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HUMAN MOVEMENT (ISSN 1899-1955)
86
R A FA L HEBI SZ1 , CRISTINA CORTIS2 , PAULINA HEBISZ1 , JACEK BORKOWSKI1 ,
AGNIESZKA JASTRZĘBSKA1
1 Department of Physiology and Biochemistry, Wroclaw University of Health and Sport Sciences, Wroclaw, Poland
2 Department of Human, Society and Health Sciences, University of Cassino and Lazio Meridionale, Cassino, Frosinone, Italy
ABSTRACT
Purpose. This study aimed to assess the impact of four distinct training programs on maximal oxygen uptake (VO2max)
and cardiovascular health markers. The programs included: 1) a polarised training program (POL) incorporating sprint
interval training (SIT), high-intensity interval training (HIIT) with long intervals, and low-intensit y training (LIT); 2) a progra m
focused solely on SIT training; 3) a program focused solely on long interval HIIT training; and 4) a program focused solely
on LIT. The outcomes of interest were VO2max, lectin-like oxidised low-density lipoprotein receptor-1 (LOX-1) expression,
and serum concentration of oxidised low-density lipoprotein (ox-LDL).
Methods. This study enrolled 40 physically active individuals, categorised into four groups. Group POL (n = 10) engaged
in a comprehensive POL training program, while group SIT (n = 10), group HIIT (n = 10), and group LIT (n = 10) participated
in dedicated SIT, HIIT, and LIT training programs, respectively. SIT included 30-second all-out repetitions, HIIT included
3-minute high-intensity repetitions, LIT performed with intensity at the first ventilatory threshold. Throughout five weeks,
participants in all groups underwent three weekly training sessions. Preceding and following the experiment, participants
underwent an incremental test and a VO2max verification test. Additionally, serum concentrations of lectin-like oxidised low-
density lipoprotein receptor-1 (LOX-1) and oxidised low-densit y lipoprotein (ox-LDL) were measured before the incremental test.
Resu lts. Following the conclusion of the experiment, notable mi xed effects were observed. Specifically, statistically significa nt
increases were identified in VO2max, with a 14.2% enhancement in the POL group and a 9.5% improvement in the HIIT
group. Moreover, there were substantial reductions in LOX-1 levels, demonstrating a 51.5% decrease in the POL group and
a 61.1% decrease in the HIIT group.
Conclusions. The findings led to the conclusion that both the POL and long interval HIIT programs were effective in
enhancing VO2max and lowering serum levels of LOX-1 among physically active individuals.
Key words: cardiorespiratory fitness, cardiovascula r health, maximal aerobic power, oxidative stress, maximal oxygen uptake
original paper
DOI: https://doi.org/10.5114/hm/186688
Correspondence address: Paulina Hebisz, Department of Physiology and Biochemistry, Wroclaw University of Health
and Sport Sciences, al. I.J. Paderewskiego 35, 51-612 Wroclaw, Poland, e-mail: paulina.hebisz@awf.wroc.pl;
https://orcid.org/0000-0003-1788-2129
Received: September 18, 2023
Accepted for publication: April 02, 2024
Citation: Hebisz R, Cortis C, Hebisz P, Borkowski J, Jastrzębska A. Effects of polarised, sprint interval, high-intensity interval,
and low-intensity training programs on aerobic fitness and cardiovascular health markers in active individuals. Hum Mov.
2024;25(2):86–96; doi: https://doi.org/10.5114/hm/186688.
© Wroclaw University of Health and Sport Sciences
2024; 25(2): 86 –96
Effects of polarised, sprint interval, high-intensity interval, and low-intensity
training programs on aerobic fitness and cardiovascular health markers in
active individuals
Introduction
Cardiorespiratory fitness has a significant impact
on human life expectancy and strongly determines
the ability to perform aerobic exercise [1]. The gold
standard for exercise assessment of cardiorespiratory
fitness is maximal oxygen uptake (VO2max) [2]. System-
atically performed training can improve VO2max [3].
The available literature compares the effectiveness of
high-intensity interval training (HIIT), low-intensity
training (LIT), and moderate-intensity training (MIT)
(close to the level of lactate threshold or second venti-
latory threshold) in improving cardiorespiratory fitness,
as assessed by VO2max measurement [4]. It has been
shown that HIIT is one of the most effective means of
improving cardiorespiratory function and, in turn,
physical performance [5–7]. Buchheit and Laursen [6]
described four HIIT formats: long interval HIIT, short
interval HIIT, sprint interval training (SIT), and re-
peated sprint training (RST). The formats of HIIT dif-
fer in the intensity and duration of exercise, intensity,
and duration of recovery periods, exercise modality,
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R. Hebisz et al., Training programs and aerobic fitness
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Human Movement, Vol. 25, No 2, 2024
number of repetitions, number of sets, as well as the be-
tween-sets recovery duration and intensity [4, 6, 8].
