2019
05
Application of hypoxicators in the rowers’ training
Neykov S.1ABE, Bachev V.1ADE, Petrov L.2BCD, Alexandrova A.2ACD,
Andonov A.1AB, Kolimechkov S.2,3CD
1
Department of Theory and Methods of Sport Training, Coaches Faculty, National Sports Academy, Sofia, Bulgaria
2
Department of Physiology and Biochemistry, Coaches Faculty, National Sports Academy, Sofia, Bulgaria
Authors’ Contribution: A – Study design; B – Data collection; C – Statistical analysis; D – Manuscript preparation;
E – Funds collection
Abstract
Purpose:
Material:
Results:
Conclusions:
Keywords:
Intermittent altitude exposure leads to improvements in aerobic performance and blood parameters
of athletes. The variety of hypoxic devices and simulated altitude training models requires a detailed
study of their effects to achieve the best results. The aim of this study was to investigate the effect of
a four-week training camp at sea level conditions, combined with normobaric hypoxia, provided by
hypoxicators during the night’s sleep of the athletes.
Sixteen rowers of the Bulgarian national team (17.13±0.83 years old) were divided into a control group
(n=8) and an experimental group (n=8) subjected to hypoxia for a period of four weeks. At the beginning
and end of the training camp, anthropometric and hematological data were measured. A submaximal
test on the Concept II rowing ergometer was performed, and the physical work capacity and anaerobic
threshold were determined.
The results showed: 1) a lack of significant changes in the aerobic performance after training camp, both
within and between groups; 2) at the end of the training camp in the experimental group a statistically
significant increase in hemoglobin concentration (156.25±4.11 vs 162.75±4.11 g/L, p<0.01) and
erythrocyte count (5.26±0.13 vs 5.49±0.10 g/L, p<0.01) was observed.
The encouraging results regarding the higher increase in blood oxygen-carrying capacity in the
experimental group did not lead to an increased working capacity. Further research should be provided in
the search for optimal hypoxic training parameters, allowing not only a rise in hemoglobin concentration,
but also the preservation of blood rheological properties.
aerobic power, hemoglobin, hypoxia training, hypoxicator, rowers.
Introduction1
Sports’ training is a complex process for improving
physical qualities and developing a high level of technical
efficiency. In endurance sports success in performance
is mainly determined by the rate of both oxygen
transportation and oxygen utilization. However, after
several years of training these rates often reach a level
which can be sustained, but not increased [1]. Thus,
a performance improvement of about 1-2% is a great
challenge. One of the most effective ways for further
development of functional capacities is altitude training
[2].
It is well known that the decreased oxygen saturation of
hemoglobin at high altitude causes activation of Hypoxia
Inducible Factor 1 (HIF-1), which targets the activation
of genes encoding erythropoietin (EPO) and the vascular
endothelial growth factor. EPO stimulates red blood cell
production in order to increase hemoglobin saturation and
oxygen delivery. In addition, HIF-1 regulates the genes
encoding the glycolytic enzymes and glucose transporters
[3]. Since hypoxia triggers ergogenic adaptation, it is of
great interest for athletes because it has the potential to
improve their performance. Hypoxic training includes
three models: live high and train high, live low and train
high, and the new trend - live high and train low (LHTL).
Altitude training could be related to some side effects,
such as mountain sickness, pulmonary edema, cardiac
© Neykov S., Bachev V., Petrov L., Alexandrova A., Andonov A.,
Kolimechkov S., 2019
doi:10.15561/18189172.2019.0505
arrhythmias, and immune system dysfunction [4]. Many
of these pathological states could be overcome [5] by
using altitude simulation devices (hypoxicators), since
they allow variations in simulated altitude and in hypoxic
exposure duration. Substantial research has shown that
intermittent altitude exposure via such devices leads
to improvements in aerobic performance, ventilatory
responses, and blood parameters [6] in a relatively short
period of time [7]. Endurance athletes from many sports
use hypoxic masks, tents, or chambers as part of their
training programs. Moreover, hypoxic training is one
of the few legal methods allowed by WADA to enhance
physical endurance. The reduction of costs for traveling
to and staying at high-altitude training sites, as well as
avoidance of increased potential for illness due to chronic
exposure to stress hormones [8, 9], are other benefits of
implementation of this type of training.
