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Abstract Background Individuals with arterial hypertension often have an autonomic nervous system (ANS) imbalance with predominance of sympathetic ANS. This predominance can lead to injury of several organs affecting its functioning. There is evidence that performing high intensity resistance training (RT) with heavier loads and a lower number of repetitions results in lower cardiovascular stress when compared with lighter loads and a higher number of repetitions. However, the effects of different protocols of RT in autonomic modulation are not known. Therefore, the aim of the study was to analyze and compare the effects of different protocols of high intensity of effort RT on autonomic cardiac modulation of hypertensive women. Methods A randomized crossover design clinical trial was conducted with 15 postmenopausal hypertensive women who underwent a control session and two high intensity RT protocols involving 6 and 15 repetition maximum (RM). Heart rate variability (HRV), systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and double product (DP) were collected pre, immediately post, 1 h post, and 24 h post each protocol. Repeated-measures ANOVA were used. Results SBP was higher for 6RM than control immediately after session (p
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Vale et al. J Transl Med (2018) 16:240
https://doi.org/10.1186/s12967-018-1615-3
RESEARCH
Acute effects of different resistance
training loads on cardiac autonomic modulation
in hypertensive postmenopausal women
Arthur F. Vale1, Juliana A. Carneiro1,2, Paulo C. V. Jardim1,3, Thiago V. Jardim1,3, James Steele4,5, James P. Fisher4
and Paulo Gentil1,2*
Abstract
Background: Individuals with arterial hypertension often have an autonomic nervous system (ANS) imbalance with
predominance of sympathetic ANS. This predominance can lead to injury of several organs affecting its functioning.
There is evidence that performing high intensity resistance training (RT) with heavier loads and a lower number of
repetitions results in lower cardiovascular stress when compared with lighter loads and a higher number of repeti-
tions. However, the effects of different protocols of RT in autonomic modulation are not known. Therefore, the aim of
the study was to analyze and compare the effects of different protocols of high intensity of effort RT on autonomic
cardiac modulation of hypertensive women.
Methods: A randomized crossover design clinical trial was conducted with 15 postmenopausal hypertensive women
who underwent a control session and two high intensity RT protocols involving 6 and 15 repetition maximum (RM).
Heart rate variability (HRV), systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and double
product (DP) were collected pre, immediately post, 1 h post, and 24 h post each protocol. Repeated-measures ANOVA
were used.
Results: SBP was higher for 6RM than control immediately after session (p < 0.05). There were no differences for DBP
among protocols (p 0.05). HR was higher for 15RM than 6RM and control immediately after and 1 h after session
(p 0.05). DP values for 15RM were significantly higher than 6RM and control immediately after the session and
remained higher than control 1 h after session (p 0.05). The indices that compose HRV (rMSSD) were lower after
15RM than 6RM and control (p 0.05). The parameters of parasympathetic activity (HF) were decreased and sym-
pathetic (LF) activity was increased for 15RM when compared to the 6RM and control session immediately after the
exercise session (p 0.05).
Conclusion: Performing high intensity RT with lower loads and a higher number of repetitions seems to promote
acute increases in sympathetic ANS activity, which may be related to cardiovascular stress. On the other hand, heavier
load and lower repetition RT did not significantly impact upon autonomic modulation when compared to a control
session.
Keywords: Heart rate variability, Resistance training, Hypertension, Autonomic modulation
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Open Access
Journal of
Translational Medicine
*Correspondence: paulogentil@hotmail.com
2 Faculdade de Educação Física e Dança, Universidade Federal de Goiás,
Campus Samambaia, Avenida Esperança S\N, Caixa Postal 131 Goiânia,
Goiás, Brazil
Full list of author information is available at the end of the article
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Vale et al. J Transl Med (2018) 16:240
Background
Arterial hypertension (AH) is a multifactorial clinical
condition characterized by elevated and sustained blood
pressure (BP) levels reaching approximately 46% of the
US population over 20years [1]. AH is one of the most
important public health problems and is considered one
of the main risk factors for cardiovascular diseases [2, 3].
e autonomic nervous system (ANS) has an impor-
tant role in regulating physiological processes both in
normal and pathological conditions [4, 5]. Individuals
with AH typically have an ANS imbalance with greater
performance and predominance of sympathetic ANS
[68]. In women, this sympathetic predominance is more
pronounced with age, possibly as a result of the decrease
in estrogen production, especially in the postmenopausal
period, which favors the occurrence of AH [9, 10].
Among the techniques used to evaluate ANS activity,
heart rate variability (HRV) is a simple and noninvasive
measure of autonomic impulses, representing one of the
most promising quantitative markers of autonomic mod-
ulation. In general, HRV describes the oscillations of the
intervals between beats (R–R intervals) that are related to
the influence of the ANS on the sinus node [4, 11, 12].
Recent studies showed that resistance training (RT) may
promote positive adaptations in the ANS with a conse-
quent increase in HRV as well as a chronic increase in
muscle strength and a decrease in BP [1316].
Whilst RT is considered effective in positively modulat-
ing the ANS, there is a shortage of studies evaluating the
impact of different RT protocols on ANS. Understanding
these responses would provide guidance for the most effi-
cacious RT prescription for improvement in cardiovascu-
lar adaptation while decreasing other cardiovascular risk
factors, particularly in populations such as those with AH
who it may be advisable to avoid high levels of acute car-
diovascular stress. erefore, the aim of the study was to
analyze and compare the effects of different protocols of
high intensity of effort RT on hemodynamic parameters
and autonomic cardiac modulation of postmenopausal
hypertensive women.
