1 00:00:01,840 --> 00:00:08,320 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff. Lauren Vogelbaum. 2 00:00:08,440 --> 00:00:13,080 Speaker 1: Here picture a brisk morning at the sandy shore of 3 00:00:13,119 --> 00:00:17,960 Speaker 1: San Francisco Bay. Tony Gilbert is not a former Olympian swimmer. 4 00:00:18,320 --> 00:00:20,919 Speaker 1: He's not part of a super athlete team, though he 5 00:00:21,079 --> 00:00:24,599 Speaker 1: knows swimmers like that, and he's not wearing a wetsuit. 6 00:00:25,640 --> 00:00:28,920 Speaker 1: In his usual swim trunk, swim cap, earplugs and goggles, 7 00:00:29,160 --> 00:00:32,800 Speaker 1: Gilbert wades into the forty six degree fahrenheit water that's 8 00:00:32,880 --> 00:00:37,520 Speaker 1: seven degrees celsius, and swims out into the murky Bay. 9 00:00:37,680 --> 00:00:41,240 Speaker 1: Gilbert is a hobby cold water swimmer. He's been doing 10 00:00:41,240 --> 00:00:44,120 Speaker 1: it for over a decade. He returns to shore some 11 00:00:44,159 --> 00:00:49,120 Speaker 1: forty minutes later, exhilarated for the article. This episode is 12 00:00:49,120 --> 00:00:51,440 Speaker 1: based on haws toff Work spoke with Gilbert back in 13 00:00:51,440 --> 00:00:55,840 Speaker 1: twenty twenty two. He said, it's really cold, but we 14 00:00:55,880 --> 00:00:59,040 Speaker 1: wouldn't do it if it wasn't fun. It's invigorating. Really. 15 00:00:59,400 --> 00:01:01,840 Speaker 1: The first few minutes are still the worst. Then you 16 00:01:01,920 --> 00:01:04,920 Speaker 1: get going, the endorphins kick in and you love it. 17 00:01:07,160 --> 00:01:09,280 Speaker 1: Gilbert is one of the members of the South End 18 00:01:09,360 --> 00:01:13,560 Speaker 1: Rowing Club, founded in eighteen seventy three. Who regularly take 19 00:01:13,600 --> 00:01:18,000 Speaker 1: dips in the frigid bay for fun. Gilbert's swims usually 20 00:01:18,120 --> 00:01:20,600 Speaker 1: range from twenty to forty minutes, but he's gone as 21 00:01:20,600 --> 00:01:24,880 Speaker 1: long as ninety minutes. The curious onlookers might wonder how 22 00:01:24,880 --> 00:01:29,320 Speaker 1: he doesn't experience hypothermia or why he actually enjoys swimming 23 00:01:29,400 --> 00:01:33,800 Speaker 1: in such cold waters. It turns out that the human 24 00:01:33,840 --> 00:01:37,120 Speaker 1: body has evolved some pretty helpful tools to acclimate two 25 00:01:37,200 --> 00:01:42,280 Speaker 1: different kinds of cold stress when necessary, depending on the frequency, duration, 26 00:01:42,520 --> 00:01:47,480 Speaker 1: and severity of the cold experienced. Basically, when we need 27 00:01:47,520 --> 00:01:51,320 Speaker 1: to move around and be comfortable in non life threatening 28 00:01:51,400 --> 00:01:56,400 Speaker 1: chili conditions, our bodies can habituate to the cold. When 29 00:01:56,400 --> 00:01:58,840 Speaker 1: the cold gets a little more serious, we can go 30 00:01:58,920 --> 00:02:04,160 Speaker 1: through more intense adaptations. To talk about all this, first, 31 00:02:04,280 --> 00:02:06,640 Speaker 1: let's go over how your body tries to protect you 32 00:02:06,800 --> 00:02:12,399 Speaker 1: when you experience cold. Okay, human beings are warm blooded mammals, 33 00:02:12,639 --> 00:02:16,440 Speaker 1: which means that we thermoregulate to keep a stable internal 34 00:02:16,440 --> 00:02:20,280 Speaker 1: body