The existence of different devices, as well as a variety
of simulated altitude training models, requires the detailed
study of their effects to achieve the best results in training
and competition. Therefore, the aim of this study was to
investigate the effect of four weeks of training camp at sea
level using hypoxicators to provide normobaric hypoxia
during the night’s sleep of the athletes, the LHTL model.
Materials and methods
Participants
Sixteen athletes from the Bulgarian national youth
team in academic rowing of mean age 17.13 ± 0.83 years
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problems of physical
training and sports
with mean height 183.75 ± 4.61 cm and mean weight
77.79 ± 7.42 kg took part in the study. The rowers had
about 4-5 years of training experience. They have been
winners of national junior championships, international
junior rake regattas, and the Balkan championships,
and they have achieved from 6th to 12th at the European
Championships for Adolescents and Youths.
All participants received detailed information about
the objectives and conducting of the study, and signed an
informed consent form in accordance with the Helsinki
Declaration of Human Research.
Study design
The study was conducted over a one-month period
at the team’s training camp at a 600-meter altitude dam.
The rowers were divided into two groups: eight athletes
were subjected to hypoxia during their night-time sleep
(experimental group), and another eight athletes were
selected as a control group. The hypoxia was introduced
by masks, connected to MAG-20 hypoxicators (Mountain
Air Generator 20, Higher Peak, USA) that simulated
1600 m, 2000 m, 2400 m, and 2800 m altitude for a period
of one week each (Figure 1).
The training program during the experiment was the
same for both groups (Table 1). The rowers had three half
days of rest – each Tuesday, Thursday and Sunday.
At the beginning and end of the training camp, the
anthropometric data of the athletes (weight, height, and
body composition) were measured and all participants
performed a single submaximal test on the Concept II
rowing ergometer. The test consisted of four three-minute
exercise bouts separated by 30s rest periods. The starting
workload was 200W, and the subsequent loads increased
by 40W (240, 280 and 320W) - a modification according
to Klusiewicz et al. [10]. At the end of each step, the
heart rate was registered and during the rest periods the
concentration of capillary blood lactate was measured.
The test continued until a heart rate of 170 bpm, as well
as a lactate concentration greater than 4 mmol/L were
reached.
The test was used for determining PWC170 (Physical
Work Capacity) and the anaerobic threshold – intensity of
exercise at which lactate concentration reached 4mmol/L
(AnT-4). The following calculations were made: PWC170
per kilogram of body weight (PWC170/BW), heart rate
at AnT-4 (HRAnT-4), and AnT-4 per kilogram of body
weight (AnT-4/BW). The absolute and relative maximum
oxygen consumption (VO2max and VO2max/BW) and
PWC170 were calculated by regression equations [10].
Figure 1. Experimental design. The simulated hypoxic exposure of the experimental group was eight hours every night.
Table 1. Rower’s training program during experimental period
Training session character
Training session content
Part of the total
training volume
A – mixed regime training
– aerobic lactic interval
training
40-60 s work and 120 s rest
in 3-4 series
34-35 %
B - aerobic regime, for
maintaining high level of
endurance
C - aerobic regime, for
maintaining high level
of physical fitness and
emotional recreation
6 х 2 min repeated and
steady rowing at different
distances, or 3 х 4 km rowing
in the same conditions
Non-specific training, such
as cross-country running,
stretching, gymnastics
exercises, and rowing
ergometer training
240
53-55 %
10-12 %
One week microcycle included:
4-5 building training sessions.
Each training session lasted 90100 min.
3-4 maintaining training sessions
for rowing technique. Each
training session lasted 75-90
min.
4-5 general effect training
sessions. Each training session
lasted 30 min.
2019
05
At the beginning and the end of the camp, venous
blood samples were taken from the athletes.
Physical characteristics
Body Weight (BW) was measured within an accuracy
of 0.05 kg, and body composition was evaluated using the
bioelectrical impedance method (Tanita 418, Japan). Body
Height (BH) was measured to the nearest 0.5 cm using
a stadiometer. Body Mass Index (BMI) was calculated
as BW (kg) divided by BH (m) squared. Hear rate was
registered by the Polar H7 heart rate sensor (USA).
