Why Don’t Sled Dogs Ever Get Tired?

Hi, this is Kate from MinuteEarth. Humans are not the fastest mammals on the
planet, but over really long distances, we can outrun every other species on land…
except certain dogs. The greatest ultramarathoners on the planet
are husky/malamute mixes bred for sled racing: while pulling a load, they run five back-to-back
marathons in a day, day after day, for more than a week. That’s because of the totally unique way
they turn food into energy. Like all mammals, sled dogs rely on two types
of fuel: there’s glycogen, which comes from carbs and sugar, and is quick to ignite and
fast-burning, like natural gas. And there’s fat and protein, which come
from…well…fat and protein – which are not that flammable and burn slowly, kind of
like logs. Glycogen can power a runner on its own for
periods of short, intense exercise, but because it burns up fast, long-distance runners rely
mostly on their supply of slow-burning fats and proteins. In order to turn fats and proteins into energy,
though, most mammals need to also keep burning a small but steady supply of glycogen. And that turns out to be a serious problem,
because the body’s glycogen storage tanks are pretty small, and converting carbs and
sugars into glycogen takes a little while. So runners burn glycogen faster than they
can make it – if they run for long enough, their supply will inevitably run out, and
they’ll bonk. Sled dogs never bonk, because early in the
race, their bodies somehow shift over to burning fat and protein without needing to use any
glycogen at all. And since fat and protein can be turned into
energy pretty much immediately, the dogs can refuel throughout the race without ever worrying
about running out of glycogen. We still don’t know how this fuel-burning
trick works, but we do know that after 9 days and 1000 miles through the snow and ice, most
dogs finish the race with the same baseline vitals that they started with. In fact, unlike human ultra-athletes, who
often need months to recover, the dog teams that do best in one ultrarace are often the
ones that have just recently returned from another one. When it comes to feats of endurance, sled
dogs turn the competition to … mush!. Hey! So after four years without a dedicated website,
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100 Replies to “Why Don’t Sled Dogs Ever Get Tired?”

  1. Sled dogs are not Huskey, Mal crosses. Huskies are sled dogs. Mals are sled dogs. Alaskan Huskies are a mix of many dog breeds that generally includes husky.

  2. I have a husky, her name is Ellie. I love her so much, plus we never catch up to her, lol. She has escaped the house… But, we always just get her back, lol.

  3. Mammals:Runs
    Most mammals : tired
    Human and sledogs : git gud
    sledogs : that is for u too
    humman : wait what?
    human : tired
    sledogs : git gud
    humans :oh I will get good…
    human : buulds rocket that uses air as fuel and out"run" sledigs
    human : git smart

  4. You didn't take in consideration heat because this type of dog live in cold region of hearth but for other regions of earth heat is a huge problem and if human can run longer than most animals is because we can sweat (some animals can but in much smaller scale)to cool ourselves (we run longer for other reasons like our muscles that are made to be less powerful but last longer)

  5. This is really unrelated to the video, but ya know when you see one of those comments with a time button on it, and you are about to get at that time? Yea me too

  6. Ima race my horse against other people and we have guns so when we are riding the horse we try shooting the targets and you need to get a bulls eye on all the targets to win
    ima give my horse a golden Apple and REEEEED BULL
    I bet my horse is gonna beat those dogs
    A golden Apple some witch made and some redbull

  7. To all the people making comments about how these dogs are "abused" or being "mistreated". I own two adult huskies, one male, one female. The female is 55 pounds and the male is 65 pounds- he may be a small percent wolf. Both are pure white, the sweetest most gentlest dogs you could be around- until you get them on a leash and harness. Then its all out the window. Many people watch these videos and make quick judgement, but don't understand the power of these animals. I'm an average adult male- 6', 175 lbs on a good day, just one of these dogs will pull on that leash for hours, and especially in the snow I have to fight to keep from being pulled forward – thats just ONE dog. I don't ever walk both dogs by myself single-handedly. I have on occasion been forced to walk both of them on the leash and let me tell you- its freaking scary how strong just two of these dogs are. I've trained them pretty well, but even still if they get a millisecond inkling that were about to walk or go for a run all bets are off. Just two of these dogs could drag and pull me with some effort- in fact many people do whats referred to as "skiijoring" aka skis + 2-3 sled dogs. NOW, I want you to imagine the power of 8-15 of these dogs. That sled and one guy weighs jack to them

