Physiological responses during the practice of synchronized swimming: A systematic review

Abstract

This study is aimed at analysing the scientific literature related to physiological responses in synchronized swimmers, produced from 2006 to 2016. A systematic review was conducted using electronic databases (Google Scholar, PubMed, SportDiscus, Web Science, Scielo and Scopus) in national and international journals. The articles were selected using the following inclusion criteria: composed samples of synchronized swimmers of both sexes, articles in English, Spanish and Portuguese, published from 2006 to 2016. Ten studies were included. The concentration of the articles and their publication was as follows: Europe (77%) and North America (23%). The protocols used analyse physiological responses in synchronized swimmers athletes during competitions or laboratory tests, lactate measurements, heart rate, rates of perceived exertion, VO2 and lung volume. The subjects of 100% of the studies included in this review were athletes of junior and senior categories who volunteered. Only 03 of the 10 studies have compared the physiological responses in volunteers who were not synchronized swimmers to synchronized swimmer athletes. The studies were conducted using different methodologies, which makes it difficult to compare them, so the standardization of instruments and definitions is essential for the scientific advancement in this field. In addition, it would be interesting to expand the research of these physiological responses in synchronized swimmers using base level or beginners as sample.

Full text

REVIEW ARTICLE
Physiological responses during the practice of
synchronized swimming: a systematic review
K
atia Ponciano
1
, Maria Luiza de Jesus Miranda
1
, Miwako Homma
2
,Jo
~
ao Marcelo Queiroz Miranda
1
, Aylton
J. Figueira J
unior
1
,C

assio De Miranda Meira J
unior
3
and Danilo Sales Bocalini
1
1
Translational Physiology Laboratory, Postgraduation in Physical Education of Sao Judas Tadeu University, Sao Paulo, SP, Brazil,
2
University of Tsukuba,
Institute of Health and Sport Sciences, Japan and
3
School of Arts, Sciences and Humanities, University of Sao Paulo, SP, Brazil
Summary
Correspondence
Katia Ponciano, Translational Physiology Labora-
tory. Postgraduation in Physical Education os Sao
Judas Tadeu University, Taquari Street 546,
Mooca, Sao Paulo, SP, Brazil
E-mail: kcapristi@gmail.com
Accepted for publication
Received 19 June 2016;
accepted 25 November 2016
Key words
athletes; competitions; physiological responses;
review; synchronized swimmers
This study is aimed at analysing the scientific literature related to physiological
responses in synchronized swimmers, produced from 2006 to 2016. A systematic
review was conducted using electronic databases (Google Scholar, PubMed,
SportDiscus, Web Science, Scielo and Scopus) in national and international journals.
The articles were selected using the following inclusion criteria: composed samples
of synchronized swimmers of both sexes, articles in English, Spanish and Por-
tuguese, published from 2006 to 2016. Ten studies were included. The concentra-
tion of the articles and their publication was as follows: Europe (77%) and North
America (23%). The protocols used analyse physiological responses in synchro-
nized swimmers athletes during competitions or laboratory tests, lactate measure-
ments, heart rate, rates of perceived exertion, VO
2
and lung volume. The subjects
of 100% of the studies included in this review were athletes of junior and senior
categories who volunteered. Only 03 of the 10 studies have compared the physio-
logical responses in volunteers who were not synchronized swimmers to synchro-
nized swimmer athletes. The studies were conducted using different
methodologies, which makes it difficult to compare them, so the standardization of
instruments and definitions is essential for the scientific advancement in this field.
In addition, it would be interesting to expand the research of these physiological
responses in synchronized swimmers using base level or beginners as sample.
Introduction
Synchronized swimming (SS) is an Olympic sport with rules
governed by the Manual for Synchronized Swimming, Judges,
Coaches and Referees (FINA, 2013). Its practice incorporates
elements and/or adaptations of other sports such as swim-
ming, rhythmic gymnastics, ballet and dance. SS requires
some specific items such as strength, kinesthetic knowledge
and complex technical skills (Yamamura et al., 1999; Pazikas
et al., 2005; Alentejano et al., 2008).
According to the FINA Handbook, competitions are com-
posed of two sessions: figures (without music) and routines
(with music and choreography). The figures are performed
without music, artistic swimsuits, accessories and even
make-up; the athletes must wear black swimsuits and white
caps (Fugita & Ponciano, 2013), thus providing an essentially
technical score. The athletes can compete in the following cat-
egories: solo (individual swimmer), duet (two athletes), team
(eight athletes), free combination (ten athletes) and highlight
routines (ten athletes) (FINA, 2013).
The technical routine involves performing predetermined
elements which are selected every 4 years. The free routine
has no figure requirements so it allows more flexibility to
demonstrate grace, artistry performance and creativity
(Rodrıguez-Zamora et al., 2012). Solo, duet and team routines
have five mandatory elements nowadays (FINA, 2013).
Considering the complexity of this modality, the search
for ways of improving the performance through technical
efficiency and artistic factors, as well as its growing popular-
ity and professionalization and the clarification of the physio-
logical changes that occur during its practice becomes
important.
Some studies (Davies et al., 1995; Chu, 1999; Mountjoy,
1999; Yamamura et al., 1999; Ebine et al., 2000; Pazikas et al.,
2005; Alentejano et al., 2008, 2010; Rodrıguez-Zamora et al.,
2012, 2013) have analysed the physiological responses in figures
Clin Physiol Funct Imaging (2017) doi: 10.1111/cpf.12412
1©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd

