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The 80 percent rule :0)

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The 80 percent rule :0)

Postby Alby426 » Thu Sep 12, 2013 6:50 am

Very often, when I go up a mountain, I encounter people that struggle and, tell me that they are fit and, train a lot by running and biking. The same people wonder why they struggle so much at altitude so, I came up with an explenation that seems to make the point easily.

THE 80 % RULE:

If you train at sea level and, can bike sustaining 80% effort level, since at 14000 feet there is only about 60% athmospheric pressure, it means only 60% oxygen, this means that you can sustain only approximately 45% effort level, up there, without burning out.
For individuals that train in the Front Range (6000 feet), the effort level raises to about 55%.

Please, don't try to dissicate this with complicated scientific analisys, just keep it that simple as, at that altitude, when you explain it, the lack of oxygen also affects cognitive abilities :shock:

Have a great day and, see you up there.
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Re: The 80 percent rule :0)

Postby ajkagy » Thu Sep 12, 2013 7:12 am

is there much of a difference for those that live/train at 10,000ft?
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Re: The 80 percent rule :0)

Postby madbuck » Thu Sep 12, 2013 7:18 am

What is "effort level" and where do these numbers come from?

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Re: The 80 percent rule :0)

Postby Scott P » Thu Sep 12, 2013 7:25 am

THE 80 % RULE:

If you train at sea level and, can bike sustaining 80% effort level, since at 14000 feet there is only about 60% athmospheric pressure, it means only 60% oxygen, this means that you can sustain only approximately 45% effort level, up there, without burning out.
For individuals that train in the Front Range (6000 feet), the effort level raises to about 55%.


Although it is a nice thought, it really doesn't work linear or just as a simple multiplication of the percentages. This is because the body starts making immediate changes as you ascend to higher altitudes. If you were transported immediately within a fraction of second to moderate altitudes it might somewhat follow that pattern, but if the change in altitude is too much your "effort" level can quickly drop to zero percent. If you were only transported to say 5000 feet, because of the way your body works, the drop in percentage wouldn't be near as much as the drop in atmospheric pressure.

Most of us aren't transported to altitudes in a fraction of a second though, so the body starts to adapt as we ascend to altitudes.

is there much of a difference for those that live/train at 10,000ft?


There is a difference. If you timed yourself running a mile at 10,000 feet, even if you have always lived there, and then dropped to sea level and then timed yourself running a mile, there should be a difference.

If interested, throughout several years and over different time periods, the military has done studies to try and figure out how much (which of course is different for every person), but you would have to look for the info.
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Re: The 80 percent rule :0)

Postby madbuck » Thu Sep 12, 2013 7:38 am

Scott P wrote:
THE 80 % RULE:

If you train at sea level and, can bike sustaining 80% effort level, since at 14000 feet there is only about 60% athmospheric pressure, it means only 60% oxygen, this means that you can sustain only approximately 45% effort level, up there, without burning out.
For individuals that train in the Front Range (6000 feet), the effort level raises to about 55%.


Although it is a nice thought, it really doesn't work linear or just as a simple multiplication of the percentages. This is because the body starts making immediate changes as you ascend to higher altitudes.


Yes, that is exactly what I was afraid of in the oversimplification.
Also, there are going to be non-linearities with respect to oxygen percentage and how aerobic the effort is, compared to the relevant metabolic processes and energy sources for those efforts. And, dependency on amount of time spent at altitude as well as genetic factors.

Scott P wrote:There is a difference. If you timed yourself running a mile at 10,000 feet, even if you have always lived there, and then dropped to sea level and then timed yourself running a mile, there should be a difference.


In fact, this Running Calculator is based on Jack Daniels's (the coach/ex phys PhD) famous "running formula," and shows a sea-level time to be ~91% of an acclimated 10,000' time. While not perfect, I've found it to be pretty useful.
Last edited by madbuck on Thu Sep 12, 2013 9:26 am, edited 1 time in total.

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Re: The 80 percent rule :0)

Postby Theodore » Thu Sep 12, 2013 8:50 am

Anyone have something they want me to test out? :-D I live almost exactly at 1000 ft ASL. If my hikes go as planned and the weather holds out, I'll be on top of Princeton about this time tomorrow. 13,000+ feet of gain in 14-15 hours...

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Re: The 80 percent rule :0)

Postby masonpips » Thu Sep 12, 2013 9:04 am

Theodore wrote:Anyone have something they want me to test out? :-D I live almost exactly at 1000 ft ASL. If my hikes go as planned and the weather holds out, I'll be on top of Princeton about this time tomorrow. 13,000+ feet of gain in 14-15 hours...


Went from 700 feet on Thursday (6 pm flight) to top of Grays/Torreys mid-day Friday. Felt pretty good, breathing was major issue (20 steps, stop to breathe, repeat). Did Belford/Oxford on Saturday, felt about 200% better and on Monday when I summited Pikes, never had to stop for breath. I run and hike at home (including 50-100 foot climbs) plus climb bleachers 2x/week. All I can do here, just have to expect the first hiking day will be a little tougher and then it gets A LOT easier!

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Re: The 80 percent rule :0)

Postby edhaman » Thu Sep 12, 2013 9:20 am

Part of what previous posts say, although not this simply: It is not just a matter of fitness; it is also a matter of acclimatization. I also understand that it has been rather clearly established that being fit does NOT translate into less susceptibility to AMS.

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Re: The 80 percent rule :0)

Postby ThuChad » Thu Sep 12, 2013 10:35 am

My completely unscientific theory is if I can run an 8-9 minute mile without stopping at 1000 ft. For X distance. I can hike comfortably the same distance of X at altitude.

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Re: The 80 percent rule :0)

Postby ajkagy » Thu Sep 12, 2013 11:01 am

madbuck wrote:In fact, this Running Calculator is based on Jack Daniels's (the coach/ex phys PhD) famous "running formula," and shows a sea-level time to be ~91% of an acclimated 10,000' time. While not perfect, I've found it to be pretty useful.



interesting...so in other words, if you've lived at 10k ft. for a long time you'll still never be as fast as you are at 10k ft. then if you lived at sea level.
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Re: The 80 percent rule :0)

Postby jomagam » Thu Sep 12, 2013 11:24 am

There's no general rule, you just have to try out how you react to altitude. My anecdotal evidence is that people with low blood pressure tend to do worse at altitude relative to normal or high blood pressure folks. You can throw all the numbers out the window.

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Re: The 80 percent rule :0)

Postby JChitwood » Thu Sep 12, 2013 12:53 pm

Wow, never heard the low blood pressure angle, but mine is on the low side and for years I have suffered in the mountains. When I first started climbing in 1994 I was a competitive triathlete in great shape but got hammered by altitude sickness about every time. Now 19 years later at age 53, I am not in the shape I was but still train regularly and just can't get up the hill. Not so much altitude sickness these days, just out of breath with my heart rate redlining. My climbing partner who is five years older and in similar condition waits on me constantly no matter how much training I do. I was so concerned after last year that I had a complete cardio and carotid artery workup this January. The results were normal and the MD had no answers, just said everybody is affected by altitude in different ways. Also told me to train harder, guess that is always good advice.
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