Changes

Some notes on If you're travelling to higher altitude training and or using [[Altitude Training]] to improve performance, it's worth understanding the science of how altitude effects athletes. The key takeaways are that acclimation takes about two weeks and most people will benefit from iron supplements, ideally starting weeks or months before altitude exposure. (Iron supplements should be taken under medical supervision and iron levels checked regularly. I use [https://www.walkinlab.com/ferritinserumtest.html Walk In Labs] to check my Serum Ferritin levels.)=The Effects of altitudeAltitude=

* Altitude is generally considered High altitude as 1500 to 3500m (5,000' to 11,500'), Very high altitude as 3500 to 5500m (11,500' to 18,000'), and Extreme altitude as above 5500m (18,000')<ref name="ParalikarParalikar2010"/>.* Rapid ascent from near sea level to above 2500m/8,000' can result in problems ranging from mild sickness to life-threatening Acute Mountain Sickness (AMS), but with gradual acclimation extreme altitudes can be tolerated<ref name="ParalikarParalikar2010"/>. * One "rule of thumb" is that above 3000m/10,000', you shouldn't sleep more than 300m/1,000' higher than the previous night<ref name="ParalikarParalikar2010"/>. * A key feature of acclimation to altitudes up to 5,000m/16,000' is an increase in breathing<ref name="West2006"/>. Other changes include an increase in heart rate, increase in blood pressure, increase in red blood cells, reduction in blood volume (increased urine output), increase in capillary density, and an increase in mitochondria and oxidative enzymes<ref name="Goldfarb-RumyantzevAlper2013"/>. However, the increase in capillary density might be at least partly due to a reduction in muscle fiber size<ref name="MizunoSavard2008"/>.* The human body adjusts to lower blood oxygen saturation by producing more in many ways, and one key adaptation that is of interest to athletes is an increase in red blood cells, but the performance improvements from [[Altitude Training]] may come from additional sources<ref name="Nonhematological"/><ref name="GoreHopkins2005"/>. * The extra red effects of altitude are non-linear. From sea level to Leadville (10,170 ft), your blood oxygen levels may drop 6% from 96% to 90%. Going up another 4,000 ft to Pike's Peak (14,110), blood cells offsets some of the lower performance oxygen levels may drop a further 8% to 82%. Running is harder at altitude, as well as providing better performance seen by the [[VO2max]] drop. At Leadville your [[VO2max]] may drop by ~15% (range 4-30%)* [[SpO2|SpO₂]] at low altitudemay be slightly misleading as the oxygen deliver to the muscles may be modified by O₂ dissociation curve shifts caused by changes in pH, PCO₂, and blood temperature<ref name="DempseyWagner1999"/>. However, [[SpO2|SpO₂]] is cheap and easy to monitor and should not be ignored. * There is great individual variability in the response to altitude<ref name="ChapmanStray-Gundersen1998"/>. Some studies have classified subjects as 'responders' and 'non-responders' due to the significance of this variability. This variability can change over time within an individual. I met someone in Tanzania who had been a porter on Kilimanjaro (19,334 ft) until he lost his ability to cope with the altitude.