Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff. Lauren Vogelbaum.
Speaker 1: Here picture a brisk morning at the sandy shore of
Speaker 1: San Francisco Bay. Tony Gilbert is not a former Olympian swimmer.
Speaker 1: He's not part of a super athlete team, though he
Speaker 1: knows swimmers like that, and he's not wearing a wetsuit.
Speaker 1: In his usual swim trunk, swim cap, earplugs and goggles,
Speaker 1: Gilbert wades into the forty six degree fahrenheit water that's
Speaker 1: seven degrees celsius, and swims out into the murky Bay.
Speaker 1: Gilbert is a hobby cold water swimmer. He's been doing
Speaker 1: it for over a decade. He returns to shore some
Speaker 1: forty minutes later, exhilarated for the article. This episode is
Speaker 1: based on haws toff Work spoke with Gilbert back in
Speaker 1: twenty twenty two. He said, it's really cold, but we
Speaker 1: wouldn't do it if it wasn't fun. It's invigorating. Really.
Speaker 1: The first few minutes are still the worst. Then you
Speaker 1: get going, the endorphins kick in and you love it.
Speaker 1: Gilbert is one of the members of the South End
Speaker 1: Rowing Club, founded in eighteen seventy three. Who regularly take
Speaker 1: dips in the frigid bay for fun. Gilbert's swims usually
Speaker 1: range from twenty to forty minutes, but he's gone as
Speaker 1: long as ninety minutes. The curious onlookers might wonder how
Speaker 1: he doesn't experience hypothermia or why he actually enjoys swimming
Speaker 1: in such cold waters. It turns out that the human
Speaker 1: body has evolved some pretty helpful tools to acclimate two
Speaker 1: different kinds of cold stress when necessary, depending on the frequency, duration,
Speaker 1: and severity of the cold experienced. Basically, when we need
Speaker 1: to move around and be comfortable in non life threatening
Speaker 1: chili conditions, our bodies can habituate to the cold. When
Speaker 1: the cold gets a little more serious, we can go
Speaker 1: through more intense adaptations. To talk about all this, first,
Speaker 1: let's go over how your body tries to protect you
Speaker 1: when you experience cold. Okay, human beings are warm blooded mammals,
Speaker 1: which means that we thermoregulate to keep a stable internal
Speaker 1: body temperature, usually a little warmer than our environment at
Speaker 1: which our organs and systems function well. For most humans,
Speaker 1: that internal or core body temperature is right around ninety
Speaker 1: seven to ninety nine degrees fahrenheit, which is thirty six
Speaker 1: point one to thirty seven point two celsius. We are
Speaker 1: able to stay right at that temperature because well, a
Speaker 1: we've invented things like clothes, but b our digestive system
Speaker 1: and cells break down the food we eat and metabolize
Speaker 1: the glucose in it into a compound that our cells
Speaker 1: can use for energy called adenisine triphosphate or ATP, and
Speaker 1: heat is a byproduct. When you get too cold, like
Speaker 1: your body temperature drops below ninety five degrees fahrenheit or
Speaker 1: thirty five celsius, your organs can't function and begin to
Speaker 1: shut down, which is bad. This is the aforementioned hypothermia,
Speaker 1: and it can kill you. So when your body detects
Speaker 1: a drop in temperature, it has a few defensive measures
Speaker 1: it'll take to keep your core warm. You might start shivering.
Speaker 1: This is an involuntary type of muscle contractions that start
Speaker 1: in the torso and move to the limbs. What's happening
Speaker 1: here is your body is attempting to create more internal heat.
Speaker 1: Your muscles produce some heat whenever they contract through a
Speaker 1: complicated biomechanical process that I don't understand very well. But
Speaker 1: this is why moving around can help you warm up.
Speaker 1: But more importantly for shivering, those repeated and rapid contractions
Speaker 1: use up ATP real fast, prompting your cells to metabolize
Speaker 1: more glucose into ATP plus heat. Of course, your skin
Speaker 1: is one of the first line systems that your body
Speaker 1: has to sense the cold, and it has a couple
Speaker 1: of tricks to pull too. It might go over in goosebumps,
Speaker 1: which is another type of involuntary muscle contraction, but instead
Speaker 1: of big muscles giving you big shivers, these are tiny
Speaker 1: muscles contracting in your skin to generate a bit of
Speaker 1: heat and raise up your hair follicles, thus trapping a
Speaker 1: bit of air near the skin and thus holding on
Speaker 1: to a little bit of body heat. This might have
Speaker 1: a negligible effect in humans and work out better for
Speaker 1: our furrier cousins. But your skin can also perform another
Speaker 1: involuntary function called cutaneous vasoconstriction. That means vascular constriction in
Speaker 1: your skin. That is, your blood vessels contract, letting less
Speaker 1: blood flow through them at your skin level. You shed
Speaker 1: heat through your skin, and especially via blood flowing close
Speaker 1: to skin level, so cutaneous vaso constriction keeps that blood
Speaker 1: and thus that heat closer into your core to keep
Speaker 1: your inner organs warm. This is why your extremities your
Speaker 1: hands and feet get cold the fastest in chili conditions.
Speaker 1: Your body is trying to keep its heat towards your core.
Speaker 1: In these our modern times, we tend to moderate the
Speaker 1: amount of cold that we're exposed to by bundling up
Speaker 1: and spending more time in heated indoor areas. But even
Speaker 1: when we only dip into cold temperatures briefly, even with
Speaker 1: a minimum of skin exposed, our bodies can habituate to it.
