Evidence
of exercise-induced O2 arterial desaturation in non-elite sportsmen and
sportswomen following high-intensity interval-training.
Mucci P, Blondel N, Fabre C, Nourry C, Berthoin S.
Laboratoire d'Analyse Multidisciplinaire des Pratiques
Sportives, UFR-STAPS de Lievin-Universite d'Artois,
The aim of this study was to investigate the development of exercise-induced
hypoxemia (EIH defined as an exercise decrease > 4 % in oxygen arterial
saturation, i. e. SaO (2) measured with a portable pulse oximeter) in twelve
sportsmen and ten sportswomen (18.5 +/- 0.5 years) who were non-elite and not
initially engaged in endurance sport or training. They followed a
high-intensity interval-training program to improve V.O (2)max
for eight weeks. The training running speeds were set at approximately 140 %
V.O (2)max running speed up to 100 % 20-m maximal running
speed. Pre- and post-training pulmonary gas exchanges and SaO (2) were measured
during an incremental running field-test. After the training period, men and
women increased their V.O (2)max (p < 0.001) by
10.0 % and 7.8 %, respectively. Nine subjects (seven men and two women)
developed EIH. This phenomenon appeared even in sportsmen with low V.O (2)max
from 45 ml x min (-1) x kg (-1) and seemed to be associated with inadequate
hyperventilation induced by training: because only this hypoxemic group showed
1) a decrease in maximal ventilatory equivalent in O (2) (V.E/V.O (2), p <
0.01) although maximal ventilation increased (p < 0.01) with training, i. e.
in EIH-subjects the ventilatory response increased less than the metabolic
demand after the training program; 2) a significant relationship between SaO
(2) at maximal workload and the matched V.E/V.O (2) (p < 0.05, r = 0.67)
which strengthened a relative hypoventilation implication in EIH. In
conclusion, in this field investigation the significant decrease in the minimum
SaO (2) inducing the development of EIH after high-intensity interval-training
indicates that changes in training conditions could be accompanied in
approximately 40 % non-endurance sportive subjects by alterations in the degree
of arterial oxyhemoglobin desaturation developing during exercise.
Effects
of intermittent hypoxic training and detraining on ventilatory chemosensitive
adaptations in endurance athletes.
Katayama K, Sato K, Matsuo H, Ishida K, Mori S, Miyamura M.
The effects of flying:
processes, consequences and prevention.
Shepherd L, Edwards SL.
Barnet Accident and Emergency,
The dangers of flying have recently been highlighted in the media; however, the
available literature is contradictory, as are current recommendations for
travellers. The purpose of this article is to provide an account of the
research that has been undertaken to investigate the possible consequences of
air travel. It will examine the effect that flying has on the body, especially
the respiratory and circulatory systems, by studying the theoretical and
empirical literature. The aim is to provide nurses with a sound insight into
the effects of long-distance flying on the body, and the potential adverse
effects/complications, such as deep vein thrombosis and pulmonary embolism,
that may occur as a result. In addition, it provides information on the
treatment options available and should enable nurses to give sound prophylactic
advice after discharge. By encouraging passengers to take precautions, the
number of people affected by flight could be reduced.
Publication Types:
· Review
· Review, Tutorial
Intermittent altitude
exposures reduce acute mountain sickness at 4300 m.
Beidleman BA, Muza SR, Fulco CS, Cymerman A, Ditzler D, Stulz D, Staab JE, Skrinar GS, Lewis SF, Sawka MN.