* Some variability may be due to differences in iron intake/availability. Low blood iron (serum ferritin < 20 ng/ml female, < 30 ng/ml male) may limit the body's ability to generate new red blood cells, which is part of the altitude adaptation. See below for more details on iron supplementation. * Generally, 'live high, train low' seems to work better than 'live high, train high'. [[Intermittent Hypoxic Exposure]] may have additional benefits over other [[Altitude Training Approaches]]. * The effects Altitude acclimatization takes time, with 2 weeks being a point of altitude are non-lineardiminishing returns. From sea level This is based on a study of athletes traveling to Leadville (102340m/7,170 ft)766' that showed a performance decrease of 26% on arrival, your blood oxygen levels drop they recovered by 6.0% from 96after 7 days, another 5.7% to 90after 14 days, but only another 1.4%after 21 days<ref name="Schuler-2007"/>. These findings seem broadly similar for those sleeping in an altitude tent (normobaric hypoxia) <ref name="Townsend-2002"/>. Going up another 4* Training needs to be reduced at altitude,000 ft and this reduction can lead to Pikedetraining. 's Peak (14Live high,110)train low' and [[Intermittent Hypoxic Exposure]] help mitigate this problem. * It is a myth that if you can't arrive at altitude with time to acclimate, blood oxygen levels drop it's best to arrive near within a further 8% to 82%day of your event. * Running This is harder based on the idea that performance at altitude as seen by declines for a period before improving. However, research shows that the VO2max dropreduction in performance occurs immediately and improves gradually over time<ref name="SchulerThomsen2007"/>. At Leadville your VO2max will drop by ~15% moderate altitudes (range 41700m/5,600') performance was better after just 18 hours compared with 6 hours<ref name="Weston-30%)2001"/>.=Nutrition and Altitude=* AthletesThere' performance may drop noticeably even s good evidence that nutrition is important for altitude acclimation, at relatively low altitudesleast as far as iron goes. For other nutrients, the evidence is a little less clear. At 1==Iron==For adaptation to altitude,900 ftprobably the most critical nutrient is Iron. Low iron stores can result in reduced adaptation to altitude<ref name="Stray-GundersenAlexander1992"/> and altitude training will reduce the body's stores of iron<ref name="Roberts-1992"/>. It's been suggested that iron supplementation may need to be started some months prior to the needed altitude acclimation due to the time taken for iron store to accumulate<ref name="Askew1995"/>, and six weeks may be insufficient time<ref name="ChapmanStray-Gundersen1998"/>. One study found that in a 5 minute maximal exertion test was 6% group of 178 athletes, iron stores (maleserum ferritin) reduced by 33% without supplementation, reduced by 14% with 105mg/day of iron and increased by 37% with 210 mg/day of iron<ref name="ConnorGovus2015"/>. Further, the non-supplemented athletes only increased hemoglobin mass by 1.1%, those on 105mg/day by 3.3% and those on 210 mg/day by 4.0% (female) lower than at sea level. * Athletes may suffer more at The supplements were started one week before, and during, altitude than sedentary peopleexposure. The supplements were not given randomly but based on serum ferritin status. Those with levels above 100 ug/L were not supplemented, those with 30-100 ug/L were given 105 mg/day and those below 30 ug/L were given 210 mg/day. This suggests that even those with good iron status may need supplementation. However, that's a lot of iron, considering the RDA for men is only 8 mg/day and women 18 mg/day, and the tolerable upper intake is only 45 mg/day. Taking more than womenfour times the tolerable upper intake is a little worrying, and the study made no mention of reported side effects. The study used a prolonged release supplement that included 105 mg iron with 1,000 mg Vitamin C (which can increase absorption of Iron) in a product called "Ferro Grad C. "* Generally ==Antioxidants==There's some indications that "live high, train low' " may increase the need for antioxidants<ref name="PialouxMounier2008"/>. However, while