Discussion of Hypoxia and Altitude Training
by Brendan Gabriel
Introduction | Discussion | Conclusion
I want to investigate the physiological effects of altitude training that I have found which support the theory of improved VO2 max, and the effects that might be detrimental to overall performance. Many of the physiological changes in acclimatization to altitude seem to be inconclusive to their effect on VO2 max. I have tried to way up the pros and cons below:
An increase in capillary density could increase blood flow to the muscles, which could help O2 transport to the muscles. This could slightly improve VO2 max.
An increase of the oxidative capacity-dues to higher mitochondrial density- in the muscles might help increase vo2 max, as the muscles would be able to utilize more O2. However most increases in VO2 max are down to the delivery of O2.
Hypoxic Ventilory Response
HVR has been shown to increase slightly after endurance training at altitude [Ref 4]. Other studies have shown an increased Ventrilory rate during altitude training [Ref 6]. I believe this could help the athlete to a slightly increased minute ventilation at sea-level, which could increase VO2 max as more 02 is entering the lungs and is able to be transferred to the blood.
Most studies show the main factor which increases VO2 is the fact that
RBC mass and haemoglobin mass have been shown to increase after altitude training [Ref 2]. This means the blood can carry more O2. Which can increase delivery to the muscles. This can increase VO2 max.
But if the plasma volume is not increased it may also put more strain on the heart which may actually impair athletic performance [Ref 5]
However the body has been shown to compensate for this with an increase in plasma volume post hypoxic training. This can increase maximal stroke volume and maximal cardiac output, which can increase VO2 max. [Ref 2]
Blood pressure has been shown to increase after altitude training in other studies. [Ref 4]
Heart rate is decreased at training and at rest. After altitude training for 2-3 weeks [Ref 2], this could enhance performance at sea-level as it would indicate more stroke volume reserve and this would increase VO2max.
However, maximal hr has been shown to decrease at altitude, along with maximal training intensity and aerobic power [Ref 6] this means training at altitude is below the max intensity of training at sea-level.
Blood lactate levels are increased at higher hrís [Ref 2] however, studies also show that after acclimatization maximal levels are reduced at altitude [Ref 6] again this could suggest lower training intensity at altitude. With a lower vo2 max during training performed at altitude.
It seems that the main effect on VO2 max is the increased Haemoglobin density [Ref 2], allowing the blood to transport more O2, therefore increasing O2 delivery to the working muscles. However, I believe this would not have the same effect without the increase in plasma volume the body compensates with after return to sea-level [Ref 2]. This reduces strain on the heart due to increased blood viscosity, and increases stroke volume, all of which I believe would increase VO2 max.
A graph showing the Physiological changes in blood after altitude training.
Low-low=low altitude training and living
High-high=high altitude training and living
My main conclusion from my research is that acclimatisation to altitude does improve the bodyís ability to utilise O2 in a substantial number of athletes. Nearly all studies show an improvement in Vo2 max in all participants.
max and O2 max measured in normoxia and hypoxia before and after the 6-wk training period
Values are means Ī SE. max, maximal power output; pre, before; post, after. Significant difference, pre- vs. post training values, * P < 0.05.
This graph shows that training at high intensity at hypoxia increases VO2max more than the same training at normoxia, showing a 20% increase.
Power increases were similar in both conditions, but show slightly better results at Hypoxia.
The effect also seems to depend on individual athletes also. Studies show that athletes with a big difference between supine and standing hr, have more chance of decreasing their VO2 max, while athletes with a small difference have less chance of increasing VO2 max. [Ref 2]
However I conclude that training intensity at altitude is lower than at sea-level. This could lead to a decrease in power at maximal intensity in some athletes.
A number of studies show very good improvements of VO2 max and performance for athletes living at 2000-3000m and moving down to a lower altitude to train.
Studies on swimmers [Ref 7], runners [Ref 6], and skiers [Ref 2] show improvements in VO2max and performance for this method of training.
I believe this is due to the effects on the body of acclimatisation to altitude such as increased haemoglobin mass, increased plasma volume and therefore increased cardiac output. This results in lower sub-maximal HR which would give the athlete a higher reserve.
Also the improvements in capillary and mitochondria density, and slight increases in Ventilation rate could slightly improve VO2 max.
But it negates the effects of a lower training intensity indicated by lower maximal hr, lower maximal lactate levels and decreased vo2 max during training [Ref 6]
Therefore in conclusion a compromise of living at an altitude of 2000-3000m, and training at an intermediate altitude of around 1000-1500m for about 10 days, seems to show the best results in increased VO2max and performance in most athletes.
[Ref 1]-J Appl Physiol 91: 173-182, 2001;
Vol. 91, Issue 1, 173-182, July 2001
Molecular adaptations in human skeletal muscle to endurance training under simulated hypoxic conditions
[Ref 2]Cross Country Skiing: Olympic Handbook of Sports Medicine
By Heikki Rusko
Contributor Heikki Rusko
Published by Blackwell Publishing, 2003
ISBN 0632055715, 9780632055715
[Ref 3] J Appl Physiol 81: 1946-1951, 1996;
Journal of Applied Physiology
Vol. 81, No. 5, pp. 1946-1951, November 1996
EXERCISE AND MUSCLE
Muscle tissue adaptations of high-altitude natives to training in chronic hypoxia or acute normoxia
[Ref 4] J Appl Physiol 88: 1221-1227, 2000;
Vol. 88, Issue 4, 1221-1227, April 2000
Cardiovascular response to hypoxia after endurance training at altitude and sea level and after detraining
[Ref 5] The Use of Blood Doping as an Ergogenic Aid.
ACSM Position Stand
Medicine & Science in Sports & Exercise. 28(10):127-134, October 1996.
Sawka, Michael N. Ph.D., FACSM, (Chair); Joyner, Michael J. M.D.; Miles, D. S. Ph.D., FACSM; Robertson, Robert J. Ph.D., FACSM; Spriet, Lawrence L. Ph.D., FACSM; Young, Andrew J. Ph.D., FACSM
[Ref 6] J Appl Physiol 83: 102-112, 1997;
Journal of Applied Physiology
Vol. 83, No. 1, pp. 102-112, July 1997
"Living high-training low": effect of moderate-altitude acclimatization with low-altitude training on performance
Benjamin D. Levine1 and James Stray-Gundersen2
[Ref 7] British Journal of Sports Medicine. 40(2):e4, February 2006.
Roels, B 1; Hellard, P 2; Schmitt, L 3; Robach, P 4; Richalet, J-P 5; Millet, G P 1