Biophysics and Biomedical Modeling Division, United States
Army Research Institute of Environmental Medicine,
Acute mountain sickness (AMS) commonly occurs at altitudes exceeding 2000-2500
m and usually resolves after acclimatization induced by a few days of chronic
residence at the same altitude. Increased ventilation and diuresis may
contribute to the reduction in AMS with altitude acclimatization. The aim of
the present study was to examine the effects of intermittent altitude exposures
(IAE), in combination with rest and exercise training, on the incidence and
severity of AMS, resting ventilation and 24-h urine volume at 4300 m. Six
lowlanders (age, 23 +/- 2 years; body weight, 77 +/- 6 kg; values are means +/-
S.E.M.) completed an Environmental Symptoms Questionnaire (ESQ) and Lake Louise
AMS Scoring System (LLS), a resting end-tidal partial pressure of CO2 ( PETCO2)
test and a 24-h urine volume collection at sea level (SL) and during a 30 h
exposure to 4300 m altitude-equivalent (barometric pressure=446 mmHg) once
before (PreIAE) and once after (PostIAE) a 3-week period of IAE (4 h.day(-1), 5
days.week(-1), 4300 m). The previously validated factor score, AMS cerebral
score, was calculated from the ESQ and the self-report score was calculated
from the LLS at 24 h of altitude exposure to assess the incidence and severity
of AMS. During each IAE, three subjects cycled for 45-60 min.day(-1)
at 60-70% of maximal O2 uptake (VO2 max) and three subjects rested. Cycle
training during each IAE did not affect any of the measured variables, so data
from all six subjects were combined. The results showed that the incidence of
AMS (%), determined from both the ESQ and LLS, increased (P<0.05) from SL (0
+/- 0) to PreIAE (50 +/- 22) at 24 h of altitude exposure and decreased
(P<0.05) from PreIAE to PostIAE (0 +/- 0). The severity of AMS (i.e. AMS
cerebral symptom and LLS self-report scores) increased (P<0.05) from SL
(0.02 +/- 0.02 and 0.17 +/- 0.17 respectively) to PreIAE (0.49 +/- 0.18 and
4.17 +/- 0.94 respectively) at 24 h of altitude exposure, and decreased
(P<0.05) from PreIAE to PostIAE (0.03 +/- 0.02 and 0.83 +/- 0.31
respectively). Resting PETCO2 (mmHg) decreased (i.e. increase in ventilation;
P<0.05) from SL (38 +/- 1) to PreIAE (32 +/- 1) at 24 h of altitude exposure
and decreased further (P<0.05) from PreIAE to PostIAE (28 +/- 1). In
addition, 24-h urine volumes were similar at SL, PreIAE and PostIAE. In
conclusion, our findings suggest that 3 weeks of IAE provide an effective
alternative to chronic altitude residence for increasing resting ventilation
and reducing the incidence and severity of AMS.
Publication Types:
· Clinical Trial
Attenuated
ANF response to exercise in athletes with exercise-induced hypoxemia.
Durand F, Mucci P, Hayot M, Couret I, Bonnardet A, Prefaut Ch.
Laboratoire Sport, Sante, Altitude, Departement STAPS,
Some highly trained endurance athletes develop an
exercise-induced hypoxemia (EIH) at least partially due to a hemodynamic factor
with a potential stress failure on pulmonary capillaries. Atrial natriuretic
factor (ANF) is a pulmonary vasodilatator and its release during exercise could
be reduced with endurance training. We hypothesized that athletes exhibiting
EIH, who have a greater training volume than non-EIH athletes, have a reduced
ANF release during exercise explaining the pathophysiology of EIH. Ten highly trained
EIH-athletes (HT-EIH), ten without EIH (HT-nEIH), and nine untrained (UT) males
performed incremental exercise to exhaustion. No between group differences
occurred in resting ANF plasma levels. In contrast to HT-nEIH and UT (p <
0.05), HT-EIH showed a smaller increase in ANF concentration between rest and
maximal exercise (HT-EIH: 8.12 +/- 0.69 vs. 14.1 +/- 1.86 pmol x l (-1);
HT-nEIH: 10.46 +/- 1 vs. 18.7 +/- 1.8 pmol x l (-1); UT: 6.23 +/- 0.95 vs.
20.38 +/- 2.79 pmol x l (-1)). During the recovery, ANF levels decreased
significantly in HT-nEIH and UT groups (p < 0.05). Electrolyte values
increased in all groups during exercise but were higher in both trained groups.
In conclusion, this study suggested that ANF response to exercise may be important
for exercise-induced hypoxemia.
Publication Types:
· Clinical Trial
· Controlled Clinical Trial
| Eur
J Appl Physiol. 2004 Jun;92(1-2):75-83. Epub 2004 Feb 26. |
Effect of
intermittent hypoxia on oxygen uptake during submaximal exercise in endurance
athletes.
Katayama K, Sato K, Matsuo H, Ishida K, Iwasaki K, Miyamura M.
