Sep 21
Authors:

Rémi Mounier, Vincent Pialoux, Belle Roels, Claire Thomas, Grégoire Millet, Jacques Mercier, Jean Coudert, Nicole Fellmann, Eric Clottes

Impact factor: 1.75, Cited half life: 8.4, Immediacy index: 0.25

Journal: Arbeitsphysiologie

Intermittent hypoxic exposure with exercise training is based on the assumption that brief exposure to hypoxia is sufficient to induce beneficial muscular adaptations mediated via hypoxia-inducible transcription factors (HIF). We previously demonstrated (Mounier et al. Med Sci Sports Exerc 38:1410-1417, 2006) that leukocytes respond to hypoxia with a marked inter-individual variability in HIF-1alpha mRNA. This study compared the effects of 3 weeks of intermittent hypoxic training on hif gene expression in both skeletal muscle and leukocytes. Male endurance athletes (n = 19) were divided into an Intermittent Hypoxic Exposure group (IHE) and a Normoxic Training group (NT) with each group following a similar 3-week exercise training program. After training, the amount of HIF-1alpha mRNA in muscle decreased only in IHE group (-24.7%, P < 0.05) whereas it remained unchanged in leukocytes in both groups. The levels of vEGF(121) and vEGF(165) mRNA in skeletal muscle increased significantly after training only in the NT group (+82.5%, P < 0.05 for vEGF(121); +41.2%, P < 0.05 for vEGF(165)). In leukocytes, only the IHE group showed a significant change in vEGF(165) (-28.2%, P < 0.05). The significant decrease in HIF-1alpha mRNA in skeletal muscle after hypoxic training suggests that transcriptional and post-transcriptional regulations of the hif-1alpha gene are different in muscle and leukocytes.

European journal of applied physiology. 01/11/2008;

http://www.researchgate.net/publication/23482667_Effect_of_intermittent_hypoxic_training_on_HIF_gene_expression_in_human_skeletal_muscle_and_leukocytes

Sep 17
Authors:

David Bentley, Belle Roels, Claire Thomas, Robert Ives, Jacques Mercier, Grégoire Millet, David Cameron-Smith

Journal: Arbeitsphysiologie

The purpose of this study was to examine the relationship between skeletal muscle monocarboxylate transporters 1 and 4 (MCT1 and MCT4) expression, skeletal muscle oxidative capacity and endurance performance in trained cyclists. Ten well-trained cyclists (mean +/- SD; age 24.4 +/- 2.8 years, body mass 73.2 +/- 8.3 kg, VO(2max) 58 +/- 7 ml kg(-1) min(-1)) completed three endurance performance tasks [incremental exercise test to exhaustion, 2 and 10 min time trial (TT)]. In addition, a muscle biopsy sample from the vastus lateralis muscle was analysed for MCT1 and MCT4 expression levels together with the activity of citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD). There was a tendency for VO(2max) and peak power output obtained in the incremental exercise test to be correlated with MCT1 (r = -0.71 to -0.74; P < 0.06), but not MCT4. The average power output (P (average)) in the 2 min TT was significantly correlated with MCT4 (r = -0.74; P < 0.05) and HAD (r = -0.92; P < 0.01). The P (average) in the 10 min TT was only correlated with CS activity (r = 0.68; P < 0.05). These results indicate the relationship between MCT1 and MCT4 as well as cycle TT performance may be influenced by the length and intensity of the task.

European journal of applied physiology. 01/04/2009;

FULL ARTICLE

http://www.researchgate.net/researcher/38177302_Belle_Roels

Sep 15

The problem of hypoxia is a multi-headed Medusa in physiology and clinical medicine. Two main aspects of this problem are hotly discussed: the destructive and the constructive action of hypoxia. One viewpoint belonging primarily to western scientists is perfectly expressed in Barcroft’s words: “Hypoxia not only intercepts the machine, but also damages the mechanism”. The second veiwpoint, expressed primarily by the former Soviet Union (FSU) scientific schools, reads as follows: “Hypoxia (even severe but brief and intermittent) can cause beneficial effects on an organism”. However, many a scientific publication was in Russian or Ukrainian and because they were not widely available in other countries, these research findings remained obscure. The purpose of this review is to summarize some past and recent achievements in the field of intermittent hypoxic training (IHT), giving special consideration to applied problems in the treatment of bronchial asthma (BA).

