Altitude Training & Effects On Performance
ALTITUDE TRAINING & EFFECTS ON PERFORMANCE
What is High Altitude?
Altitude is defined on the following scale:
A: High 8,000 – 12,000 feet (2,438 – 3,658 meters).
B: Very High 12,000 – 18,000 feet (3,658 – 5,487 meters).
C: Extremely High 18,000+ feet (5,500+ meters).
Since few people have been to such altitudes, it is hard to know who may be affected. There are no specific factors such as age, sex, or physical condition that correlate with susceptibility to altitude sickness. Some people get it and some people don’t, and some people are more susceptible than others.
Most people can go up to 8,000 feet (2,438 meters) with minimal effect. If you haven’t been to high altitude before, it’s important to be cautious. If you have been at that altitude before with no problem, you can probably return to that altitude without problems as long as you are properly acclimatized.
ACCLIMATIZATION.
The major cause of altitude illnesses is going too high too fast. Given time, your body can adapt to the decrease in oxygen molecules at a specific altitude. This process is known as acclimatization and generally takes 1-3 days at that altitude. For example, if you hike to 10,000 feet (3,048 meters), and spend several days at that altitude, your body acclimatizes to 10,000 feet (3,048 meters). If you climb to 12,000 feet (3,658 meters), your body has to acclimatize once again. A number of changes take place in the body to allow it to operate with decreased oxygen.
A: Red blood cell count increases. Lack of oxygen stimulates the release of erythropoietin, the hormone responsible for red blood cell production, within 3 hours and reaches a peak after 24 to 48 hours. The concentration of red blood cells within a given volume of blood is called hematocrit. In sea level residents, hematocrit is about 45-48%. With 6 weeks exposure to an altitude of 4540m (14895ft) these levels can increase to 59%. Initial exposure to altitude decreases plasma volume. However, this begins to increase slightly with long-term acclimatization to altitude.
B: Pulmonary ventilation stabilizes. But it remains increased during rest and exercise compared to sea level.
C: Sub maximal cardiac output decreases. While sub maximal cardiac output increases in the acute stage, following acclimatization to altitude it decreases to below sea level values. This is primarily due to a further reduction in stroke volume, which presumably occurs as changes in the oxygen-carrying capacity of the blood take the burden off the heart.
D: Muscle cross sectional area decreases. Muscle biopsy studies following 4 to 6 weeks at altitude show that slow-twitch and fast-twitch fiber area decreases by as much as 20-25%. This decreases muscle area by 11-13%. It may be that muscle wasting of this nature is due to loss of appetite that often accompanies living at altitude.
ACUTE RESPONSE TO ALTITUDE.
Up to 1500m (4921ft), altitude has little effect on the body. Above this level, studies on men show the cardiovascular, respiratory and metabolic systems are affected. Unfortunately, there are few studies on women and children at altitude and their responses may differ slightly.
RESPIRATORY SYSTEM RESPONSE TO ALTITUDE
A: Breathing rate increases at rest and during exercise. A smaller number of oxygen molecules per given amount of air means that increased ventilation is required to consume the same amount of oxygen as at sea level.
B: Oxygen diffusion decreases. At sea level oxygen exchange from the lungs to the blood is unhindered and the oxygen-carrying component of blood, hemoglobin, is about 98% saturated with oxygen. As altitude increases and the partial pressure of oxygen in the air drops, so does the pressure gradient between oxygen in the lungs and blood. This decreases the saturation of hemoglobin to about 90-92% at 2439m (8000ft). In effect, less oxygen passes (diffuses) from the lungs to the blood.
C: The diffusion gradient at the active tissues decreases. As mentioned above, oxygen passes from the lungs to the blood due to a pressure gradient. The same process occurs when oxygen-rich arterial blood reaches the active tissues. The partial pressure of oxygen in arterial blood is about 100mmHg at sea level. In body tissue, it is a steady 40mmHg – a difference or pressure gradient of 60mmHg. At an altitude of 2439m (8000ft), arterial oxygen pressure decreases to 60mmHg so the difference or pressure gradient drops to just 20mmHg – a 70% reduction. In effect, less oxygen passes (diffuses) from the blood to the tissues.
D: VO2 max decreases. Maximal oxygen uptake begins to decrease significantly above an altitude of 1600m (5249ft). For every 1000m (3281ft) above that VO2 max drops by approximately 8-11%. At the summit of Everest, an average sea level VO2 max of 62ml/kg/min can drop to 15ml/kgmin (3). For individuals with a sea level VO2 max less than 50 ml/kg/min would be unable to move as their VO2 max would drop to 5 ml/kg/min – enough only to support resting oxygen requirements.
