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Archive for December, 2009

I’ve Got CIVD

No, it’s not some obscure sexual disease. It’s a human physiological response that allows us, in many cases, to go out barefoot for longer and in colder temperatures than we might have thought possible.

CIVD stands for “Cold-Induced Vasodilation”, and it describes what the body does when your extremities get cold. What happens is that, when exposed to cold, the body restricts blood flow to your extremities. However, if your body core temperature is maintained (that is, you are otherwise dressed warmly), your body, after a bit of time, will send extra blood to those extremities to warm them back up. It dilates (opens) the blood vessels, hence the term “vasodilation”. This automatic response is of course very important to the Inuit, who need to be able to, for instance, thread hooks for fishing in pretty extreme conditions.

It takes about 8-10 minutes for this warming to happen. The body then cycles this cooling/warming. After a while in the warm state, it will restrict the vessels again and your extremities will get cold again. My guess is that the body is testing to see if core body temperature really can be maintained. But then, after a bit, vasodilation occurs again, and the extremities warm up again. This cycle can happen a few times before a steady-state is arrived at.

This response can be conditioned. Practicing in the cold can speed up the vasodilation response. You can see that in this graph:

Onset of CIVD

from “Effect of chronic local cold exposure on finger temperature responses”. The control shows that, in unconditioned people, it can take 10 minutes for vasodilation to occur. However, for this particular person, training (or conditioning) reduced that to 2 minutes, and the (in this case) finger never got as cold as for the unconditioned control.

It turns out, however, that some people do respond better to conditioning that others. This graph shows pretty much the best-case scenario. Some people showed only a minimal response to conditioning.

So, how does this apply to barefooters? Well, it means that, in reasonably chilly temperatures, we may be able to do more than we think. If we are not conditioned, our feet may get cold before that magic 10 minutes and we may give up just before the body is about to rewarm them. By being aware of this physiological reaction, we may be able to take advantage of it to enjoy going barefooted longer.

One thing to keep in mind is that we must make sure we keep our core body temperature warm. There’s an old saying, “If you feet are cold, put on a hat.” It’s a myth that “ 40 to 45 percent of body heat” is lost through the head, but, as usual, even the debunkings need to be more carefully examined. Yes, if you are stark naked then no, you will not lose 40 to 45 percent of body heat through your head. But if you are well-bundled up, and only your head is uncovered, of course you will be losing most of your heat there. Adding a hat could tip the balance between being cold and being warm. So, once again, if you are barefooting in the cold, do make sure to bundle yourself up well. Members of the Society for Barefoot Living have found that ankle warmers do a nice job of helping keep blood warm all the way down to the ankle so that it can do a good job keeping the feet warm.

I was recently on a barefoot hike in which I was able to observe CIVD directly. The temperature was about 30° (-1C). There was about an inch of snow on the ground, but its thickness varied depending on which part of the trail I was walking on. Some of it had had enough other people walk on it to have removed the snow while other parts had the full one inch.

(Side note: walking in snow is often colder than just walking on cold ground. On cold ground, I have fairly thick soles that do a good job of insulating my feet from that cold. However, it seems that getting snow on top of my feet, and particularly on top of my toes, is what really chills them down quickly.)

My CIVD response seemed to take a while to kick in, even though my core body temperature was just fine, since my trails took me up and down some hills. At about the 6-minute mark my feet were definitely feeling cold. But at the 8-minute mark, the CIVD kicked in and my feet suddenly felt perfectly comfortable. By 26 minutes, though, they were feeling cold again (that’s the cycling). At 30 minutes they were toasty again, and they remained just fine for the next half hour they stayed that way, even when I was getting snow on top of them.

I did want to make sure that it wasn’t the case that my feet had gone numb, fooling me into thinking they were warm. To test that, I looked for a twig, shut my eyes, and then tried to feel for the twig with just my feet. I found it fine, and was able to pick it up with my toes. Good check.

Finally, another word of warning. Be aware of what you are doing, and do not stretch beyond your limits. If you foolishly go out in zero degree weather and wait 10 minutes for CIVD to kick in, you will have frozen your feet long before it has a chance to. Worse than that, if you damage your feet that way, you won’t be able to enjoy regular barefooting, and you’ll never be able to train your feet to enjoy cooler temperatures.

Also, in a comment to the previous entry, Barefoot Josh warned about cold and wet conditions. Even wet conditions alone can be a bit of a challenge, because your feet absorb the water and get soft. When soft, they don’t protect as well against much of anything. Adding cold on top of that (when your skin is less pliable) just aggravates things. Again, while limits can be pushed, don’t push so hard you fall off a cliff.

So, yeah, I’ve got CIVD. And so do you.

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But . . . but . . . it’s cold!

Bare feet can attract a fair bit of attention or wonderment even when it is warm out, but during the wintertime, folks really don’t know what to make of it.

I suspect one reason is that so many people’s feet are regularly cold. However, regular barefooters don’t seem to suffer from the cold feet that so many shod people do.