Historical aspects

Historically, first steps in the use of IHT were for training pilots, mountaineers and athletes. The pioneering research, carried out in 1939-1943 (see 1 for review), showed that even a small altitude elevation produces positive adaptation effect, improving lung ventilation and increasing hemoglobin concentration and arterial oxygen saturation. The research of the time drew attention not only to constructive and creative hypoxic training but also to possible curative effects of hypoxic adaptation. More than 30 years later, other studies have shown that a training protocol that includes gradual adaptation to hypobaric hypoxia improves the working capacity and endurance of athletes and astronauts. Inhalation of hypoxic gas mixtures to produce IHT was rapidly introduced into sports training and diseases treatment procedures. IHT protocols and equipment were devised and manufactured for this purpose.

FULL ARTICLE

Sep 1

2010 by Oleg Bassovitch

Recently published Letter to the Editor titled “Intermittent hypoxic training: risks versus benefits” (Hinghofer-Szalkay, 2010) suggested inquiring into the  long-term risks of Intermittent Hypoxic Training” (IHT), that is also called Therapeutic Hypoxia (TH). The letter points at potential risk of Reactive Oxygen Species (ROS) formation. From the biomedical point of view it is important to separate hazards associated with the use of a device / system and physiological risks and benefits of the therapy itself.

Undoubtfully, a device for human or animal treatments must be meeting essential requirements for medical devices e.g. electrical medical safety and electromagnetic compatibility (IEC 60601-1, 2007).

Devices and systems for hypoxia intervention are called “hypoxicators” and were recently suggested by Australian Therapeutic Goods Administration being mandatory regulated for all applications (TGA, 2008). Hypoxicator falls under the common definition of medical device because of it intended use e.g. “modification of physiological process” (Council Directive 93/42/EEC, 1993).

This letter is a brief review of physiological risks associated with the use of hypoxicators and IHT for human performance enhancement, in both athletic and sedentary populations.

ACCESS TO FULL ARTICLE

http://www.springerlink.com/content/4632×38184754513/

Aug 20

The outcomes of reside lower with sporadic subjection to hypoxia, train reduced instruction on efficiency of cyclists are discussed right here.

Ongoing subjection to natural elevation may increase complications for the hurt athlete as well as common recovery could get slowed. The endurance athlete has being provided accurate time periods of recovery following each and every stress workout. Numerous higher performing altitude training camps get the better of cyclists from climbing down to coast level to get high intensity training purpose.

The objective of height training plans is always to improve conditioning ranges in participants either by providing raises ranges of tension in the course of the training sessions or recovery or decreased amounts of stress.Bike riders who get involved within competition come across different training troubles when of working on altitude training. A smart rider or a trainer can be aware of timings of elevation training throughout the season in order that he or she might obtain optimum advantages out of the education plan.

A good fitness instructor has to accomplish bunch of analysis throughout the program with the altitude base exercising towards the best suited cyclist.

Typically the injured athletes might obtain more gains by working the simulated over sea riding because of better heart reply for decreased potential result.Every single physical education practice session induces variation from the rider for the environment and they accomplish the conditioning plateau. A well organized improve within the tension values with the strength exercising lead the rider to greater overall performance.The cyclist who is avoided from increased energy outputs at seaside degree can certainly work out at a high elevation to attain comparatively large core rates.

Better sea level performance may be as a result of elevated EPO release by filtering system, higher red cell mass and highest breathable air assimilation by muscle groups.Irregular hypoxic exposure does alter hematocrit, and alsoperformance during sleep, proving its effectiveness. Endurance training at increased altitudes raises the content level of blood cells and non-hematological results.Increase in plasma level (hemoconcentration) which happens next to the altitude training is incorrectly recognized for increased cellular size.

A note about EPO (Erythropoietin)

Treatments of EPO are unquestionably banned wordwide and result in thickening associated with bloodstream and even heart failure. Get better educated in relation to EPO before deciding these banned actions. Cyclists or runners will improve their overall performance by understanding a little more about complete book of road bike training

Scientists have done a lot of studies and written evaluations on altitude training being a approach supporting to different athletic divisions of sport science.