Biochemical analyses
Lactate concentration was measured in peripheral
blood by using Lactate Pro 2, Japan.
Venous blood samples were taken by authorized
medical staff, and were analyzed in a clinical laboratory
for the following indicators: hemoglobin concentration,
RBC count, hematocrit level, mean corpuscular volume
(MCV), mean corpuscular hemoglobin (MCH), mean
blood corpuscular hemoglobin concentration (MCHC),
white blood cell (WBC) count and differential, platelet
count and other derivatives, consisting of 22 indicators
in total.
Statistical analysis
The data were analyzed statistically by using variance
analysis; the reliability of the differences in the average
values of the indicators was determined by Student’s
t-test for dependent and independent samples by SPSS
statistical software (SPSS for Windows, version 16.0,
2008, SPSS Inc., Chicago, USA).
Results
Table 2 presents the basic anthropometric data of the
athletes from the control and experimental groups. The
average age of the rowers in the experimental group was
17.50 ± 0.58 years, while that in the control group was
16.75 ± 0.96 years. Average weight of the control group
was 79.48 ± 8.22 kg and of the experimental group 76.10
± 7.29 kg. The average stature of the control group was
183.63 ± 5.15 cm and of the experimental group 183.88 ±
4.80 cm. There were no statistically significant differences
between these parameters, although some of the indexes
of the rowers from the control group were higher than
those of the athletes from the experimental group, as
follows: weight was higher by about 3 kg, and mean fat
percentage and relative muscle mass were higher by about
2-3%. Only the average BMI of the control group was
about 1 kg/m2 lower. The anthropometric indicators did
not show statistically significant differences before and
after the one-month training period.
Table 3 presents the results of the submaximal
functional tests performed. There were no significant
changes in the parameters at the beginning and at the end
of the training camp both within and between groups.
A very good repeatability of the achievements of the
tested individuals was observed, leading to a high degree
of correlation between the results of the submaximal
test before and after the training camp. The calculated
correlation coefficients were as follows: for AnT-4 r
= 0.63311, for HRAnT-4 - r = 0.60, for PWC170 and
derivative calculated VO2max r = 0.88, and for VO2max/
BW r = 0.90.
The baseline values of the hematological parameters
did not differ between both groups and were within
normal limits, except for the relative lymphocyte count
(LY%) (Table 4), which was significantly lower in the
control group vs the experimental group (p < 0.05) before
the training camp.
At the end of the training camp the blood indexes of
the control group showed a slight, insignificant increase
as the hemoglobin concentration rose from 151.00 ±
3.92 to 154.5 ± 4.20 g/L. During the period of testing the
erythrocytes and hematocrit levels remained practically
the same, and those of leukocytes increased slightly, albeit
significantly, yet completely within the normal range
(from 6.11 ± 1.04 to 6.75 ± 0.83 g/L, p <0.05) (Table 4).
In the experimental group at the end of the training
camp a statistically significant increase in hemoglobin
concentration (from 156.25 ± 4.11 to 162.75 ± 4.11 g/L,
Table 2. Anthropometric data of the athletes from the control and experimental groups.
Age
(years)
Group
Before
Control Group
Height
(cm)
Weight
(kg)
BMI
(kg/m2)
FAT%
(%)
MM%
(%)
183.63 ± 5.15
79,48 ± 8,22
23,62 ± 2,96
14,90 ± 4,08
42,55 ± 2,31
79,65 ± 8,87
23,66 ± 2,98
12,78 ± 3,68
43,63 ± 2,3
76,10 ± 7,29
22,47 ± 1,29
16,38 ± 6,39
40,48 ± 4,4
76,03 ± 6,74
22,46 ± 1,2
15,25 ± 3,2
40,08 ± 4,00
16.75 ± 0.96
After
Before
Experimental
Group
183.88 ±4.80
17.50 ± 0.58
After
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training and sports
p <0.01) and erythrocyte count (from 5.26 ± 0.13 to 5.49
± 0.10 g/L, p <0.01) were observed, and a slight but
significant decrease in hematocrit levels (from 0.48 ± 0.02
to 0.47 ± 0.02, p <0.05) was registered (Table 4).