and routines; however, the samples, the conditions of the techni-
cal analysis and the analysed physiological parameters are varied.
The purpose of this study was to describe items of analysis
of the scientific studies related to the physiological responses
during the practice of synchronized swimming (SS) in accor-
dance with the Preferred Reporting Items for Systematic
Reviews and Meta-Analyses (PRISMA) Statement (Liberati
et al., 2009; Shamseer et al., 2015).
Method
Search strategy and selection of studies
The electronic search of articles published in English language
was conducted in the following databases: Google Scholar,
PubMed, SportDiscus, Web Science, Scielo and Scopus using as
descriptors SS and physiological responses –alone or in
combination. The selection of the articles followed these inclu-
sion criteria: synchronized swimmers of both sexes; samples con-
taining physiological analysis; publication date from January
2006 to May 2016. The following components were used as
exclusion criteria: results about biomechanics, nutrition, motor
learning and psychological studies, dissertations and theses.
The procedure consisted primarily of reading the title of the
manuscripts and analysing the abstracts of all the selected articles.
In all the databases, 92 scientific articles were found and only arti-
cles that met the inclusion and exclusion criteria were selected.
After this selection, the full text of all chosen articles was
obtained and subsequently examined under the established
criteria. This analysis excluded 18 articles that were duplicated
and over 64 articles with titles and abstracts which did not
contain physiological responses besides other studies with no
relation to the modality in accordance with the inclusion cri-
teria, as shown at Fig. 1.
Figure 1 Flow chart of selection of articles.
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al.2