Advanced long distance runners, demonstrated better sea level efficiency by one.One percent, consequently of the week’s “live high, practice low” technique. Australian experts have detected better activities by “live high” technique with out any kind of increases in reddish colored blood cell mass or maybe increased air expire, realizing their thoughts and opinions that results is improved with height training which can be separate from breathable air expiration.Experts associated with this technique think this a clear placebo-handled device offers not been formed yet.

Concrete facts does not be found promoting the flexibility associated with irregular hypoxia exposure.Paperwork Accessible On Altitude Exercising. Another researcher stated the fact that professional sports researcher coming from Sydney have demostrated profound curiosity on that procedure that is a method associated with height exercise.In the year late 2001, the two scientists stated that the particular ,”live higher, train low” technique in elevation workouts was initially highly successful for athletes taking part in four hundred track race.Wilber published a couple of reviews reports about the evaluation of various high level exercising methods practiced by triathletes which represent diverse competitions. published obvious and evaluations about elevation training of which was go through and got achieved positive results by the riders and their trainers who took portion within world competitors.

SOURCE

Jun 25

Object: The hypoxic training methods are widely studied since 1968. But different training styles may cause different results.Heart is an important part of kinetic system. Hypoxia acclimatization,especially under the process of exercise could lead lots of physiological changes that propitious to aerobic capability. We studied the effect of hypoxic on the myocardial ultrastructure and aerobic oxidation function of rest and training rats in order to make full realize of the HiLo training on bodies.Materials and Methods:140 male Spargue-Dawley rats were randomly divided into 4 groups: normoxia control group(N),intermittent hypoxic group(H),normoxia training group(T) and HiLo group(HT).N and T are both divided into 3 sub-groups as the time that lday,7days and 28days;H and HT are both divided into 4 sub-groups as the time that lday、7day、8days and 7days after the intermittent hypoxic.Therefore there are totally 14 sub-groups, each one with 10 rats.After all the groups had been adapted for one week, the T and HT performed closely monitored training in treadmills(grade of 5,at the speed of 20m/min,duration of lh/day,6 days/week) for 4 weeks;the last HT group performed one more week after the hypoxia training.(All the trainings are out of the tent) During the 4 weeks experimental period,we employed the 13.6%concentration of oxygen(equal to altitude 3500m) in the hypoxic tent.H and HT groups were exposed to hypoxia for 12h every day.Sample collection and measurements were performed when the hypoxic groups just got out of the tent.The indexes we measured contains that the ATP synthase activity,the LDH synthase activity,the SDH synthase activity of myocardial.and the morphological observation. 1.In contrast to the N groups,the ATP synthase activity of myocardial increased significantly in the H groups;In the T groups,there was slightly decrease in the lday sub-group.And it respectively increased 7.9%and 32.2%in the 7days and 28days sub-groups;In the HT groups,it increased 40.7%,92.9%and 109.2%in the 7days,28days and 7days after the intermittent hypoxic sub-groups respectively.2.In contrast to the N groups,the LDH synthase activity of myocardial had just a slightly increased in all the intermittent hypoxic sub-groups; In the T groups,it increased 6.5%and 8.4%in the 7days and 28days sub-groups respectively;In the HT groups,it respectively increased 8.6%,13.8%,16.3%in the 7days,28days and 7days after the intermittent hypoxic sub-groups.In addition,the LDH synthase activity of myocardial slightly decreased in lday sub-groups of T and HT.3.In contrast to the N groups,the SDH synthase activity of myocardial respectively increased 31.4%,12.7%and 23.7;5.0%and 24.6%;34.5%, 61.8%and 75.9%in H,NT and HTs’ 7days,28days and 7days after the intermittent hypoxic sub-groups.4.Myocardial ultrastructure of mitochondria,myofibrils and myofilament were observed by transmission electron microscope.The results show that HiLo training could improve ultrastructure of mitochondria,myofibrils and myofilament.Therefore the aerobic metabolism ability and energy utilization would be strengthened as a result.Conclusion:1.During the process of 4 weeks HiLo and 1 week training after HiLo, the SDH synthase, LDH synthase and ATP synthase activity of myocardial increased obviously as time passes by. The results show that HiLo training can improve the myocardial synthase ability,hence strengthen the myocardial aerobic oxidation effectively.  2.The hypoxia acclimatization and endurance training of 4 weeks can improve the myocardial ultrastructure,making the mitochondria get more and the density of mitochondrial crista get high.The aerobic metabolism ability got strongly impoved,especially during the days after the intermittent hypoxic.