Methods
Experimental approach to the problem
A randomized crossover study was conducted to com-
pare cardiac autonomic modulation and other hemo-
dynamic parameters in hypertensive women, aged
45–69years. Tests were performed before, immediately
after, 1 and 24h after different protocols of resistance
training with high intensity of effort. e study involved
the comparison of three conditions: control, resistance
training with lighter loads and higher number of rep-
etitions (15 repetitions maximum, 15RM) and resistance
training with heavier loads and a lower number of repeti-
tions (six repetitions maximum, 6RM). e selection of
participants was performed through the analysis of medi-
cal records at the University Hospital where preliminary
data were obtained from the candidates for study par-
ticipation. During the first contact via telephone, it was
verified if the participants filled the participation criteria
and the participants were invited to an initial visit for
presentation, clarifications regarding the methodological
procedures and any other doubts that could exist about
the progress of the research. e study was approved by
the Institutional Research Ethics Committee (Protocol
1,641,089).
Participants
e sample consisted of 15 hypertensive and postmeno-
pausal women, who were regularly enrolled in Univer-
sity Hospital care and who accepted to participate in
the study. Exclusion criteria involved: current smoker or
user of tobacco products; chronic alcoholism; body mass
index (BMI) exceeding 35kg/m2; hormone replacement
therapy; beta-blocker use; use of anti-depressive and/
or anxiolytic drugs; recent cardiovascular event such
as acute myocardial infarction, stroke or heart failure
( 3months); diabetes; heart failure and/or renal failure;
musculoskeletal, untreated joint disease, or other inca-
pacitating disease that could prevent the performance of
the protocols. e drugs used to control AH were: diu-
retics (14 participants), angiotensin-converting enzyme
inhibitors (7 participants) and angiotensin II receptor
blockers (9 participants). Patients using any class of beta-
blockers was excluded because it’s the only drug for AH
control that interference on ANS responses in the differ-
ent protocols [17, 18].
Anthropometric measures
All anthropometric measures were performed using the
World Health Organization standardization [19]. Body
mass was measured using a portable electronic scale with
a capacity of up to 200kg and with a variation of 0.1kg
(OMRON HBF-214; OMRON Heath Care, Inc, Illinois,
USA, 2013). e measurement was performed with the
patient positioned in the center of the platform, without
support and without making movements, in orthostatic
posture, with arms hanging vertical alongside the body.
Height was measured using a portable stadiometer with a
variation of 0.1cm (Seca Stadiometer; Seca GmBH & Co,
Hamburg, Germany). e participants were instructed
to stand barefoot, in an upright position, with their legs
extended, feet parallel and heels together aligned with the
door. BMI was calculated as the ratio between mass and
the square of the participant’s height (kg/m2).
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Vale et al. J Transl Med (2018) 16:240
Strength testing
Initial familiarization sessions were performed in order
to adapt the participants to the practice and execution of
the RT exercises. e exercises used were bench press,
lat pull down and 45 ̊ leg press. e participants were
individually supervised by at least two researchers on
the correct execution of each exercise. During the famil-
iarization session, each participant performed three sets
of 12–15 repetitions with the minimum possible load in
each exercise as warm-up. After 3-day intervals, the par-
ticipants returned to University Hospital to perform the
repetition maximum tests. e 15RM test started with
a warm-up of 12 repetitions at a self-selected comfort-
able load. After warm-up, the participants performed
up to five attempts with progressive load increases until
the participant could not complete the 16th repetition
for each of the proposed exercises. e participants were
allowed to rest 5min between each attempt. Following a
period of at least 3days each participant returned to the
University Hospital for the 6RM test. e test started
with a warm-up of 12 repetitions at a comfortable load.
After the warm-up period, up to five attempts with pro-
gressive load increase were performed until the partici-
pant could not complete the 7th repetition for each of
the proposed exercises. Five minutes of rest were allowed
between each attempt.
Experimental protocol
After determination of the loads of 6RM and 15RM,
the participants performed three different experimen-
tal protocols: a control session, a RT session with 6RM,
and a RT session with 15RM. e order of execution of
the sessions was performed randomly by lot. A period
of 3days was given between each session. e protocols
were performed at the same time of day (8–10 am) and
in a room with controlled temperature (22°C), in order
to avoid the influence of the circadian cycle and external
conditions. e participants were instructed to fast for
8h, to avoid consumption of alcohol and stimulants (cof-
fee, teas, soft drinks, etc.) 24h before each test session, to
not perform strenuous physical activities 48h previous to
the tests and to follow similar routines for all sessions. A
food record was given to each participant to record the
time, quantities and preparation of each food consumed
the day before the first test. en they were oriented
to follow the same pattern in the days before the other
sessions.