At the start and the end of the training camp, in both
groups, statistically significant, reciprocal changes in
mean corpuscular volume (MCV) and mean corpuscular
hemoglobin concentration (MCHC) were observed.
The average volume of erythrocytes measured at the
beginning vs the end of the training period decreased in
both groups, while the average hemoglobin concentration
in erythrocytes increased.
Discussion
The anthropometric indexes of the rowers in this study
are comparable to those of international standard rowers.
For instance, the data for the members of the Croatian
national team (2008 year) of average age 17.6 ± 0.4
Table 3. Submaximal functional test results.
Group
Before
Control Group
After
Before
Experimental
Group
After
PWC170
(W)
274,77
±
59,48
264,57
±
41,35
252,71
±
35,12
PWC/BW
(W/kg)
3,47
±
0,73
3,32
±
0,37
3,31
±
0,21
VO2max
(l/min)
5,30
±
0,45
5,22
±
0,31
5,13
±
0,27
VO2max/BW
(ml/kg/min)
67,14
±
7,7
66,01
±
5,68
67,70
±
3,62
ANT
(W)
303,24
±
13,87
306,77
±
38,84
288,08
±
20,63
ANT-4/BW
(W/kg)
3,84
±
0,33
3,85
±
0,25
3,8
±
0,27
HRANT-4
(bpm)
180,71
±
16,12
184,75
±
5,69
180,23
±
7,43
253,56
±
43,57
3,32
±
0,34
5,14
±
0,33
67,75
±
2,8
274,02
±
15,65
3,62
±
0,23
178,05
±
12,39
Table 4. Results of the hematological analyses of the rowers from the control and experimental group at the beginning
and the end of the test period.
RBC
(T/L)
Hgb
(g/L)
Hct
MCV
(fL)
MCHC
(g/L)
WBC
(G/L)
5,03
±
0,30
151,00
±
3,92
0,47
±
0,01
93,55
±
6,14
321,8
±
10,21
6,11
±
1,04
5,14
±
0,21
154,5
±
4,20
0,45
±
0,01
Before
5,26
±
0,13
156,25
±
4,11
0,48
±
0,02
87,5
±
5,82
cb***
91,98
±
1,9
344,8
±
10,72
cb***
325,0
±
6,98
6,75
±
0,83
cb*
5,76
±
0,93
After
5,49
±
0,10
eb**
ca*
162,75
±
4,11
eb**
ca*
0,47
±
0,02
eb*
85,33
±
1,65
eb***
347,5
±
3,42
eb**
6,58
±
1,94
Group
Before
Control Group
After
Experimental Group
LY%
(%)
36,75
±
3,74
eb*
37,05
±
8,50
LY#
Plt
(G/L) G/L
45,73
±
5,71
46,1
±
6,32
2.27
±
0.61
212,0
±
32.83
2.54
±
0.91
232,0
±
25.39
2.6
±
0.33
204,0
±
34.01
2.94
±
0.45
207.2
±
33.56
e – experimental group, c – control group, b – before, a – after, * - p <0.05, ** - p <0.01, *** - p <0.001. Example: eb**
- statistically significant vs experimental group at p < 0.01, before training camp.
242
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years (n=18) showed an average body weight of 86.1 ±
4.1 kg and height average 188.9 ± 3.6 cm. Similar data
were reported in the large anthropometric study of 383
(89%) rowers in the 1997 World Rowing Championship,
Hazewinkel, Belgium, where the non-finalists had an
average weight of 80.6 ± 5.0 kg and an average height
of 186.3 ± 6.1 cm, and the finalists had an average
weight of 84.8 ± 7.1 kg and an average height of 189.3
± 5.0 cm, with an average age of 17.8 ± 0.7 years for all
individuals tested [11]. Using the percentile tables of the
latter study, the data of the rowers tested in this research
can be evaluated as follows: the height in both groups,
about 183 cm, corresponded to P25; the average weight
of the control group of 79.48 ± 8.22 kg corresponded to
P50, and the average weight of the experimental group of
76.10 ± 7.29 kg corresponded to P25.
