Why Cold Weather Messes With Your Heart Rate (and Why Effort Beats Pace)

From a running coach who has seen a lot of winter runs go sideways.

If you’ve ever stepped outside on a cold morning, started running at what should feel easy, glanced at your watch, and thought, “Why is my heart rate doing THAT?” — welcome. You’re not broken. Winter just changes the rules.

Cold weather doesn’t just make running uncomfortable. It places real demands on your cardiovascular system, and if you train by pace year-round, winter can feel confusing fast. This is where learning to run by effort becomes one of the most important skills you can develop as a distance runner.

Let’s break it down.

Cold Is Stress — Even Before You Start Running

Cold exposure triggers your body’s stress response before your run even begins. Blood vessels constrict to protect core temperature, muscles feel tighter, and your nervous system shifts into a more alert state.

From a coaching perspective, that means:

• Your heart has to work harder to circulate warm blood

• Oxygen delivery becomes slightly less efficient

• Heart rate can spike sooner than expected

  
  

None of this has anything to do with fitness. It’s simply physiology responding to the environment.

Why Pace Stops Telling the Truth in Winter

Pace is an output. It’s what your body produces after accounting for terrain, temperature, wind, clothing, and internal stress.

Cold weather throws off that equation.

In winter:

• Muscles are stiffer and need more energy to produce force

• Running economy decreases slightly

• Warm-up time increases (even if you don’t feel like waiting)

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Trying to force summer paces in winter conditions often leads to:

• Running too hard on “easy” days

• Accumulated fatigue

• Slower recovery between workouts

• Increased injury risk

  
  

From a coach’s seat, this is one of the most common mistakes I see.

Heart Rate Gets Weird — And That’s Normal

Cold weather can cause:

• Higher heart rate at lower paces

• Delayed heart rate settling

• Larger spikes on small hills or surges

  
  

If you chase pace anyway, your cardiovascular system ends up doing extra work just to keep you warm — not to build fitness. That’s a poor tradeoff.

Effort Is the Most Honest Metric in Cold Weather

Effort accounts for what pace can’t.

When I coach runners through winter, we talk a lot about internal cues:

• Can you breathe through your nose?

• Can you speak in full sentences?

• Does this feel sustainable for a long time?

  
  

An easy run should feel:

• Controlled

• Conversational

• Like you could go longer if needed

  
  

If the effort feels right but the pace is slower, that’s still a successful run.

How to Train Smarter in the Cold

A few coach-approved adjustments;:

• Extend your warm-up by 5–10 minutes

• Expect heart rate to run higher early

• Dress to protect your core, not just your legs

• Let pace float, especially on easy days

• Use perceived effort as your primary guide

  
  

Winter isn’t about forcing performance. It’s about maintaining consistency and staying healthy.

The Big Picture

Cold weather running teaches patience. It forces runners to stop chasing numbers and start listening to their bodies — a skill that pays off hugely in spring racing.

From a coaching standpoint, the runners who thrive long-term aren’t the ones who stubbornly hit pace in January. They’re the ones who respect the season, train by effort, and let fitness accumulate quietly.

Your pace will come back.

Your job right now is to keep showing up — smart, steady, and aware.