Upon arrival at the University Hospital the partici-
pants were referred to the clinical research laboratory
and were advised to remain in the supine position for
10min. After this period, systolic blood pressure (SBP)
and diastolic blood pressure (DBP) were measured using
an oscillometric device (OMRON, model HEM-705CP;
OMRON Heath Care, Inc, Illinois, USA). Heart Rate
(HR) and HRV were collected using a heart rate moni-
tor (Polar® V800, Electro Oi, Finland) using consecu-
tive heart rate intervals (RR interval) for 10min. During
this period, the participants were oriented to remain in
the supine position, avoid any movement, remain silent,
do not sleep and maintain spontaneous breathing. After
resting measures, participants were given 30g of malto-
dextrin diluted in 300mL of potable water.
e participants assigned to the sessions of 6RM or
15RM performed the three exercises already mentioned
(lat pulldown, barbell bench press and 45° leg press) in
three sets of 6RM or 15RM depending on the protocol
chosen for the day. e exercises were selected following
a minimal dose approach, based on multi-joint exercises
[20, 21]. Before each session, 10 repetitions were per-
formed at 30% of the 6RM load in each exercise as warm
up. e participants were oriented to training to momen-
tary concentric failure, as previously defined to control
effort between conditions [22]. During training, the loads
were adjusted between each set to allow momentary con-
centric failure to occur in the required repetition range
(6 or 15RM). e participants were advised to perform
the exercises with a controlled repetition duration, taking
2–3s for each phase of movement and no pauses between
muscle actions. e rest intervals between sets and exer-
cises lasted for 2 min. Immediately after the training
sessions, HRV, SBP, DBP and double product (DP) were
collected. Two other measures were performed: 1 and
24h after the session, always following the methodology
adopted in the initial resting data collection. During the
control session the participants followed the same proce-
dures, but substituted the RT session for 20min of rest in
the laboratory. e time was stipulated according to the
average duration of the RT sessions.
Heart rate variability analysis
After completion of three test sessions, data obtained
from each participant was transferred from the heart
rate monitor through a transmission cable supplied
by the device. Data processing and analysis were per-
formed using Kubios HRV 3.0.2 software (© Kubios Oy,
Finland). Artifacts such as peaks or discrepant intervals
were manually extracted to correct possible errors in
the values analyzed. e parts of greater stability of the
signal were selected for the analyzes, which included at
least 256 consecutive beats [4]. e analyzes were made
from linear time domain models: rMSSD (the square root
of the mean squared differences of successive R–R inter-
vals), and in the frequency domain, through the spectral
analysis: low frequency components (LF) being repre-
sentative of the sympathetic component of the system,
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Vale et al. J Transl Med (2018) 16:240
high frequency (HF) being representative of the parasym-
pathetic component of the system and the ratio LF/HF
representing the sympatho-vagal balance. e HRV was
also analyzed by nonlinear models from the Approximate
Entropy (ApEn) analysis, which enabled the quantifica-
tion of the sympathetic and parasympathetic compo-
nents of the autonomic modulation of the heart rate.
Data analysis
Data are presented as mean ± standard deviation. e
values for the HRV, SBP, DBP and DP before and after the
three experimental sessions were compared by repeated
measures ANOVA with a 3 × 4 (protocol × time). If
necessary, multiple comparisons with confidence adjust-
ment by the Bonferroni procedure were used as post hoc
analyses. e analyses were performed with IBM SPSS
Statistics 21 software (SPSS Inc., Chicago, Illinois, USA).
e main factors were the protocol (control, 6RM and
15RM) and the time (rest, after the session, 1h after and
24h after). e alpha value of p 0.05 was considered
significant.
Results
All participants completed the three protocols. e char-
acteristics of the participants are presented in Table1.
According to the results of the randomization by lot,
three women performed the control session first, nine of
the 6RM session, and three the15RM session. e vol-
ume of work performed (sets × repetitions × load) in the
different protocols are present in Table2.
Blood pressure
e SBP and DBP data before and after the different
RT protocols (control, 6RM and 15RM) are described
in Table 3. Rest values were similar for all protocols
(p 0.05). Compared with the resting values, there was
an increase in SBP for the 6RM protocol immediately
Table 1 Characteristics of subjects
SD standard deviation
Variables Mean ± SD
Age (years) 57.73 ± 6.11
Body mass (kg) 65.77 ± 10.37
Heigth (m) 1.56 ± 0.08
Body mass index (kg/m2) 26.90 ± 3.74
Table 2 Work performed in different exercise protocols
Values expressed as mean ± standard deviation. Work calculated as sets × repetition × load
Groups Bench press Pull down Leg press Total session work
6RM 305.33 ± 39.53 534.36 ± 98.29 2008 ± 406.38 2847.70 ± 508.67
15RM 535 ± 59.54 1037.66 ± 231.24 3743.53 ± 711.83 5316.20 ± 837.87
Table 3 Cardiovascular parameters at rest, immediately after, 1 h after and 24 h after the resistance training protocols
Values expressed as mean ± standard deviation
SBP systolic blood pressure, DBP diastolic blood pressure, HR heart rate, DP double product
* Significantly different from pre-intervention (p 0.05). Significantly different from the control session (p 0.05). Significantly different from the 6RM session
(p 0.05)
Variables Groups Rest After 1 h 24 h
SBP (mmHg) Control 132.26 ± 17.92 131.26 ± 17.48 133.73 ± 18.39 127.20 ± 14.30
6RM 128.33 ± 17.07 140.33 ± 16.99* 130.86 ± 17.63 129.93 ± 16.07
15RM 130.80 ± 21.22 137.06 ± 14.94 130.00 ± 17.55 128.26 ± 14.41
DBP (mmHg) Control 78.06 ± 7.30 78.26 ± 8.31 79.73 ± 7.76 75.00 ± 8.76
6RM 79.13 ± 9.58 77.60 ± 11.30 77.86 ± 10.82 76.20 ± 8.94
15RM 77.00 ± 7.21 76.20 ± 11.02 77.13 ± 9.21 77.73 ± 9.35
HR (bpm) Control 67.86 ± 6.63 65.98 ± 7.26 64.04 ± 8.26 70.67 ± 8.36
6RM 66.00 ± 6.35† 76.24 ± 9.35† 68.59 ± 8.66 70.49 ± 7.71
15RM 68.70 ± 9.17 85.32 ± 13.21†73.82 ± 11.23†72.06 ± 9.54
DP (mmHg bpm) Control 8987.45 ± 1640.27 8650.36 ± 1477.97* 8544.24 ± 1544.29* 8981.66 ± 1391.14
6RM 8467.05 ± 1422.9010,718.28 ± 2090.03*8972.57 ± 1756.20* 9128.50 ± 1280.63*
15RM 9012.49 ± 2025.25 11,769.10 ± 2783.33*†‡ 9608.14 ± 2212.70†‡ 9211.75 ± 1377.20
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Vale et al. J Transl Med (2018) 16:240
after RT (128 ± 17 vs. 140 ± 17 mmHg; p 0.05). ere
was no significant difference in DBP values immediately
after RT between groups (78 ± 10 vs. 78 ± 11 mmHg,
p 0.05). ere were no differences in blood pressure
between protocols at any other time point.