Some authors assess changes in cardiorespiratory
fitness as a result of a program focused solely on one
form of training: SIT, HIIT or LIT [4, 9, 10]. Others, in
turn, evaluate the impact of training programs incor-
porating several forms of training, with one example
being a polarised training program (POL) [11, 12]. It
is described as a training cycle characterised by po-
larisation of the training intensity and incorporates
low-intensity training as well as high-intensity training
[11, 12]. The volume of low-intensity training sessions
is approximately 80% of the total training volume,
while the high-intensity training is approximately 20%
of the total training volume [11–13]. In polarised train-
ing programs, moderate-intensity training at the level
of the lactate threshold or the second ventilatory thresh-
old (VT2) is not used [7, 13], or these training sessions
account for a small part of the training program (up to
5–10% of the total training volume) [14]. Some authors
showed that a polarised training program induced
greater improvements in aerobic capacity among ath-
letes compared to a program consisting of LIT and MIT
[15, 16] and compared to a program focused solely on
LIT, a program focused solely on MIT, or a program
focused solely on HIIT [12]. The available literature
lacks information on the effects of a polarised training
program consisting of two HIIT formats (long interval
HIIT and SIT) and LIT on cardiorespiratory fitness
among active, but non-athlete individuals.
However, cardiovascular fitness can be compro-
mised, for example, by arteriosclerosis [17]. Arterio-
sclerosis causes narrowing of the lumen of blood ves-
sels, leading to reduced blood flow, resulting in tissue
hypoxia [17, 18]. The development of arteriosclerosis is
associated, among other things, with the oxidation of
low-density lipoproteins (LDL) under oxidative stress,
leading to the formation of the oxidised form of LDL
(ox-LDL) [18, 19]. Then, ox-LDL can be attached, for
example, to the lectin-like oxidised low-density lipo-
protein receptor-1 (LOX-1) within macrophages and
vascular smooth muscle cells, contributing to the for-
mation of foam cells [17, 19]. LOX-1 expression can be
increased by proatherogenic factors [17]. It is believed
that regular physical exercise reduces the risk of arte-
riosclerosis [17]. The individuals characterised by low
VO2max were also characterised by an unfavourable
lipid profile [18]. It has been shown that regular physi-
cal activity decreases the ox-LDL concentration [20].
However, this effect occurred only in the group with
the highest training load, in which moderate- and high-
intensity training was performed at least three times
a week [20]. In turn, in groups in which low- or moder-
ate-intensity training was performed less than three
times a week, there was no decrease in ox-LDL con-
centration [20]. On the other hand, a high training load
may be a factor that increases the risk of coronary ar-
teriosclerosis of the carotid and peripheral arteries [21].
Atherosclerotic plaques were observed in the carotid
and peripheral arteries in a group of marathon runners
aged 45–75 years, performing high- and moderate-in-
tensity training lasting 2–4 hours every day [21, 22].
The literature lacks information on changes in the con-
centration of ox-LDL and LOX-1 in the blood as a result
of performing a polarised training program that com-
bines low- and high-intensity training, therefore, this
became the aim of the presented study.
This study aimed to assess the impact of four dis-
tinct training programs on maximal oxygen uptake
and cardiovascular health markers, such as serum
LOX-1 and ox-LDL concentrations. The programs in-
cluded: 1) a polarised training program (POL) incor-
porating SIT, HIIT with long intervals, and LIT; 2) a pro-
gram focused solely on SIT; 3) a program focused solely
on long interval HIIT; and 4) a program focused solely
on LIT. We hypothesised that POL would produce bet-
ter results in these aspects than programs consisting
of one-format training sessions.
Materials and methods
Participants and study design
Forty physically active individuals took part in the
randomised controlled trial. Each of the participants
undertook recreational physical activity at least twice
a week, for a total time of at least 2–3 hours each week.
The level of physical activity was characterised based
on an interview with the individuals recruited for the
experiment. None of the participants trained as an
athlete or participated in any sports competition. All
participants were non-smokers and did not use drugs.