some studies suggest that antioxidant supplementation might be beneficial<ref name="Tauler-2006"/><ref name="Goldfarb-2007"/>, it seems the preponderance of evidence is that antioxidant supplements may hinder recovery and adaptation to work better than training stress<ref name="Gomez-Cabrera-2008"/><ref name="Peternelj-2011"/><ref name="Teixeira-2009"/>. ==Carbohydrate==It'live highs unclear if the macronutrient mix of carbohydrate/protein/fat should be different at altitude, train as most claims of the need for a highcarbohydrate diet at altitude are based on sea level studies rather than any change due to altitude<ref name="MichalczykCzuba2016"/>. ==Vitamin D==There's no evidence for Vitamin D supplementation at altitude specifically, though there is the suggestion<ref name="MichalczykCzuba2016"/> that Vitamin D benefits might be particularly valuable as it may act as a vasodilator<ref name="Li-2004"/><ref name="Wacker-2013"/>. There is minimal data around 's also the use possibility that longer term (months) exposure to extreme altitude could result in bone loss<ref name="TanakaMinowa1992"/>. =Hydration and Altitude=Within 90 minutes of intermittent hypoxic exposureto higher altitudes, urine output increases<ref name="HildebrandtOttenbacher2000"/><ref name="Swenson-1995"/>, either resulting in the loss of water and sodium<ref name="SwensonDuncan1995"/>. The diuretic effects of low pressure at altitude may be exacerbated by the temperature, as cold conditions can result in "cold diuresis"<ref name="Scott-2004"/><ref name="HynynenIlmarinen1993"/>. One study suggests that hydration could exacerbate performance problems at rest or during exercisealtitude, but the indications are study was short term (1 hour) and used dehydration that was not related to the altitude<ref name="CastellaniMuza2010"/>. While there is a net loss of water as a response to altitude, it's unclear if increased fluid intake would help or hinder performance . There is an argument that this loss of fluid is an important adaptation to altitude that concentrates the blood and reduces the demand on the heart<ref name="Grover-1986"/>. There is some evidence that increased hydration does improve not increase the blood volume and may exacerbate fluid retention<ref name="Bärtsch-1991"/>. (Fluid retention is the build up of fluid between or inside the cells rather than in the blood.) There is further risk of [[Hyponatremia]] with these approachesexcessive drinking, so caution is needed, and the advice to "drink to thirst" would seem to remain valid. See below for more details(Note that while people with kidney problems may be able to tolerate short durations at modest altitudes, the risks are unclear<ref name="LuksJohnson2008"/>. )* =Assessing Altitude acclimatization generally takes 1-2 weeksImpact=The Lake Louise Scoring System (LLSS) is used to assess the severity of AMS (Acute Mountain Sickness, or altitude sickness). The 2018 version of the LLSS scores headache, Gastrointestinal symptoms, fatigue, dizziness, and functional disruption to provide an overall assessment of AMS severity<ref name="RoachHackett2018"/>. (Sleep disruption was removed as it does not appear to be well corelated with 4 weeks AMS<ref name="SchulzHall2014"/>.) However, analysis has shown that a single question is just as effective as the recommended minimum LLSS<ref name="MeierCollet2017"/>. This is the Clinical Functional Score, which asks "overall if you had any symptoms, how did they affect your activity?", with possible answers of # "Not at all."# "Symptoms present but did not force any change in activity or itinerary."# "My symptoms forced me to stop the ascent or to achieve benefitsgo down on my own power. "* Training needs # "I had to be reduced at evacuated to a lower altitude."