Comments on The Science of Sport: Exercise in the Cold: Part I

"Similarly, in South Africa in 1985, during a 56km...

2008-01-29T18:19:32.336+02:00

"Similarly, in South Africa in 1985, during a 56km race, a temperature of 19 degrees combined with wind and rain was enough to see 8 runners taken to the medical tent with body temperatures below 37 degrees celsius."

I remember that race well. I'd just failed to break 2:40 at the Sun City marathon that year, because the temps were in the 80's (F) instead of in the 60's as in the past 3 years, and they'd changed the course to finish uphill. I'd planned to take that fitness and get a top-100 finish at Two Oceans. In the event I was running in the usual mesh vest and shorts with 7% body fat.. got so cold I had to run too fast early just to stay warm, and fell apart at 44km. Finished 108th, c'est la vie.
Since moving to Colorado, I've found out one or more things about running in the cold.. mostly that I don't like it.

Hi, Ross.I'm in Alberta, Canada right now so this ...

2008-01-26T19:22:36.226+02:00

Hi, Ross.

I'm in Alberta, Canada right now so this post was suddenly interesting (I am from the Philippines).

I suppose putting on a jacket helps the afterdrop for most people. In severe cases, I imagine that both factors need to be addressed, reduce heat loss as well as have a gradual decline in heat production that is matched by a gradual increase in temperature--a kind of "cool down" whose goal is to keep you warm.

Hi ChrisThanks for the compliments, great to have ...

2008-01-26T06:37:18.188+02:00

Hi Chris

Thanks for the compliments, great to have you along!

You're quite right, there's no co-incidence here - it's all physiology. In the cold, the demand on the body to send blood to the skin for cooling is reduced, and so the blood distribution is different - you have an increased "central blood volume", which is a physiological concept for the blood in the core of the body. To simplify, this means that the volume pumped by the heart PER contraction (called Stroke Volume) is higher in the cold. Hence, it needs to pump less often. In the heat, because more blood is sent to the skin, the stroke volume is relatively lower, and the heart rate is higher.

A couple of other things add to this - one is your body temperature, which may be slightly lower (depending on how cold we're talking). There's evidence that a colder heart pumps less often - a direct temperature effect. And finally, you sweat less, and so your plasma volume doesn't decrease as much. This means you can pump less often, because you are not compensating for a decrease over time.

Hope that helps!
ROss

Hi Outdoor enthusiastWith frostbite, very basicall...

2008-01-26T06:33:27.626+02:00

Hi Outdoor enthusiast

With frostbite, very basically put, the cells freeze. Remember that the cells contain a great deal of water, and because water expands as it freezes, the cells rupture, and the tissue bursts - so you're right with your theory.

I must confess that I'm not 100% sure how the condition develops. That is, I can't tell you whether cells recover - of course, there are cases where they do, but that's very mild frostbite. If it's severe enough, as with our unfortunate runner, you lose the limb - after the Everest disaster in 1998 where Rob Hall died (the book Into Thin Air), one of the climbers lost a number of toes and fingers to frostbite. But it depends on the severity, as far as I know. Best to avoid it, in that case, I guess!

As for your trip, there's no limit to how long you can spend outdoors, provided you are sufficiently clothed. If you cover your extremities, you can spend far longer than an hour outside - but it's all down to the clothing you wear. In particular, fingers, toes and ears, and if it's really cold, a face mask is a good idea. If you have those, you won't be in any danger at all.

Regards
Ross

Thanks for publishing your stuff. I find it incred...

2008-01-26T02:35:14.550+02:00

Thanks for publishing your stuff. I find it incredibly interesting and useful.

My question:

Some friends and I who use heart rate monitors for training feedback have experienced slightly reduced heart rates in really cold weather, meaning that for any given level of perceived effort or pace, our heart rates are a few percentages of HRmax lower than in warmer weather.

Is this coincidence and chance or is there a phyisiological reason this may be happening?

Thanks Ross, Johnathon. What is happening at the l...

2008-01-25T19:32:10.130+02:00

Thanks Ross, Johnathon.

What is happening at the level of the cell/tissue/organ when cells start to freeze. Are these damages irreversible ? How rapidly does this damage happen ?

My hypothesis is that cells start to freeze and perhaps even burst. If not, a lot of the cell structures begin to loose shape and functionality at these temperatures. Just curious on this one...

Coming back to the individual who lost two toes - I'm heading to the cold northeast soon. I've been told that it should be safe to run for 40-60 minutes in the cold. (similar conditions of 20 below freezing when including wind chill into account). I'm curious to know whether I would be entailing risk in doing so of being frost bitten.

Given that most individuals who get frost bitten don't really come to know till later on, I'm guessing that there isn't any indications which I can pay attention to - to use as a warning sign.

Hope you guys are enjoying your trip to the US. Do plan a visit to the Bay Area the next time you come here.

Cheers.

Hi Outdoor enthusiastThanks for the comments. I t...

