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2:10 Marathon at Altitude

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  • 2:10 Marathon at Altitude

    I see that Samson Kikwei Tuiyange just ran a 2:10:30 in Nairobi - elevation 1675m (5500'). That's just ridiculous. Is there a list of the fastest a-a (>1000m) Marathons?

  • #2
    Ridiculous? No. It's about in line with what one would expect in Nairobi.

    Comment


    • #3
      Originally posted by malmo
      Ridiculous? No. It's about in line with what one would expect in Nairobi.
      Which is why I asked the question. How many other 2:10 or better marathons at altitude?

      Comment


      • #4
        Originally posted by Marlow
        Originally posted by malmo
        Ridiculous? No. It's about in line with what one would expect in Nairobi.
        Which is why I asked the question. How many other 2:10 or better marathons at altitude?
        Irrelevant. How any 2:10 marathons have been run in Alaska?

        Remember all altitude isn't the same. 5000' at Nairobi isn't the same as 5000' in Denver.

        The big story of this race is that first prize was 1.5 million shillings - about 20,000 USD. A huge sum in a nation of poverty.

        Comment


        • #5
          Originally posted by malmo
          Remember all altitude isn't the same. 5000' at Nairobi isn't the same as 5000' in Denver.
          What's the difference? No sarcasm, serious question.
          "A beautiful theory killed by an ugly fact."
          by Thomas Henry Huxley

          Comment


          • #6
            Originally posted by Pego
            Originally posted by malmo
            Remember all altitude isn't the same. 5000' at Nairobi isn't the same as 5000' in Denver.
            What's the difference? No sarcasm, serious question.
            The density of the air. Climbers know that climbing at 20,000 feet on McKinley is much harder than around Everest. The reason is that the air density at altitude is higher near the equator. There is a seasonal component to it as well, that malmo might better elucidate than can I.

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            • #7
              Originally posted by Pego
              Originally posted by malmo
              Remember all altitude isn't the same. 5000' at Nairobi isn't the same as 5000' in Denver.
              What's the difference? No sarcasm, serious question.
              I assumed it was a serious question from the get-go.

              I don't know, just a guess maybe 750'. I've cut-and pasted a previous conversation (Letsrun) where the issue was addressed in response to Jorge Torres saying that altitude running was easier in South America (equator) than at Boulder. FWIW I believe the best 5000 and 10000 at Nairobi are about 13:10 and 27:40.

              Poster A
              your answer is here:
              http://mtp.jpl.nasa.gov/notes/altitude/ ... cales.html

              there is lots of truth to what the op has to say.

              Your moment of science:
              The layer of air that covers our planet is insubstantial compared to the mass of the planet. The troposphere, which contains 80% of the atmospheric mass, only extends to 5 to 11 miles above the surface of the planet. This would correspond to no more than the thickness of a heavy layer of paint for a 10 inch classroom globe. The thickness of the troposphere is not uniform over the earth. A combination of centrifugal force and temperature differences make the troposphere thickest at the equator, 10 to 11 miles. It is only 5 to 6 miles thick at the poles. Due to lower temperatures the troposphere is more dense at the poles, and the net result of all contributing forces and factors is that air pressure is pretty much the same planet wide at sea level. At high altitudes this is not true.

              Since the air layer over the earth is thinner at the poles, any upward movement from the planet's surface passes through a greater portion of the air layer than the same movement would accomplish at the equator. Thus, for higher altitudes, air pressure at high latitudes is lower than it is at low latitudes.

              We can not quantify this effect until we address seasonality. In the winter the air mass over the poles cools and contracts, and the thickness of the planet's local atmospheric layer decreases. (Of course, the opposite pole is experiencing summer and its air layer is expanding.) Thus, in winter at high latitudes and high altitudes air pressure is further depressed.

              Now, to quantify: consider the altitude at which air pressure averages 0. 5 atmospheres. On Mt. McKinley, 63: N latitude, this altitude is, on the average, 18,400 feet in mid-summer, and 16,800 feet in mid-winter. In the vicinity of Mt. Everest, 30: N latitude, this altitude is 19,400 feet in mid-summer, and 18,850 feet in mid- winter.

              At the summit of McKinley, 20,320 feet actual altitude, the average air pressure in mid-summer is about 0.453 atmospheres, which would correspond to a Himalayan summer altitude of 21,650 feet. In winter the summit pressure for McKinley, 0.420 atm., corresponds to a Himalayan winter altitude of 22,800 feet, and a Himalayan summer altitude of 23,460 feet.

              Chimborazo, 20,700 feet actual altitude, is essentially on the equator ( 2: S latitude) and so its summit pressure of about 0.472 atm. does not vary much seasonally.


              Poster B

              Us Dept. of Defense:

              "The mean barometric pressure at sea level is 760 mmHg(1013millibars) and falls as altitude increases. As theweight of upper atmospheric gases compresses the lowergas, this fall is not linear, the rate of decline in pressuredecreasing as the altitude increases. At the Equator, thebarometric pressure at high altitudes is higher thanelsewhere on the globe,11a phenomenon related to theparadox of the coldest atmospheric air lying above theEquator. Everest is at latitude 28oN, where the summitpressure is considerably greater than at a hypotheticalmountain of the same altitude near one of the poles.12The increase in barometric pressure of 17 mmHgbrought about by this so-called equatorial bulge isenough to improve maximal oxygen uptake and thusmake possible the ascent of Mt Everest without supplementary oxygen"

              http://64.233.169.104/search?q=cache:45 ... cd=1&gl=us

              Wikipedia: Gravity

              "Gravity is weaker at lower latitudes (nearer the equator), for two reasons. The first is that in a rotating non-inertial or accelerated reference frame, as is the case on the surface of the Earth, there appears a 'fictitious' centrifugal force acting in a direction perpendicular to the axis of rotation. The gravitational force on a body is partially offset by this centrifugal force, reducing its weight. This effect is smallest at the poles, where the gravitational force and the centrifugal force are orthogonal, and largest at the equator. This effect on its own would result in a range of values of g from 9.789 m•s−2 at the equator to 9.832 m•s−2 at the poles.[1]

              The second reason is that the Earth's equatorial bulge (itself also caused by centrifugal force), causes objects at the equator to be farther from the planet's centre than objects at the poles. Because the force due to gravitational attraction between two bodies (the Earth and the object being weighed) varies inversely with the square of the distance between them, objects at the equator experience a weaker gravitational pull than objects at the poles.

