Effects of high altitude on humans
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-525-6884
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [2] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
There are several effects of high altitude on humans:
The percentage saturation of hemoglobin with oxygen determines the content of oxygen in our blood. After the body reaches around 7000 feet (2100 m) above sea level, the saturation of oxyhemoglobin begins to plummet.[1]
Effects
Altitude acclimatization, the physiological adaptions to altitude, can have immediate and long term effects.
Immediate effects
- Hyperventilation
- Fluid loss (due to a decreased thirst drive and decrease in ADH)
- Increase in heart rate (HR)
- Slightly lowered stroke volume
Longer term effects
- Lower lactate production (because reduced glucose breakdown decreases the amount of lactate formed).
- Compensatory alkali loss in urine
- Decrease in plasma volume
- Increased Hematocrit (polycythemia)
- Increase in RBC mass
- Higher concentration of capillaries in skeletal muscle tissue
- Increase in myoglobin
- Increase in mitochondria
- Increase in aerobic enzyme concentration
- Increase in 2,3-BPG
- Hypoxic pulmonary vasoconstriction
- Right ventricular hypertrophy
Altitude and athletic performance
In the athletic arena, it is thought that acclimatization from living and training at high altitudes enhances performance compared to living and training at sea level. However, this may not always be the case. Any positive acclimatization effects may be negated by a de-training effect as the athletes are usually not able to exercise with as much intensity at high altitudes compared to sea level.
This conundrum led to the development of the altitude training modality known as "Live-High, Train-Low" whereby the athlete spends many hours a day resting and sleeping at one (high) altitude, but performs a significant portion of their training, possibly all of it, at another (lower) altitude. A series of studies conducted in Utah in the late '90s by researchers Ben Levine, Jim Stray-Gundersen, and others, showed significant performance gains in athletes who followed such a protocol for several weeks. [1] [1]
Other studies have shown performance gains from merely performing some exercising sessions at altitude, yet living at sea-level. [1]
For those who wish to adjust to high altitudes, or to obtain the associated athletic performance, but without being at high altitudes, state-of-the-art altitude acclimatization devices exist. Chambers that reduce barometric pressure, or hypoxic systems (altitude tents or altitude rooms[1]) with increased nitrogen concentration (which reduces oxygen), are used by athletes to acclimatize to high altitudes.
To achieve the full potential athletic gains from at-rest altitude acclimatization, one must maintain altitude exposure for a significant period of time and the effects are only transitory. A study [1] using simulated altitude exposure for 18 days, yet training closer to sea-level, showed performance gains were still evident 15 days later.
The physiological adaptation that is mainly responsible for the performance gains achieved from altitude training, is a subject of discussion among researchers. Some, including American researchers Ben Levine and Jim Stray-Gundersen, claim it is primarily the increased Red Blood Cell Volume [1]. Others, including Australian researcher Chris Gore, and New Zealand researcher Will Hopkins, dispute this and instead claim the gains are primarily a result of other adaptions such as a switch to a more economic mode of oxygen utilization [1]
See also
- Altitude sickness
- Altitude tent
- Gamow bag
References
External links
- Physiology at MCG 4/4ch7/s4ch7_32
- Altitude sickness and high altitude acclimatisation
- IPPA: High Altitude Pathology Institute
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