Heart rate
e HR data before and after the control, 6RM and 15RM
protocols are described in Table3. e results show a sig-
nificantly higher HR after 6RM in comparison to control
immediately after the exercise session: (76.24 ± 9.35bpm
vs 65.98 ± 7.26bpm; p < 0.05). Heart rate was significantly
higher, immediately (85.32 ± 13.21 bpm), and 1 h after
(73.82 ± 11.23 bpm) in the 15RM protocol when com-
pared to control (65.98 ± 7.26 and 6404 ± 8.26bpm); and
6RM (76.24 ± 9.35 and 68.59 ± 8.66).
Double product
e DP data before and after the different protocols (con-
trol, 6RM and 15RM) are described in Table3. e results
of the DP show significant differences in both 6RM:
(10,718.28 ± 2090.03) and 15RM (11,769.10 ± 2783.33)
immediately after the session in comparison to the con-
trol (8650.36 ± 1477.97); p < 0.05. e values for 15RM
were significantly higher than both 6RM and control
immediately after the session and 1 h after the ses-
sion (p < 0.05). Within groups comparison revealed that
there was a significant difference for groups 6RM and
15RM between baseline and immediately after exercise
(p < 0.05).
Heart rate variability
e HRV indices are described in Table4 and in Figs.1,
2 and 3. Rest values were similar for all protocols in all
variables (p 0.05). e 15RM protocol resulted in sig-
nificantly lower values of rMSSD index immediately after
the exercise session when compared to the 6RM and con-
trol protocols (p < 0.05). For the LF index there were no
significant differences between the protocols of 6RM and
control, however the 15RM protocol resulted in signifi-
cantly higher values compared to control 1h after session
and to 6RM immediately after session (p < 0.05). In the
HF index there was a contrary response; 15RM protocol
resulted in significantly lower values when compared to
the group control and 6RM (p < 0.05). e measurements
of the LF/HF ratio showed a significant increase in the
values for the 15RM protocol in relation to the others
immediately after the session (p < 0.05). Within groups
comparison revealed that there was a significant differ-
ence in the LF and HF for 15RM protocol immediately
after exercise when compared to baseline (p < 0.05).