According to a review of the Italian rowing federation
[12], the percentage body fat of rowers is very low, with
average values of 11.55 ± 2.31%.
Furthermore, the percentage body fat of the individuals
tested in this study (Table 2) was slightly higher than that
of the Croatian rowing champions and members of the
Croatian national team (2008 year), whose athletes had
12.9 ± 2.1% of body fat [13]. However, the maximum
oxygen consumption of the same group of rowers (62.5 ±
4.7 mL/kg/min), which was determined by performance of
a maximum aerobic test, was a little lower in comparison
to our respondents. The estimated average relative
maximum oxygen consumption of the rowers tested
in our study (about 67 mL/kg/min) was in accordance
with the published norms for field oarsmen [14], which
corresponded to the maximum score - “High”.
In regards to the estimated AnT-4, the data in published
literature are scanty. To the best of our knowledge only
two research papers track the changes in AnT-4 in LHTL
method. In a study of Polish rowers with similar to the
above-mentioned anthropometric data, the average value
for AnT-4 of 307 ± 41W was found [15], which is very
close to our results. However, the heart rate at AnT-4 in
Polish rowers was lower, 164 ± 9 bpm compared to around
180 bpm in our athletes. In the second work, volunteers
were subjected to intermittent hypoxia, and although a
significantly increased power output at the anaerobic
threshold (228 ± 28 W to 239 ± 24 W, p = 0.04) was
observed, there were no significant changes in VO2max
and in the cycling exercise [16].
It should be mentioned that the submaximal test results
obtained before and after the training camp demonstrated
a high correlation. It seems that the application of this
test is a good opportunity for longitudinal tracking of the
functional condition of rowers without disturbing their
training schedule.
The changes in the red blood count during hypoxic
training are logically the most intriguing and therefore the
most studied. In our experiment there were no differences
between the control and the experimental groups at the
beginning of the training camp, except in lymphocyte
counts (LY%). It is probably due to redistribution in
the number of different leukocyte types as the baseline
absolute lymphocyte count (LY #) is practically the same
(Table 4).
When comparing the hematological parameters at the
beginning and at the end of the study a statistically significant
rise in erythrocyte and hemoglobin concentrations in the
experimental group was observed: from 5.26 ± 0.13 to
5.49 ± 0.10 T/L, p <0.01 for erythrocytes and from 156.25
± 4.11 to 162.75 ± 4.11 g/L, p <0.01 for hemoglobin. The
differences in these parameters at the end of the study
between the control and the experimental group were
greater. Similar observations have been reported in a
hypoxic training experiment of elite Nordic skiers, under
the LHTL scheme, exposed to simulated hypoxia for 11
hours a day, in three stages of 6 days at 2500, 3000, and
3500 meters above sea level respectively [17]. In the
quoted study there were no changes in hematological
parameters in the control group, in contrast to the
experimental group, where the hemoglobin concentration
increased from 147 ± 8.0 to 150 ± 4.0 g/L and the red blood
cell count from 4.88 ± 0.43 to 5.08 ± 0.30 T/L. However,
regardless of the improvements in the blood count, no
improvement in functional parameters was observed in
these athletes. The VO2max in the experimental group
decreased, albeit insignificantly from 61.7 ± 4.4 to 59.3 ±
2.0 mL/kg/min [17]. In another study, where two groups
of highly trained athletes were subjected to 8 hours per
night for two consecutive nights a week over 3 weeks
under either short-term normobaric hypoxia (simulating
3636 m altitude) or in normobaric normoxia, there was
no improved aerobic or anaerobic performance, although
short-term normobaric hypoxia exposure increased the
levels of a number of hematological parameters [18]. Our
results also did not show changes in VO2max at the end
of the training camp.
In addition to the blood oxygen-transporting capacity
the rheological properties of the blood should also be
considered. Blood fluidity has been reported previously
to positively correlate with aerobic working capacity,
the performance time until exhaustion, and blood lactate
response [19]. In addition to hemodynamic parameters,
improvements in hemorheological parameters are likely
to aid better performance. Increased blood fluidity may
improve oxygen delivery to muscles during exercise in
well-trained individuals [20].