temperature, usually a little warmer than our environment at 35 00:02:20,280 --> 00:02:24,680 Speaker 1: which our organs and systems function well. For most humans, 36 00:02:24,800 --> 00:02:28,600 Speaker 1: that internal or core body temperature is right around ninety 37 00:02:28,600 --> 00:02:31,679 Speaker 1: seven to ninety nine degrees fahrenheit, which is thirty six 38 00:02:31,720 --> 00:02:36,040 Speaker 1: point one to thirty seven point two celsius. We are 39 00:02:36,120 --> 00:02:39,760 Speaker 1: able to stay right at that temperature because well, a 40 00:02:40,040 --> 00:02:44,320 Speaker 1: we've invented things like clothes, but b our digestive system 41 00:02:44,400 --> 00:02:48,040 Speaker 1: and cells break down the food we eat and metabolize 42 00:02:48,040 --> 00:02:50,560 Speaker 1: the glucose in it into a compound that our cells 43 00:02:50,639 --> 00:02:54,880 Speaker 1: can use for energy called adenisine triphosphate or ATP, and 44 00:02:55,000 --> 00:02:59,520 Speaker 1: heat is a byproduct. When you get too cold, like 45 00:02:59,560 --> 00:03:03,200 Speaker 1: your body temperature drops below ninety five degrees fahrenheit or 46 00:03:03,240 --> 00:03:07,000 Speaker 1: thirty five celsius, your organs can't function and begin to 47 00:03:07,000 --> 00:03:12,239 Speaker 1: shut down, which is bad. This is the aforementioned hypothermia, 48 00:03:12,520 --> 00:03:16,280 Speaker 1: and it can kill you. So when your body detects 49 00:03:16,280 --> 00:03:19,160 Speaker 1: a drop in temperature, it has a few defensive measures 50 00:03:19,200 --> 00:03:23,960 Speaker 1: it'll take to keep your core warm. You might start shivering. 51 00:03:24,680 --> 00:03:28,160 Speaker 1: This is an involuntary type of muscle contractions that start 52 00:03:28,160 --> 00:03:32,040 Speaker 1: in the torso and move to the limbs. What's happening 53 00:03:32,080 --> 00:03:35,480 Speaker 1: here is your body is attempting to create more internal heat. 54 00:03:36,720 --> 00:03:40,040 Speaker 1: Your muscles produce some heat whenever they contract through a 55 00:03:40,280 --> 00:03:44,040 Speaker 1: complicated biomechanical process that I don't understand very well. But 56 00:03:44,480 --> 00:03:47,080 Speaker 1: this is why moving around can help you warm up. 57 00:03:48,280 --> 00:03:53,000 Speaker 1: But more importantly for shivering, those repeated and rapid contractions 58 00:03:53,240 --> 00:03:57,600 Speaker 1: use up ATP real fast, prompting your cells to metabolize 59 00:03:57,600 --> 00:04:02,200 Speaker 1: more glucose into ATP plus heat. Of course, your skin 60 00:04:02,280 --> 00:04:04,400 Speaker 1: is one of the first line systems that your body 61 00:04:04,440 --> 00:04:06,680 Speaker 1: has to sense the cold, and it has a couple 62 00:04:06,680 --> 00:04:10,480 Speaker 1: of tricks to pull too. It might go over in goosebumps, 63 00:04:10,640 --> 00:04:14,320 Speaker 1: which is another type of involuntary muscle contraction, but instead 64 00:04:14,360 --> 00:04:17,880 Speaker 1: of big muscles giving you big shivers, these are tiny 65 00:04:17,960 --> 00:04:20,640 Speaker 1: muscles contracting in your skin to generate a bit of 66 00:04:20,680 --> 00:04:24,000 Speaker 1: heat and raise up your hair follicles, thus trapping a 67 00:04:24,000 --> 00:04:26,280 Speaker 1: bit of air near the skin and thus holding on 68 00:04:26,360 --> 00:04:29,800 Speaker 1: to a little bit of body heat. This might have 69 00:04:29,839 --> 00:04:32,479 Speaker 1: a negligible effect in humans and work out better for 70 00:04:32,520 --> 00:04:36,560 Speaker 1: our furrier cousins. But your skin can also perform another 71 00:04:36,600 --> 00:04:43,080 Speaker 1: involuntary function called cutaneous vasoconstriction. That means vascular constriction in 72 00:04:43,120 --> 00:04:47,120 Speaker 1: your skin. That is, your blood vessels contract, letting less 73 00:04:47,160 --> 00:04:51,000 Speaker 1: blood flow through them at your skin level. You shed 74 00:04:51,040 --> 00:04:53,880 Speaker 1: heat through your skin, and especially via blood flowing close 75 00:04:53,920 --> 00:04:58,560 Speaker 1: to skin level, so cutaneous vaso constriction keeps that blood 76 00:04:58,720 --> 00:05:01,760 Speaker 1: and thus that heat closer into your core to keep 77 00:05:01,800 --> 00:05:05,839 Speaker 1: your inner organs warm. This is why your extremities your 78 00:05:05,920 --> 00:05:09,280 Speaker 1: hands and feet get cold the fastest in chili conditions. 79 00:05:09,640 --> 00:05:12,080 Speaker 1: Your body is trying to keep its heat towards your core. 80 00:05:13,920 --> 00:05:16,960 Speaker 1: In these our modern times, we tend to moderate the 81 00:05:17,000 --> 00:05:19,800 Speaker 1: amount of cold that we're exposed to by bundling up 82 00:05:20,000 --> 00:05:24,200 Speaker 1: and spending more time in heated indoor areas. But even 83 00:05:24,240 --> 00:05:27,400 Speaker 1: when we only dip into cold temperatures briefly, even with 84 00:05:27,480 --> 00:05:31,400 Speaker 1: a minimum of skin exposed, our bodies can habituate to it. 85 00:05:32,480 --> 00:05:35,960 Speaker 1: We experience habituation, for example, over the course of several 86 00:05:36,040 --> 00:05:39,400 Speaker 1: cold mornings during ten minute dashes out for coffee or 87 00:05:39,480 --> 00:05:45,280 Speaker 1: to walk the dog. Habituations are like physical memory. Instead 88 00:05:45,320 --> 00:05:48,760 Speaker 1: of wasting valuable bodily energy sending up red flags to 89 00:05:48,800 --> 00:05:51,480 Speaker 1: your central nervous system. Every time your body is exposed 90 00:05:51,560 --> 00:05:55,239 Speaker 1: to a cold event, your body remembers it and responds less. 91 00:05:55,360 --> 00:05:59,640 Speaker 1: Over time, you won't shiver as much, and your skin 92 00:05:59,680 --> 00:06:03,000 Speaker 1: and extras will stay warmer for longer because your body 93 00:06:03,040 --> 00:06:08,599 Speaker 1: won't immediately draw blood inward to protect those vital organs. Basically, 94 00:06:08,760 --> 00:06:11,840 Speaker 1: your body realizes that the cold isn't going to seriously 95 00:06:11,920 --> 00:06:15,240 Speaker 1: damage you and that's also not going away, so it 96 00:06:15,279 --> 00:06:18,000 Speaker 1: adjusts to let you function better in the midst of it. 97 00:06:19,160 --> 00:06:21,320 Speaker 1: And it's a lot easier to function when you're not 98 00:06:21,400 --> 00:06:25,919 Speaker 1: shivering and your fingers aren't numb. This is how cold 99 00:06:25,960 --> 00:06:30,040 Speaker 1: water swimmers can tolerate near freezing water. They habituate to it, 100 00:06:31,240 --> 00:06:33,960 Speaker 1: but a swimmer can't adjust to swimming long lengths and 101 00:06:34,040 --> 00:06:38,599 Speaker 1: cold waters on their first trip. Gilbert said, you have 102 00:06:38,680 --> 00:06:42,240 Speaker 1: to be regular, consistent with cold water swimming to stay acclimated. 