Discussion
e results of the present study suggest that the perfor-
mance of a session of high intensity of effort RT using
lighter loads and a higher number of repetitions (15RM)
Table 4 Linear and non-linear parameters of the heart rate variability at rest, immediately after, 1 h after and 24 h
after the resistance training protocols
Values expressed as mean ± standard deviation. rMSSD square root of the square mean of the differences between the adjacent normal RR intervals, expressed in
milliseconds, high frequency HF, expressed in standard units, LF low frequency, expressed in normalized units, LF/HF ratio high/low frequency, Ap En approximate
Entropy
* Significantly different from pre-intervention (p 0.05). Significantly different from the control session (p 0.05). Significantly different from the 6RM session
(p 0.05)
Variables Groups Rest After 1 h 24 h
rMSSD (ms) Control 21.51 ± 14.26 27.38 ± 18.93* 33.50 ± 22.17* 28.60 ± 29.24
6RM 26.50 ± 16.92 23.12 ± 18.58 22.24 ± 14.88*21.51 ± 14.97*
15RM 21.26 ± 13.05 12.62 ± 16.33*†17.74 ± 11.1624.08 ± 22.91
LF (μn) Control 54.60 ± 18.55 54.82 ± 17.82 48.17 ± 22.15 53.05 ± 26.47
6RM 54.80 ± 22.56 53.82 ± 21.16 54.94 ± 20.11 53.99 ± 19.24
15RM 53.62 ± 22.88 64.74 ± 20.68*60.40 ± 18.0758.78 ± 18.16
HF (μn) Control 45.30 ± 18.61 45.10 ± 17.83 51.60 ± 21.95 46.83 ± 26.40
6RM 45.06 ± 22.62 46.04 ± 21.11 44.94 ± 20.07 45.96 ± 19.21
15RM 46.26 ± 22.82 34.26 ± 21.39*39.45 ± 18.0441.09 ± 18.10
LF/HF Control 1.58 ± 1.20 1.61 ± 1.35 1.49 ± 1.75 2.08 ± 2.27
6RM 1.90 ± 1.72 1.72 ± 1.49 1.60 ± 1.11 1.70 ± 1.72
15RM 2.10 ± 2.76 3.63 ± 3.32†‡ 2.25 ± 2.06 1.90 ± 1.38
ApEn Control 1.14 ± 0.13 1.14 ± 0.15 1.07 ± 0.16 1.11 ± 0.16
6RM 1.14 ± 0.16 1.17 ± 0.23 1.09 ± 0.17 1.16 ± 0.19
15RM 1.16 ± 0.10 1.22 ± 0.20 1.17 ± 0.08†‡ 1.12 ± 0.18
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Vale et al. J Transl Med (2018) 16:240
promoted greater changes in cardiovascular parameters
such as DP and HR, indicating greater cardiovascular
stress, when compared to 6RM and control. On the other
hand, the performance of a high intensity of effort RT
session using heavier loads and fewer repetitions (6RM)
did not change the analyzed cardiovascular parameters
when compared to a control condition. erefore, despite
the two protocols involving high intensity of effort, the
heavier load and the fewer repetition protocol (6RM)
induced lower cardiovascular stress and therefore might
be considered a safer alternative, particularly for those
with AH.
e use of HRV parameters as an indication of car-
diovascular risk is already well established [4]. However,
its relationship with the practice of RT in people with
hypertension is not well understood. Some authors, such
as Lima etal. [23] and Rezk et al. [24], suggest that RT
with heavier loads leads to an increase in sympathetic
activation due to the greater mechanical overload in the
vascular system [25], with consequent decrease in HRV.
However, our results showed that HRV components that
indicate sympathetic activation were greater after RT
performed at lighter loads and a higher repetition range
(15RM). According to our results, immediately after the
15RM protocol, there was an increase in the sympathetic
predominance, as demonstrated by the variables LF and
LF/HF, and a decrease in the parasympathetic predomi-
nance as demonstrated by the rMSSD and HF variables.
Regarding HR and DP, the values for 15RM were greater
than the control and 6RM protocols. On the other hand,
the 6RM protocol did not result in significant changes in
HRV when compared to the control condition. is sug-
gests that load might not influence sympathovagal bal-
ance. Other variables such as total work volume and time
under tension might be related to the sympathetic acti-
vation system and consequent increase in cardiovascular
risk, as previously suggested [23, 24].
Despite the recent evidence presenting RT as an alter-
native for the treatment of several comorbidities, includ-
ing cardiovascular diseases [26, 27], its prescription is
often neglected for patients with AH in many guidelines
[28, 29]. When RT is recommended, the guidance is to
perform it using lighter loads and a higher number of
repetitions, arguing that heavier load RT would not be
safe [3032]. Our results challenge this suggestion, since
after RT using heavier loads, the responses of variables
such as BP and HRV were similar to those at rest. On the
other hand, the practice of RT with lighter loads resulted
in an increase in DP response and a decrease in HRV
immediately after its execution, with these changes per-
sisting even 1h after the session end. Chronic studies are
warranted to analyze the long-term effect of different RT
protocol on cardiovascular function in order to test if this
acute effects translate into chronic results.
RT might have several benefits for patients with
hypertension, such as decreasing resting BP [26, 27, 33]
and increasing muscle strength. As for the last, it has
been previously reported that higher levels of muscle
strength are associated with lower mortality rates both
in the general population [3436], and in people with
AH [37]. erefore, increasing muscle strength might
be an important aim of RT protocols. Considering that
previous studies showed that training with a higher or
lower number of repetitions results in similar strength
gains, when performed to failure [3841], and further,
even microvascular adaptations appear to be similar
whether using heavier or lighter loads [42] the choice
of protocol might be based on other aspects, such as
safety and discomfort. In this regard, previous studies
reported that the practice of RT with lighter loads and
greater number of repetitions generates greater dis-
comfort when compared to RT with heavier loads and
fewer repetitions [39, 43]. Moreover, previous stud-
ies have shown that performing RT with heavier loads
and a lower number of repetitions resulted in smaller
increases in blood pressure and pulse rate during train-
ing when compared with training at lighter loads and
higher number of repetitions [4446]. When combined
Fig. 1 Changes observed in the low frequency values after the
control sessions (triangles), 6RM (lozenges), 15RM (squares), where
the time 1 rest, time 2 after the intervention, time 3 one hour after
the intervention and time 4 twenty hours after the intervention.
*Significantly different from pre-intervention (p 0.05). Significantly
different from the control session (p 0.05). Significantly different
from the 6RM session (p 0.05)
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Page 7 of 9
Vale et al. J Transl Med (2018) 16:240
with these previous findings, our results suggest that
the protocols with a heavier load and lower repetitions
might be recommended to promote increases in muscle
strength and improve health parameters in hyperten-
sive patients while resulting in a reduced cardiovascu-
lar overload.