Results
Table 1 presents the ranking of the methodological quality of
the studies related to interventions format through the data-
base PEDro (Physiotherapy Evidence Database).
Combining all search methods, we identified ten articles
fulfilling the inclusion criteria as seen in Table 2.
Table 3 contains the sample characterization (athlete or
non-athlete) of the selected studies. The selected studies have
samples aged between 13–23 years, age average of 1913
267 years; average of training experience years in SS of
801 255 years for studies using athletes in the junior
and senior groups (Bante et al., 2007; Alentejano et al., 2008,
2010; Rodrıguez-Zamora et al., 2012, 2013; 2014). Three
studies (Naranjo et al., 2006; Alentejano et al., 2010, 2012)
investigated the responses using a control group (CG)
without experience in the modality and three other studies
(Naranjo et al., 2006; Alentejano et al., 2012; Schaal et al.,
2013) did not mention training experience but reported that
their samples were composed of athletes.
In the last 10 years, studies on SS (Alentejano et al., 2008;
Rodrıguez-Zamora et al., 2012, 2013; Rodrıguez-Zamora et al.,
2014) have focused their physiological analysis during routine
performances. The variables that are most investigated are as
follows: blood lactate concentration (Naranjo et al., 2006;
Bante et al., 2007; Rodrıguez-Zamora et al., 2012, 2013; Schaal
et al., 2013, 2015), heart rate (HR) (Naranjo et al., 2006;
Bante et al., 2007; Alentejano et al., 2012, 2010; Rodrıguez-
Zamora et al., 2012, 2013; Schaal et al., 2013, 2015;
Rodrıguez-Zamora et al., 2014), oxygen consumption
(Naranjo et al., 2006; Bante et al., 2007; Alentejano et al.,
2010, 2012; Schaal et al., 2013), rates of perceived exertion
(Rodrıguez-Zamora et al., 2012, 2013; Schaal et al., 2013,
2015; Rodrıguez-Zamora et al., 2014), two analytical condi-
tions in apnea (Naranjo et al., 2006; Alentejano et al., 2008,
2010, 2012; Rodrıguez-Zamora et al., 2013) and alternating
apnea –with the face in and out of the water (Alentejano
et al., 2008, 2010; Rodrıguez-Zamora et al., 2013).
Table 4 shows the basic characteristics of studies regarding
their type, sample, evaluation protocol and the investigated
parameters. All 10 (100%) studies were cross-sectional. All of
them had junior and senior athletes as samples (Naranjo et al.,
2006; Alentejano et al., 2008, 2010, 2012; Rodrıguez-Zamora
et al., 2012, 2013; Schaal et al., 2013, 2015; Rodrıguez-
Zamora et al., 2014) and one of them (Bante et al., 2007)
analysed youth and senior athletes. Regarding the protocols,
the use of rates of perceived exertion is recent, and it has
Table 1 PEDro quality scale analysis of the ten selected studies.
Author/Year/Country
Criteria
1
Criteria
2
Criteria
3
Criteria
4
Criteria
5
Criteria
6
Criteria
7
Criteria
8
Criteria
9
Criteria
10
Criteria
11
Naranjo et al. (2006) Yes No No Yes No No No Yes Yes Yes Yes
Bante et al. (2007) Yes No No Yes No No No Yes Yes Yes Yes
Alentejano et al. (2008) Yes No No Only one
group
No No No Yes Yes _ Yes
Alentejano et al. (2010) Yes No No Yes No No No Yes Yes Yes Yes
Alentejano et al. (2012) Yes No No Yes No No No Yes Yes Yes Yes
Rodrıguez-Zamora
et al. (2012)
Yes No No Yes No No No Yes Yes Yes Yes
Rodrıguez-Zamora
et al. (2013)
Yes No No Yes No No No Yes Yes Yes Yes
Schaal et al. (2013) Yes No No Only one
group
No No No Yes Yes –Yes
Rodrıguez-Zamora
et al. (2014)
Yes No No Yes No No No Yes Yes Yes Yes
Schaal et al. (2015) Yes No No Only one
group
No No No Yes Yes –Yes
All trials indexed on Physiotherapy Evidence Database (PEDro) are assessed for methodological quality and statistical reporting using the PEDro
Scale that considers the following criteria: (1) eligibility criteria and source of participants; (2) random allocation; (3) concealed allocation; (4)
baseline comparability; (5) blinding of subjects; (6) blinding of therapists; (7) blinding of assessors; (8) measures of key outcomes from more
than 85% of participants; (9) intention-to-treat analysis; (10) between-group statistical comparisons; (11) point measures and measures of vari-
ability.
Table 2 Number of articles found in each database at every stage.
Database
‘Synchronized
swimming’ AND/OR
‘physiological
responses’
2006–2016
Selected titles
and abstracts
(accordingly to
inclusion and
exclusion criteria)
Google Scholar 74 64
PubMed 05 05
Web Science 03 03
Scopus 05 04
SportDiscus 05 03
Scielo 00 00
TOTAL 92 79
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al. 3

Table 3 Description of the sample characterization (athlete and non-athlete) of the ten selected studies.
Author (year) –
Country Age Height Body mass (kg) Body fat (%) Lean body mass (kg) Years of SS practice (years)
Naranjo et al.
(2006) –Spain
1608 278 (SS) 16138 588 (SS) 5345 588 (SS) Not available Not available Not available
2392 365 (CG) 17300 923 (CG) 6504 645 (CG)
Bante et al.
(2007) –Greece
21601 (SS –Senior) 167511 (SS –Senior) 56812 (SS –Senior) 21408 (SS –Senior) 25903 (SS –Senior) 9 (SS –Senior)
13809 (SS –Youth) 160112 (SS –Youth) 44816 (SS –Youth) 23108 (SS –Youth) 21 04 (SS –Youth) 5 (SS –Youth) (average
and deviation are
not mentioned)
Alentejano et al.
(2008) –Canada
20 18 (SS) 173341 (SS) 58340 (SS) Not available Not available 10 30 (SS)
Alentejano et al.
(2010) –Canada
18 2 (SS) 170652 (SS) 60569 (SS) Not available Not available 9 40 (SS)
22 3 (CG) 169289 (CG) 65488 (CG) 0 (CG)
Alentejano et al.
(2012) –Canada
18 2 (SS) 169170 (SS) 58073 (SS) Not available Not available Not available
18 2 (SS) 171232 (SS) 62661 (SS)
23 2 (CG) 165177 (CG) 665119 (CG)
21 2 (CG) 172787 (CG) 65371 (CG)
Rodrıguez-Zamora
et al. (2012) –Spain
21436 (SS –Senior) 163751 (SS –Senior) 53253 (SS –Senior) Not available Not available 8715 (SS –Senior)
15110 (SS –Youth) 168980 (SS –Youth) 54363 (SS –Youth) 11733 (SS –Youth)
Rodrıguez-Zamora
et al. (2013) –Spain
17935 (SS –Senior) 165163 (SS –Senior) 52455 (SS –Senior) Not available Not available 9831 (SS –Senior)
Schaal et al.
(2013) –France
20318 (SS –Senior) 170148 (SS –Senior) 61146 (SS –Senior) Not available Not available Not available
Rodrıguez-Zamora
et al. (2014) –Spain
17430 (SS –Senior) 164061 (SS –Senior) 52064 (SS –Senior) Not available 19214 (SS –Senior) 9326 (SS –Senior)
Schaal et al.
(2015) –France
20404 (SS –Senior) Not available Not available Not available Not available 2504 (SS –Senior)
SS, synchronized swimming; CG, control group.
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al.4