The purpose of the present study was to clarify the following: (1) whether
steady state oxygen uptake (VO(2)) during exercise decreases after short-term
intermittent hypoxia during a resting state in trained athletes and (2) whether
the change in VO(2) during submaximal exercise is correlated to the change in
endurance performance after intermittent hypoxia. Fifteen trained male
endurance runners volunteered to participate in this study. Each subject was
assigned to either a hypoxic group (n=8) or a control group (n=7). The hypoxic
group spent 3 h per day for 14 consecutive days in normobaric hypoxia [12.3
(0.2)% inspired oxygen]. The maximal and submaximal
exercise tests, a 3,000-m time trial, and resting hematology assessments at sea
level were conducted before and after intermittent normobaric hypoxia. The
athletes in both groups continued their normal training in normoxia throughout
the experiment. VO(2) during submaximal exercise in
the hypoxic group decreased significantly (P<0.05) following intermittent
hypoxia. In the hypoxic group, the 3,000-m running time tended to improve
(P=0.06) after intermittent hypoxia, but not in the control group. Neither peak
VO(2) nor resting hematological parameters were
changed in either group. There were significant (P<0.05) relationships
between the change in the 3,000-m running time and the change in VO(2) during submaximal exercise after intermittent hypoxia.
The results from the present study suggest that the enhanced running economy
resulting from intermittent hypoxia could, in part, contribute to improved
endurance performance in trained athletes.
Publication Types:
· Clinical Trial
· Randomized Controlled Trial
Intermittent hypoxic
training protects canine myocardium from infarction.
Zong P, Setty S, Sun W, Martinez R, Tune JD, Ehrenburg IV, Tkatchouk EN, Mallet RT, Downey HF.
Department of Integrative Physiology, University of North Texas Health Science
Center, Fort Worth, Texas 76107-2699, USA. pzong@hsc.unt.edu
This investigation examined cardiac protective effects
of normobaric intermittent hypoxia training. Six dogs underwent intermittent
hypoxic training for 20 consecutive days in a normobaric chamber ventilated
intermittently with N2 to reduce fraction of inspired oxygen (FiO2) to
9.5%-10%. Hypoxic periods, initially 5 mins and increasing to 10 mins, were
followed by 4-min normoxic periods. This hypoxia-normoxia protocol was
repeated, initially 5 times and increasing to 8 times. The dogs showed no
discomfort during intermittent hypoxic training. After 20 days of hypoxic training,
the resistance of ventricular myocardium to infarction was assessed in an acute
experiment. The left anterior descending (LAD) coronary artery was occluded for
60 mins and then reperfused for 5 hrs. At 30 mins of LAD occlusion, radioactive
microspheres were injected through a left atrial catheter to assess coronary
collateral blood flow into the ischemic region. After 5 hrs reperfusion, the
heart was dyed to delineate the area at risk (
Exercise induced arterial
hypoxemia in swimmers.
Spanoudaki SS,
Maridaki MD, Myrianthefs PM,
Baltopoulos PJ.
Division of Sports Medicine and Biology of Exercise, Laboratory of Functional
Anatomy,TEFAA
AIM: Exercise induced arterial hypoxemia (EIAH) is a reduction in arterial
oxygenation, which may result from a drop in arterial oxygen pressure and
therefore in oxygen saturation. We examined EIAH in swimmers, while till now it
was known to occur in cyclists and runners. METHODS: We studied 8 male highly
trained swimmers (age: 23+/-1.7; (.-)VO(2peak),
5.3+/-0.1 l/min and 8 male ex-swimmers (age: 21.5+/-0.6; (.-)VO(2peak),
3.4+/-0.3 l/min). All subjects performed 200-meter freestyle at maximum effort.
Hemoglobin saturation (SaO(2)%) was measured using a
finger pulse oximeter before exercise in the water in an upright position and
immediately after exercise, within 5 seconds. RESULTS: Highly trained swimmers
developed a statistically significant decrease in SaO(2)%
(from 98.3+/-0.3 to 94+/-0.9, p= or <0.01) after exercise, while ex-swimmers
did not (from 98.4+/-0.3 to 96.8+/-0.3 ns). The 4% decrease in SaO(2)% observed in highly trained swimmers can be
characterized as mild EIAH. CONCLUSIONS: Our study suggests that highly trained
swimmers but not ex-swimmers may develop mild EIAH after 200 meters freestyle
swimming at maximum effort.
Effects
of hypoxic interval training on cycling performance.
Roels B, Millet GP, Marcoux CJ, Coste O, Bentley DJ, Candau RB.