Conclusion
In conclusion, performing RT with lower loads and a
higher number of repetitions seems to promote acute
increases in sympathetic ANS activity, which may be
related to cardiovascular stress. On the other hand,
heavier load and lower repetition RT did not significantly
impact upon autonomic modulation when compared to
a control session. e study is not without limitations,
such as, the absence of BP and HRV measurement during
the protocols. However, there are reasonable amounts
of evidence comparing different protocols on BP during
exercise, as previously cited. As for HRV, it is not pos-
sible to reliably measure it during exercise by currently
available methods; however, it is reasonable to suggest
that, if it is altered after the interruption of the exercises,
similar dynamics might be seen during exercise. Future
studies should confirm if the present findings are repro-
duced in different populations and also evaluate the long
term effects of different protocols in order to allow a bet-
ter insight into the risk–benefit ratio of such approaches
with respect to health outcomes and adverse events.
Abbreviations
AH: arterial hypertension; BP: blood pressure; ANS: autonomic nervous system;
HRV: heart rate variability; R–R intervals: intervals between beats; RT: resistance
training; RM: repetitions maximum; BMI: body mass index; SPB: systolic blood
pressure; DPB: diastolic blood pressure; HR: heart rate; DP: double product;
rMSSD: square root of the mean squared differences of successive R–R inter-
vals; LF: low frequency; HF: high frequency; LF/HF: ratio low frequency high
frequency; ApEn: approximate entropy.
Authors’ contributions
PG and JAC designed the study. AFV and JAC performed the experiment. AFV,
JAC and PG analysed the data and wrote the manuscript. TVJ, PCVJ, JPF and JS
participated in the design of the study and helped to draft the manuscript. All
authors read and approved the final manuscript.
Author details
1 Programa de Pós Graduação em Ciência da Saúde, Universidade Federal de
Goiás, Goiânia, Brazil. 2 Faculdade de Educação Física e Dança, Universidade
Federal de Goiás, Campus Samambaia, Avenida Esperança S\N, Caixa Postal
131 Goiânia, Goiás, Brazil. 3 Liga de Hipertensão Arterial, Universidade Federal
de Goiás, Goiânia, Brazil. 4 Centre for Health, Exercise, and Sport Science,
School of Sport, Health and Social Sciences, Southampton Solent University,
Southampton, UK. 5 Ukactive Research Institute, London, UK.
Acknowledgements
Not applicable.
Competing interests
The authors declare that they have no competing interests.
Fig. 2 Changes observed in the high frequency values after the
control sessions (triangles), 6RM (lozenges), 15RM (squares), where
the time 1 rest, time 2 after the intervention, time 3 one hour after
the intervention and time 4 twenty hours after the intervention.
*Significantly different from pre-intervention (p 0.05). Significantly
different from the control session (p 0.05). Significantly different
from the 6RM session (p 0.05)
Fig. 3 Changes observed in the ratio low frequency/high frequency
values after the control sessions (triangles), 6RM (lozenges), 15RM
(squares), where the time 1 rest, time 2 after the intervention, time
3 one hour after the intervention and time 4 twenty hours after
the intervention. Significantly different from the control session
(p 0.05). Significantly different from the 6RM session (p 0.05)
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Page 8 of 9
Vale et al. J Transl Med (2018) 16:240
Availability of data and materials
The data of the current study are available at request for scientists wishing to
use them with kind full permission.
Consent for publication
Not applicable.
Ethics approval and consent to participate
All participants read and signed an informed consent document with the
description of the testing procedures. The study was approved by the Insti-
tutional Research Ethics Committee (Protocol 1,641,089), and conformed to
standards for the use of human subjects.
Funding
This research was conducted with authors’ institutional founds.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in pub-
lished maps and institutional affiliations.
Received: 18 July 2018 Accepted: 22 August 2018
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... Exercise helps to lower BP, but patients with arterial hypertension were advised to avoid high levels of acute cardiovascular stress (Vale et al., 2018) because of the sympathetic predominance. Even though aerobic exercise was demonstrated to be able to inhibit sympathetic predominance (Esler, 2011), the effect of resistance exercise on decreasing sympathetic activity has not yet been identified in previous studies (Trevizani et al., 2018). ...
... A transient research has found high-intensity resistance exercise (HE) can lead to a significant increase in systolic blood pressure (SBP) after the exercise, while low-intensity resistance exercise (LE) cannot, but LE can lead to a significant increase in the low frequency/high frequency (LF/ HF) ratio (Vale et al., 2018). Hence, it remains unclear whether high-intensity and low-intensity exercise are unfavorable to patients with hypertension, and the exploration of resistance exercise suitable for hypertensive patients is required to reduce BP and avoid cardiovascular disease risks. ...
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... ,47 Gjovaag et al. (2016) reported greater systolic blood pressure following a moderate load/high rep (15RM) compared to a high load/low rep (4RM) RT protocol in patients with coronary artery disease. Similarly, Vale et al. (2018) observed a greater sympathetic activation in hypertensive women during a 15RM when compared to a 6RM loading scheme. ...
