Why Don’t Sled Dogs Ever Get Tired?
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Why Don’t Sled Dogs Ever Get Tired?

September 6, 2019


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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Only registered users can comment.

  1. Is not corect'😡THE HORSES ARE SO FASTER NOT DOGS !!!!!!YOUR AER NOT CCCOOORRREEECCTTT😠😠😠😠😡😡😡😡😡😤😤😤😤👿👿👿😼🏇🏇🏇🏇🏇🏇🏇

  2. I have raw fed husky who gets 5-7 hours of exercise in spring- summer and 12 hours during winter. Feel bad for low quality kibble fed non exercised huskies.

  3. owning an alaskan malmute is- tiring let me tell you that. i have 3 of em and they take you on walks rather than you taking them on walks-

  4. Dog deaths at the Iditarod are so routine that the official rules blithely state that some “may be considered unpreventable.”

    The Iditarod has killed more than 150 dogs since it began in 1973. Five died in 2017 alone.

  5. Human beats other animals cause we are better at sweating to prevent overheating.
    I don't think heatstroke was a issue at Arctic.

  6. 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.

  7. 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.

  8. 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

  9. 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)

  10. 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

  11. 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
    RED BULL GIVES YOU WIIIIIIIINGS
    I bet my horse is gonna beat those dogs
    A golden Apple some witch made and some redbull
    HEH

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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.

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