UPRES EA 3759 Faculty of Sport Sciences, 700 avenue
Pic St Loup, 34090
PURPOSE: The aim of this study was to test the hypothesis that intermittent
hypoxic interval training improves sea level cycling performance more than
equivalent training in hypoxia or normoxia. METHODS: Thirty-three well-trained
cyclists and triathletes (25.9 +/- 2.7 yr, VO(2max) 66.1 +/- 6.1
mL.min(-1).kg(-1)) were divided into three groups: intermittent hypoxic (IHT, N
= 11, P(I)O(2) of 100 mm Hg), intermittent hypoxic interval training (IHIT, N =
11) and normoxia (Nor, N = 11, P(I)O(2) of 160 mm Hg) and completed a 7-wk
training program, consisting of two high-intensity (100 or 90% relative peak
power output) interval training sessions each week. Each interval training
session was performed in a laboratory on the subject's own bicycle, in normoxic
or hypoxic conditions for the Nor and the IHT group,
respectively. The IHIT group performed warm-up and cool-down plus recovery from
each interval in hypoxic conditions. In contrast to IHT, interval exercise
bouts were performed in normoxic conditions. RESULTS: Mean power output during
a 10-min cycle time trial improved after the first 4 wk of training by 5.2 +/-
3.9, 3.7 +/- 5.9, and 5.0 +/- 3.4% for IHIT, IHT, and Nor, respectively,
without significant differences between groups. Moreover, mean power output did
not show any significant improvement in the following 3 wk in any group. VO(2max) (L.min(-1)) increased only in IHIT during the
training period (8.7 +/- 9.1%; P < 0.05). No changes in cycling efficiency
or in hematological variables (P > 0.05) were observed. CONCLUSION: Four
weeks of interval training induced an improvement in endurance performance.
However, short-term exposure to hypoxia (approximately 114 min.wk(-1))
did not elicit a greater increase in performance or any hematological
modifications.
Evidence
of exercise-induced O2 arterial desaturation in non-elite sportsmen and sportswomen
following high-intensity interval-training.
Mucci P, Blondel N, Fabre C, Nourry C, Berthoin S.
Laboratoire d'Analyse Multidisciplinaire des Pratiques
Sportives, UFR-STAPS de Lievin-Universite d'Artois,
The aim of this study was to investigate the development of exercise-induced
hypoxemia (EIH defined as an exercise decrease > 4 % in oxygen arterial
saturation, i. e. SaO (2) measured with a portable pulse oximeter) in twelve
sportsmen and ten sportswomen (18.5 +/- 0.5 years) who were non-elite and not
initially engaged in endurance sport or training. They followed a
high-intensity interval-training program to improve V.O (2)max
for eight weeks. The training running speeds were set at approximately 140 %
V.O (2)max running speed up to 100 % 20-m maximal
running speed. Pre- and post-training pulmonary gas exchanges and SaO (2) were
measured during an incremental running field-test. After the training period,
men and women increased their V.O (2)max (p <
0.001) by 10.0 % and 7.8 %, respectively. Nine subjects (seven men and two
women) developed EIH. This phenomenon appeared even in sportsmen with low V.O
(2)max from 45 ml x min (-1) x kg (-1) and seemed to be associated with
inadequate hyperventilation induced by training: because only this hypoxemic
group showed 1) a decrease in maximal ventilatory equivalent in O (2) (V.E/V.O
(2), p < 0.01) although maximal ventilation increased (p < 0.01) with
training, i. e. in EIH-subjects the ventilatory response increased less than
the metabolic demand after the training program; 2) a significant relationship
between SaO (2) at maximal workload and the matched V.E/V.O (2) (p < 0.05, r
= 0.67) which strengthened a relative hypoventilation implication in EIH. In
conclusion, in this field investigation the significant decrease in the minimum
SaO (2) inducing the development of EIH after high-intensity interval-training
indicates that changes in training conditions could be accompanied in
approximately 40 % non-endurance sportive subjects by alterations in the degree
of arterial oxyhemoglobin desaturation developing during exercise.
| Eur
J Appl Physiol. 2004 Aug;92(4-5):470-6. Epub 2004 May 8. |
Effects
of training in normoxia and normobaric hypoxia on time to exhaustion at the
maximum rate of oxygen uptake.
Messonnier L,
Geyssant A, Hintzy F, Lacour JR.
