One of the aspects in which many amateurs ape professionals is the legendary altitude training. They exploit the holidays to go to the mountains to train: If you go back to the stronger merit of the rise, if you go slower you are not yet acclimated. So much good will, but zero scientific notions.
The first blunder – Many people think:
at altitude it goes slower because there is less oxygen.
From a scientific point of view, the phrase has no thickness; for comparison, it is as if you say to a mathematician that two triangles have the same area (the areas are equivalent!) or to an economist that “the economy is bad because there is less work”. What does it mean that there is less work? That the unemployment rate rose? That a young man is more difficult to find work? Which decreased the number of employees? The “less” does not say anything because it is not clear which unit of measurement is used, is a term that is used by those who attempt a crude explanation of the problem.
The air composition is practically stable up to 80-100 km altitude; both at sea level and at altitude, the oxygen percentage is more than 21% (condition A). What changes is the atmospheric pressure. Since air is a mixture of compressible gas, the atmospheric pressure decreases with height (condition B). The effect of these two conditions is that the oxygen partial pressure decreases (each gas in a mixture exerts a partial pressure).
In fact, on every book of exercise physiology you will find that:
with the share reduces the oxygen partial pressure.
The partial pressure of the oxygen in the air mixture is due to the total atmospheric pressure for its concentration:
partial pressure = atmospheric pressure * concentration.
The pulmonary exchanges (which are of type diffusive) depend on the partial pressures of the gases. If the oxygen partial pressure in the alveoli is 100 mmHg, and that of oxygen in the blood is 40 mmHg is not difficult to understand that oxygen tends to pass from the alveoli into the blood in order to balance the pressure.
If the air oxygen partial pressure decreases, this process of passage of oxygen in the blood will be slowed down. It is what happens in the deep sea.
The second blunder – Resides in the sentence:
I made a good altitude training: fifteen days at 1,200 m.
To understand why the “good” is too necessary to consider what happens in the blood where oxygen binds to hemoglobin. Consider hemoglobin as the bus which receives oxygen molecules that arrive and that then transports in the various areas of the body. Without this bond it is as if the bus never arrived. Unfortunately, the hemoglobin does not always work the same way. Its effectiveness depends on how they get the oxygen molecules. It is as if the driver opened the bus doors for a few moments: those who are too slow or distracted can not go up. Depending on the speed of the passengers is possible to calculate how much they will go up. It is a question of hemoglobin dissociation curve. With a partial pressure of 100 mmHg of oxygen (the normal at sea level; the outside of the body the oxygen partial pressure is about 160 mmHg, in the inspired air, which is saturated with water vapor and air already flawed from the respiratory tract, is reduced until you get in the alveolar air at 100 mmHg) hemoglobin saturation is 98%, that is, in our metaphor rises to 98% of the oxygen molecules arriving bus. If the pressure drops to 40 mmHg only 75% of the salt molecules, that is, the hemoglobin is saturated to 75%.
Since the partial pressure at altitude is lower, the less hemoglobin binds oxygen. This is why high altitude you go slower in the aerobic tests. But beware: the hemoglobin saturation curve is NOT linear with the partial pressure of oxygen and thus the height to which we are. It has a sigmoid shape: if saturated with 10 mmHg to 10%, saturated with 40 mmHg to 75%, with 60 mm Hg of pressure already saturated to 90% while with 100 mmHg saturated, as said, to 98%.
Translating all in height, hemoglobin saturation is 95% to 1200 m, a difference of 3% compared to sea level. Very significant in the case of the performance of a single race, but not significant in the case of training. In fact one of the sports physiology principles is that:
fluctuations caused by acclimatization depends on the magnitude of the variation and duration of exposure.
A variation of only 3% requires an exposure period eight times longer than a variation of 24% (5000 m). Therefore the benefits that are acquired at 1200 m with 15 days are equivalent to those you have in two days at 5000 m. Obviously these talks are sketchy, but tend to make people understand how one can define
altitude training that effected at elevations higher than 1,800 m.
Altura and doping (1) – a given practice is necessary to detect before continuing:
if the height easily produce the benefits we would not need doping (erythropoietin).
Indeed, the high ground has often been misused to justify performance achieved by the intake of EPO. Many physiologists have exposed this attempt and this should illuminate the coaches who feel the deep sea with a clean alternative to doping. We will return to this point.
effects of the rise – We have seen that the main problem is the altitude hypoxia, that is, the reduced oxygen partial pressure (not, as might suggest the term, the reduced amount of oxygen!). Hypoxia causes an impressive array of effects, including even death if the altitude is considerable (over 5000 m) and the subject is not acclimated.