=Effects of hypoxia=Low levels of SpO₂ effect brain functioning as shown in the following table<ref name="Anesthesia"/>.{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"! style="background-color: #F2F2F2;" |SpO₂! style="background-color: #F2F2F2;" |Description! style="background-color: #F2F2F2;" |Effect! style="background-color: #F2F2F2;" |Notes|-| style="background-color: #F9F9F9;" |100-80%| style="background-color: #F9F9F9;" |Mild Hypoxia| style="background-color: #F9F9F9;" |Normal brain functioning| style="background-color: #F9F9F9;" |This mild level of hypoxia does not affect the functioning of the brain, but some people can be sensitive enough to detect changes.|-| style="background-color: #F9F9F9;" |80-60%| style="background-color: #F9F9F9;" |Moderate Hypoxia| style="background-color: #F9F9F9;" |Decreasing brain function| style="background-color: #F9F9F9;" |Vision can be altered, including tunnel vision. Coordination is impaired in things like handwriting will deteriorate. Below 80% the skin may become blue (cyanosis). Mental functioning is impaired, sometimes creating euphoria or tranquility, including indifference to everything including pain. At this level some people become fixated on whatever they were doing when the hypoxia began, which can be dangerous. Memory and speech can also be impaired. There may be older treat visual hallucinations, feelings of depersonalization and even out of body experiences.|-| style="background-color: #F9F9F9;" |60-40%| style="background-color: #F9F9F9;" |Severe hypoxia| style="background-color: #F9F9F9;" |[[Muscle]] paralysis| style="background-color: #F9F9F9;" |Apparent unconsciousness.|-| style="background-color: #F9F9F9;" |<40%| style="background-color: #F9F9F9;" |Extreme hypoxia| style="background-color: #F9F9F9;" |Unconsciousness and this reduction eventually death| style="background-color: #F9F9F9;" ||}=Hypoxia and Altitude=The following table<ref name="Mehler1981"/> gives an idea of different [[SpO2|SpO₂]]levels at different altitudes. Intermittent Hypoxic Exposure can lead to detrainingincrease [[SpO2|SpO₂]]levels at a given altitude<ref name="HetzlerStickley2009"/>, which are specified in the table below for some altitudes. 'Live highHowever, the actual [[SpO2|SpO₂]] value at a given altitude will vary on many factors, train low' helps mitigate so use this problemas a rough guide only. * {| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"! style="background-color: #F2F2F2;" |'''Altitude(feet)'''! style="background-color: #F2F2F2;" |'''Altitude acclimatization generally seems to last several weeks(meters)'''! style="background-color: #F2F2F2;" |'''Air Pressure(mmHg)'''! style="background-color: #F2F2F2;" |'''Oxygen Pressure(mmHg)'''! style="background-color: #F2F2F2;" |''' % of sea level Oxygen'''! style="background-color: #F2F2F2;" |'''Equivalent O2 partialpressure at sea level'''! style="background-color: #F2F2F2;" |'''SpO₂Unconditioned'''! style="background-color: #F2F2F2;" |'''SpO₂Conditioned'''|-| style="background-color: #F9F9F9;" |0| style="background-color: #F9F9F9;" |0| style="background-color: #F9F9F9;" |760| style="background-color: #F9F9F9;" |159| style="background-color: #F9F9F9;" |100| style="background-color: #F9F9F9;" |20.9| style="background-color: #F9F9F9;" |98%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |5,000| style="background-color: #F9F9F9;" |1,524| style="background-color: #F9F9F9;" |639| style="background-color: #F9F9F9;" |134| style="background-color: #F9F9F9;" |84| style="background-color: #F9F9F9;" |17.6| style="background-color: #F9F9F9;" |95%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |7,500| style="background-color: #F9F9F9;" |2,286| style="background-color: #F9F9F9;" |584| style="background-color: #F9F9F9;" |122| style="background-color: #F9F9F9;" |77| style="background-color: #F9F9F9;" |16.1| style="background-color: #F9F9F9;" |93%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |9,000| style="background-color: #F9F9F9;" |2,740| style="background-color: #F9F9F9;" |554| style="background-color: #F9F9F9;" |116| style="background-color: #F9F9F9;" |73| style="background-color: #F9F9F9;" |15.3| style="background-color: #F9F9F9;" |90.3% (+/-3.4%)| style="background-color: #F9F9F9;" |93.8% (+/-2%)|-| style="background-color: #F9F9F9;" |10,000| style="background-color: #F9F9F9;" |3,048| style="background-color: #F9F9F9;" |534| style="background-color: #F9F9F9;" |112| style="background-color: #F9F9F9;" |70| style="background-color: #F9F9F9;" |14.6| style="background-color: #F9F9F9;" |89%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |11,000| style="background-color: #F9F9F9;" |3,360| style="background-color: #F9F9F9;" |514| style="background-color: #F9F9F9;" |107| style="background-color: #F9F9F9;" |68| style="background-color: #F9F9F9;" |14.2| style="background-color: #F9F9F9;" |86.4 % (+/- 4.8%)| style="background-color: #F9F9F9;" |90.2% (+/-2.7%)|-| style="background-color: #F9F9F9;" |12,500| style="background-color: #F9F9F9;" |3,810| style="background-color: #F9F9F9;" |487| style="background-color: #F9F9F9;" |102| style="background-color: #F9F9F9;" |64| style="background-color: #F9F9F9;" |13.4| style="background-color: #F9F9F9;" |87%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |14,000| style="background-color: #F9F9F9;" |4,267| style="background-color: #F9F9F9;" |460| style="background-color: #F9F9F9;" |96| style="background-color: #F9F9F9;" |61| style="background-color: #F9F9F9;" |12.7| style="background-color: #F9F9F9;" |83%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |15,000| style="background-color: #F9F9F9;" |4,570| style="background-color: #F9F9F9;" |443| style="background-color: #F9F9F9;" |93| style="background-color: #F9F9F9;" |58| style="background-color: #F9F9F9;" |12.1| style="background-color: #F9F9F9;" |81.7% (+/-6%)| style="background-color: #F9F9F9;" |89.1% (+/-3%)|-| style="background-color: #F9F9F9;" |16,500| style="background-color: #F9F9F9;" |5,029| style="background-color: #F9F9F9;" |418| style="background-color: #F9F9F9;" |87| style="background-color: #F9F9F9;" |55| style="background-color: #F9F9F9;" |11.5| style="background-color: #F9F9F9;" |77%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |18,000| style="background-color: #F9F9F9;" |5,490| style="background-color: #F9F9F9;" |395| style="background-color: #F9F9F9;" |83| style="background-color: #F9F9F9;" |52| style="background-color: #F9F9F9;" |10.9| style="background-color: #F9F9F9;" || style="background-color: #F9F9F9;" |84.9% (+/-4%)|-| style="background-color: #F9F9F9;" |20,000| style="background-color: #F9F9F9;" |6,096| style="background-color: #F9F9F9;" |365| style="background-color: #F9F9F9;" |76| style="background-color: #F9F9F9;" |48| style="background-color: #F9F9F9;" |10.0| style="background-color: #F9F9F9;" |65%| style="background-color: #F9F9F9;" ||-| style="background-color: #F9F9F9;" |21,000| style="background-color: #F9F9F9;" |6,400| style="background-color: #F9F9F9;" |351| style="background-color: #F9F9F9;" |73| style="background-color: #F9F9F9;" |46| style="background-color: #F9F9F9;" |9.6| style="background-color: #F9F9F9;" || style="background-color: #F9F9F9;" |79.2% (+/-6%)|-| style="background-color: #F9F9F9;" |25,000| style="background-color: #F9F9F9;" |7,620| style="background-color: #F9F9F9;" |299| style="background-color: #F9F9F9;" |62| style="background-color: #F9F9F9;" |39| style="background-color: #F9F9F9;" |8.2| style="background-color: #F9F9F9;" |<60%| style="background-color: #F9F9F9;" ||}=See Also==

* [[Hypoxia Comparison of Altitude Training Systems]]* [[Book Review – of Altitude Training and Athletic Performance]]* [[Intermittent Hypoxic Exposure]] and [[Intermittent Hypoxic Exposure 101]]* [[Chronic Mountain Sickness]]* [[Viagra, Exercise and Altitude]]=References=<references><ref name="Anesthesia">anesthesia and hypoxia, Anesthesia !!website!!, http://www.anesthesiaweb.org/hypoxia.php, 2018-05-31 !!access-date!!</ref><ref name="HetzlerStickley2009">Ronald K. Hetzler, Christopher D. Stickley, Iris F. Kimura, Michelle LaBotz, Andrew W. Nichols, Kenneth T. Nakasone, Ryan W. Sargent, Lawrence P.A. Burgess, The Effect of Dynamic Intermittent Hypoxic Conditioning on Arterial Oxygen Saturation, Wilderness & Environmental Medicine, volume 20, issue 1, 2009, pages 26–32, ISSN [http://www.worldcat.org/issn/10806032 10806032], doi [http://dx.doi.org/10.1580/08-WEME-OR-218.1 10.1580/08-WEME-OR-218.1]</ref><ref name="Mehler1981">"The Pilot: An Air Breathing Mammal," Mehler, Stanley R. MD, Human Factors Bulletin, Flight Safety Foundation, 1981</ref><ref name="MeierCollet2017">David Meier, Tinh-Hai Collet, Isabella Locatelli, Jacques Cornuz, Bengt Kayser, David L. Simel, Claudio Sartori, Does This Patient Have Acute Mountain Sickness?, JAMA, volume 318, issue 18, 2017, pages 1810, ISSN [http://www.worldcat.org/issn/0098-7484 0098-7484], doi [http://dx.doi.org/10.1001/jama.2017.16192 10.1001/jama.2017.16192]</ref><ref name="SchulzHall2014">Christian Schulz, David P. Hall, Ian J. C. MacCormick, Alex T. Phythian-Adams, Nina M. Rzechorzek, David Hope-Jones, Sorrel Cosens, Stewart Jackson, Matthew G. D. Bates, David J. Collier, David A. Hume, Thomas Freeman, A. A. Roger Thompson, John Kenneth Baillie, Network Analysis Reveals Distinct Clinical Syndromes Underlying Acute Mountain Sickness, PLoS ONE, volume 9, issue 1, 2014, pages e81229, ISSN [http://www.worldcat.org/issn/1932-6203 1932-6203], doi [http://dx.doi.org/10.1371/journal.pone.0081229 10.1371/journal.pone.0081229]</ref><ref name="RoachHackett2018">Robert C. Roach, Peter H. Hackett, Oswald Oelz, Peter Bärtsch, Andrew M. Luks, Martin J. MacInnis, J. Kenneth Baillie, Eric Achatz, Edi Albert, Jon S. Andrews, James D. Anholm, Mohammad Zahid Ashraf, Paul Auerbach, Buddha Basnyat, Beth A. Beidleman, R.R. Berendsen, Marc Moritz Berger, Konrad E. Bloch, Hermann Brugger, Annalisa Cogo, Ricardo Gonzalez Costa, Andrew Cumpstey, Allen Cymerman, Tadej Debevec, Catriona Duncan, David Dubowitz, Angela Fago, Michael Furian, Matt Gaidica, Prosenjit Ganguli, Michael P.W. 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West, Matt Wilkes, Gabriel Willmann, Michael Yaron, Ken Zafren, The 2018 Lake Louise Acute Mountain Sickness Score, High Altitude Medicine & Biology, volume 19, issue 1, 2018, pages 4–6, ISSN [http://www.worldcat.org/issn/1557-8682 1557-8682], doi [http://dx.doi.org/10.1089/ham.2017.0164 10.1089/ham.2017.0164]</ref><ref name="Weston-2001">AR. Weston, G. Mackenzie, MA. Tufts, M. Mars, Optimal time of arrival for performance at moderate altitude (1700 m)., Med Sci Sports Exerc, volume 33, issue 2, pages 298-302, Feb 2001, PMID [http://www.ncbi.nlm.nih.gov/pubmed/11224821 11224821]</ref><ref name="DempseyWagner1999">Jerome A. Dempsey, Peter D. Wagner, Exercise-induced arterial hypoxemia, Journal of Applied Physiology, volume 87, issue 6, 1999, pages 1997–2006, ISSN [http://www.worldcat.org/issn/8750-7587 8750-7587], doi [http://dx.doi.org/10.1152/jappl.1999.87.6.1997 10.1152/jappl.1999.87.6.1997]</ref><ref name="SchulerThomsen2007">B. Schuler, J. J. Thomsen, M. Gassmann, C. 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