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Objectives: The effects of resistance training (RT) and the potential role of isolated training variables on arterial stiffness (AS) remain inconclusive. This review summarises the current literature examining the acute effects of RT on AS from a distinct perspective, considering ‘intensity of effort’ as an independent loading variable, potentially affecting AS responses to RT. Design: Systematic review Methods: SPORTDiscus, PubMed/MEDLINE, CHINAHL and Google Scholar electronic databases were searched between 2000 and 2022. Randomised control trials, non-randomised or repeated measures comparative studies assessing arterial responses to acute RT protocols measured by pulse wave velocity (PWV) were included. Results: From the 645 articles identified, 16 articles were included. Ten studies reported a significant increase in carotidfemoral PWV (cfPWV) post-exercise (p < 0.05), with increases between 2% and 20.8% reported. Five studies found no significant differences in cfPWV while in one study femoral-dorsalis pedis PWV decreased by 14%. Loading intensities ranging from 30% to 95% of 1RM had an ambiguous effect on AS, although there was a trend towards increased AS following acute RT. Higher intensities of effort and slower repetition velocities appeared to further increase AS. Conclusions: Available evidence shows a trend for increased AS following acute RT. Nonetheless, it remains to be deter mined whether additional RT variables (e.g., intensity of effort, repetition duration) could attenuate or limit increases in AS. Further research, having more RT variables controlled, is needed to draw definite conclusions.
... 9,10 Therefore, a safe intensity of RE, for both acute bout and training programs, should be considered to prevent the risks of cardiovascular complications during or after RE in CHF. 9,10 Although some studies investigated the acute effects of RE on HRV in patients with hypertension 11,12 and coronary artery disease, 13 there is a lack of literature regarding the acute effects of RE on HRV in patients with CHF. Moreover, a wide spectrum of the intensity of RE has been recommended in the previous studies 14, 15 and guidelines have mentioned the intensity from 30% to 80% of the 1-repetition maximum with no clear evidence that which exact intensity is safer and would have more positive impacts. ...
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Background: Although a wide spectrum of resistance exercise intensities was recommended in the guidelines, none of them investigated the acute effects of different intensities of the resistance exercise on cardiac autonomic function in patients with chronic heart failure. This study aimed to investigate the acute effects of the low and high intensities of the resistance exercise on heart rate variability in chronic heart failure. Methods: This randomized controlled trial was performed between October 2019 and December 2020. Fifty-seven patients with chronic heart failure (New York Heart Association class II and class III) underwent hemodynamic, functional capacity, and heart rate variability (time and frequency domains) assessments. They were randomly divided into R1, R2, and control groups. The intervention consisted of performing a short aerobic exercise including 15 minutes of walking at an intensity of 50% reserved heart rate for all 3 groups and additional resistance exercise with the intensity of 50% 1-repetition maximum and 75% 1-repetition maximum for R1 and R2 groups, respectively. Results: The standard deviation of normal to normal intervals and standard deviation of average NN intervals became significantly lower in R2 (P =.031), and both high-frequency power and low-frequency power were significantly higher in R1 (P =.039 and P =.004, respectively) after the intervention. No significant changes were observed in the control group. Between-group changes were not significant for hemodynamics and functional capacity after treatment. The between-group comparison demonstrated a significant increase in root mean square of successive differences of the NN intervals in R1 in comparison to the control (P =.035). Conclusions: These findings indicate that resistance exercise in 50% 1-repetition maximum in comparison to 75% 1-repetition maximum had more favorable effects on the heart rate variability in chronic heart failure.
... 6 This exercise strategy was adopted to maximize the cardiovascular strain, since cardiovascular overload during circuit resistance exercises seems to rely more on the exercise volume (number of sets and repetitions) rather than the applied load. 44 Additionally, we included short bouts of walking between resistance exercises. This helped to increase cardiorespiratory strain because people after stroke expend more energy at a given walking speed than apparently healthy individuals. ...
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Purpose: To investigate whether mixed circuit training (MCT) elicits the recommended exercise intensity and energy expenditure in people after stroke, and to establish the between-day reproducibility for the percentages of heart rate reserve (%HRR), oxygen uptake reserve (%VO2R), and energy expenditure elicited during two bouts of MCT. Methods: Seven people aged 58 (12) yr, who previously had a stroke, performed a cardiopulmonary exercise test, a non-exercise control session, and two bouts of MCT. The MCT included 3 circuits of 10 resistance exercises at 15-repetition maximum intensity, with each set of resistance exercise interspersed with 45-s of walking. Expired gases were collected during the MCT and control session and for 40 min afterward. Control session was necessary to calculate the net energy expenditure associated with each bout of MCT. Results: Mean %VO2R (1st MCT: 51.1%, P = .037; 2nd MCT: 54.0%, P = .009) and %HRR (1st MCT: 66.4%, P = .007; 2nd MCT: 67.9%, P = .010) exceeded the recommended minimum intensity of 40%. Both %VO2R (P = .586 and 0.987, respectively) and %HRR (P = .681 and 0.237, respectively) during the 1st and 2nd bouts of MCT were not significantly different to their corresponding gas exchange threshold values derived from cardiopulmonary exercise testing. Mean net total energy expenditure significantly exceeded the minimum recommend energy expenditure in the 1st (P = .048) and 2nd (P = .023) bouts of MCT. Between-day reproducibility for %HRR, %VO2R, and energy expenditure was excellent (ICC: 0.92-0.97). Conclusions: MCT elicited physiological strain recommended for improving health-related fitness in people after stroke and these responses demonstrated excellent between-day reproducibility.
