Ultimate limit of human endurance found

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Alpinum
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Ultimate limit of human endurance found

Post by Alpinum »

Interesting read:

https://www.bbc.com/news/health-48527798

Amazing how little it is.
I'd like to see what function the curve has (energy vs time).


Could explain why I've always got along on expeditions and long trips with 2800 - 3200 kcal intake/day with only loosing max. 10 % body mass.
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PaulE
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Re: Ultimate limit of human endurance found

Post by PaulE »

The paper it comes from (linked in the BBC article) was interesting too. I wonder if the adaption to elevated energy consumption and expenditure for very extended periods during pregnancy is part of the reason for a narrowing of the performance gap between male and female athletes as events increase in duration?
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Alpinum
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Re: Ultimate limit of human endurance found

Post by Alpinum »

*hmpf*

found the graph I was hoping for... must have been a bit early.

Cheers Paul for pointing it out:
https://advances.sciencemag.org/content/5/6/eaaw0341
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Re: Ultimate limit of human endurance found

Post by Bearbonesnorm »

Sometimes, the ultimate limit of human endurance would appear to be simply making it to another bedtime :wink:
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Re: Ultimate limit of human endurance found

Post by RIP »

Or making it through a bowl of prunes without involving Ralph or Huey.

V interesting read was that. I'll probably just still continue tramping well below my limits though. Nice to have summat in reserve. Interesting point re digestion too ( snap, Sean :wink: ) - validates my view that after a nice dinner one should slump in front of the telly and have a snooze, or if bikepacking to stay in the cafe/pub a bit longer talking rubbish before setting off again.
Last edited by RIP on Thu Jun 06, 2019 8:31 am, edited 1 time in total.
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Re: Ultimate limit of human endurance found

Post by sean_iow »

Interesting that they mention the limit may be due to the ability to digest enough calories to replace the expenditure.

I'm sure I've heard said, and often say to people, that long endurance events (over a period of days) are an eating competition and not a cycling one. Training will only get you to a certain level of fitness and after that it's just eating lots and the mental strength to keep going,
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Re: Ultimate limit of human endurance found

Post by psling »

Quite topical at the moment too when you consider the troop movements into France after D Day; quite often moving under extreme duress with minimal sleep and zero rations for several days.
Could you imagine a 5 day bikepacking trip with hardly any food and someone lobbing live grenades at you along the way :shock:
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Re: Ultimate limit of human endurance found

Post by Bearbonesnorm »

Could you imagine a 5 day bikepacking trip with hardly any food and someone lobbing live grenades at you along the way :shock:
Brilliant Peter, a new BB event right there :-bd
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Re: Ultimate limit of human endurance found

Post by PaulB2 »

I vaguely remember reading that Ranulph Fiennes was eating whole sticks of butter to keep his calories up on one antarctic expedition or other, going through 8000 calories a day, and still lost over 20 kilos of weight.
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Re: Ultimate limit of human endurance found

Post by Scud »

I think it is why we are seeing sports nutrition companies trying to get the largest amount of carbs in the easiest digestible form in to sports drinks etc, SiS with products like Beta Fuel etc where they are packing in 80g of carbs in a 500ml drink.

As you say it is actually a battle as to how you can keep fuelling and digesting, rather than purely performing.

Strangely how sports nutrition advice goes full circle, i did my sports science degree 20 years ago and then it was "carbs are king", we then recently went through the age of keto, minimal carbs and the like, but it seems to come full circle and again we are back to realising that complex carbs (with correct fats and protein in balance) before an event, with the most digestible simple carbs during an event are the best thing to keep you running long-term.
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Re: Ultimate limit of human endurance found

Post by jameso »

sean_iow wrote: Thu Jun 06, 2019 8:26 am Interesting that they mention the limit may be due to the ability to digest enough calories to replace the expenditure.

I'm sure I've heard said, and often say to people, that long endurance events (over a period of days) are an eating competition and not a cycling one. Training will only get you to a certain level of fitness and after that it's just eating lots and the mental strength to keep going,
The calorie intake thing makes sense. Our bodies manage output as a survival thing once we're past a certain point, and I expect 5 or more days of 16-18hrs at 70% HR counts - as far as I understand it it's also really unusual mix of intensity and duration for humans, evolved for fight/flight rather than long and steady (hence heart issues relatively common in endurance sports regulars). I've read about how the body has more stored energy than we will usually access but it will shut down the system to preserve reserves. It can be fooled into giving them up via small amounts of carbs hitting the bloodstream etc (the 'carb wash' trick I think it's called?) but no idea whether this can work repeatedly. I expect not, knowing how drained you can get after a long time on the bike - you're down to fat-burning pace and avoiding muscle wastage may be the main thing.