Participants were divided into four groups: group POL
(n = 10, including 8 men and 2 women), group SIT (n =
10, including 7 men and 3 women), group HIIT (n = 10,
including 7 men and 3 women), and group LIT (n = 10,
including 7 men and 3 women).
The division into groups was made using block ran-
domisation. The participants were divided into four-
person blocks. Each block included participants with
a similar VO2max value. Then, from each block, one
participant was randomly assigned to each training
group. The block randomisation method was intended
to minimise the impact of the participants’ initial
88 Human Movement, Vol. 25, No 2, 2024
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R. Hebisz et al., Training programs and aerobic fitness
physical fitness on the study results. To assess the risk
of bias, the ROB2 software for randomised clinical tri-
als was used. The assessment was carried out in six
areas (randomisation process, timing of identification
or recruitment of participants, deviations of intended
interventions, missing outcome data, measurement of
the outcome, and selection of the reported result). A low
level of risk of biased judgement was obtained in each
area. During the experiment, each group performed
a different training program: group POL, group SIT,
group HIIT, and group LIT. A detailed description of
the training programs can be found below in the train-
ing intervention section.
Immediately before performing laboratory exercise
tests (both before and after the training intervention),
immunoenzymatic tests were performed to detect IgM
and IgG antibodies against the receptor-binding do-
main – the S1 subunit of the S protein of the SARS-
CoV-2 virus (TestLine Clinical Diagnostics, Brno, Czech
Republic) in blood serum samples. The tests were per-
formed before the vaccination campaign began, so the
participants could not have antibodies that appeared
after receiving the vaccination. Positive results of IgM
(above 16 U · ml–1) obtained immediately before the
laboratory exercise tests were treated as a sign of in-
fection and were the reason for exclusion from the
study. Positive results of IgG (above 16 U · ml–1) ob-
tained immediately before the laboratory exercise tests
performed after the training intervention were consid-
ered evidence of infection during the experiment, and
such a participant was excluded from the study. Par-
ticipants excluded from the study were replaced by
newly recruited individuals. Participants were selected
so that the groups consisted of a similar number of
men and women (only in the POL group there was one
woman less than in the other groups). The anthropo-
metric and physiological characteristics of the groups
are shown in Table 1.
Test procedures
Each participant underwent laboratory tests be-
fore and after the experiment, which included a resting
venous blood sample and incremental step test – done
on one day, and a test verifying the level of maximal
oxygen uptake (VO2max verification phase) – done on
a subsequent day. During the 48 hours preceding the
incremental step test, participants did not perform any
exercise or training. Each of the performance tests was
performed in controlled laboratory conditions (tem-
perature 20°C and humidity 45–50%).
Collection and labelling of blood samples
A 5 ml blood sample was collected from a vein at the
elbow bend of each participant. Blood samples were
taken 30 minutes before the incremental test, and at
least 150 minutes after eating a standardised carbohy-
drate meal. Blood samples were collected in Sarstedt
tubes with serous granules (Stamar, Poland) and then
allowed to clot at room temperature for 30 min. The
samples were then centrifuged for 10 min at 3000 rpm
(Eppendorf Centrifuge 5810, Hamburg, Germany). Se-
rum was extracted and then stored in Eppendorf tubes
at –80°C. Following all blood collections, analyses of
the ox-LDL and (LOX-1) concentrations were performed.
After thawing, the samples were analysed by ELISA.
Marking was performed using immunoenzymatic
assay kits for ox-LDL (Wuhan Fine Biotech Co. Ltd.,
Wuhan, China) and LOX-1 (Wuhan Fine Biotech Co.
Ltd., Wuhan, China).
Incremental Step Test
The incremental step test was performed on a Lode
Excalibur Sport cycle ergometer (Lode BV, Groningen,
The Netherla nds). The test consisted of several 3-minute
steps. During each step, the effort was performed with
constant intensity – power. When 3 minutes elapsed,
the power was increased. The starting workload was
50 W for men and 40 W for women and increased every
3 min by 50 W for men and 40 W for women until
volitional exhaustion was reached. For example, for men
50 W 100 W 150 W 200 W, etc., for women
40 W 80 W 120 W 160 W, etc. The duration
of the incremental test may affect the VO2 peak value
[23, 24]. Therefore, different power increments were
used among men and women. This approach reduces
the differences in test duration between men and wom-
en [23, 24]. Time and instantaneous power output were
continually recorded. If the participant was unable
to complete the last 3-minute step, then 0.28 W for
men and 0.22 W for women was subtracted for each
missing second from the current level of power. In this
way, maximal aerobic power (Pmax) was calculated
[16, 25].
