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  1. #1
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    Default Limit to Human Endurance

    Here is an interesting article about how the ultimate limit on long term endurance activities is how many calories your body can process and use over the long term. It also gives some insight into the answer to the perennial question "How many calories do you burn per day on the AT?"

    https://interestingengineering.com/s...uman-endurance
    If you don't stand for something, you will fall for anything.

  2. #2

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    Cool subject. It concerns me of course due to how much decent food (calories and protein) a backpacker can carry long term.

    Google up "Ranger School" and you'll find an interesting article on Wikipedia with this wonderful quote---

    Physical effects
    Following the completion of Ranger School, a student will usually find himself "in the worst shape of his life".

    Military folk wisdom has it that Ranger School's physical toll is like years of natural aging; high levels of fight or flight stress hormones . . . . , along with standard sleep deprivation and continual physical strain, inhibit full physical and mental recovery throughout the course.
    https://en.wikipedia.org/wiki/Ranger_School

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    Quote Originally Posted by Tipi Walter View Post
    Cool subject. It concerns me of course due to how much decent food (calories and protein) a backpacker can carry long term.

    Google up "Ranger School" and you'll find an interesting article on Wikipedia with this wonderful quote---

    Physical effects
    Following the completion of Ranger School, a student will usually find himself "in the worst shape of his life".

    Military folk wisdom has it that Ranger School's physical toll is like years of natural aging; high levels of fight or flight stress hormones . . . . , along with standard sleep deprivation and continual physical strain, inhibit full physical and mental recovery throughout the course.
    https://en.wikipedia.org/wiki/Ranger_School

    This is was certainly true for me. I could not have passed the Ranger PT test if they gave it prior to graduation. RLTW
    76 HawkMtn w/Rangers
    14 LHHT
    15 Girard/Quebec/LostTurkey/Saylor/Tuscarora/BlackForest
    16 Kennerdell/Cranberry-Otter/DollyS/WRim-NCT
    17 BearR
    18-19,22 AT NOBO 1562.2
    22 Hadrian's Wall
    23 Cotswold Way

  4. #4
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    Quote Originally Posted by Tipi Walter View Post
    Cool subject. It concerns me of course due to how much decent food (calories and protein) a backpacker can carry long term.

    Google up "Ranger School" and you'll find an interesting article on Wikipedia with this wonderful quote---

    Physical effects
    Following the completion of Ranger School, a student will usually find himself "in the worst shape of his life".

    Military folk wisdom has it that Ranger School's physical toll is like years of natural aging; high levels of fight or flight stress hormones . . . . , along with standard sleep deprivation and continual physical strain, inhibit full physical and mental recovery throughout the course.
    https://en.wikipedia.org/wiki/Ranger_School
    I just read david goggins’ book and he went through both navy seal and ranger school and he found the ranger school toughest due to calorie restrictions.

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    Quote Originally Posted by Maineiac64 View Post
    I just read david goggins’ book and he went through both navy seal and ranger school and he found the ranger school toughest due to calorie restrictions.
    When I asked my son how Ranger School compared to our Sierra High Route hike, his answer surprised me. He said it was about the same physically but the difference was they could eat something like 2400 calories.
    enemy of unnecessary but innovative trail invention gadgetry

  6. #6

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    Quote Originally Posted by Maineiac64 View Post
    I just read david goggins’ book and he went through both navy seal and ranger school and he found the ranger school toughest due to calorie restrictions.
    Quote Originally Posted by Malto View Post
    When I asked my son how Ranger School compared to our Sierra High Route hike, his answer surprised me. He said it was about the same physically but the difference was they could eat something like 2400 calories.
    I've been restricting daily caloric load for more than 20 yrs as pre hike prep for similar motivations as SEAL and Ranger schooling. You learn to operate mentally and physically at a high level without the over consumption U.S. civies are accustomed. Same with sleep. This approach to backpacking assumes a decent level of fitness pre hike. It's not a hike yourself into LD hiking shape(psychologically, physically, emotionally, spiritually) approach. It fits into UL backpacking. Operating on a restricted daily caloric load correlates with less food wt. Consider this approach uses the restricted caloric load technique on soldiers already fit with little body fat to make up for energy making them fitter and able to withstand extremes of combat.

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    Quote Originally Posted by Dogwood View Post
    ....... Consider this approach uses the restricted caloric load technique on soldiers already fit with little body fat to make up for energy making them fitter and able to withstand extremes of combat.
    Here is a link to the research article itself. https://advances.sciencemag.org/content/5/6/eaaw0341

    As I read it, what the scientists found basically is that if you expend energy in excess of 2.5 times your Rest Metabolic Rate then the deficit can't be made up from eating more food instead you lose body fat and muscle mass. So for soldiers undergoing intense training, restricting calories below 2.5 times their RMR really doesn't make them fitter. It just increases loss of body fat and muscle mass. It may psychologically prepare them for the hardships they may encounter.
    If you don't stand for something, you will fall for anything.