103 00:06:42,720 --> 00:06:44,400 Speaker 1: You have to swim two to three days a week 104 00:06:44,440 --> 00:06:47,160 Speaker 1: to stay acclimated, and the few times I did have 105 00:06:47,200 --> 00:06:49,520 Speaker 1: a break or fall off schedule, I would start back 106 00:06:49,560 --> 00:06:52,279 Speaker 1: at square one. Start with a short ten minute swim 107 00:06:52,320 --> 00:06:55,479 Speaker 1: one day, and then the next day try fifteen twenty, 108 00:06:55,720 --> 00:07:00,679 Speaker 1: and then back to thirty or forty five minutes. Even 109 00:07:00,839 --> 00:07:03,880 Speaker 1: the best, most adjusted swimmers get too cold and have 110 00:07:04,000 --> 00:07:07,479 Speaker 1: to stop when their body tells them it's time. Gilbert said, 111 00:07:07,880 --> 00:07:10,800 Speaker 1: your body keeps warm at the core, so your extremities 112 00:07:10,840 --> 00:07:15,160 Speaker 1: can get cold, especially your fingers are toes. On longer swims, 113 00:07:15,240 --> 00:07:17,680 Speaker 1: you'll even see some people get a claw hand or 114 00:07:17,800 --> 00:07:19,760 Speaker 1: some people get numb in the lips for a few 115 00:07:19,800 --> 00:07:21,880 Speaker 1: minutes and slur their words when they get out of 116 00:07:21,920 --> 00:07:26,480 Speaker 1: the water. This, by the way, is part of why 117 00:07:26,520 --> 00:07:29,760 Speaker 1: cold water swimmers swim with buddies of form clubs and 118 00:07:29,880 --> 00:07:33,520 Speaker 1: enlist more experienced swimmers to help teach new hobbyists how 119 00:07:33,520 --> 00:07:37,600 Speaker 1: to stay safe. If you're interested, definitely look into organizations 120 00:07:37,640 --> 00:07:42,440 Speaker 1: in your area. Anyway, Over the past couple of decades, 121 00:07:42,560 --> 00:07:45,520 Speaker 1: researchers have been looking into another way that our bodies 122 00:07:45,560 --> 00:07:49,240 Speaker 1: protect us from the cold. It turns out that shivering 123 00:07:49,360 --> 00:07:51,840 Speaker 1: is not the only cold induced way that our bodies 124 00:07:51,920 --> 00:07:58,360 Speaker 1: have of producing heat to warm us up. Enter brown fat. Now, 125 00:07:58,720 --> 00:08:01,640 Speaker 1: body fat in general is a good insulator and can 126 00:08:01,680 --> 00:08:04,720 Speaker 1: help your core stay warm, but there are different kinds 127 00:08:04,720 --> 00:08:09,720 Speaker 1: of body fat, white, brown, and beige. A white fat 128 00:08:09,760 --> 00:08:12,120 Speaker 1: is the kind you probably think of when you think 129 00:08:12,160 --> 00:08:14,880 Speaker 1: of body fat. It's made up of cells that store 130 00:08:14,920 --> 00:08:18,320 Speaker 1: lipids to cushion and insulate our innerds and to save 131 00:08:18,360 --> 00:08:22,400 Speaker 1: potential energy for a rainy day. It's creamy white in 132 00:08:22,520 --> 00:08:26,280 Speaker 1: color because each cell is basically just an envelope of lipids, 133 00:08:26,400 --> 00:08:30,520 Speaker 1: with the cells operative equipment the nucleus and mitochondria squished 134 00:08:30,520 --> 00:08:34,120 Speaker 1: out to the sides. Brown and beige fat are so 135 00:08:34,240 --> 00:08:37,760 Speaker 1: named because they contain a lot more rusty colored, iron 136 00:08:37,840 --> 00:08:41,600 Speaker 1: rich mitochondria at giving the cells a brown or beige color. 