I've got minimal experience with anything over 10-12 days, but 2 things I have learned from a number of 'shorter' trips - 1 is that I seem to adapt in some ways after 5-7 days and go into a second phase of strength/endurance, proably provided you're trained and adapted in the first place and not too depleted by then. 2nd is that it really is managed attrition on longer, higher output rides. Looking after yourself up to and beyond that adaptation point (in perhaps different ways) seems to be the most important factor. Training for fitness is important for efficiency and conditioning/recovery but if you ruin yourself in the first 3 or 4 days you just may not recover and lose more over the next period than the early speed gained you. Perhaps better to go steady until that 5-7 day point then see how well you're coping.
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Re: Ultimate limit of human endurance found

Post by redefined_cycles »

In relation to what Reg (which could be a massive debate in itself) rightly says...

There's 2 systems at work here. Resting and Digesting and Fight or Flight (am sure its much more complex than that byt for my little brain and whats relevant to me/us).

Fight/flight: When you wanna/need to punch someones lights out cos their dog has just shat all over the footpath... or (flight) when said dog is a big scary dog and the owner a "full retard meany".

Hence whats most important to us in this part of the the Nervous System is that when in fight/flight mode the body moves it services away from Resting and Digesting functions. Hence the willy (sorry for using that example but its one of the 2 that I know and can explain) wont have as much blood flow to it and the stomach also. I imagine alot of the riders in the HT550 were in this "fight/flight" mode for extended periods or somewhere in that ballpark at least.

Hence why when on a long ride, the body doesnt have enough resources to the stomach to 'churn' and if you end up eating something too solid its all too easy to become stomach cramped. Hence why it might explain that during and after big ITTs or multi day rid8ng hard, ones poo ends up coming out a bit watery :-bd ... My understanding is that it (the stomach) must keep throwing out lots of acid to allow that digestion....

Resting and Digesting: well you get the point right... Sex is an activity (by way of example) that can only really happen when in the resting/digesting mode. Otherwise bloods not sent to the willy as much as is needed etc etc :lol:

Anyway.... so... erm... thats probably (from quickly having read the article but I know all the figures are not there and it is the BBC reporting it afterall and*) why the Tour De France guys probably manage to run on a higher basal metabolic rate overall. As they have them extended periods between riding (for trying for resting and digesting although I imagine from all the drugs and having been in the fight/flight mode, wouldn't be able to get a 'ahem' anytime soon) which allows the body to gain the energy -kindof - to keep going....

Anyway... :-bd
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Re: Ultimate limit of human endurance found

Post by jameso »

I vaguely remember reading that Ranulph Fiennes was eating whole sticks of butter to keep his calories up on one antarctic expedition or other, going through 8000 calories a day, and still lost over 20 kilos of weight.
The chap I ended up racing pretty much head to head in the TDR had been to one of the poles and a few other expeditions of that type, we talked about food a lot while riding together for 24hrs or so :grin: and he said olive oil and peanut butter was their fuel of choice for calorie:weight ratio. I ate a lot of Reece's PB cups on that ride. Processed cheese slices were also really good - packable, calorie and protein-dense, a bit heavy though. Might well be the lack of variety and vitamins etc that starts to get to you though, there must be things other than calories that you're loosing fast that don't get replaced.

All in all, it's not good for you :lol: throw in the sleep deprivation and the overall effect makes a very good case for leisurely touring in Europe.
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Re: Ultimate limit of human endurance found

Post by redefined_cycles »

jameso wrote: Thu Jun 06, 2019 10:32 am
sean_iow wrote: Thu Jun 06, 2019 8:26 am Interesting that they mention the limit may be due to the ability to digest enough calories to replace the expenditure.

I'm sure I've heard said, and often say to people, that long endurance events (over a period of days) are an eating competition and not a cycling one. Training will only get you to a certain level of fitness and after that it's just eating lots and the mental strength to keep going,
The calorie intake thing makes sense. Our bodies manage output as a survival thing once we're past a certain point, and I expect 5 or more days of 16-18hrs at 70% HR counts - as far as I understand it it's also really unusual mix of intensity and duration for humans, evolved for fight/flight rather than long and steady (hence heart issues relatively common in endurance sports regulars). I've read about how the body has more stored energy than we will usually access but it will shut down the system to preserve reserves. It can be fooled into giving them up via small amounts of carbs hitting the bloodstream etc (the 'carb wash' trick I think it's called?) but no idea whether this can work repeatedly. I expect not, knowing how drained you can get after a long time on the bike - you're down to fat-burning pace and avoiding muscle wastage may be the main thing.