Table 4 Essential characteristics of the ten selected studies.
Author (year) –
Country Journal
Type
of study Sample Evaluation protocol Significant results
Naranjo et al.
(2006) –Spain
International
Journal Sports
Medicine
Cross-
sectional
25 athletes
SS athletes (13)
and volleyball
athletes (12 CG)
Were made test 1 and test 2 in cycle
ergometer at the same intensity.
HR; V
E
; VC; BF; VT; VO
2
;VCO
2
and LA were analysed
In SS athletes was observed had significant increase in VE, VO
2
eVCO
2
in test 2
when compared test 1, without changes in HR. The respiratory quotient (RQ)
remained constant and similar values for blood lactate with no significant
difference. The CG had higher increased V
E
,VO
2
eVCO
2
in test 2 than those in
the swimmers. HR and blood lactate increased. The V
E
vs VCO
2
relationship
showed two different slopes for both tests.
Bante et al. (2007)
–Greece
The Journal of
Sports Medicine
and Physical
Fitness
Cross-
sectional
16 SS athletes
Youth (8) and
Senior (8)
Anthropometric variables were
measured and the somatotype
checked. The tests included warm-
up exercises outside the water,
swimming and the specific of
performing 4 compulsory figures
and routine. P
ET
CO
2
; LA; HR; V
E
;
BF; VO
2peak
and VO
2
were analysed
The ectomorph somatotype predominated In both groups. Performance scores
(average scores of the 4 compulsory figures) were higher for senior compared
to youth (78406 versus 71207). VO
2peak
in the senior and youth
athletes was similar and also no difference in VO
2
at the end of the routine
between senior and youth athletes. The LA concentration at the VO
2peak
test was
significantly higher in senior compared to youth athletes but after the simulated
routine was similar in the both groups and significantly lower compared with
the VO
2peak
test. No difference was found between the two categories of
swimmers and between the two tests for both absolute and normalized EPOC
values. Senior and youth athletes had similar VO
2
kinetics parameters. However,
tand t
1/2
were significantly higher after the routine compared to VO
2peak
test
for both categories. P
ET
CO
2
responses during recovery from the VO
2peak
and the
simulated routine showed the P
ET
CO
2
after the VO
2peak
was similar in senior
and youth athletes. P
ET
CO
2
during the first 90 s of the recovery from the
VO
2peak
test averaged 4062 and decreased to 34515 mmHg during the
second 90 s. Similarly, P
ET
CO
2
decreased from 42918 at the first 90 s to
37214 mmHg at the last 90 s of recovery. Interestingly, the mean P
ET
CO
2
during the second half of the recovery was higher after the routine test,
compared with the VO
2peak.
And the mean breathing frequency was higher
following the VO
2peak
test compared with the simulated routine, only during
the first half of recovery. The V
E
in absolute values was higher in senior
compared to youth athletes in both tests. V
E
was higher following the VO
2peak
test compared with the simulated routine only during the first half of recovery
(continued)
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al. 5

