead leaves, invisible patches in the shadow of a wall. Three adjustments handle almost everything:

• Shorten your stride and increase cadence. A foot that lands under your center of gravity slips far less than one that lands in front. See cadence in running.
• Give up intensity sessions on questionable ground. A speed work session on an icy patch isn't courage, it's a gamble. Reschedule it, or do it on a treadmill.
• Choose your route for the ground, not for the time. A well-lit, clear park loop is better than a nice trail in frozen woodland.

The night, which lasts five months

Between November and February, most weekday runs happen in the dark. Two non-negotiable points: be seen (reflective vest or clothes with bands, not just a light color — a white jacket isn't visible at night) and see (a headlamp changes your relationship with the ground, thus your fall risk).

And an organizational tip worth more than any gear: prepare your things the night before. The obstacle to a winter run is almost never the cold, it's the moment you're looking for your gloves at 6:30 PM in the dark.

Hydration, which we forget in winter

The sensation of thirst is significantly reduced by cold, and cold air is very dry: you lose water through breathing without noticing. On a long winter run, you dehydrate just as much as in summer, with fewer signals to alert you. Drink without waiting to feel thirsty, just like in summer.

What winter allows, and what we often waste

This is the point most plans miss. Winter isn't a season to get through while waiting for spring: it's the season that determines spring.

With no race to prepare for immediately, winter is the ideal window to build fundamental endurance — easy volume that develops capillary networks and baseline aerobic capacity without nervous fatigue. It's also the time to fit in two weekly strength sessions, because you have the time and it's dark anyway.

A runner who spends winter doing easy volume and strength work arrives in March with a solid base; a runner who spends winter doing hard sessions on frozen ground arrives in March injured or tired. The 80/20 split has never made more sense than in January.

The treadmill is not a failure

During widespread icing, the treadmill is the smart choice, not a shameful retreat. It lets you complete your planned intensity session under controlled conditions. Two adjustments: set it at 1% incline to compensate for the lack of air resistance, and accept that the displayed pace won't exactly match outdoor pace.

Adapt rather than endure

The right question in winter isn't "do I go out," it's "what do I do today, given the ground, light and wind." Sports Coach AI builds your week from your data and adjusts it when conditions change — moving a quality session rather than skipping it is exactly the decision that separates a useful winter from a wasted one.