Why Is Running in the Cold Harder? (And Why It Feels So Much Tougher)
If you’ve stepped outside for a winter run and wondered why running in the cold is harder than it should be, you’re not alone. Your pace might be slower, your breathing harsher, and your legs feel heavier than they did a few weeks ago. Fortunately, this isn’t a loss of fitness — it’s usually just a consequence of the conditions.
So why is running in the cold harder? Several physiological and environmental factors are at play. Here’s what you need to know.
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Why Is Running in the Cold Harder?
You’re not imagining it — running in the cold actually is harder, especially once temperatures approach freezing and below.
While cool weather is often ideal for endurance performance, true cold conditions introduce several physiological and environmental stressors that increase effort at the same pace and feel harsher on the body.
Cold air, muscle stiffness, wind resistance, higher energy demands, and even psychological factors all combine to make winter miles feel tougher. Here are seven key reasons why running in the cold is harder.
1. Cold Air Makes Breathing Feel Harder
Cold air is typically drier than warm air. When you inhale it, your body has to warm and humidify that air before it reaches your lungs.
That process can irritate airways and, in some runners, cause mild airway constriction. The result? Breathing feels sharper, harsher, and more uncomfortable — especially at higher intensities.
In very cold conditions, the air can even sting your nostrils. Many runners (myself included) notice that this discomfort changes their breathing pattern. You might switch to mouth breathing earlier than usual, take shallower breaths, or instinctively cover your face to warm the air — all of which can subtly affect rhythm and perceived effort.
Even if your cardiovascular fitness hasn’t changed, altered breathing patterns and airway irritation alone can make a run feel significantly more difficult.
2. Your Muscles Are Less Efficient When They’re Cold
Muscles function best when they’re warm.
In colder temperatures, muscle elasticity decreases and nerve signals travel slightly more slowly. That means your muscles may feel stiffer and less responsive — particularly during the first 10–15 minutes of a run.
This is one reason winter runs often feel disproportionately difficult at the start. Once you warm up properly, things usually improve — but that initial heaviness can distort your perception of effort.
Stiffness can also creep back in later during runs. After prolonged exposure to cold air, legs can begin to feel heavy, sluggish, or even slightly numb. On cold long runs, I’ve found that toward the end my legs often become stiff and more difficult to move — almost like they’re partially frozen. As a result, my stride feels less fluid and I have to consciously work harder to maintain proper form.
When stiffness begins to affect control or gait, it’s often a sign it’s time to head indoors and warm up rather than push through.
3. You Burn More Energy Staying Warm
When you run in the cold, your body isn’t just powering forward motion — it’s also working to maintain core temperature.
That added thermoregulatory demand increases overall energy expenditure. Add in heavier clothing, gloves, and layers, and you’re carrying more weight than usual. If there’s snow or slush underfoot, your stride becomes less efficient.
All of this increases the energy cost of running in cold weather — which means the same pace requires more effort.
4. Wind, Snow and Winter Terrain Increase Resistance
Wind is particularly common in the colder months and is one of the biggest hidden effort multipliers.
A steady headwind increases resistance and accelerates heat loss, forcing your body to work harder to maintain pace.
Snow and ice add another layer of difficulty. You may have to weave around icy patches, slow down to maintain balance, or wade through snow that feels almost like running on sand. Each adjustment breaks rhythm and reduces running economy. Even subtle footing changes activate stabilizing muscles around the ankles, knees, and hips more than usual.
All of this adds up — and can make winter miles feel far more demanding than the same route in dry, warmer conditions.
5. Your Heart Rate May Respond Differently
Cold weather can affect heart rate in complex ways.
In some cases, heart rate may run slightly higher due to cold stress and increased sympathetic nervous system activation. In other situations — particularly in very cold temperatures — heart rate may appear slightly suppressed during steady efforts.
Either way, cardiovascular strain can feel different compared to mild conditions. That mismatch between pace and heart rate can leave runners wondering why running in the cold is harder, even when their training hasn’t changed.
6. You May Be Neglecting Your Nutrition and Hydration
Cold weather can also quietly disrupt fuelling habits, which can impact both your pace and perceived effort.
During long runs or harder sessions, you’d normally fuel to support performance. But eating a frozen gel, chewing through stiff energy chews, or drinking near-ice-cold water isn’t very appealing when you’re already cold. Many runners simply skip it.
Carrying fluids can also feel uncomfortable — holding a cold bottle when your hands are already freezing isn’t fun. And because thirst cues are blunted in cold weather, you may not realize you still need to hydrate.
Even mild dehydration or under-fuelling can increase perceived effort, slow you down, and make a winter run feel disproportionately hard.
7. Winter Motivation Is Lower (And That Matters)
While physiology plays a major role, the difficulty of winter running isn’t purely physical.
Winter removes many of the positive cues associated with running, which subtly increases how hard each mile feels. Shorter daylight hours, darker mornings, heavier clothing, and less sunlight can all reduce motivation and mood. When motivation dips, perceived effort rises.
The Sweet Spot: When Cooler Is Actually Better
When it comes to running performance, it’s important to distinguish between cool and cold weather.
Research consistently shows that endurance performance tends to peak around 7–13°C (45–55°F). Some runners perform well up to about 15°C (59°F) depending on humidity and race distance, but this cooler range is widely considered optimal.
Why? Because cooler air allows your body to dissipate heat efficiently. You don’t need to divert as much blood flow toward cooling, cardiovascular strain stays lower, and overheating — one of the biggest performance limiters in endurance sport — is less likely.
Interestingly, extreme heat has a similar performance cost in the opposite direction. When temperatures climb too high, pace slows and effort rises due to overheating. In other words, both too hot and too cold can negatively affect performance — just for different reasons.
This is one reason so many major marathons are scheduled in spring and fall, when average temperatures often fall within that optimal range. Events like the Boston Marathon in April, the Berlin Marathon in September, and the Chicago Marathon in October aim to give runners ideal racing conditions. Here in Toronto, we even have both a spring and fall marathon for that very reason.
But once temperatures approach freezing (0°C / 32°F) and below — especially with wind, snow, or ice — the physiological costs start to outweigh the cooling benefits. That’s when winter running begins to feel harder.
How to Make Cold Weather Runs Feel Easier
If your winter runs feel tougher than usual, a few small adjustments can help:
- Extend your warm-up by 5–10 minutes at an easy pace
- Start slower than you think you need to
- Dress appropriately and cover extremities — but avoid overdressing
- Use a buff or face covering to warm inhaled air
- Focus on effort rather than pace
- Accept that winter isn’t always PR season
- Try to schedule key runs on milder days when possible
- Consider using the treadmill for speed work or structured sessions
Sometimes the smartest winter strategy is simply recalibrating expectations. And if you’re really not enjoying running in the cold, consider switching things up temporarily with a winter sport that maintains similar endurance and strength benefits.
The Bottom Line
If you’ve been wondering why running in the cold is harder, the answer is simple: your body is doing more.
It’s warming and humidifying the air you breathe. It’s maintaining core temperature. It’s moving stiffer muscles. It’s fighting wind and unstable footing. And it’s doing all of that in conditions that can subtly lower motivation.
Cool weather can boost performance — but once temperatures drop toward freezing, the balance shifts.
If your winter miles feel tougher than usual, it doesn’t mean you’ve lost fitness. It means physics and physiology are at work.