The main visible effect of hypoxia hyperventilation. Dempsey and Schone have studied the problem from a quantitative point of view (qualitatively not take a rocket scientist to understand that not rushing Himalayas ago sbanfare more!). Briefly, the receptors (chemoreceptors) in charge of monitoring the oxygen partial pressure send their alarm that triggers an increase in the depth and rate of breathing. Unfortunately (Torre-Bueno, 1985), this mechanism does not compensate for the reduced partial pressure due to the height and performance deteriorates beyond a certain proportion. It should be noted that hyperventilation is subjective, it is possible that some individuals react better to hypoxia. It is also essential to know that the damage from hypoxia are not the same for the different tissues; the muscle responds better than nervous: the subject would be able to exert more muscle strength if the central nervous system react in the same way (in fact beyond a certain point the muscles still work, but the subject loses consciousness!).
The second effect of hypoxia is the increase in cardiac output which is realized with an increased frequency. It also increases the systemic blood pressure due to an increased secretion of plasma catecholamines (noradrenaline and adrenaline; to 4,300 m there is an increase that goes from 50 to 90%, Surks).
Risks – It is quite clear that the benefits of the rise are such only if the choice for altitude training is remarkable. Train at 3000 m is much more interesting that train at 1800 m. The problem is that the greater the risk. There are three main diseases related high place: acute mountain sickness (headache, dizziness, nausea, constipation, vomiting, insomnia, typical of the units above 2500 m, begins a few hours after arrival at altitude and resolves in a few days ), high altitude pulmonary edema (typical for higher than 3000 m shares, occurs 12 to 96 hours after the arrival), high altitude cerebral edema (affects about 1% of patients in excess of 2,700 m and can reach to coma and death if not treated properly). Other complications (retinal hemorrhage) occur for typically alpine altitudes (6000 m). Since even the simple, but common, acute mountain sickness penalizes physical activity, typically the living room is limited to altitudes of less than 2,500 m, but this obviously also reduces the possible benefits of altitude.
Altura and doping (2) – After knowing the risks of the rise, the question arises why it is moral to stimulate the physical with the rise and immoral stimulate it with doping. If doping is bad because the high seas should be good? In fact the simple fact that the rise is natural and the external administration of EPO is not an entirely marginal, indeed proves that not everything that is natural is good. The high ground stresses the physical just like an artificial dose of erythropoietin, a multitude being in the literature for both cases of serious problems situations (including death). This fact is demonstrated by the position of some coaches who rightly now are more interested in the practical benefits of the rise that those “physiological.” I quote the excellent text on the marathon for evolved athletes Arcellis-Canova: “in many cases today, it is preferred to train at an intermediate position (around 1,000 m), where you can find the environmental benefits of a cool temperature and flatter than the high mountain trails, without running the risks associated with the share of more than 2,000 meters. ”
The long-term effects – If hyperventilation, increased cardiac output (by increasing the frequency) and blood pressure are short-term effects, for training is also interesting to study the long-term effects. One of the consequences is the hyperventilation respiratory alkalosis (increase in plasma pH) which manifests itself with a greater elimination of bicarbonates and therefore a decreased buffering capacity of lactic acid. This long-term consequence is particularly bad because the body in an attempt to restore lost balances assumes an abnormal breathing rhythm (the so-called periodic breathing).
long-term positive factors are the increase of the plasma mass and an increase in red blood cells; both they combine to increase the oxygen-carrying capacity of the blood. The increase of red blood cells is carried out for an increased production of erythropoietin following hypoxia (within 15 hours after the stimulus). As shown by the studies Reynafarje and Groves, the increased production of red blood cells is maintained until the subject remains at altitude. Because the hematopoietic cycle lasts seven days or so, it must be a week before it establishes an increase in hematocrit. With a stay at 4,000 m hematocrit may increase from 43 to 48 (Hannon).
Agrees to train at high altitude? – To answer necessary to summarize the well-established research contributions:
it takes two weeks to acclimatise to 2,300 m and an extra week for every 500-600 m (Maresh);
in the first week it is impossible to perform heavy workouts (Kollian);
with the stay at altitude increases oxygen transport by the blood, but decreases the maximum oxygen consumption, ie aerobic power (10% per 1,000 m starting from 1,500 m, Buskirk, Cymerman, Pugh, Squires).
Returning to the sea blood values return to normal level in two weeks, while the maximum oxygen consumption tends to become again what primitive faster. Because the former is a positive factor, while the second is negative must hit (times are obviously individual) on the day when the budget is in favor of the athlete. This explains the failure of many stays at high altitude.
In addition to the first two points it is difficult to play an effective workout while staying on high ground, a factor which further makes it problematic to draw some benefit from the quota.
There are many studies (among which the best known is Adams) that demonstrate how the training at high altitude is not particularly significant in improving the performance of the subject. It should be clear by now that it is really unrealistic to hope to benefit from a simple week in a mountain resort! The best strategy is therefore that suggested by Arcellis-Canova and many other technical: living around 1,200 m with climate benefits evident in the summer.