Source:

Jun 18

Acute Intermittent Hypoxia on Spinal Plasticity The objective of this study is to examine the effects of repeated episodes of mild acute intermittent hypoxia (AIH) on motoneuron activity in persons with incomplete spinal cord injury (SCI). In particular, we will quantify the effects of repeated exposure to AIH on limb muscle activity, and determine if changes in the observed muscle responses are accompanied by enhanced voluntary torque strength and walking performance. If true, such changes may indicate hypoxia-induced spinal plasticity resulting in functionally useful enhancement of motor output. Findings from this project could offer new insight into a possible mechanism of neuromodulation of spinal motoneuron pools and recovery of neuromotor function following SCI.

Jun 6

Tuesday, June 1st, 2010

What is Altitude Training?

Altitude training, also known as hypoxic training, involves exercising in, living in or otherwise breathing oxygen reduced air for the purpose of improved athletic performance, pre-acclimatization to altitude and/or physical wellness.

Traditionally, individuals had to travel to or live at high elevations to obtain the benefits of this phenomenon. Through the production of the mountain air generators we can simulate altitudes of up to 21,000ft/6,400m. As a result, athletes, fitness enthusiasts and health conscious individual’s worldwide can take advantage of the benefits associated with altitude training while at sea-level.
Proven Benefits
. Maximized speed and endurance
. Elevated strength and power

SOURCE

May 27

Most Tibetans are genetically adapted to life on the “roof of the world,” according to a new study.

The Tibetan Plateau (map) rises more than 13,000 feet (4,000 meters) above sea level. At such heights, most people are susceptible to hypoxia, in which too little oxygen reaches body tissues, potentially leading to fatal lung or brain inflammation.

To survive the high life, many Tibetans carry unique versions of two genes associated with low blood hemoglobin levels, the researchers found.

Since hemoglobin is the oxygen-carrying component of red blood cells, the find might seem “really counterintuitive,” said study leader Tatum Simonson at the University of Utah’s Eccles Institute of Human Genetics in Salt Lake City.

“Usually, if you or I or any nonadapted person went to high altitude, we would increase our hemoglobin levels to compensate for the low amount of oxygen.”

But high hemoglobin levels have been linked to complications such as hypertension and chronic mountain sickness, Simonson said.

These negative effects could have led to a genetic mutation among Tibetans that “prevented them from making as much” hemoglobin, she noted.

(Related: “Japanese Guts Are Adapted to Sushi.”)

Tibetan Genes Keys to Treating Height Sickness?

Previous research had found that Tibetans compensate for low oxygen levels by taking more breaths per minute than people living at sea level. In addition, Tibetans’ blood vessels are wider, making them more efficient at delivering oxygen to body tissues.

Simonson and her colleagues searched for the genetic basis of high-altitude adaptations by collecting blood samples from villagers in Tibet living at 14,720 feet (4,486 meters) above sea level. (Get insider’s tips on life in Lhasa, capital of China’s Tibet Autonomous Region.)

The team then looked for patterns of genetic variation in the Tibetans’ DNA and compared their findings to existing data on gene variation in lowland Chinese and Japanese populations, which are closely related to Tibetans.

Several variants of genes associated with high-altitude living, such as those that process oxygen, were found in Tibetans but not in their low-living neighbors. That includes the two genes that are strongly associated with low hemoglobin production.

(Related: “Ancient Climate Change Rocked Tibetan Cultures, Research Suggests.”)

Future research is aimed at teasing out more details about what exactly the altered genes do, which could help scientists find ways to “prevent people from getting sick” at high altitudes, Simonson said.