I've got minimal experience with anything over 10-12 days, but 2 things I have learned from a number of 'shorter' trips - 1 is that I seem to adapt in some ways after 5-7 days and go into a second phase of strength/endurance, proably provided you're trained and adapted in the first place and not too depleted by then. 2nd is that it really is managed attrition on longer, higher output rides. Looking after yourself up to and beyond that adaptation point (in perhaps different ways) seems to be the most important factor. Training for fitness is important for efficiency and conditioning/recovery but if you ruin yourself in the first 3 or 4 days you just may not recover and lose more over the next period than the early speed gained you. Perhaps better to go steady until that 5-7 day point then see how well you're coping.
When watching the vids/writeups from post ride reports of both James Hayden(in one of the TCRs) and Dr Ian Walker (North Cape epic 4000 I think) both talked/wrote about going easy in the initial days - although Ian almost went too hard and suffered.... he found yoghurts best for the stomach - whilst the noted others that went too hard and then suffered later. Ian got a few 100 mile runs under his belt aswell I think so some serious adaptations of body there..

Either way, aint the body just absolutely amazing as to what it can do! :-bd...

One thing to add here. The brain, it never allows the body to hit its peak power outputs at any point. It has an inbuilt lmiter that ensures it (the organs) stay safe... Miraculous (learnt that from one of the BBC endurance series docs. Can't remember the name sorry)
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Re: Ultimate limit of human endurance found

Post by redefined_cycles »

My mate just sent me the same (bbc) article and being a Muzlamic (like myself according to some of the Tommy Robinson lot) he also sent a verse of the Quran underneath. Really sums it up for me to be honest and especially some of the feats many of the BBs manage to achieve.

" In the earth, there are signs for those who (seek truth to) believe [20] and in your ownselves! So, do you not perceive? [21] (Quran; chapter 51-Dharyat/The Scattering Dust) ".

Apologies in advance :geek: and totally understand if it needs to be deleted :-bd
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Re: Ultimate limit of human endurance found

Post by jameso »

I imagine alot of the riders in the HT550 were in this "fight/flight" mode for extended periods or somewhere in that ballpark at least.
Fight/Flight is basically adrenaline isn't it? Prob not riding on adrenaline for more than a few minutes at the start, or the odd downhill that can give you a great pick-up when you're otherwise flagging. 'Nervous energy mode' maybe? I don't think many would be feeling that for long though.

(and surely no need apologise for quoting the Quran, or anything else linked to a faith. Can't see anyone here having a jot of an issue with it)
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Re: Ultimate limit of human endurance found

Post by redefined_cycles »

Fight/flight... yup. Adrenaline it is and hence why I'm obviously wrong on that regards but its still in some sort of nervous system mode that supresses the 'resting and digesting' system (ie. Meaning that the body doesnt appropriate its focus in that dept/them organs...

Either way. This thread indeed deserves the 'Thread of the Day' award (wouldn't you agree Reg) and maybe we should donate some of our own (maybe Karl and if someone can convince Liam Glenn) to the research depts.

On that note (and if anyones intwrested which obviously they are) theres 18 free days of this MOOC* remaining. I'm still in week 1 and have so far learnt as my take home message: Previously (roughly speaking) endurance training used to be 80/20 split. With 80 percent at low intensity (go8ng slow to go fast and all that jazz) and 20 percent at lactate(ish) threshold but more current thinking is 80 to 85 at low intensity and the remainder 15 (or at least 5 of that 15) at above threshold (in the anaerobic zone I believe which would be pretty painful).

Obviously Josh Kato had a training regimen that obviously worked and was more 'everyday' and this must be whats probably best for us (full time worker) types.

*https://www.futurelearn.com/courses/end ... erformance
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Re: Ultimate limit of human endurance found

Post by jameso »

^ that is an interesting link, signed up, thanks .. very much of interest. I don't train 'properly' most years but what I did learn a few years back has really helped in that my fast/slow ride balance has a similar structure and some benefit from that, rather than 'just riding'. Of course I still do 'just ride', it's just that I often make decisions on what to do with the time I have based on that 80/20* type of idea, or knowing I need recovery not more miles, etc. The best bit of training for endurance speed was realising how much time you should spend going slow :) Seems counter-intuitive at first but over the time period of a worthwhile plan it's effective.

