Why does running in the cold slow you down

Quit ringing my bell wrote:

Does anyone find it hard to breathe while running in the cold (20's or below)? Today I especially had trouble breathing and my pattern felt very regular, especially while maintaining six thirties or faster.

Yep, I find it a little tougher to maintain a steady breathing pattern while running. It seemed like I would have to stop running in order for me to catch my breath.

I can't breathe when I am running into a cold headwind, mainly due to the cold air being forced down my throat.

RunGambit wrote:

Haji - I am going from personal experience but I imagine there has to be some science behind it.

I understand that some people are better at handling the cold mentally (or are more used to it because they train in cold weather) but take it to the extreme; do you think you can run as fast a 5k in 0 degree weather as you can in 50 degree weather (all other things being equal)?

Good question. I am sure that at some point extreme cold would slow you down. I'm not sure which factor it would be to slow you down though. Hard to breath due to the cold maybe? I know when I was a much younger man, it hurt to run in anything below 40 degrees. Today I laugh at that. I've run, not raced, in near 0 temps and breathing really doesn't bother me. Maybe one can adapt to the cold a lot better than the heat. Seems the body can heat itself up better than cool it down, especially when running.

My marathon PR came on a day where the race started at 23 degrees. Even then I sweated through my hat, gloves and shirt.

The breathing thing is bogus. You breathe fine in the cold. The oxygen binding is also bogus, your body maintains equilibrium pretty well.

Your muscles work better when warmed up. Think about why you do an easy jog, stretching, and strides before a hard effort. Obviously it's harder to stay warm in low temperatures due to blood vessel constriction, etc.

Poor footing, heavy clothing, and psychological factors are the other ones that have been mentioned, and yes, those contribute to a slowdown.

But that's it.

I brought this up before but nobody has explicitly commented on it. What about the fact that in colder weather your body has to expend energy keeping your core temperature constant. Does anyone think this slows you down?

RunGambit wrote:

I brought this up before but nobody has explicitly commented on it. What about the fact that in colder weather your body has to expend energy keeping your core temperature constant. Does anyone think this slows you down?

I think it slows you down. More so in the heat though than in the cold. When you are running at a good effort, your body is going to produce heat regardless of the air temp because you are working hard.

If it is hot the body has to work hard to cool you down.

If it is cold, you still sweat so the body is still working to keep you cool just not as hard maybe.

for me I can tell a big difference when the temps get down below 25 degrees. above that, I dont really notice THAT much of a difference. again, for me, the sweet sweet spot for temps for good distance running is 45-60 degrees, cool, but not cold.

Haji: If it is hot the body has to work hard to cool you down.

If it is cold, you still sweat so the body is still working to keep you cool just not as hard maybe.

In the heat I suspect it's less a matter of slowing down because of the herculean energy demands of keeping cool; more like, your body/brain really doesn't want you to outrun your (limited) ability to keep your core temp at a safe level. Survival instinct, hard-wired. Of course some can override this to a degree others cannot, e.g. Alberto "all that is man" Salazar.

And in the cold, my hunch is that as long as you're dressed reasonably and moving at a good clip, it's not really costing (much?) extra energy to keep you warm. I imagine it's more like a car's heater: for once this excess heat the engine's always producing anyway is actually useful.

Yes, it's true that there are many factors that affect pacing at any temperature. As mentioned, there is the addition of extra clothing which restricts movement/adds mass and the necessity of the body to remain in a homeostatic state (i.e. keeping its temperature constant). However, I was simply pointing out the major factor for slowing in colder temperatures.

To answer a previous poster...no, the air is not at body temperature when it's in your lungs. Oxygen and hemoglobin bindings follow a standard dissociation curve. At lower temperatures, oxygen more readily binds to hemoglobin but has a more difficult time releasing. The converse is true for warm weather. Of course, this system is also affected by blood pH...which is another issue entirely.

Regardless, a lack of oxygen reaching the cells means that muscles cannot do their job as efficiently as they normally would at higher temps. Therefore, you are slower than the same effort at a warmer temp. This estimate is not exact, but (for example) a 7:00 pace at warm temps may translate to a 7:20 when using the same effort in a colder environment.

Interesting article here. Cold running empties your glycogen faster.

for reals wrote:

The breathing thing is bogus. You breathe fine in the cold. .

That is absolutely not true. The cold air irritates your bronchial tubes. It takes a lot of energy to spit and blow your nose all the time when running in the cold.