During the incremental step test, the respiratory
function was measured using a Quark CPET analyser
(Cosmed, Rome, Italy), which was calibrated before
each test with a reference gas mixture of carbon dioxide
(5%), oxygen (16%), and nitrogen (79%). Tidal volume
was analysed on a breath-by-breath basis to determine
the oxygen uptake (VO2), volume of carbon dioxide ex-
pired (VCO2) and volume of air breathed per minute
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R. Hebisz et al., Training programs and aerobic fitness
89
Human Movement, Vol. 25, No 2, 2024
(VE). The absolute and relative (per kg of body mass)
VO2 peak was calculated based on the data averaged
over 30-s intervals. Based on the respiratory data re-
cords from the incremental test, the first ventilatory
threshold (VT1) was determined at the point preced-
ing the first non-linear increase in volume of air
breathed per minute per volume of oxygen consumed
(VE · VO2–1) without a concomitant increase in volume
of air breathed per minute per volume of carbon dioxide
expired (VE · VCO2–1) equivalent [24]. The second ven-
tilatory threshold (VT2) was at the point preceding
the second non-linear increase in VE · VO2–1 accom-
panied by an increase of VE · VCO2–1 equivalent [24].
The heart rate (HR) was recorded using a Polar H10
sensor (Polar Electro Oy, Tempele, Finland).
VO2max verification phase
The verification phase was preceded by a warm-up
consisting of five 5-minute exercises at an intensity
corresponding to the power achieved at VT1, then
10 min at a power corresponding to half the distance
between the VT1 and the VT2. The warm-up was fol-
lowed by a 10-minute passive break. A load of 110%
Pmax was applied during the verification phase. The
verification phase used the same procedures for meas-
uring respiratory parameters as the incremental step
test. The higher VO2 peak value (of those measured
in the incremental step test and the verification phase)
was defined as the maximal oxygen uptake (VO2ma x).
Using the same principle, maximal values for volume
of air breathed per minute (VEmax) and heart rate
(HRmax) were indicated. Maximal exercise respiratory
rate (RERmax) was determined based on data collect-
ed in an incremental step test.
Training interventions
During the 5-week experiment, participants in each
study group performed 3 training sessions per week,
each training session lasting approx. 45–50 min (1st–2nd
week) and approx. 60–65 min (3rd–5th week). The course
of the experiment is shown in Figure 1. The POL group
performed a polarised training program consisting of
SIT, long interval HIIT, and LIT. The SIT group per-
formed a program focused solely on SIT; the HIIT group
performed a program focused solely on long interval
HIIT; and the LIT group performed a program focused
solely on LIT. All training sessions were performed on
a Monark LT2 cycle ergometer (Monark, Varberg, Swe-
den), and are described below:
(a) Sprint interval training (SIT), consisting of 6–10
repetitions at maximal intensity (all-out effort at a torque
factor of 0.7 Nm · kg–1) lasting 30 s. The training ses-
sion comprised two sets, with 3–5 maximal repetitions
executed in each set. Active rest intervals of 90 sec-
onds separated repetitions, during which participants
engaged in exercise at a power not exceeding 25 W.
Between the sets, a 15-minute active rest period was
implemented, during which exercise was conducted
at the power level reached at VT1, as determined in the
incremental step test. In the initial phase of the experi-
ment (1st–2nd week), all participants completed 6 rep-
etitions during SIT. Subsequently, in the later weeks
of the experiment (3rd–5th week), the participants in-
creased the number of repetitions to 10 during SIT.
(b) High-intensity interval training (HIIT) with long
intervals, consisting of 4–5 bouts lasting 3 min and
performed at an intensity of 90% Pmax (measured
during the incremental test). An active rest of 6 min was
used between these bouts, during which effort was per-
Figure 1. Course of the experiment (VO2max – maximal oxygen uptake)
90 Human Movement, Vol. 25, No 2, 2024
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R. Hebisz et al., Training programs and aerobic fitness
formed with an intensity corresponding to the power
achieved at VT1. During the first part of the experi-
ment (1st–2nd week), all participants performed 4 bouts
during HIIT. In the following weeks of the experiment
(3rd–5th week), the participants performed 5 bouts dur-
ing HIIT.
(c) Low-intensity training (LIT) of 45–60 min, per-
formed with intensity corresponding to the power
achieved at VT1. During the first part of the experi-
ment (1st–2nd week), all participants performed 45 min
of LIT. In the following weeks of the experiment (3rd–5th
week), the participants performed 60 min of LIT.