There’s no real reason feet should be colder than, say, your hands. Genetically, they are very similar appendages. If you don’t need gloves, you probably don’t need shoes, either. True, when barefoot, the soles of your feet are touching the ground, but there are a couple of things that ameliorate that. First, in the fall and the early winter the ground is often warmer than the air temperature. Later in the winter and into early spring the ground often is colder than the air, but regular barefooters usually have a fairly thick buildup of padding on their soles, and that provides insulation. Second, if there is a wind of some sort, the wind is usually much lower near the ground (where your feet are), so your feet are not subjected to the wind chill that your hands are.

There is another reason that a bare foot can stay warm: it can move and gets good blood flow. Lacing up a shoe does do a good job of keeping the shoe on, but that tightness can restrict the flow of warm blood to the foot (actually, since veins are on the outside, not arteries, it’s probably blood flow out of the foot that is restricted, but if blood has trouble getting out, new blood has trouble getting in). Additionally, when your foot is bare all of its parts can work together to massage warm blood in and out. The movement and use of its 26 bones and over 100 muscles, tendons, and ligaments is helping to pump blood through all parts of the foot. When your foot is bound inside of a shoe, practically none of those parts are moving relative to each other—they are held immobile by the shoe, and so the blood flow is reduced. No wonder shod feet get cold!

It is also the case that the body adapts. If, as winter approaches, you keep going barefoot, your feet will acclimate and will get better and better at tolerating (and even relishing) colder temperatures. Various barefooters also report that, year-to-year, cold tolerance increases. It seems it can take 3-5 years of winters before the feet finally realize what they have to do to remain completely comfortable in temperatures that make the shod shudder at just the thought of going barefoot.

In our modern society, most folks aren’t outside for all that long anyways. Most barefooting in the winter is probably done between our cars and a store. For that short distance, even in quite cold conditions, the feet can take it just fine. Again, if you don’t need to put on gloves to run into a store, you probably don’t need shoes, either. Nothing will happen to them over that short distance (except, maybe, a bit of invigoration).

After getting acclimated, a barefooter can still feel the cold, it’s just that their feet aren’t cold. It’s like eating ice cream. The ice cream feels cold when you eat it, but it doesn’t make you cold, and it feels great going down (unless you do too much, too quickly; then, brain freeze). Going barefoot in the cold is like that. It’s mostly a great, different sensation, as long as it is not overdone, just like ice cream.

Let me end with a word of warning. Subfreezing cold can be dangerous. In the winter, know what you are doing, know your limits, and carry emergency footwear in your car, along with a spare blanket, snow brush, and roadside flares.

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Oz Revisited

As an addendum to the last entry, I’ve thought of another way of expressing what is going on there when wearing shoes:

Your feet have independent front and rear suspensions.

The front axle is at the ball of your foot, ahead of the arch; the rear axle is at your heel.

When you put on shoes, your feet no longer have that independent action. Instead, they are really more like a toy car, with a single axle that runs from side to side in the front and another in the rear. The tires are locked onto each axle and have no independent action. The front and rear axles are also pretty much locked together. If a real car was still designed that way, it, too, would show all sorts of weird tire wear. Shoes do the same thing, and we see it in the wear on the soles.

That’s not how feet are supposed to work. They really do have independent front and rear suspensions that can compensate for all sorts of terrain, and peculiarities of our bodies.

As an example, about 5 years ago, I was forced to wear shoes in a building (I had to go there, and they had a rule). While there, I turned, my foot caught in the carpeting (because of the footwear), and I shattered a bunch of cartilage in my knee. After a bunch of expensive MRIs and rehab, it’s (mostly) usable again.

However, since that time, I have extra-thick callus near my big toe, and only on that one side. My foot is compensating for the fact that my knee has those problems, and that foot can do it because of its independent suspension. When I am forced to wear shoes, I find that it really bothers my knee, because my shod feet can no longer compensate. That’s what the independent suspension is good for.

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Paging Dr. Oz . . .

The Thursday Dr. Oz Show had a segment entitled “How to Find the Best Shoe for You” that just didn’t quite get it. First, he mentioned the difference between flat, normal, and high arches. Then, he went on to discuss shoe wear patterns. While doing so, he then discussed the “right” kind of shoe for that pattern.

He called the wear patterns “normal,” “high roller,” and “low roller.” I suspect he was trying to dumb down what is called over- and under-pronation. For high rollers, the wear is on the inside at the toe and the outside at the heel, and he claimed that these sorts are particularly susceptible to plantar fasciitis and heel spurs. His solution was a very stiff sole. For low rollers, the wear is on the outside of the toe and the outside of the heel, and his solution was a very cushiony sole.

As usual, orthotics were presented as a general solution.

A few observations . . .

The whole wear bit seems to me to be an artifact of shoe-wearing. Take a look at your heel. Is it flat across the rear the way a shoe heel is? No. It is rounded. When you step on your heel while barefooted, your foot lands the way it wants to land, where it wants to land. When forced to wear the shoe, the shoe’s heel simply may not line up with the way your foot wants to land, hence the excess wear.