Laboratoire de Modelisation des Activites Sportives, Departement
STAPS,
The effects of endurance training in normoxia or in hypoxia on time to exhaustion
( T(lim)) at the work rate corresponding to peak oxygen uptake (VO(2peak))
were examined at sea level in 13 healthy subjects. Before and after training
the subjects performed the following: (1) incremental exercises up to exhaustion
to determine peak oxygen uptake in normoxia (VO(2peak)N), the percentage of
this value at the 4 mmol l(-1) blood lactate concentration (VO(2)4%N) and
the work rate corresponding to VO(2peak)N (Pa(peak)N), (2) a 5-min 90% Pa(peak)N
exercise followed by a 10-min passive recovery to determine the maximal blood
lactate concentration (La(max)) measured during the recovery, and (3) a T(lim)
at Pa(peak)N. Training consisted of pedalling 2 h a day, 6 days a week, for
4 weeks. Five subjects trained in normobaric hypoxia [HT; partial pressure
of inhaled oxygen ( P(I)O(2)) 89 mmHg] and eight
subjects trained at the same relative work rates in normoxia (NT; P(I)O(2)
141 mmHg). The training-induced improvement of all the measured parameters
were closely matched between the HT and the NT ( P>0.05).
Training increased T(lim) by 59.7% [164(40) s]. The
value of T(lim) was related to VO(2)4%N and to La(max)
before and after training. Also, the training-induced improvement of T(lim) was related to the concomitant decrease in La(max).
It is concluded that: (1) endurance training including continuous high-intensity
exercises improves T(lim) for exercises performed
at the same relative (higher absolute) work rate after training, (2) intermittent
hypoxic training has no potentiating effect on T(lim) as compared with training
in normoxia, and (3) the intra-individual training-induced improvement of
T(lim) was associated with metabolic alteration in relation to lactate accumulation.
Oxidative
stress in the systemic and cellular responses to intermittent hypoxia.
Prabhakar NR,
Kumar GK.
Department of Physiology and Biophysics,
Patients with chronic intermittent hypoxia (IH) caused by recurrent apneas
have a greatly increased risk for developing hypertension, myocardial infarctions,
and stroke. The purpose of this article is to highlight some of the recent
studies focusing on the mechanisms associated with systemic and cellular effects
of IH in experimental animals and cell culture models. Rats exposed to chronic
IH exhibited elevated blood pressures and increased sympathetic nerve activity,
partly due to enhanced reflexes arising from carotid bodies. Direct recordings
of the carotid body sensory activity showed that chronic IH selectively augmented
hypoxic sensitivity, and induced a novel form of functional plasticity manifested
as sensory long-term facilitation. In cell culture models, prior exposure
to IH resulted in facilitation of hypoxia-induced transmitter release and
activation of several protein kinases. IH caused activation of c-Fos and activator
protein-1 (AP-1) transcription factor and tyrosine hydroxylase, an AP-regulated
downstream gene. For a given duration and intensity of hypoxia, IH was more
potent and caused longer-lasting activation than continuous hypoxia. Scavengers
of reactive oxygen species (ROS) prevented IH-induced systemic and cellular
responses. Inhibition of complex I of the mitochondrial electron transport
chain appears to be one of the sources for IH-induced generation of ROS. The
persistent oxidative stress may contribute to the progression of morbidity
associated with chronic IH caused by recurrent apneas, and antioxidants might
be of considerable therapeutic value in preventing the progression of disease
associated with chronic IH.
Persistent
respiratory changes following intermittent hypoxic stimulation in cats and
human beings.
Morris KF, Gozal D.
Department of Physiology and Biophysics, University of South Florida Medical
Center, 12901 Bruce B Downs Blvd. MDC Box 8, Tampa, FL 33612-4799, USA. kmorris@hsc.usf.edu
Repeated intermittent hypoxia or other stimulation of carotid chemoreceptors
produces a consistent long-term increase in respiratory nerve activity in
vagotomized, artificially ventilated anesthetized or decerebrate animals,
but variable results have been reported in more intact preparations. We sought
additional variables that could be measured to help gain an understanding
of persistent respiratory responses to intermittent hypoxia. The variance
of respiratory phases decreased in 10 of 11 recordings from vagotomized anesthetized
cats during long-term facilitation induced by carotid chemoreceptor stimulation.