              In combination, the equatorial bulge and the effects of centrifugal force mean that sea-level gravitational acceleration increases from about 9.780 m/s² at the equator to about 9.832 m/s² at the poles, so an object will weigh about 0.5% more at the poles than at the equator.[2]


              Altitude
              Gravity decreases with altitude, since greater altitude means greater distance from the Earth's centre. All other things being equal, an increase in altitude from sea level to the top of Mount Everest (8,850 metres) causes a weight decrease of about 0.28%. (An additional factor affecting apparent weight is the decrease in air density at altitude, which lessens an object's buoyancy.[3]) It is a common misconception that astronauts in orbit are weightless because they have flown high enough to "escape" the Earth's gravity. In fact, at an altitude of 400 kilometres (250 miles), equivilant to a typical orbit of the Space Shuttle, gravity is still nearly 90% as strong as at the Earth's surface, and weightlessness actually occurs because orbiting objects are in free-fall.

              If the Earth was of perfectly uniform composition then, during a descent to the centre of the Earth, gravity would decrease linearly with distance, reaching zero at the centre. In reality, the gravitational field peaks within the Earth at the core-mantle boundary where it has a value of 10.7 m/s², because of the marked increase in density at that boundary."


              Poster C (yours truly)

              The the differences in gravity are so minute that there would be no noticeable differences in gas concentrations caused by the differences in gravity.

              G = Gravity
              R = Earth's Radius

              Boulder 40’ Lattitude Gco = ???? m/s^2
              New York 40’ Lattitude Gny = 9.802m/s^2

              Gny/Gco = (Rco/ Rny)^2

              9.802/Gco = (6369.6km/6368km)^2

              9.802/Gco = 1.000251262

              9.802/1.0005 = Gco = 9.797m/s^2

              The pull of gravity at Boulder is 99.94899% compared to New York City. Translation: negligible

              --------------------------

              The Earths radius at the equator is 6378km. The differences in gravity at 5000’ at 40 latitude compared to 5000’ at 0 latitude is:

              Geq/Gco = (Rco/ Req)^2

              Geq/9.797 = (6369.6km/6379.6km)^2

              Geq = (0.9968674)*(9.797) = 9.766 m/s^2

              The pull of gravity at 5000' on the equator is 99.968% of Boulder's gravity. Translation: negligible

              ------------------

              The reason why running is easier at altitude at the equator than at mid latitudes is due to change in the pressure gradients, as already posted by a previous rocket scientist [Poster A].

              Comment


              • #8
                Makes sense.
                "A beautiful theory killed by an ugly fact."
                by Thomas Henry Huxley

                Comment


                • #9
                  Doesn't take into account latitude, but a fun little calculator to play with.

                  http://www.altitude.org/calculators/airpressure.htm

                  (edit) better calculator

                  http://www.altitude.org/calculators/alt ... efacts.htm

                  Comment


                  • #10
                    Originally posted by Pego
                    Makes sense.
                    More (see table 1 and 2)

                    http://jap.physiology.org/cgi/content/full/81/4/1850

                    Comment


                    • #11
                      Originally posted by malmo
                      Originally posted by Pego
                      Makes sense.
                      More (see table 1 and 2)

                      http://jap.physiology.org/cgi/content/full/81/4/1850
                      What I don't see in the article is an effect on hematocrit. Would three months of intensive training in Denver produce a greater increase in hematocrit than in Nairobi? Has that been studied? One would assume, yes it should, but I've made wrong assumptions before. Once, or twice, perhaps :wink: .
                      "A beautiful theory killed by an ugly fact."
                      by Thomas Henry Huxley

                      Comment


                      • #12
                        wow, ya learn sumpin new every day - thanks!

                        Comment


                        • #13
                          You're welcome. Science in the natural world isn't neat and tidy, but there is a method to the madness.

                          Comment


                          • #14
                            Originally posted by malmo
                            You're welcome. Science in the natural world isn't neat and tidy, but there is a method to the madness.
                            All that kinda stuff fascinates me.

                            Comment


                            • #15
                              Originally posted by malmo
                              FWIW I believe the best 5000 and 10000 at Nairobi are about 13:10 and 27:40
                              The Nairobi M clocking is still likely to be pretty damn quick as a sea-level equivalent.

                              We have got very little to go on, but 13'00/27'00 - 27'10 are probably matching times for an athlete at sea-level, for which you can linearly extrapolate to a M ( just for a comparator, baseline time time )

                              13'10 & 27'40 in Nairobi weren't run by same guy, but it goes with general assumption that the times get relatively slower the further the distance run ( maybe have expected Nairobi best to be ~ 27'20 - 27'30 based on a 13'10 best there ) - extrapolating this to a M gives a comparator time somewhere 3'00 - 4'00 slower at the M than sea-level

                              1st ( primitive) guess would be to take 3'00 - 4'00 off that 2"10'30 for a

                              ~ 2"06'30 - 2"07'30

                              equivalent at sea-level

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