Among the parameters tested by us at the end of the
study, compared to the beginning, we observed in the
experimental group a slight but significant hematocrit
reduction from 0.48 ± 0.02 to 0.47 ± 0.02, which is
contrary to an increased erythrocyte count (RBC) and
increased hemoglobin, and is probably due to a decrease
in the average volume of erythrocytes (MCV) (Table 4).
These changes in MCV could represent the physiological
principle for maintenance of favorable blood viscosity
[21]. However, a recent study [22] demonstrated that
high MCHC and low MCV had a negative impact on
the deformability of erythrocytes and correlate with
their increased rigidity. In this way the rheological
properties of the blood deteriorate. The lack of progress
in aerobic performance against the improved blood
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training and sports
oxygen-transporting capacity, noted by us and by other
authors [18], may be due to a reciprocal deterioration in
the blood rheological properties associated with MCV
reduction and MCHC increase, and thus, a difficult
passing of erythrocytes through microcirculation. The
negative impact of hypoxia on blood viscosity has
been demonstrated on experimental animals that were
subjected to 5 weeks chronic and intermittent (8 hours per
day) hypoxia [23]. The results suggested that intermittent
hypoxia and continuous hypoxia led to increased whole
blood viscosity that impairs the functions of red blood
cells and promotes platelet aggregation in rats.
Conclusions
Our results suggest that: 1) the submaximal rowing
specific test used by us is suitable for studying the
dynamics of AnT-4 and PWC170 without disturbing
training schedules; 2) one-month training at low altitude,
combined with 8 hours hypoxic application per night, does
not increase the physical fitness performance in rowers
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Acknowledgements
This paper is the equal work of all authors. The authors
declare no conflict of interest.
This study was supported by the National Sports
Academy (NSA № - 681 / 07.04.2015, “Modern aspects
of altitude training in athletes from sports endurance”).
Conflict of interests
The authors declare that there is no conflict of interests.
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Information about the authors:
Neykov S.; http://orcid.org/0000-0002-3336-0454; svilen.neykov@abv.bg; Department of Theory and Methods of Sports
Training, Coaches Faculty, National Sports Academy; National Sports Academy 1700, Sofia, Bulgaria.
Bachev V.; http://orcid.org/0000-0003-0481-2412; batchevv@yahoo.com; Department of Theory and Methods of Sports
Training, Coaches Faculty, National Sports Academy; National Sports Academy 1700, Sofia, Bulgaria.
Petrov L.; http://orcid.org/0000-0003-1209-959X; dr.lubomir.petrov@gmail.com; Department of Physiology and Biochemistry,
National Sports Academy; National Sports Academy 1700, Sofia, Bulgaria.
Alexandrova A.; http://orcid.org/0000-0002-7007-3665; a_alexandrova_bas@yahoo.com; Department of Physiology and
Biochemistry, National Sports Academy; National Sports Academy 1700, Sofia, Bulgaria.
Andonov S.; http://orcid.org/0000-0003-3029-4778; andonov_svetoslav@yahoo.com; Department of Theory and Methods of
Sports Training, Coaches Faculty, National Sports Academy; National Sports Academy 1700, Sofia, Bulgaria.
Kolimechkov S.; (Corresponding author); http://orcid.org/0000-0003-0112-2387; dr.stefan.kolimechkov@gmail.com;
Department of Physiology and Biochemistry, National Sports Academy; National Sports Academy 1700, Sofia, Bulgaria.
Cite this article as:
Neykov S, Bachev V, Petrov L, Alexandrova A, Andonov A, Kolimechkov S. Application of hypoxicators in the rowers’ training.
Pedagogics, psychology, medical-biological problems of physical training and sports, 2019;23(5):239–245.
https://doi.org/10.15561/18189172.2019.0505
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
(http://creativecommons.org/licenses/by/4.0/deed.en).
Received: 23.07.2019
Accepted: 09.09.2019; Published: 17.09.2019
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