Table 4 (Continued)
Author (year) –
Country Journal
Type
of study Sample Evaluation protocol Significant results
Alentejano et al.
(2008) –Canada
International
Journal of Sports
Physiology and
Performance
Cross-
sectional
11 SS athletes The time analysis was made from
the videotaped performance of the
11 top soloists during finals. The
total time out of the water, the
number of times the swimmers had
their face in or out of the water,
and the longest and the second
longest face immersion (FI). For
the purpose of this analysis, FI
periods were considered the time
the swimmers were holding their
breath or exhaling underwater. All
technical merit scores (TM) were
noted
There were no significant differences between the top soloists and those placing
7th to 11th in any of the FI times measured. The majority (10/11, 91%) of the
longest FI periods occurred in the first third of the solo. Four of 11 solos (36%)
began with the longest FI period. The second longest FI period varied
considerably, with 27% (3) of the soloists having the second longest FI period
in the first third of the solo, 45% (5) in the second third and 27% (3) in the
last third. There was a significant difference for the TM scores (top
group =95117 versus bottom group =91310; mean SD). As
would be expected, relative and absolute distance was significantly correlated
(r=0975, P<005), and the years of experience of the athletes correlated with
the TM scores (r=0693, P<005). No other significant correlations were
found between any of the variables
Alentejano et al.
(2010) –Canada
Research in Sports
Medicine
Cross-
sectional
30 women
15 SS athletes and
15 active female
university
students (CG)
The study required that each
participant attended 3 laboratory
sessions, 2 orientation sessions and
1 experimental test. BH times,
PETO
2;
PETCO
2
; reasons for ending
BH; VO
2;
HR and S
a
O
2
were
analysed
The SS athletes had longer apnea periods than the CG. The SS group had
significantly longer BH times compared with the CG. BH times increased
significantly in both groups from BH 1 to BH 5. The principal reason described
by the SS stopping BH was involuntary lung movements –could not, 6 –
(40%) and by the CG was panic 5 –(333%). There was a significant main
effect for HR 15 s prior to BH (SS>C), at the onset of BH (SS >C), and at 30 s
and 45 s during BH (SS<C, respectively). There was a significant main effect for
S
a
O
2
regarding BH independent group of time, which indicates that the S
a
O
2
decreased as increased BH times. The estimated oxygen required, the measured
from SS during BH ranged from 52% to 445% lower than the estimated
values, but in only one case (BH 4 for SS) was the net result significantly
different from zero. The C group had only 67% and 68% lower for two out of
five trials, but none of the net results were significantly different from zero. The
HR during recovery significantly increased between the end of the BH to 10 s
after the BH ended and significantly decreased between 10 s after BH and 25 s
after BH for the SS. Trends for EPBHOC were very similar independent of the
groups. Both groups were very near total recovery (in reaching the baseline
relative to VO
2
) by 25 s into recovery
(continued)
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al.6

Table 4 (Continued)
Author (year) –
Country Journal
Type
of study Sample Evaluation protocol Significant results
Alentejano et al.
(2012) –Canada
Journal of Human
Kinetics, Section
–Aquatic
Activities
Cross-
sectional
30 women
15 SS athletes and
15 active female
university
students (CG)
The procedures were the same as
those used in the previous study by
the same authors (2010). The
subjects were instructed to
determine the peak oxygen
consumption (VO
2
peak) while
immersed in water and how to use
the apparatus custom designed for
underwater exercise using a
modified Monark ergometer. BH
times, PETO
2;
PET CO
2;
VO
2;
HR,
S
a
O
2
and V
E
were analysed
The PETO
2
was significantly lower for SS when the BH trials were performed in
an ascending order. The results also indicated that as BH time increased, PETO
2
decreased significantly for SS and CG, but no differences were observed for
PETCO
2
. PETCO
2
was significantly higher for SS than for C but not PETO
2
when
the BH trials were performed in descending order. Note that two BH untrained
subjects from the ’10 s initial’ group were only able to finish one 25 s BH
period. There was a significant decrease in HR after the 20 and 25 s BH during
exercise for the SS group regardless of the order that the BH was performed.
However, HR significantly decreased in the C group only when the BH was
performed in a descending order. V
E
was significantly lower for SS compared to
C after 20 s of BH when the BH trials were performed in a descending order of
duration. Furthermore, V
E
decreased significantly after 5 s for both groups when
BH for 20 and 25 s regardless of the order. There was also significant decrease
within 5 s for the C group during the 10 s BH when performed in an
ascending order. As well, V
E
significantly decreased after 25 s of recovery for
both groups and conditions the 25 s BH period
Schaal et al.
(2013) –France
Applied
Physiology,
Nutrition and
Metabolism
Cross-
sectional
11 SS athletes This study investigated the effect of
whole-body cryostimulation
(WBC), contrast-water therapy
(CWT), active recovery (ACT) and
passive condition (PAS) protocols
on the parasympathetic reactivation
and metabolic parameters of
recovery in elite synchronized
swimmers who performed 2
simulated competition ballets (B1
and B2 with phases of apnea
adding up to 64% of the total
time) separated by 70 min.
VO
2peak
; LA during VO
2max400
;
HRV and RPE were analysed
Each ballet caused significant decreases in HRV indices. At PreB2, all HRV indices
had returned to PreB1 levels in the CWT, PAS and ACT protocols, whereas the
WBC protocol yielded a two- to fourfold increase in vagal-related HRV indices,
compared with PreB1. WBC and ACT were the only protocols to yield
significantly higher VO
2peak
values at B2 than at B1, with gains of 5432%
and 3429%, respectively. Every swimmer reached a higher VO
2peak
during
B2 after using WBC in recovery. RPE
m
values peaked at PostB1 and PostB2, and
returned to resting levels at the end of recovery (PreB2) for all protocols except
WBC, during which RPE
m
remained slightly but significantly elevated, compared
with PreB1. PAS was the only protocol associated with significantly higher RPE
m
at PostB2 than at PostB1. The RPE
g
values were significantly lower at PreB2 than
at PreB1 after a shorter second warm-up for all protocols except WBC
(P=007). PAS was also associated with significantly lower ratings on the
visual analog scale than all other protocols
(continued)
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al. 7