*For me it wasn't so much as 80/20, just a basic plan for as much base/distance work as possible, some SS/tempo miles for fun and only 1 HIT session on the turbo per week.
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Re: Ultimate limit of human endurance found

Post by RIP »

"Sex is an activity (by way of example) that can only really happen when in the resting/digesting mode" - Shaf's right, I'm enjoying this thread. Very educational. However there can be situations when after the 'activity' things rapidly turn fight/flight :grin: . Back to the calorie stuff now I think...
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Re: Ultimate limit of human endurance found

Post by psling »

Classic case Reg of 'How can you tell when a lass from [insert town of choice] is having an orgasm? She drops her bag of chips'. Well, that could cover the digesting part, anyway... :shock:
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Re: Ultimate limit of human endurance found

Post by whitestone »

Back on topic (not the chocolate bar :roll: ) reading through the paper I haven't found a correlation/correspondence between the energy intake and power output. I.e. is it upper end zone 2 (endurance), lower or higher? Roughly how many Watts/Kg does it equate to?

As for training: when I was running I'd do one HIIT session a week, usually hill reps, a couple of tempo sessions and the rest were just "plodding" so probably 5%, 15%, 80% ratio in terms of time. I'd be lucky if the hill rep session lasted more than 40mins as doing it correctly was pretty brutal.

Edit:

I did a bit of searching and use of online calculators and came up with this.

The human body is around 25% efficient so 4000KCal as input is roughly equal to 4000 KJoules of output so that’s 4 million Watt/seconds. Let’s say you are on the move for 18hrs that’s 18 * 60 * 60 seconds = 64800 seconds.

4,000,000/64800 = 61.7W

Using British Cycling's power zone calculator and assuming that the rider can output 3W/kg in an FTP test then the upper limit of zone 1 (active recovery) is 125W so riding at 61.7W is a very easy pace. Change the rider's output to 2W/kg lowers the zone 1 limit to 83W. You'd have to have an FTP of 1.5W/kg before you left zone 1.
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Re: Ultimate limit of human endurance found

Post by Lazarus »

i would be impressed to see someone zone 1 a long high off road mountain climb, on a fully ladden Bikepacking bike, with just 62 watts,
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Re: Ultimate limit of human endurance found

Post by whitestone »

Lazarus wrote: Thu Jun 06, 2019 6:40 pm i would be impressed to see someone zone 1 a long high off road mountain climb, on a fully ladden Bikepacking bike, with just 62 watts,
True.

The figure would be an average over the course of the day. Remember that the point is that you can sustain this level indefinitely whilst maintaining body weight. Now we all know that on a multi-day ride despite keeping every cafe and cake shop near our route in business that we lose weight. What this tells us is that that level of effort is not infinitely sustainable.

Basically if your BMR is 1600KCals/day then you can only take on board 4000KCals (again indefinitely)

But ... If you consume more than 4000KCals per day, does that mean that the excess simply isn't absorbed and is just excreted?
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Re: Ultimate limit of human endurance found

Post by Lazarus »

What this tells us is that that level of effort is not infinitely sustainable.
My body tells me that i dont need science :wink:

I suppose you get rest down hill and the like hence the average may be attainable.

Not sure what happens to the excess food but you may vomit it out as you are not able to digest it[ ie you are at the limits of what the body can absorb whilst also exercising .
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Re: Ultimate limit of human endurance found

Post by Asposium »

whitestone wrote: Thu Jun 06, 2019 5:08 pm Back on topic (not the chocolate bar :roll: ) reading through the paper I haven't found a correlation/correspondence between the energy intake and power output. I.e. is it upper end zone 2 (endurance), lower or higher? Roughly how many Watts/Kg does it equate to?

As for training: when I was running I'd do one HIIT session a week, usually hill reps, a couple of tempo sessions and the rest were just "plodding" so probably 5%, 15%, 80% ratio in terms of time. I'd be lucky if the hill rep session lasted more than 40mins as doing it correctly was pretty brutal.

Edit:

I did a bit of searching and use of online calculators and came up with this.

The human body is around 25% efficient so 4000KCal as input is roughly equal to 4000 KJoules of output so that’s 4 million Watt/seconds. Let’s say you are on the move for 18hrs that’s 18 * 60 * 60 seconds = 64800 seconds.

4,000,000/64800 = 61.7W

Using British Cycling's power zone calculator and assuming that the rider can output 3W/kg in an FTP test then the upper limit of zone 1 (active recovery) is 125W so riding at 61.7W is a very easy pace. Change the rider's output to 2W/kg lowers the zone 1 limit to 83W. You'd have to have an FTP of 1.5W/kg before you left zone 1.
Firstly .... :ugeek: :geek:

i rode JOGLE in 8 and a half days, hardly ultraendurance i appreciate; however, my average heart rate was 105, max 150, and 29,806kCal
i have an FTP of 3.5w/kg if Zwift and Garmin are to be believed
perhaps i was being soft, though the head wind and rain didn't feel so
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