Speaker 1: We experience habituation, for example, over the course of several
Speaker 1: cold mornings during ten minute dashes out for coffee or
Speaker 1: to walk the dog. Habituations are like physical memory. Instead
Speaker 1: of wasting valuable bodily energy sending up red flags to
Speaker 1: your central nervous system. Every time your body is exposed
Speaker 1: to a cold event, your body remembers it and responds less.
Speaker 1: Over time, you won't shiver as much, and your skin
Speaker 1: and extras will stay warmer for longer because your body
Speaker 1: won't immediately draw blood inward to protect those vital organs. Basically,
Speaker 1: your body realizes that the cold isn't going to seriously
Speaker 1: damage you and that's also not going away, so it
Speaker 1: adjusts to let you function better in the midst of it.
Speaker 1: And it's a lot easier to function when you're not
Speaker 1: shivering and your fingers aren't numb. This is how cold
Speaker 1: water swimmers can tolerate near freezing water. They habituate to it,
Speaker 1: but a swimmer can't adjust to swimming long lengths and
Speaker 1: cold waters on their first trip. Gilbert said, you have
Speaker 1: to be regular, consistent with cold water swimming to stay acclimated.
Speaker 1: You have to swim two to three days a week
Speaker 1: to stay acclimated, and the few times I did have
Speaker 1: a break or fall off schedule, I would start back
Speaker 1: at square one. Start with a short ten minute swim
Speaker 1: one day, and then the next day try fifteen twenty,
Speaker 1: and then back to thirty or forty five minutes. Even
Speaker 1: the best, most adjusted swimmers get too cold and have
Speaker 1: to stop when their body tells them it's time. Gilbert said,
Speaker 1: your body keeps warm at the core, so your extremities
Speaker 1: can get cold, especially your fingers are toes. On longer swims,
Speaker 1: you'll even see some people get a claw hand or
Speaker 1: some people get numb in the lips for a few
Speaker 1: minutes and slur their words when they get out of
Speaker 1: the water. This, by the way, is part of why
Speaker 1: cold water swimmers swim with buddies of form clubs and
Speaker 1: enlist more experienced swimmers to help teach new hobbyists how
Speaker 1: to stay safe. If you're interested, definitely look into organizations
Speaker 1: in your area. Anyway, Over the past couple of decades,
Speaker 1: researchers have been looking into another way that our bodies
Speaker 1: protect us from the cold. It turns out that shivering
Speaker 1: is not the only cold induced way that our bodies
Speaker 1: have of producing heat to warm us up. Enter brown fat. Now,
Speaker 1: body fat in general is a good insulator and can
Speaker 1: help your core stay warm, but there are different kinds
Speaker 1: of body fat, white, brown, and beige. A white fat
Speaker 1: is the kind you probably think of when you think
Speaker 1: of body fat. It's made up of cells that store
Speaker 1: lipids to cushion and insulate our innerds and to save
Speaker 1: potential energy for a rainy day. It's creamy white in
Speaker 1: color because each cell is basically just an envelope of lipids,
Speaker 1: with the cells operative equipment the nucleus and mitochondria squished
Speaker 1: out to the sides. Brown and beige fat are so
Speaker 1: named because they contain a lot more rusty colored, iron
Speaker 1: rich mitochondria at giving the cells a brown or beige color.
Speaker 1: When you regularly experience cold, your body starts to activate
Speaker 1: brown and beige fat cells to basically burn their lipid
Speaker 1: stores in order to produce heat. For the article, this
Speaker 1: episode is based on how stuff Works. Spoke with Te
Speaker 1: Chung Lin, a PhD and Associate professor of biomedical research
Speaker 1: at the Masonic Medical Research Institute. He said brown fat
Speaker 1: serves as a fireplace in our body to keep us warm.
Speaker 1: Individuals regularly exposed to cold, such as winter swimmers, have
Speaker 1: higher heat generation efficiency than normal healthy individuals. Some scientists
Speaker 1: argue that brown fat evolved early on in mammals and
Speaker 1: helped give us a leg up from other species. Human
Speaker 1: babies are born with a lot of brown fat to
Speaker 1: protect them from cold at birth. Adults tend to retain
Speaker 1: a little brown fat stored mostly between our shoulder blades.
Speaker 1: Beige fat cells, meanwhile, seem to arise within populations of
Speaker 1: white fat cells due to things like cold stress, and
Speaker 1: then go about burning off their stored energy to help
Speaker 1: keep the body warm. Researchers are still looking into how
Speaker 1: brown and beige fat work and how they might be
Speaker 1: connected to health factors like blood press usure and blood
Speaker 1: sugar regulation. There's a hope that if we could figure
Speaker 1: out how to boost the action of these fats, it
Speaker 1: might help keep people healthier. So maybe those coldwater swimmers
Speaker 1: are onto something. Gilbert said, coldwater swimming feels like you're
Speaker 1: taking a bite out of life. There's nothing else like it.
Speaker 1: Today's episode is based on the article can our Bodies
Speaker 1: Learn to withstand frigid Temperatures? On how stuff works dot com,
Speaker 1: written by Alison Troutner. Brain Stuff is production of iHeartRadio
Speaker 1: in partnership with how Stuffworks dot Com, and it is
Speaker 1: produced by Tyler Klin. Four more podcasts from my heart
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