Table 4 (Continued)
Author (year) –
Country Journal
Type
of study Sample Evaluation protocol Significant results
Rodrıguez-Zamora
et al. (2012) –
Spain
PLOS ONE
www.plosone.
org
Cross-sectional 34 SS athletes
Youth (24) and
Senior (10)
All routines were performed during
actual competition. The total
competition score (TCS) for a
technical routine is composed of
separate scores for execution and
overall impression; for free
routines, the TCS is composed of
separate scores for technical merit
and artistic impression. In both
cases, TCS is up to a maximum of
100 points. All routines were
continuously recorded using a
digital video camera. LA
peak
;HR
and RPE were analysed
The pattern of HR response during the execution of the six routine programmes
was similar in most of the HR parameters for the entire group of swimmers.
However, significant differences were noted in recovery HR (HRpost3 and
HRpost5) between the TS and the FT routines. Likewise, HRpost3 was higher in
TD as compared to FT routines. Although HR
pre
was significantly higher in
juniors than in seniors. The maximal values resting blood lactate were attained
at the 5th or 7th min during the recovery period in all cases. For the entire
group of swimmers, LA
peak
was higher in the FS routine than in the TD and FT.
LA
peak
was also significantly higher in the FD than in the FT routines. About the
RPE scores in all groups and routines, values for FS and FD exercises were
higher than both team routines FT and TT. In both duet routines, FD and TD,
scores were higher than in TT. RPE scores were significantly higher in juniors
than in seniors. In the senior group, RPE values were higher in the FS routine
than in both team routines FT and TT. The TS and FD elicited higher RPE values
than TT. Swimmers attained higher scores in the FT than in the TD. Even if this
was an absolute competition, seniors were rated higher than juniors. TCS
performance scores negatively correlated with HR
pre
and HR
min
and positively
correlated with HR
range
Rodrıguez-Zamora
et al. (2013) –
Spain
International
Journal Sports
Medicine
Cross-sectional 17 SS athletes
Senior (07) and
Junior (10)
All routines were performed during
actual competition. The total
competition score (TCS) for a
technical routine is composed of
separate scores for execution and
overall impression; for free
routines, the TCS is composed of
separate scores for technical merit
and artistic impression. In both
cases, TCS is up to a maximum of
100 points. All routines were
continuously recorded using a
digital video camera. LA
peak
;HR
and RPE were analysed
RPE scores for all routines ranged from 6 (‘hard–very hard’) to 10 (‘extremely
hard’) and did not differ among the four different routines. Likewise, the
pattern of the HR response was not different among routines for any of the
studied parameters. Differences were noted among routines in LA
peak
, with
lower values in TD than in TS and FD. No significant differences were observed
among routines in MIM, IM
max
and TIM >10 s. NIM was higher in FD than in
TD and TS and also higher in FS than in TS. Differences were also observed in
TIM, with higher values in FD than in FS, and in both technical routines, TD
and TS. Differences were also noted in RIM %, which was higher in TS than in
TD and FS. The TS showed lower NIM >10 s than FD. About RPE, significant
correlations between performance (TCS), and physiological and immersion
parameters during SS routines were found. About linear correlation coefficients
between competitive performance (TCS) and physiological parameters and IM
parameters showed TCS positively correlated with LA
peak
and 2 immersion
parameters (NIM and IM
max
) and inversely correlated with MIM and HR
pre
(continued)
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al.8