CARDIOVASCULAR SYSTEM RESPONSE TO ALTITUDE
i) Blood volume decreases. Plasma volume decreases by up to 25% within the first few hours of exposure to altitude and doesn’t plateau until after a few weeks. This is partially a deliberate response by the body as reducing plasma (the watery part of blood) in effect increases the density of red blood cells. While no extra red blood cells have been produced in this acute phase, the amount of hemaglobin per unit of blood (called hematocrit) is now increased – resulting in greater oxygen transport for a given cardiac output.
ii) Cardiac output increases during rest submaximal exercise. During the first few hours at altitude stoke volume decreases during submaximal exercise, a result of the reduction in plasma volume. Heart rate increases enough to compensate for this and to actually slightly raise cardiac output. After a few days however, oxygen extraction becomes more efficient reducing the need to increase cardiac output. In fact after 10 days acclimatization to altitude results in a lower cardiac output at any given, submaximal exercise intensity compared to sea level.
iii) Maximal cardiac output decreases. During exhaustive exercise at maximum levels both maximal stroke volume and maximal heart rate decrease with altitude. This obviously combines to have a significant effect on maximal cardiac output. In conjunction with the reduced diffusion gradient to drive oxygen from the blood to working tissues, it is easy to see why VO2 max and endurance performance is hindered.
METABOLIC RESPONSES TO ALTITUDE
Lack of oxygen availability and utilization at altitude places a greater demand on anaerobic metabolism to produce energy. This result in an increase in the concentration of Lactic Acid at any given submaximal exercise intensity compared to sea level. In contrast, lactate concentration is lower during maximal effort.
ATHLETIC PERFORMANCE ALTITUDE
As would be expected the acute responses mentioned above have a detrimental effect on exercise performance – in particular the endurance events. VO2 max decreases significantly as altitude increases. Running at 12km/h for example will equate to a higher percentage of VO2 max when completed at altitude compared to sea level.
Conversely, ‘anaerobic’ events lasting under a minute such as sprinting, throwing and jumping activities are not impaired at moderate altitude. In fact, they can actually be improved due to the thinner air and less aerodynamic resistance.
ACCLIMATIZATION IMPROVES PERFORMANCE?
The research is inconclusive. In theory, some adaptations that take place during prolonged exposure to the hypoxic conditions at 1500 m (4921 ft) or more above sea-level, should improve VO2 and endurance performance at sea-level.
However, maximal cardiac output is also decreased with exposure to altitude. Along with dehydration and a loss of lean muscle mass these detrimental effects may explain why living and training at altitude does not improve VO2 max or endurance performance on a return to sea-level.
Those few studies that have shown altitude training to have an ergogenic effect on sea-level performance are easy to criticize. Subjects have not usually reached a training peak so it becomes difficult to determine whether increases in aerobic power and / or endurance performance are the result of the adaptations to altitude or intensive training.
The major problem athletes living at altitude face is a significant reduction in training intensity. At 4000 m (13,122 ft) athletes can only exercise at 40% of their sea-level VO2 max compared to 80% at sea-level for example. Breathing hypoxic gases significantly reduces power output and this could lead to substantial detraining negating any of the ergogenic effects associated with acclimatization.
LIVE HIGH – TRAIN LOW
Is it possible to induce the positive changes associated with altitude acclimatization without the associated negative effects?
One banned and unethical and potentially dangerous tactic is blood doping and erythropoietin injections, which increase the blood’s oxygen carrying capacity.
Secondly in an attempt to curb the detraining effect of reduced exercise intensity at altitude, Levine and Stray-Gundersen studied the effect of living high and training low on endurance performance. This is an ethical and the right way to improve the endurance performance.
EXPERIMENT 1.
A group of 39 middle-distance runners were split into three altitude training groups :-
a) Live high – train low group,
b) Live high – train high group
c) Live low – train low control group.
RESULTS.
Unlike the control group, both “live high” groups increased their VO2 max on a return to sea-level by 5%. This was in direct proportion to the increase in red cell mass volume. However, only the “live high – train low” group improved their endurance performance as measured by a 5km time trial. Velocity at VO2 max and maximal steady state also improved in this group helping to shave an average of 13.4 seconds off their time.
EXPERIMENT 2.
The same researchers carried out a further altitude training study on elite male and female runners and found similar performance enhancing effects of living high and training low. The athletes’ 3km time was measured before and after a period of 27 days living at altitude (2500m, 8200ft) interspersed with training sessions at sea-level. VO2 max increased an average of 3.2% and performance by an average of 1.1%. While this may seem like a negligible improvement, 1.1% at an elite level translates into a significant performance advantage.
Further altitude training studies, both at real altitude and simulated altitude, have shown that living high and training low can improve running economy, 800m, 1500m 3km performance, 400m performance, sub maximal cycling performance and muscle buffer capacity.
These favorable results have stimulated interest in how athletes can “live high – train low” without having to actually move to high elevations. Several methods exist for artificially re-creating the hypoxic environment at altitude. These include hypobaric chambers, increasing the air’s nitrogen content and altitude sleeping tents.
Sleeping tents are likely to be the most affordable and accessible option and don’t seem to disrupt normal sleep quality. However, more research is needed to confirm whether these apartments do indeed improve performance.
By:-
Khizer Hayat Raja
Sr. Lecturer in Physical Education & Sports
International Weightlifting Coach & Expert
E. mail: wlexpert@yahoo.com
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About the Author:
Affiliated with Olympic style weightlifting since 1989. First as player and from 1998 as a coach. Author of a book and keen in research work.
Presently serving as Sr. Lecturer in Physical Education and Sports in Education Department. Coaching and training many Juniors & Seniors in Olympic style weightlifting. Produced many National and International weightlifters within and out side the country.
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