Statistical analysis
Data were reported as mean, standard deviation, and
confidence intervals. To assess the normality distri-
bution of the data, the Shapiro-Wilk test was used. It
was shown that the distribution of LOX-1 in the after-
experiment measurements was statistically signifi-
cantly different compared with the normal distribu-
tion in the POL, SIT and HIIT groups. In addition, the
distribution of ox-LDL was different compared with
the normal distribution in each group at before and
after experiment measurements. With the other vari-
ables, no statistically significant differences were found
compared to the normal distribution. Analysis of vari-
ance with repeated measures (ANOVA) was used to
identify statistically significant main effects when the
variables were not significantly different compared to
a normal distribution. The Scheffe test was used as
a post-hoc test. Where variables differed from a normal
distribution, Friedman analysis of variance was used
to compare differences between repeated measure-
ments.
Before the experiment, the minimum study group
size was estimated using the G-Power software, as-
suming a minimum very large 2 of 0.35 at p < 0.05 in
the analysis of variance. In this way, it was determined
that the entire study group should be at least 40 peo-
ple. All statistical procedures were conducted using
the Statistica 13 software.
Results
The ANOVA results revealed significant main ef-
fects for repeated measurements and mixed effects for
repeated measurements a nd group concerning VO2max
(F = 26.02, p = 0.000, 2 = 0.426 and F = 9.316, p =
0.000, 2 = 0.444, respectively), VO2max expressed in
l · min–1 (F =2 7.025, p = 0.000, 2 = 0.429 and F = 7. 263,
p = 0.000, 2 = 0.377, respectively), and Pmax (F =
48.133, p = 0.000, 2 = 0.572 and F = 8.615, p = 0.000,
2 = 0.418, respectively). Additionally, a significant
effect of repeated measurements was observed
for VEmax (F = 14.567, p = 0.001, 2 = 0.288). Post-hoc
tests indicated that both VO2max and Pmax increased
after the experiment in the POL and HIIT groups
(Ta ble 2).
Using Friedman analysis of variance, statistically
significant differences in repeated measurements for
LOX-1 were demonstrated, when all study participants
(n = 40) were included in the analysis without division
into groups ( 2 = 5.158, p = 0.023), in the POL group
(2 = 9.000, p = 0.003) and the HIIT group ( 2 = 4.500,
p = 0.034) (Table 3). There were no statistically signifi-
cant differences in repeated measurements for ox-LDL
in any of the study groups (Table 3).
Discussion
The present study assessed the impact of four dis-
tinct training programs on maximal oxygen uptake,
maximal aerobic power and cardiovascular health
markers, such as serum LOX-1 and ox-LDL concen-
trations, in active individuals. The programs included:
1) a polarised training program incorporating SIT, long
interval HIIT, and LIT; 2) a program focused solely
on SIT; 3) a program focused solely on long interval
HIIT; and 4) a program focused solely on LIT. It was
shown that after 5 weeks of training in the POL group
and HIIT group, the maximal oxygen uptake and maxi-
mal aerobic power increased and the LOX-1 concen-
tration decreased. In turn, no statistically significant
changes were observed in the SIT group and LIT group.
In the POL group, Pmax and VO2max increased by
11.1% and 14.2%, respectively, and in the HIIT group by
10.2% and 9.5%, respectively.
The results of the presented study are similar to the
study by Hebisz et al. [16], which compared the im-
pact of two training programs on the aerobic capacity of
cyclists. Hebisz et al. [16] showed that the POL pro-
gram was more effective in improving aerobic capac-
ity (VO2max and Pmax) than a program consisting of
LIT and MIT. Both in the present study and the study
Hebisz et al. [16] POL program incorporating SIT,
long interval HIIT and LIT, the difference between
the POL protocols was the number of training sessions,
which were 5 training sessions per week for 8 weeks
in the study by Hebisz et al. [16] and 3 training sessions
per week for 5 weeks in the presented study.