Findings were published online May 13 in the journal Science.

LINK TO SOURCE

May 15

Objective:In order to provide a theoretical basis and applied methods for hypoxic training applied in sports practice, this thesis studied the mechanism of hypoxic training promoting angiogenesis on muscular tissue by exploring the effect of hypoxic training on regulating the hypoxic responsive genes on muscular issue, the effect of the hypoxic responsive genes on boosting angiogenesis on muscular issues, and the angiogenesis mechanism of hypoxic training muscular tissue.Material and Methods:Hypoxia cell culture and electrophoretic mobility shift assay were applied to study the protein-DNA binding activity of hypoxia induced factor-1 and vascular endothelium growth factor gene, and fms-like tyrosine kinase-1 of human umbilicus vein endothelial cell under hypoxia. 3×3 factorial experiment, progressive treadmill exercise, hypoxia and super-hypoxia increasing by degree were used to establish animal model with different training pattern and different hypoxic stimulus. Thereafter, Blood-gas analysis, in situ hybridization, immunohistochemical technology and computer image processing methods were used to study the effect of hypoxic training on the oxygen binding status of arterial blood, the effect of oxygen binding status of arterial blood on hypoxia induced factor-1αof muscular tissue, and then the promoting effect of hypoxic training on genes transcription of vascular endothelium growth factor and fms-like tyrosine kinase-1. In addition, Enzyme linked immunosorbnent assay, Stereology, immunohistochemical technology and computer image processing methods were used to study the accelerating effect of vascular endothelium growth factor and fms-like tyrosine kinase-1 on hypoxic training angiogenesis of muscular tissue. In the end, transmission electron microscope was applied to study the morphological mode of angiogenesis of hypoxic training muscular tissue.Conclusions:Different Oxygen content mixed gases were administered to culture human umbilical vein endothelium cell to found hypoxia cell culture model for ex vivo study of hypoxic training, and an animal model of hypoxic training was successfully established by progressive treadmill exercise and hypoxic stimulus with progressive hypoxia.Simple hypoxia (hypoxia content from 18.2kPa to 15.2 kPa ) and super- hypoxia (hypoxia content from 17.4 kPa to 11.3kPa ) could not increase density of micro- blood vessel. Normoxic training, hypoxic training, and hypoxic administration after training could increase density of micro- blood vessel. Interaction occurred between hypoxic administration and training pattern, and hypoxic administration and training pattern had different main effects. From the changing of micro- blood vessel, hypoxic training was found to be better than normoxic training to micro- blood vessel on muscular tissue.In vivo, hypoxia could increase binding activity of HIF-1 of culture human umbilical vein endothelium cell and VEGF、Flt-1 DNA. The binding activity was regulated by oxygen content within a certain range. Ex vivo, hypoxia could decrease arterial blood oxygen binding; hypoxic training was the most efficient stimulus to decrease arterial partial pressure of oxygen, while it could decrease arterial blood oxygen binding to a large degree. The transcription regulation mechanism of angiogenesis of hypoxic training muscular tissue was: affected by the degree of oxygen binding, hypoxic training could increase the protein expression of HIF-1 o?n muscular tissue and the increase could promote the genes transcription of VEGF and Flt-1.The mechanism of hypoxia responsive genes promoting the angiogenesis of hypoxic training muscular tissue was: hypoxic training could increase the protein of angiogenesis hypoxia responsive genes VEGF and Flt-1, and after VEGF protein was produced, it could secrete by autocrine or by paracrine, combine with Flt-1 receptor on the vascular endothelium cell membrane, and participate in the angiogenesis of muscular tissue. Hypoxia, training, and hypoxic training all could reduce the content of serum VEGF, meanwhile, the proteins of VEGF on muscular tissue increased and the Flt-1 receptors also increased. Therefore, ingestion and utilization of VEGF from circulation was increased on muscular tissue.Angiogenesis on muscular tissue could be performed by means of sprouting and no-sprouting, among which no-sprouting angiogenesis pattern, i.e. intussusceptive microvascular growth, was the major way, suggesting that muscular tissue could take faster and more economical angiogenesis pattern to satisfy the demands of energy and metabolization.

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