The variance of expiratory time was reduced in 10 awake human beings exposed
to repetitive, brief episodes of isocapnic hypoxia (6% O(2)
in N(2), 60s). Respiratory frequency was increased in humans and tidal volume
decreased so that minute ventilation remained unchanged. The results suggest
that there are persistent changes in the output of the respiratory central
pattern generator following intermittent peripheral chemoreceptor stimulation
or hypoxia.
Publication Types:
· Clinical Trial
· Controlled Clinical Trial
[The effect of intermittent
normobaric hypoxia on oxygen metabolism in hypertonic pilots]
[Article in Russian]
Razsolov NA,
Potievskii BG,
Potievskaia VI.
Oxygen tissue metabolism was evaluated in hypertonic pilots in order to draw
up an optimal treatment plan. Oxygen metabolism kinetics was determined with
the help of transcutaneous polarography and the local ischemic extremity test
was applied to measure the O2 utilization efficiency. Breathing mixture of
90% nitrogen and 10% oxygen (GGS-10) was used in therapeutic sessions of intermittent
normobaric hypoxia. Results point to the reduced tissue breathing intensity
and cell functional energy reserve in hypertonic patients. However, O2 metabolism
is much closer to normal in pilots as compared with non-flyers. In pilots,
O2 utilization is more intensive, energy supply of cells is higher, O2 transport
and utilization are well-balanced, and tissue breathing is less reactive to
the hypoxic factor. Dynamic kinetics of O2 metabolism tested post treatment
suggested activation of O2 tissue metabolism in the hypertonic pilots rather
than O2 transport which was stimulated in non-flyers. In addition, by the
end of treatment the pilots were advised to extend the period of breathing
GGS-10 leaving the period of air breathing unchanged. Consequently, the pilots
were more adaptable to hypoxia than the non-flyers and, therefore, improved
O2 tissue metabolism more rapidly.
[Effects of intermittent
normobaric hypoxia training on heart rate variability]
[Article in Chinese]
Xu X, Lu LL, Chen ZH, Liu XX, Li YZ.
Objective: To observe the influences of intermittent normobaric hypoxia (INH)
training on heart rate variability (HRV) under hypoxia. Method: Eight subjects
were trained with INH for 4 weeks (24 d), subjects' HRV level, recorded during
exposure to hypoxia (10% O2) before and after the training, were compared
and analyzed. Result: After the INH training, average of normal to normal
Intervals (R-R), standard deviation of normal to normal Intervals (SDNN),
total power (TP), high frequency (HF) and low frequency (LF) increased significantly
during hypoxia (P<0.05 - P<0.001); normalized low frequency (LFn), normalized
high frequency (HFn) and LF/HF showed no significant change. Conclusion: 1)
INH training can increase subjects' HRV under hypoxia; 2) INH training can
not only be used to increase the tolerance of hypoxia, but it is also good
for increasing astronaut's flying tolerance under special environment.
[Effects of hypoxic acclimatization
on myocardial contents of total protein, malondialdehyde and nitric oxide
in rats]
[Article in Chinese]
Long
CL, Yin ZY, Wang H.
Institute of Toxicology and Pharmacology,
Objective: To study the effects of acute hypoxia and acute hypoxia after intermittent
hypoxic acclimatization on myocardial contents of total protein, malondialdehyde
(MDA) and nitric oxide (NO) in rats. Method: Myocardial contents of total
protein, MDA and NO were investigated in rats after intermittent hypoxic acclimatization
(simulated high altitude 3000 m and 5000 m, 4 h/d, 2 weeks respectively) and
normal rats after they were exposed to hypoxia (simulated high altitude 8000
m) for 4 h. Result: Compared with normal control rats, the myocardial contents
of total protein and NO in acute hypoxic rats were reduced significantly,
and the myocardial content of MDA was increased significantly. After intermittent
hypoxic acclimatization, the myocardial contents of total protein and NO of
rats were significantly higher and the myocardial content of MDA was significantly
lower compared with those in acute hypoxic rats. Conclusion: After intermittent
hypoxic acclimatization, the myocardial contents of total protein and NO of
rats were increased significantly and the content of myocardial MDA was decreased
significantly. This is one of the biochemical mechanisms of hypoxic acclimatization
of the heart.
Effects
of intermittent hypoxic training and detraining on ventilatory chemosensitive
adaptations in endurance athletes.
Katayama K, Sato K, Matsuo H, Ishida K, Mori S, Miyamura M.