The training programs applied in the POL and HIIT
groups in the presented study showed high effective-
ness compared to the studies by Helgerud et al. [26]
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Human Movement, Vol. 25, No 2, 2024
Table 2. Physiological parameters measured before and after the experiment
Parameters
Before experiment After experiment
mean ± SD 95%CI mean ± SD 95%CI
lower upper lower upper
POL group
VO2max (ml · min–1 · kg–1) 45.65 ± 7.74 40.12 51.20 52.13 ± 6.84* 47.23 57.02
VO2max (l · min–1) 3.33 ± 0.75 2.80 3.87 3.76 ± 0.81* 3.18 4.33
Pmax (W) 282.4 ± 61.9 238.1 326.7 313.8 ± 60.8* 270.3 357.3
VEmax (l · min–1) 131.8 ± 34.2 107.3 156.3 151.7 ± 34.1 127.3 176.1
RERmax 1.14 ± 0.07 1.09 1.19 1.09 ± 0.02 1.08 1.11
HRmax (bpm) 183.1 ± 15.4 172.1 194.1 186.8 ± 11.3 178.7 194.9
SIT group
VO2max (ml · min–1 · kg–1) 47.68 ± 9.16 41.13 54.23 49.79 ± 8.58 43.66 55.93
VO2max(l · min–1) 3.65 ± 0.61 3.21 4.09 3.86 ± 0.57 3.45 4.27
Pmax (W) 296.0 ± 49.8 260.3 331.7 302.9 ± 47.8 268.7 337.1
VEmax (l · min–1) 145.2 ± 25.3 127.1 163.3 151.5 ± 28.2 131.3 171.8
RERmax 1.13 ± 0.04 1.10 1.16 1.10 ± 0.04 1.08 1.13
HRmax (bpm) 186.3 ± 11.3 178.2 194.4 187.2 ± 10.4 179.8 194.6
HIIT group
VO2max (ml · min–1 · kg–1) 48.72 ± 10.66 41.10 56.35 53.34 ± 10.29* 45.98 60.69
VO2max ( l·mi n –1) 3.35 ± 0.84 2.75 3.96 3.68 ± 0.79 3.11 4.24
Pmax (W) 274.1 ± 70.8 223.4 324.8 302.0 ± 70.1* 251.8 352.2
VEma x ( l·m i n–1) 129.0 ± 39.6 100.7 157.3 138.3 ± 32.3 115.2 161.4
RERmax 1.12 ± 0.03 1.10 1.15 1.11 ± 0.03 1.08 1.13
HRmax (bpm) 188.7 ± 9.1 182.2 195.2 192.2 ± 7.6 186.8 197.6
LIT group
VO2max (ml · min–1 · kg–1) 50.59 ± 7.85 44.98 56.21 49.00 ± 6.97 44.01 53.99
VO2max (l · min–1) 3.62 ± 0.56 3.23 4.02 3.53 ± 0.53 3.15 3.91
Pmax (W) 279.4 ± 44.5 247.6 311.2 282.0 ± 46.7 248.6 315.4
VEmax (l · min–1) 131.1 ± 28.9 110.4 151.8 137.5 ± 22.4 121.4 153.5
RERmax 1.11 ± 0.07 1.06 1.16 1.12 ± 0.07 1.07 1.16
HRmax (bpm) 192.6 ± 9.3 185.9 199.3 191.3 ± 9.1 184.8 197.8
POL – polarised training group, SIT – sprint interval training group, HIIT – high-intensity interval training group,
LIT – low-intensity training group, VO2max – maximal oxygen uptake, Pmax – maximal aerobic power during the
incremental test, Vemax – maximal pulmonary ventilation, RERmax – maximal exercise respiratory rate value,
HRmax – maximal heart rate, mean – arithmetic mean value, CI – lower and upper confidence intervals
* p < 0.05 – significant difference between before and after experiment values
and Astorino et al. [27], in which physically active in-
dividuals also performed at least 3 training sessions
per week. Helgerud et a l. [26] demonstrated that VO2max
increased by 5.5% and 7.2% after 8 weeks of HIIT
training performed by active individuals. Astorino et al.
[27] obtained an increase in VO2max of 6% and 5.5%
after 3 weeks of HIIT training performed by a group of
men and women. Esfarjani and Laursen [28] showed
that VO2max improved by 9.1% after 10 weeks of per-
forming a training program incorporating HIIT and LIT.
Macpherson et al. [29] showed that after 6 weeks
of running training, VO2max increased by 11.5% in
a group performing SIT and by 12.5% in group per-
forming LIT. An increase in VO2max by 12% was ob-
served by Sökmen et al. [30] after 9–10 weeks of SIT
training. Slightly smaller changes in VO2max (4–8%)
were shown by Bailey et al. [31] and Zelt et al. [32]
after 2–4 weeks of SIT training. In a meta-analysis,
Vollaard et al. [33] showed consistent evidence that
SIT increases VO2max. Other studies have shown that
VO2max increased by 4–7% after 6–10 weeks of LIT
training [30, 34]. In the presented study, no statisti-
cally significant changes in VO2max were observed
in the SIT and LIT groups.