137 00:08:42,840 --> 00:08:47,079 Speaker 1: When you regularly experience cold, your body starts to activate 138 00:08:47,160 --> 00:08:50,440 Speaker 1: brown and beige fat cells to basically burn their lipid 139 00:08:50,480 --> 00:08:55,320 Speaker 1: stores in order to produce heat. For the article, this 140 00:08:55,360 --> 00:08:57,760 Speaker 1: episode is based on how stuff Works. Spoke with Te 141 00:08:57,840 --> 00:09:01,480 Speaker 1: Chung Lin, a PhD and Associate professor of biomedical research 142 00:09:01,520 --> 00:09:06,319 Speaker 1: at the Masonic Medical Research Institute. He said brown fat 143 00:09:06,400 --> 00:09:09,240 Speaker 1: serves as a fireplace in our body to keep us warm. 144 00:09:09,720 --> 00:09:13,880 Speaker 1: Individuals regularly exposed to cold, such as winter swimmers, have 145 00:09:14,040 --> 00:09:21,200 Speaker 1: higher heat generation efficiency than normal healthy individuals. Some scientists 146 00:09:21,320 --> 00:09:24,240 Speaker 1: argue that brown fat evolved early on in mammals and 147 00:09:24,360 --> 00:09:28,079 Speaker 1: helped give us a leg up from other species. Human 148 00:09:28,120 --> 00:09:30,400 Speaker 1: babies are born with a lot of brown fat to 149 00:09:30,480 --> 00:09:34,280 Speaker 1: protect them from cold at birth. Adults tend to retain 150 00:09:34,400 --> 00:09:37,520 Speaker 1: a little brown fat stored mostly between our shoulder blades. 151 00:09:38,720 --> 00:09:42,800 Speaker 1: Beige fat cells, meanwhile, seem to arise within populations of 152 00:09:42,840 --> 00:09:46,640 Speaker 1: white fat cells due to things like cold stress, and 153 00:09:46,920 --> 00:09:50,080 Speaker 1: then go about burning off their stored energy to help 154 00:09:50,160 --> 00:09:54,520 Speaker 1: keep the body warm. Researchers are still looking into how 155 00:09:54,600 --> 00:09:57,640 Speaker 1: brown and beige fat work and how they might be 156 00:09:57,679 --> 00:10:00,800 Speaker 1: connected to health factors like blood press usure and blood 157 00:10:00,840 --> 00:10:05,560 Speaker 1: sugar regulation. There's a hope that if we could figure 158 00:10:05,600 --> 00:10:08,280 Speaker 1: out how to boost the action of these fats, it 159 00:10:08,440 --> 00:10:13,560 Speaker 1: might help keep people healthier. So maybe those coldwater swimmers 160 00:10:13,600 --> 00:10:18,400 Speaker 1: are onto something. Gilbert said, coldwater swimming feels like you're 161 00:10:18,440 --> 00:10:21,680 Speaker 1: taking a bite out of life. There's nothing else like it. 162 00:10:26,520 --> 00:10:29,560 Speaker 1: Today's episode is based on the article can our Bodies 163 00:10:29,679 --> 00:10:32,880 Speaker 1: Learn to withstand frigid Temperatures? On how stuff works dot com, 164 00:10:32,920 --> 00:10:36,360 Speaker 1: written by Alison Troutner. Brain Stuff is production of iHeartRadio 165 00:10:36,440 --> 00:10:38,480 Speaker 1: in partnership with how Stuffworks dot Com, and it is 166 00:10:38,520 --> 00:10:41,600 Speaker 1: produced by Tyler Klin. Four more podcasts from my heart 167 00:10:41,679 --> 00:10:45,400 Speaker 1: Radio visit the iHeartRadio app, Apple Podcasts, or wherever you 168 00:10:45,400 --> 00:10:57,240 Speaker 1: listen to your favorite shows.