  8. Weird as it sounds Humans also have similar endurance to dogs, running for multiples and multiples on end, except of course we run in hot as hell places and these dogs run in the bitter winter cold

    Sad to see so many humans waste that inborn talent nowadays tho

  9. Make a video about how did earth form beacause your cideo is called minute earth so I got that idea please i got no idea how earth forms

  10. Every living being burns out and get tired no matter how great their endurance, we all need a bit of a break for rest, food, and sleep even high energy sled dogs

  11. I bet we humans can beat these boys in warmer climate, they have nice energy preservance trick but we also have one- sweat. Dogs will overheat quickly if they keep running under the searing sun.

  12. I hate everyone saying doggo…. it's a dog and there's a type of dog called argentino DOGO. They are masterpieces of animals and most other dogs dont deserve the name (light-hearted but serious)?😓😜

  13. This is bullshit video.
    Huskies are not the only animals that can outrun humans in a marathon.
    Certain antelope, carnivora and most importantly land birds can outrun humans.
    Ostrich are the best runners on land right now, this is thanks to their airsac respiratory system which is superior to that of mammals.

  14. Totally unique ? What is the difference between totally unique and unique ?

    Well, please explain how something can be partly unique.

  15. everybody gets tired. everybody feels pain. how we deal with pain and fatigue is what differentiates athletes from others.

  16. *Animals don't burn proteins. Animals can convert proteins into glucose and then use that as fuel, which is a different thing. The process is slower than digesting dietary carbohydrates and extremely inefficient, so normally only happens in very small amounts unless protein consumption is very high and/or during starvation. Only microorganisms like bacteria can directly burn aminoacids.

    Long distance runners are fueled by fats almost exclusively (directly or by conversion to ketones).

  17. News flash humans can actually run on fat without the need for carbs at all ultra marathon runners are starting to adopt this type of diet because they get far superior results than they do with a carb diet

  18. The caveat to sled dogs being able to run so far is they can only do it in cold weather. Unlike humans who could run 200 miles in 40c weather. Dogs would not be able to effectively keep themselves cool in any other climate, so while they may have the greatest tool for long distance energy, they dont have the ability to use it anywhere.

  19. It is such a dumb statement too say a human can outrun any animal.

    Yeah sure if you choose the exact requirements of the race to suit the human… but that doesn't really count. It is a blatantly misleading statement at best.

    A house spider can outrun any animal…
    over a 1mm distance across a silk thread.

  20. you forgot that they don't over heat doe to freezing environment, the main reason other animals can't run long distances (humans sweat to avoid overheating, which is why humans can run farther than most animals)

  21. Just remember these dogs can only run in the cold because if you’d put them in the heat they don’t sweat like humans, so humans are still the fastest in hot weather

  22. Not true at all. We can outrun all terrestrial species. While sled dogs, camels, antelope and a few others can put in a faster marathon time for 40k or so, a human can run marathon speed for the entire day and cover more than 300km everyday. No other species of terrestrial animal is capable of covering that distance or even coming close to it. It would take sled dogs close to 3 days to match our daily run.

  23. Redo the competition in a warm environment. That is our competitive advantage. We can sweat from our skin and that is how our ancestors survived on the savanna. We simply overheated our prey, by having a superior cooling system. It's similar to hyenas who do it by taking turns at running though. We are evolved to run far (slowly) in a warm environment and overheating our prey. That is why we do so well at long distances.

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