  8. #8

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    Here is a calculator that will estimate your BMR, and calories burned for various exercise levels, based on gender, age, height, and weight.

    https://www.thecalculatorsite.com/he...calculator.php

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    Just in case anyone was wondering if the above article applies to extreme hiking (the FKT hikers is what I am referring to here).

    I had noted that their prime example was the race across America and that the runners averaged about a marathon a day. Then you compare that to Stringbean's average of about 48 miles a day on the AT and you wonder if they missed something. Extreme hikers are clearly out on the edge of what is humanly possible.

    So I contacted the lead author Dr. Pontzer at Duke and asked him.

    It turns out the extreme hikers match the data exactly and Stringbean is in their database.

    So the gauntlet has been thrown down. It's up to you speedsters to prove them wrong.

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    I was thinking that you might be able to work backwards and figure out how many miles you could hike per day over 6 months without wrecking yourself. If 2.5 times your BMR is an upper limit then for me that would be about 4000 cal/day (1585 cal BMR x 2.5). Using this calculator ( https://caloriesburnedhq.com/calorie...ng/#calculator ) to figure out how many calories you burn hiking, about 12 miles per day assuming a pack weight of 25 lbs walking 6 hours per day (2 mph) uphill and downhill with a 5-10% grade would require about 4000 cal. The article did not make clear whether the 2.5 x BMR is the total amount of calories you can expend or if that is on top of your BMR which would make quite a difference.
    If you don't stand for something, you will fall for anything.

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    Anish discusses her physical changes on the PCT is some detail in her book Thirst. ​She is certainly out on the ragged edge of what's possible.
    "It's fun to have fun, but you have to know how." ---Dr. Seuss

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    IIRC the NAZI's gave their troops some sort of drugs that allowed them to ruck something like over 100km per day. Yes drug assisted, but it is within the limits of the human body.

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    The article addresses very short term extreme efforts and the numbers generated. And goes on to describe how the numbers change as the duration of the event increases. Short term limits are very different than long term ones. And using drugs to enhance short term will carry an extra physical penalty which must be paid...but if you are likely going to be dead in a few days due to the Soviet army it does not make much difference.

  14. #14

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    Quote Originally Posted by Starchild View Post
    IIRC the NAZI's gave their troops some sort of drugs that allowed them to ruck something like over 100km per day. Yes drug assisted, but it is within the limits of the human body.
    Yeah, methamphetamine. It was synthesized by a Japanese chemist working in Germany and later given to not only German troops but Allied and other Axis troops in WW II including, as a dirty little U.S. military and U.S. gov't approved secret, U.S. troops to avoid sleep and fatigue and increase endurance.


    Japanese, U.S., British and German military personnel are reported to have used the stimulant to enhance endurance and ward off fatigue on long campaigns.

    https://www.history.com/topics/crime/history-of-meth



    It's become convenient and customary to isolate Nazis as only engaging in questionable behavior.

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    Quote Originally Posted by Dogwood View Post
    Yeah, methamphetamine.
    That was a later one, the earlier one was cocaine, oxycodon and something else.

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    Quote Originally Posted by Starchild View Post
    That was a later one, the earlier one was cocaine, oxycodon and something else.
    To the best of my knowledge, the Wehrmacht used Pervitin, which is basically Meth in low doses, as tablets and injections.
    Even famous Alpinists like Hermann Buhl on his famous solo first ascent of Nanga Parbat, carried and used Pervitin, which he admitted later to have saved his life.

  17. #17
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    Yeah, meth. Luckily it's readily available in the AT corridor. :-D
    Quote Originally Posted by Starchild View Post
    IIRC the NAZI's gave their troops some sort of drugs that allowed them to ruck something like over 100km per day. Yes drug assisted, but it is within the limits of the human body.

  18. #18

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    Another interesting article on this subject: The limits of human endurance: what is the greatest endurance performance of all time?

    https://www.ncbi.nlm.nih.gov/pubmed/...ncbi_mmode=std

  19. #19

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    Hmm. I learned there was a limit to human endurance when a 3 yr old standing too close for too long next to the fireplace. No scientists were around to tell me there was a limit either.

  20. #20
    Nalgene Ninja flemdawg1's Avatar
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    Jinx! buy me a coke.

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