The duration of the SIT or LIT training program may
affect the development of aerobic fitness, as no signifi-
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R. Hebisz et al., Training programs and aerobic fitness
cant changes in VO2max were observed when the ex-
periment lasted only two weeks [31, 35]. During longer
duration experiments, 6–10 weeks, a significant im-
provement in aerobic capacity was observed [28–30].
Till et al. [36] suggest that the duration of the training
intervention is important for achieving adaptive physio-
logical changes. Perhaps in the presented study, 3 train-
ing sessions per week performed for 5 weeks among
active individuals was too weak a training stimulus to
improve aerobic capacity in the SIT and LIT groups. In
the POL and HIIT groups, the duration and frequency
of the training sessions were the same, but in these
groups, the total time of high and/or maximal inten-
sity efforts was greater than in the SIT and LIT groups.
Moreover, Høydal [37] suggests that the effect of a train-
ing program on VO2max can be determined by the
baseline level of aerobic capacity. In well-trained or
physically active individuals with a high VO2max, it
is more difficult to further improve the aerobic capacity
in the training process, compared to individuals with
a low VO2max and inactive individuals [37]. In the
study Sökmen et al. [30], in which the greatest changes
in aerobic capacity were obtained (VO2max increased
by 12%), the groups performing a SIT and LIT training
program had a baseline VO2max of approx. 40–42
ml · min–1 · kg–1. In the study by Zelt et al. [32], in which
smaller changes in aerobic capacity were achieved
(VO2max increased by 4%), the baseline VO2max was
at 47–49 ml · min-1 · kg-1. In the presented study, the
baseline VO2max levels in SIT and LIT groups were
47.6 ml · min-1 · kg-1 and 50.5 ml · min–1 · kg–1, respec-
tively. Therefore, it seems conceivable that the replace-
ment of the previous physical activity with SIT or LIT
training with a total volume of approx. 3h per week was
insufficient to significantly improve the aerobic capac-
ity of the participants in the presented study.
In the presented study, no effect of the training pro-
grams used was observed on the changes of serum
ox-LDL. Data in the available literature indicate that
physical activity decreases ox-LDL levels in obese in-
dividuals [38]. Comparative data also indicate that
levels of serum ox-LDL are lower in the athlete popula-
tion (footballers) compared to physically inactive indi-
viduals [39]. However, according to Tiainen et al. [20],
the effects of training in reducing ox-LDL concentra-
tions are dependent on the volume of training per-
formed. Tiainen et al. [20] observed a decrease ox-LDL
concentrations in the group performing moderate- and
high-intensity training sessions three or more times
a week, and no change in ox-LDL in the group perfor m-
ing low- or moderate-intensity training less than three
times a week. Therefore, it is possible that the three
training sessions per week in the presented study were
too weak a stimulus to reduce the serum ox-LDL con-
centrations.
Table 3. LOX-1 and ox-LDL serum concentration before and after the experiment
Parameters
Before experiment After experiment
mean ± SD 95%CI mean ± SD 95%CI
lower upper lower upper
POLgroup
LOX-1 (pg · ml–1) 85.22 ± 55.92 42.23 128.21 41.32 ± 30.39* 17.96 64.69
ox-LDL (ng · ml–1) 23.28 ± 40.91 –8.17 54.73 14.31 ± 27.08 –6.51 35.13
SIT group
LOX-1 (pg · ml–1) 94.47 ± 62.01 50.11 138.83 107.77 ± 113.20 26.79 188.75
ox-LDL (ng · ml–1) 139.23 ± 262.64 –48.65 327.11 140.43 ± 256.54 –43.09 323.95
HIIT group
LOX-1 (pg · ml–1) 119.76 ± 109.56 35.54 203.97 46.61 ± 45.78* 11.42 81.80
ox-LDL (ng · ml–1) 88.29 ± 191.24 –58.71 235.29 114.53 ± 189.51 –31.14 260.21
LIT group
LOX-1 (pg · ml–1) 89.51 ± 46.39 56.33 122.69 104.76 ± 66.83 56.95 152.57
ox-LDL (ng · ml–1) 16.60 ± 24.89 –1.21 34.41 15.13 ± 21.63 –0.34 30.60
POL – polarised training group, SIT – sprint interval training group, HIIT – high-intensity interval training group,
LIT – low-intensity training group, LOX-1 – serum concentration of lectin-like oxidised low-density lipoprotein receptor-1,
ox-LDL – serum concentration oxidised low-density lipoprotein, mean – arithmetic mean value, CI – lower and upper
confidence intervals
* – p < 0.05 – significant difference between before and after experiment values
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Human Movement, Vol. 25, No 2, 2024
Simultaneously, the results of the presented study
showed that the POL and long interval HIIT programs
were effective in reducing the serum LOX-1 concen-
trations, while no such effect was obtained after per-
forming the SIT or LIT program. In the presented study,
the expression of LOX-1 was not determined, only the
concentration of its fragments dissolved in serum. Sci-
entific research has analysed the expression and/or
concentration of LOX-1 [40]. Assessing serum LOX-1
concentrations can be used to predict the risk of dan-
gerous circulatory events, i.e., myocardial infarction
or haemorrhagic stroke [41]. Hong et al. [19] suggested
that strong shear stress associated with laminar flow
occurs during exercise, which contributes to reduced
LOX-1 expression. Shear stress is also thought to in-
crease the release of platelet-derived microvesicles,
which can stimulate angiogenesis [42]. The magnitude
of the shear rate depends on the intensity of the exer-
cises [42, 43]. Thijssen et al. [43] showed that the shear
rate increases with the increasing exercise intensity.