2008-01-25T16:40:55.593+02:00

Hi Outdoor enthusiast

Thanks for the comments. I think your reasoning is likely sane, only because if you were doing damage, you'd likely have seen it by now. So I suspect that your timing at that water temperature is about right. I confess that I don't know of any work that has ever looked at "survival" times of human tissue when exposed to cold environments. In otherwords, i doubt it's possible to draw a graph showing time to cell death against time of exposure for different temperatures.

If I'm wrong, and someone knows of this, let me know! But interestingly, a lot of that kind of knowledge was accumulated during World War 2, in the concentration camps. As I'm sure you can appreciate, doing that kind of experiment is ethically very suspect. But in WWII, it was done, and subsequently, a lot of that knowledge has been destroyed. So there's a gap in scientific knowledge (rightly, because of the method used to gather the data), which means I don't think that your question is definitively answerable!

However, in terms of what we do know about physiology, your logic is sound. When exposed to cold water, the body's number one priority is to defend the core temperature. That's why you shift all the blood away from the extremities - it doesn't even try to keep them warm. Quite when they become vulnerable to damage I don't know, but it's another case of letting your body tell you when it will become dangerous.

Ciao
Ross

Very nice. I've actually put the above concepts in...

2008-01-25T03:09:56.764+02:00

Very nice. I've actually put the above concepts into use when running in the cold. However, I did not know about frost bite being a possibility or at least did not give that much of a thought. Something to be aware off.

Here is something else which I usually try. The Pacific ocean here is about 14 C (58 F). While swimming in the ocean (with a wet suit of course), my body does not generate enough heat to warm the extremities. So, my toes and fingers which are exposed, do start to go numb in about 70 minutes in the ocean. My theory has been that this is ok - 70 minutes or perhaps even a little longer, there is poor circulation to these parts of my body given that they can go for about 12 hours without oxygen without incurring any permanent damage. Coming out of the water in 70 minutes should allow my body to warm sufficiently to increase blood flow to the toes and fingers.

Is this reasoning sane ? Or am I risking too much by doing such a thing.

Hi AndrewThanks for the questions.To respond, afte...

2008-01-25T01:18:29.242+02:00

Hi Andrew

Thanks for the questions.

To respond, after your runs in cold weather, the feeling of coldness later on is quite typical. It happens to an even greater extent after cold water immersion, and we'll cover that in subsequent posts. But basically, what happens is that when you are exposed to the cold, your body sends blood AWAY from the skin to conserve heat. Of course, your skin and extremities are getting incredibly cold, but it doesn't affect your internal temperature, as a result of this response.

When you then stop (or get out of the water, as it were), the blood can return to the skin, which in the meantime has become incredibly cold. Pretty soon, that blood does a complete "loop" and returns to the core and the temperature drops. This afterdrop is one of the most dangerous periods in reheating people who've been exposed to the cold.

When we worked with Lewis Pugh, we saw the same thing each time he got out of the water - the biggest drop happened 10 min AFTER he got out the water, not during.

I suspect that the same happens after running, though to a lesser extent.

But of course, the main reason is that you've removed half the equation by stopping. heat storage, and hence body temperature, is a function of heat production vs. heat loss. After you stop exercise, heat loss persists (in the form of vasodilation and the sweat response and so forth), but heat production obviously does not (to the same extent anyway).

So it's probably mostly related to this. Most people will have found that simply putting on a warmer jacket helps, simply by reducing heat loss. And yes, it's in part due to the fact that the body simply doesn't see it as a 'priority' - we'll cover some of the physiology behind this in the later posts.

And then also, the severity of exercise does impact, probably via hormones. Fatigue is guaranteed to compromise your ability to keep warm. And catch-22, the cold increases the chance of fatigue, which is why it's so risky being exposed. But any prolonged exercise exposure will affect your ability to maintain temperature. That will come up in subsequent posts again.

Finally, on the frostbite issue - you can develop frostbite if the wind speeds are high enough to create an EFFECTIVE air temperature below about -20 degrees. Frostbite happens at these temperatures, to exposed skin. So it's easy to appreciate that in order to develop frostbite when the air temperature is 1 degree, you have to have some serious wind to chill the skin. But it can happen, in theory. In practice, not so common...

Cheers
Ross

A serious question:Is there any long term risk fro...

2008-01-24T23:44:11.511+02:00

A serious question:

Is there any long term risk from frozen popsicle? I can be perfectly comfortable in tight, briefs and running shorts, but it doesn't protect the manhood

Fascinating information. There's a saying: "there'...

2008-01-24T19:42:53.640+02:00

Fascinating information. There's a saying: "there's no such thing as bad weather, just bad clothing". I've run in temps of 0F with -20F wind chill without problems.

After my long runs - in any weather, hot or cold - about 15-30 minutes after finishing I find myself feeling very cold. Based on your article, this is because 1) my body is focused on recovery instead of temperature regulation, and 2) I'm no longer moving so I'm not generating excess heat. Correct?

Is it also true that frostbite is only a risk when temps are below freezing? Hypothermia is a risk at any temp, but I think frostbite requires sub-freezing temps.