There is also something else going on at the toe. When Dr. Oz had the soles of the shoe flexed, did you notice that, regardless of whether it was a stiff sole or a cushiony sole, it only flexes along the long axis. There was no flexing in the other direction.

Yet, take your bare foot and see if you can flex it right and left along the ball (push one side down while pulling the other side up, and vice versa). Of course you can. That’s all the muscles and tendons working together (in fact, there is a second arch that runs left to right across the ball of your foot). In a shoe, there is none of that left-right flexibility, so it is no wonder that there is excess wear on one side or the other of the toe of the shoe. It’s there because the foot (along with the whole ankle/leg structure) is not being allowed to be used in its natural position.

And it is also no wonder that it can lead to all sorts of foot problems.

Dr. Oz also ended the segment by showing off some Vibram Five Fingers. He had some kind words to say about barefoot running—but then he doesn’t do it himself. He uses the Vibrams instead. No explanation as to why he thought he needed them instead of just going barefoot (though, we can guess). To get the proper sensory feedback about not slamming your foot onto the ground it really helps not to cover the bottom of your foot.

One good thing he did mention about barefoot (or, I guess, minimal footwear) running is that it allows the arch to do its job, so you get the “cushioning” of the arch, instead of the heel strikes that shoes lead to. But I guess he just couldn’t take that final step to actually do his running completely barefoot.

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High Societal Pressure

Marissa Gold, of stylelist.com, took Susan Sarandon to task for hitting the Red Carpet barefoot for the premiere of her new movie, “The Lovely Bones.” According to Gold, Sarandon needed some “funky python peep-toe sandals.”

Here’s a different idea: maybe Sarandon doesn’t need to torture her feet simply because some so-called fashion maven tries to apply social pressure. Maybe Sarandon is more sensible than Victoria Beckham.

USA Today is running a poll about Sarandon’s footwear choice (or, should we say, non-choice). So far it is running 73% in Sarandon’s favor.

What many of the stories don’t mention is that Peter Jackson is the director of the movie. Jackson is of course well-known for going barefoot a lot, and Sarandon went barefoot in homage to him, according to TVNZ. It should also be noted that New Zealand just isn’t as uptight about bare feet as the United States seems to be, so anybody who thinks this is shocking just needs to learn to be a bit more multi-cultural.

If folks seem to think that Sarandon still needed to gussy things up a bit, my suggestion is that a nice pearl ankle bracelet might have done nicely.

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You’re Going to Catch a Cold

Barefooters often have to listen to other well-meaning folks telling them that “You’re going to catch a cold.”

If I feel like a snippy response, it’ll often be: “Cold viruses don’t have eyes. They can’t look and see if I have anything on my feet or not.”

Yet, there does seem to be some sort of connection between being cold and getting colds. Colds are much more numerous in winter. There was even a study, “Acute cooling of the feet and the onset of common cold symptoms” that seems to show that chilling the feet can contribute to getting a cold. Actually, although the title refers to chilling the feet, the conclusion of the study is that a general chilling of the body that contributed to the cold; their suggested explanation was that chilling the body led to vasoconstriction of the blood vessels that inhibits the body’s ability to fight off the cold virus.

Unfortunately, much of the reporting on the study focused on the bare feet, not the chilling of the body. See here, for example.

In reality, it’s the chilling of the body that causes the problem. In addition, there is another, further explanation of how that chilling can make one more susceptible to the cold virus: cold viruses prefer cooler temperatures than body temperature. For instance, “An Explanation for the Seasonality of Acute Upper Respiratory Tract Viral Infections” notes that rhinoviruses (the cold virus) replicates best at temperatures quite a bit below body temperature. If the whole body gets chilled, lowering the temperature of the nose where the virus already happens to reside (but in check), that virus might then suddenly take off replicating and overwhelm the body’s defenses.

So, it’s not the cold feet, it’s the cold nose (that is brought about from chilling the whole body).

Thus, the secret of going barefoot in colder temperatures and not encouraging the cold virus is to keep the rest of your body warm. Make sure you are sufficiently bundled up, and the fact that you are barefooted should not make a difference in getting a cold.

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From 1974:

Dear Ann Landers:

I’m a male high school student, age 18, and I happen to enjoy kicking off my shoes and going barefoot. I never wear shoes when I’m at home and I remove them often when I’m in public.

I can’t explain why, but I really get turned on running barefoot across parks and lawns, especially on rainy summer days when people are walking their dogs. I know this isn’t everyone’s bag, but it happens to be mine.

What I can’t understand is the hostility that some people show to my lifestyle. I’ve been reprimanded several time because of this. One teacher telephones my mother to discuss “the problem.”

I think it’s ridiculous. After all, who am I hurting? I graduate in June and I would love to walk up on the stage in my stocking feet and receive my diploma. What kind of reaction do you think it would create? — Shoeless Joe

Dear Joe:

After the streaking that’s gone on all over the country, a guy in stocking feet wouldn’t even be noticed.

Enjoy yourself, Bub, but don’t step on any glass, rusty nails, or whatever people might step on in parks where dogs are walked.

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