In the presented study, the POL and long interval HIIT
programs were characterised by a higher total time of
efforts performed at high intensity compared to the SIT
and LIT programs. Referring to Thijssen et al. [43], it
can be assumed that the shear stress stimulus may
have exerted a stronger effect during the training per-
formed by the POL and HIIT groups compared to the
SIT and LIT groups. Perhaps, this allowed the POL and
HIIT groups to experience changes in LOX-1 expres-
sion and thus a decrease in serum LOX-1 concentra-
tion [19].
Moreover, as reported by Gurd et al. [44] perform-
ing HIIT training affects increases in sirtuin 1 (SIRT1)
activity and SIRT1 concentrations in skeletal muscle.
It is believed that SIRT1 influences adaptation in skel-
etal muscle’s aerobic potential and may affect the reg-
ulation of LOX-1 activity [45]. Therefore, it is possible
that the training programs used in the POL and long
interval HIIT groups may have been effective in re-
ducing the serum LOX-1 concentrations and in devel-
oping the VO2max and Pmax by affecting SIRT1 ac-
tivity. In addition to changes in SIRT1 activity and
concentrations, training programs containing HIIT
efforts can decrease the activity of C-reactive protein
and interleukins [46]. C-reactive protein and inter-
leukin-18 affect the increased release of LOX-1 from
macrophages into the blood [47]. Therefore, the POL
and long interval HIIT programs may have influenced
the reduction of serum LOX-1 concentrations through
possible effects on lower pro-inf lammatory protein
ac t ivit y.
Limitations
A limitation of the presented study is the partici-
pation of women in the training groups. The impact of
women’s participation on study results was minimised
by using block randomisation. Women were assigned
evenly to each group because when divided into blocks,
they were placed in the blocks with the lowest VO2max.
Another limitation of the presented study is that the
oxidising factors, antioxidant factors, and inf lamma-
tory markers were not determined. Such markings
could contribute to a better understanding of the re-
sults obtained. Therefore, further research is needed
to determine changes in additional markers during the
training process.
Conclusions
POL and long interval HIIT programs were effec-
tive in improving aerobic fitness in physically active
individuals. Moreover, a reduction in serum LOX-1
concentrations was observed after completing the POL
and long interval HIIT programs.
Practical application: for active individuals, we rec-
ommend choosing a polarised training program or
a training program that includes long interval HIIT to
improve cardiorespiratory fitness. POL and long in-
terval HIIT programs are characterised by higher ef-
fectiveness in improving VO2max compared to pro-
grams that include SIT or LIT.
Ethical approval
The research related to human use has complied
with all the relevant national regulations and institu-
tional policies, has followed the tenets of the Declara-
tion of Helsinki, and has been approved by the Wro-
claw University of Health and Sport Sciences (approval
No.: 39/2019; date of approval: 26 November 2019).
Informed consent
Written informed consent was obtained from all
participants after the study details, procedures, and
benefits and risks were explained.
Conflict of interest
The authors state no conflict of interest.
Disclosure statement
No author has any financial interest or received any
financial benefit from this research.
94 Human Movement, Vol. 25, No 2, 2024
HUM AN MOVEMENT
R. Hebisz et al., Training programs and aerobic fitness
Funding
This research was supported by the Wroclaw Uni-
versity of Health and Sport Sciences under grant num-
ber PN/BK/2020/07.
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