HI Pattarawut..

I am not sure of the exact answer, although i am also working on intermittent hypoxia in animals and have only come across a few studies which have a longer training period (10-12 wks)... But could this possibly be that the major advantages of training including the changes in hematocrit, increased maximal oxygen capacity as well as the erythropoietin levels may return to near normal if the training period is prolonged...For example, even in high altitude sojourns, the major changes in physiology are seen in the first few weeks; the body gradually acclimatizes and with respect to athlete training, it is required that the beneficial effcts remain in play..

I hope this helps...it is just what i think..

All d best

Hello Pattarawut,

Probably it's caused by the changed mitochondral metabolism / energy process. Hereby the onset of energy distribution will change and comparison of data are biased.

Dear Pattarawut Khaosanit,

This is an interesting question. The literature suggests the main haematological benefits from the stimulation of erythropoiesis are seen at approximately 4 weeks (1,2,3). There is a suggestion of certain deleterious effects that may occur after prolonged exposure (2) that should be considered. Additionally, there is the question of individual variability to the “desirable effect” of such exposure (1) - do you therefore tailor the length of exposure based on certain subject-specific parameters or does one protocol fit all? I have added certain references that might be useful in order to start thinking about the intrinsic mechanisms that occur at different known stages of exposure and from there assess whether it is necessary for a 10+ week protocol. I hope you find what you are looking for and I wish you the best of luck.

(1)Levine BD and Stray-Gundersen J (2007) Dose-Response of Altitude Training: How Much Altitude is Enough? Hypoxia and Exercise, Advances in Experimental Medicine and Biology, Volume 588, p 233-247

(2)Rusko HK, Tikkanen HO, Peltonen JE. (2004) Altitude and endurance training. J Sports Sci. (10):928-44

(3)Millet GP, Roels B, Schmitt L, Woorons X, Richalet JP. (2010) Combining hypoxic methods for peak performance. Sports Med, 40(1):1-25

Thank you all for your help with my question. You have provided me with some great help in my research.

However, The time of exposure in IHT protocol is difference from live high train low or live high train high. But most of the research about hypoxic training used 4-6 weeks while IHT use 30min.-2 hour to train athletes in hypoxia but LHTL use 10 hours for rest in hypoxia.

I think the number of hours of exposure to hypoxia will cause difference in physiological changes. if we use IHT protocol we should extend the number of weeks of exposure to train in hypoxia because we can't extend the number of hours of exposure to hypoxia to train athletes more than 2 hours by using IHT.

I am the newest in hypoxic training research. If I was wrong please give me some information.

Thank you again,

Patt

Hi Pat,

I tend to agree with the others that have responded here, but I would also add this. We tend to use IHT as an additional stress to training. This additional stress depending on the athlete will hopefully result in the desired beneficial response. However if this stress is too prolonged or too high it could result in unwanted build-up of stress and possibly overreaching or overtraining. Exactly what you don’t want, so the IHT procedures tend to be rather short. In also saying this you must also realise that the actual altitude that the athletes receive is far greater than if they go to real altitude. In some cases you may be giving 9-10% oxygen which is equivalent to at least 6000m, hence the shorter time frame. And of course there is also the practicability of this. Most studies are short due to the time available to study the athlete subjects, or due to funding issues etc.

Hope this helps

Regards

Mike

Thank you very much for your great suggestion Mike.

Dear Pattarawut Khaosanit

I think I could had something to this discussion.

IHE and IHT are two diferent methods that will bring different adaptions. So the first one intends to had some adaptaions in the hematologie the second one intends to bring more efficiency to the mitochindrial respiration.

You can also bring the two together. For this I recommend Millet et al article

Best regards

Hello you can find the answer from ACSM 's strenght and conditioning book's aerobic conditioning part. I have just read. Have a nice work.

This supplement in BJSM will certainly help you:

http://bjsm.bmj.com/content/47/Suppl_1.toc

It is open source!

And especially this review article about the existing IHT studies and newer methods:

http://bjsm.bmj.com/content/47/Suppl_1/i45.full

Hi,

concerning altitude training, it could be also mentioned that chronic exposure may lead to a decrease in maximal cardiac output secondary to a fall in maximal heart rate and stroke volume... But these changes depends of the altitude and time duration at this altitude... These changes may offset the increase in red blood cells... have a nice work.

Regards

Thank you all,I really appreciate for your help very much.

Dear Pattarawut Khaosanit:

During the first 4-6 weeks of exposure to hypoxia, it is possible to show, statistically significant changes. Subsequently, the curve of VO2, muscle strength, among others, take the asymptotic form because the recorded values stabilize. The mechanisms that explain this behavior has been discussed extensively in the literature. This review could be helpful to him. 

Hornbein TF, Schoene RB (Eds): High Altitude: An Exploration of Human Adaptation. Marcel Dekker, Inc., New York, NY, USA; 2001.