... S. T SET muscle failure. Regarding this matter, several studies have already observed that repetitions performed close to or until failure cause high acute cardiovascular, metabolic, and neuromuscular stress in older adults, which might be detrimental in this population [76][77][78]. Therefore, as more than three sets and repetitions to failure might decrease the magnitude of the RT effect on muscle strength and size in middle-aged and older adults [16,26], prescribing 1-3 sets without repetitions to failure seems a rational option. ...
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Background Effective manipulation of the acute variables of resistance training is critical to optimizing muscle and functional adaptations in middle-aged and older adults. However, the ideal volume prescription (e.g., number of sets performed per exercise) in middle-aged and older adults remains inconclusive in the literature. Objective The effects of single versus multiple sets per exercise on muscle strength and size, muscle quality, and functional capacity in middle-aged and older adults were compared. Moreover, the effects of single versus multiple sets per exercise on muscular and functional gains were also examined, considering the influence of training duration. Methods Randomized controlled trials and non-randomized controlled trials comparing single versus multiple sets per exercise on muscle strength, muscle size, muscle quality, or functional capacity in middle-aged and older adults (aged ≥ 50 years) in the PubMed/MEDLINE, Web of Science, and Scopus databases (01/09/2021, updated on 15/05/2022) were identified. A random-effects meta-analysis was used. Results Fifteen studies were included (430 participants; 93% women; age 57.9–70.1 years). Multiple sets per exercise produced a greater effect than single sets on lower-limb strength (standardized mean difference [SMD] = 0.29; 95% confidence interval [CI] 0.07–0.51; mean difference [MD] = 1.91 kg; 95% CI 0.50–3.33) and muscle quality (SMD = 0.40; 95% CI 0.05–0.75) gains. There were no differences between single versus multiple sets per exercise for upper-limb strength (SMD = 0.13; 95% CI − 0.14 to 0.40; MD = 0.11 kg; 95% CI − 0.52 to 0.75), muscle size (SMD = 0.15; 95% CI − 0.07 to 0.37), and functional capacity (SMD = 0.01; 95% CI − 0.47 to 0.50) gains. In addition, there were no differences between single versus multiple sets on muscle strength and size gains for training durations ≤ 12 weeks or > 12 weeks. Conclusions Multiple sets per exercise produced greater lower-limb strength and muscle quality gains than single sets in middle-aged and older adults, although the magnitude of the difference was small. In contrast, single sets per exercise were sufficient to improve upper-limb strength, muscle size, and functional capacity in these populations. Despite these findings, researchers should conduct future high-quality, pre-registered, and blinded randomized controlled trials to strengthen the scientific evidence on this topic.
... However, compared to heavier loads, reaching sufficient intensity of effort with lighter loads, such as those selected in the analyzed studies, requires one to complete more repetitions. Sets composed of higher repetition numbers typically lead to greater levels of discomfort [22,60], pain [18], and cardiovascular strain [18,64]. Such byproducts may hinder trainees' motivation to exercise over time or to exercise with sufficient intensity (see footnote d ). ...
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... In order to optimize gains in hypertrophy and maximal strength independent of the lifted loads, it seems as if sufficient intensity of effort is required (i.e., approaching or reaching the point of task failure) [39,48]. However, compared to heavier loads, reaching sufficient intensity of effort with lighter loads requires one to complete more repetitions, which leads to greater levels of discomfort [19,50], pain [16], and cardiovascular strain [16,54]. Such byproducts may hinder trainee's motivation to exercise with sufficient intensity (see footnote e). ...
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Background: Traditionally, the loads in resistance training are prescribed as a percentage of the heaviest load that can be lifted once (i.e., 1 Repetitions Maximum [1RM]). An alternative approach is to allow trainees to self-select training loads. The latter approach has benefits, such as allowing trainees to exercise according to their preferences and negating the need for periodic 1RM tests. However, in order to better understand the utility of the self-selected load prescription approach, there is a need to examine what loads trainees select when given the option to do so. Objective: Examine what loads trainees select in resistance training sessions as a percentage of their 1RM. Design: Scoping review and exploratory meta-analysis. Search and Inclusion: We conducted a systematic literature search with PubMed, Web of Science and Google Scholar in September 2021. We included studies that 1) were published in English in a peer-reviewed journal or as a MSc or PhD thesis; 2) had trainees complete at least one resistance-training session composed of at least one set of one exercise in which they selected the loads; 3) trainees completed a 1RM test for the exercises that they selected the loads for. Eighteen studies were included in our main meta-analysis model with 359 participants. Results: Our main model indicated that on average participants select loads equal to 53% of their 1RM (95% Credible Interval [CI]: 49% to 58%). There was little moderating effect of training experience, age, sex, timing of the 1RM test (before or after the self-selected load RT session), number of sets, number of repetitions, and lower vs. upper body exercises. Participants did tend to select heavier loads when prescribed lower repetitions, and vice versa (logit(yi) = -0.12 [95%CI: -0.21 to -0.04]). Conclusions: Participants selected loads equal to an average of 53% of 1RM across exercises. Such loads are suitable for hypertrophic gains assuming that trainees approach or reach the point of task-failure, but may be too light for optimal strength development (as measured with 1RM). The self-selected loads prescribing approach shows promise given that it bypasses certain limitations of the traditional load prescription approach, but requires thought and further research regarding how and with whom it should be implemented.
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