Mr Mountain wrote:

That is absolutely not true. The cold air irritates your bronchial tubes. It takes a lot of energy to spit and blow your nose all the time when running in the cold.

You are absolutely wrong. For Reals is for real. Cold air doesn't irritate your bronchial tubes. By the time air gets to your bronchial tubes it is fully warmed. A breath of air has very low mass, so it doesn't take much to heat it to body temp. Simple physics. The reason some people experience irritation is due to cold air being DRY.

Slowing down specifically due to cold temperatures won't happen until you reach a point where your clothing doesn't sufficiently insulate your body to maintain blood flow to your extremities. For example, I was out for a tempo run in two layers of high quality, windproof gear in -19F. Even with that gear, I wasn't able to generate enough heat to keep my thighs from feeling cold, and I experienced a marked decrease in pace versus heart rate. The same tempo run, same clothing, but five degrees warmer (around -14F), and no problems, pace and heart rate in line with expectations.

I've had the exact same thing happen (cold legs) at 20F, during a xc race, because I chose not to wear tights. It's all about insulation. Your body will carry on normal physiological processes until it cannot. The article about glycogen utilization is correct as well--you will use glycogen more quickly in cold temps, but that is only a single factor for long training runs or races over 15K in cold temps. I had an athlete crash hard at mile ten of a half marathon because she didn't wear arm warmers (yes, they are good for something) or half tights in 35F, breezy conditions. Temperatures are only relevant to performance when they begin to interfere with self-preservation. As long as you are well-insulated, cool temps will actually help you run faster.

BTW, anybody talking about hemoglobin and oxygen binding is completely full of shit. Happy trolling.

C/M Runner wrote:

It seemed like I would have to stop running in order for me to catch my breath.

I can't breathe when I am running into a cold headwind, mainly due to the cold air being forced down my throat.

Hilarious x 2!

It's interesting that you would point out that you slowed down when it was too cold outside for what you were wearing. In such a case, your body restricted blood flow to your extremities to save your bodies most precious organs. So, this caused less oxygen rich hemoglobin to reach the cells of your legs. As a result, your body was forced into producing ATP without the necessary oxygen for its most energetically rich cycle (the electron transport chain). Of course, then, your pace decreased per the same unit effort.

Again, I'll point out that I was mentioning only ONE of the causes of increased fatigue while running in the cold. I'll even go so far as to point out that I was not even mentioning the psychological implications.

You guys have it all wrong.

It is EASIER to run when it is cold because the cold temperatures make the planet contract, making distances less. So 1 mile in 80 degree weather is like .99 miles in 10 degree weather.

It's science.

it doesn't....Americans...

The Red Nose Run (10 miler) in Birmingham on 1/9 was 17 degrees at the start and 18 at the finish. (It started at 7 AM). If I'd run a time comparable to the time I ran in an early December half marathon, I'd have run 6:51 pace. I actually ran 6:55 pace, at a slightly lower average HR (179 vs 182 for the HM.)

There are various ways of interpreting these metrics. It's possible that my fitness slipped slightly over the holidays, although I tried to maintain specific fitness for the 10-miler. Or it's possible that I just didn't run quite as hard, or that the breezes (not strong, but definitely there) hurt me a little on the rectangular criterium course. Or it's possible that, as this thread suggests, I was slowed by 17 degrees in comparison with the low 30s in which I ran the HM.

Hard to tell.

I will say that I run all my PRs in the cooler weather--which in Mississippi means November through late April. I'm one of those people who breathes easier, even thrives, when racing in the cool stuff.

Last Saturday, however, I was coughing for a couple of hours after the race. 17 is too damned cold.

To clarify a point about paces above: I ran 6:57 in the early December HM. McMillan's calculator gives 6:51 pace as the comparable pace for a 10-miler. So that's what I was shooting for. But I only managed to run 6:55s. That's slightly better than my HM pace--but not enough to compensate for the shorter distance. The issue here was: Can I attribute that slight falloff to the frigid weather of the latter race vs. the "normal" cold of the HM?

common wrote: You are absolutely wrong... Cold air doesn't irritate your bronchial tubes. By the time air gets to your bronchial tubes it is fully warmed. A breath of air has very low mass, so it doesn't take much to heat it to body temp. Simple physics. The reason some people experience irritation is due to cold air being DRY.

[...]

BTW, anybody talking about hemoglobin and oxygen binding is completely full of shit. Happy trolling.

This guy is right on all counts. The dryness is what bothers some people, the air is fully warmed by the time it reaches your lungs, and the hemoglobin stuff is just someone trolling. Here's an article on the topic: