In chapter 6, Shenk mentions that some of the crucial elements to the Kenyans' successes are "high-altitude training and mild year-round climate" (105). Many endurance athletes also train at high altitudes. However, at high altitudes, though the percentage of oxygen remains the same, the air is thinner, meaning there are fewer molecules of oxygen. Why would training at high altitudes be beneficial to athletes considering that there is less oxygen available at higher altitudes? Consider how the human body adapts and relate your answer to the circulation and respiration unit. In addition, explain how the oxygen dissociation curve would change in an environment with lower levels of oxygen. How do the adaptions the human body goes through at high altitudes relate to the body's need to remain in homeostasis? What specific examples of the body trying to maintain homeostasis show the theme of regulation?
Jessica Hua (jhua33@yahoo.com)
The affinity for oxygen can be graphed into oxygen dissociation curves that quantify affinity for hemoglobin at different partial pressures of oxygen. This example specifically would be a left Bohr shift caused by an increase of pH, decrease CO2, decrease of temperature, or fetal hemoglobin. Like the hemoglobin of the llama, the Kenyans’ altitude training would allow their hemoglobin to have a greater affinity for oxygen.
ReplyDeleteThus it is a great training technique because as they adapt to a thinner atmosphere, it will be easier for them to exercise in their prior environment in comparison as their blood tries to get the most oxygen it can when it is more readily available. It’s kind of like blood doping, but natural. This is a prime example of the body’s struggle to maintain homeostasis since it’s all about optimizing the delivery of blood to the tissues in order to achieve balance. Another example is the diving mammals that store oxygen in muscle cell myoglobin so they can go underwater long periods of time without drowning.
Because of they Kalenjin’s necessity “to run long distances as a practical matter, an average of eight to 12 kilometers a day” (Shenk 105) it is clear that it is not a genetic predisposition towards running quickly, but an environmental factor such as practicality and altitude. Kenyans are not “possessors of rare endurance genes” (Shenk 106), they just know how to train themselves or optimal performance.
Training at high altitudes is a common practice among high class athletes. This is very beneficial to an athlete in a sport that requires good cardiovascular health such as running. High altitudes contain a much lower level of oxygen in the air than at sea level. This is due to a change in air pressure that decreases the higher one goes up in altitude. Kenneth Baillie of Altitude.com, a website for altitude training, states that “The important effect of this decrease in pressure is this: in a given volume of air, there are fewer molecules present. The percentage of those molecules that are oxygen is exactly the same: 21%. The problem is that there are fewer molecules of everything present, including oxygen”.
ReplyDeleteThe athletes training in this sort of environment have to deal with a decreased supply of oxygen that that at sea level. This would put much more stress on the body and the heart than sea level training would , yet as David Shenk states on page 111, “(the athletes) are participants in a culture of the extreme, willing to devote more, to ache more, and to risk more in order to do better”. Such high altitude training would increase cardiovascular ability because a heart would adapt to beating much faster than normal at a high altitude in order to compensate for the amount of oxygen missing and deliver an adequate amount of oxygen to all the organs. This is how the body retains homeostasis. The medulla would pick up high levels of carbonic acid in the blood and respond with a quickening in heart rate. This would be equivalent to a harder workout, but achieved in a lower amount of time. An athlete that trains an hour at a high altitude as opposed to sea level will experience a much higher heart rate because the heart must deliver the same exact amount of oxygen to the organs, yet there is a smaller availability of oxygen.
Another possible benefit is described by Alison Abbott in her article A Breed Apart that was published in Nature Magazine. She states that “Australian and US research teams have studied the effects of high-altitude training, for example - a technique long thought by trainers to improve performance. Some studies have shown an increase in the level of the oxygen-carrying protein hemoglobin found in red blood cells” after high altitude training. An increased amount of hemoglobin is a very beneficial thing to an athlete because it would mean that at sea level, their blood would contain an extra amount of oxygen and therefore the heart would have to beat less to propel the oxygen throughout the body because the increased amount of hemoglobin would have the ability to transport a greater amount of oxygen at a time. As Gabriella Veytsel stated in her response, this would be an effect that is similar to blood doping in order to increase red blood cell count, yet this would be an approved and legal way to achieve such results.
Moreover, another effect of this training would be a change in oxygen dissociation levels to hemoglobin. The Biology Campbell Textbook AP Edition 8 states on page 924 that “cooperativity in oxygen binding and release is evident in the dissociation curve for hemoglobin”. Through altitude training, the athlete’s oxygen dissociation curve may experience a Left Bohr shift to increase hemoglobin’s affinity for oxygen. If this was an effect that was still experienced at sea level, the benefits would be a lower heart rate and amount of breaths during exercise. This contributes greatly to the biological theme of regulation because the body senses when it is out of homeostasis and accordingly adjusts different systems in the body such as the dissociation curve or heart rate to correct this imbalance for as long as it occurs.
(Liz Gorelick lizgorelick@yahoo.com)