Table 4 (Continued)
Author (year) –
Country Journal
Type
of study Sample Evaluation protocol Significant results
Rodrıguez-Zamora
et al. (2014) –
Spain
The Journal of
Strength and
Conditioning
Research
Cross-sectional 10 SS athletes
Senior (3) and
Junior (07)
The athletes performed TD and FD
routines in two different situations:
training (T) and competition (C).
HR and RPE were analysed
The HR profiles corresponding to one of the participants before, during and after
2 FD routines performed during T and C. An almost identical pattern was
observed, where in HR, after a period of intense anticipatory pre-activation
quickly increases, interspersed with periods of marked HR decrease. The mean
RPE scores corresponded to the ‘hard’ to ‘extremely hard’ verbal anchored
levels, and differences observed between C and T scores were not significant.
No differences were observed between routines (TD versus FD). The correlation
coefficient between T and C values for all parameters was highest for HR
range
followed by HR
min
and HR
mean
and lowest for HR
pre
. The HR
peak
correlation
closely approached statistical significance. Rate of perceived exertion during
competition was also significantly correlated with RPE during training. Rate of
perceived exertion was inversely correlated with HR
min
and HR
mean
and
positively correlated with HR
range
(continued)
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Physiological responses during the practice, K. Ponciano et al. 9

Table 4 (Continued)
Author (year) –
Country Journal
Type
of study Sample Evaluation protocol Significant results
Schaal et al.
(2015) –France
Medicine and
Science in Sports
& Exercise
Cross-sectional 10 SS athletes After 1 week of normal training
(BASE), the swimmers performed
two 2-wk IT periods randomized
order: one control IT period
(IT
CON
), during which no specific
recovery strategy was allowed (i.e.
no massages, hydrotherapy, sauna/
steam baths) and one that included
daily WBC sessions (IT
WBC
). The
two periods of IT were separated
by a 9-day taper period consisting
of light training. The contrast in
training load between BASE and
each IT was measured using the
method introduced by Foster et al.
Although the original method used
a 10-point modified Borg scale of
perceived exertion to describe the
intensity of each training session,
we used the original 6–20 Borg
scale (4) that the swimmers were
well accustomed. Exercise training
load; physiological response to
exercise submaximal and maximal;
sleep; resting endocrine parameters;
and effects of training overload on
the physiological response were
analysed
The number of training hours remained the same during BASE, IT
WBC
and IT
CON
,
but the overall training load for each period, expressed as the product of RPE
versus minutes, increased for each period. There was no difference in training
load between IT
WBC
and IT
CON
. Exercise at the end of each period, IT periods
resulted in a significant decrease in LA and HR; however, RPE was lower during
s1, s2 and s3 after IT
WBC
compared with BASE. Changes in RPE at all
submaximal intensities were directly correlated with the change in perceived
fatigue upon waking. The physiological response to maximal had significant
decrease in mean TT
400
speed which was observed from BASE to IT
CON
. The
difference in swim speed between IT
WBC
and IT
CON
was nuclear. The decrease
in performance during IT
CON
was accompanied by significant reductions in
LAB
400
and a-amylase
s400
. After both IT, changes in 400-m speed from BASE
showed large and very large correlations to changes in HR
400
and cortisol
s400
.
RPE
400
did not change significantly but showed a moderate inverse correlation
to cortisol
s400.
About sleep variables, the swimmers retired to bed 40 11 and
49 10 min later during IT
WBC
and IT
CON
compared with BASE and got up in
the morning 52 8 and 38 7 min later, respectively. Although it was
unclear whether bed time occurred earlier during IT
WBC
than IT
CON
,IT
WBC
was
associated with a trivial to very large positive effect on the get-up time. As a
result, IT
WBC
had a small to large positive effect on the total amount of time in
bed compared with IT
CON
. During IT
CON
, sleep latency increased because the
swimmers took an additional 11 5 min to fall asleep. The actual sleep
duration was significantly decreased during IT
CON
compared with BASE, with
swimmers losing 21 7 min of sleep per night, whereas no changes were
observed during IT
WBC
. Compared with IT
CON
,IT
WBC
had a significant positive
effect on actual sleep duration. IT
CON
showed a significant decrease in sleep
efficiency from BASE. Changes in perceived fatigue from BASE to both IT also
showed large correlations with changes in RPE at s1, s2 and s3. Fasted waking
cortisol did not change significantly from BASE to either IT period. There was
no significant difference in waking a-amylase
s
between any of the conditions.
However, the change in resting a-amylase
s
was negatively correlated with
change in sleep efficiency and trended towards a positive correlation with the
change in sleep latency and perceived fatigue during both IT conditions
BH, breath holding; SS, synchronized swimming; CG, control group; HR, heart rate; V
E
, ventilation; VT, volume tidal; BF, breathing frequency; VO
2
, oxygen uptake; VCO
2
, carbon dioxide production;
LA, blood lactate; VO
2peak
, peak oxygen uptake; PETCO
2
, end-tidal carbon dioxide pressure; RPE, rates of perceived exertion; TS, technical solo; TD, technical duet; TT, technical team; FS, free solo; FD,
free duet; FT, free team; IT, intensified training; WBC, whole-body cryostimulation; IT
CON
, control IT.
10 Physiological responses during the practice, K. Ponciano et al.
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd

been included as analysis in this modality since 2012
(Rodrıguez-Zamora et al., 2012, 2013; Rodrıguez-Zamora
et al., 2014; Schaal et al., 2013, 2015). Additionally, HR and
lactate analysis were the most commonly used parameters in
the publications especially when associated with apnea peri-
ods. On the other hand, the experimental designs are quite
diverse, with no standardization.
Discussion
This review study intended to present and analyse the existing
information on the physiological responses during the practice
of SS in the scientific literature. Its results may help planning
the choices of adequate tools for analysis of physiological
responses as well as develop new studies in the area.
Several studies have investigated physiological responses
during different types of training in SS, in the performance of
figures (Gemma & Wells, 1987; Homma, 1994; Homma &
Takahashi, 1999), execution of technical and free routines
(Yamamura et al., 2000) and the simulation of competitive
performance of routines (Chatard et al., 1999; Pazikas et al.,
2005) in order to quantify internal load training.
One of the most important focus of investigation on the SS
variables are the physiological effects during the time that the
players stay underwater, in apnea. However, there is no
known literature that quantifies the total amount of time that
synchronized swimmers stay underwater while performing a
routine. Maybe these long underwater sequences in routine
emphasize important aspects of athletes’ training in different
countries.
One of the ten selected studies investigated the relationship
between the duration of the apnea periods with the scores
awarded to the routines. In this study, there was a significant
difference in the technical merit scores for top soloists when
compared to the lowest score soloists (Alentejano et al.,
2008), but there were no significant differences between the
top soloists and those placed in the 7th to 11th position
regarding the capability to be underwater, measured in time.
This may explain the substantial score difference between the
top solo group (high scores) and the solo group with lower
performances (low score). The study (Alentejano et al., 2008)
that correlated the technical merit scores with the apnoea per-
iod of synchronized swimmers in a solo competition was
based on the old rules. It would be important to make new
investigations taking into consideration the new rules, once
the technical merit item has been modified. In the old rules,
the technical merit item was evaluated regarding three aspects
–execution, synchronization and difficulty. Now, the techni-
cal merit term does not exist and the three aspects were sepa-
rated –now the difficulty aspect is evaluated separately from
execution and synchronization.
In the study by Bante et al. (2007), the findings show that the
scores awarded to senior athletes were higher when compared
to youth athletes in the four studied figures. It is expected that
the more experienced the athlete is, higher is his/her capability
to be underwater in longer apnea periods, showing better
breathing and cardiac capacity, an adaptive metabolic response
to this sport (Rodrıguez-Zamora et al., 2012). Other study
(Rodrıguez-Zamora et al., 2012) observed that senior athletes
were rated higher than juniors in all routines analysed. The
scores are related to more experience (Alentejano et al., 2008).
Alentejano et al. (2008) found in the study that the athletes
performed relatively long underwater sequences that were
repeated six to eight times during a solo event and the study by
Alentejano et al. (2010) adds that the SS athletes had longer
apnea periods if compared to the CG. The HR average during
breath holding (BH) times increased significantly in both
groups from BH 1 to BH 5, in four different moments. The SS
group had significantly higher HR average during two initial
BH moments compared with the CG. However, the SS group
had a significant decrease in the HR average in the two final BH
moments. This result showed adaptive physiological response
in SS group, corroborating with study by Rodrıguez-Zamora
et al. (2012).The study by Alentejano et al. (2010) used a ques-
tionnaire that investigated psychophysiological factors which
were responsible for the interruption of apnea periods. The
answers of both SS and CGs are shown in percentages: utiliza-
tion of involuntary movements (40% versus 20%); need to
breathe (20% versus 20%); panic (1% versus 5%); tight chest
(2% versus 1%); dizziness (1% versus 1%); head started to hurt
(NA versus 66%); legs started to shake (NA versus 66%).
These factors should be known and regarded as important dur-
ing apnea periods, especially when associated with increased
duration. The training time can contribute to a better psycho-
logical and physiological response, that is greater tolerance, and
the fear factor practically ceases after longer practice of this
modality (Dujic & Breskovic, 2012). Additionally, Schagatay
et al. (2000) suggests that training reduces anxiety and increases
self-confidence resulting in increased time in apnea periods for
the subjects. The findings of this study (Alentejano et al., 2010)
are relevant in relation to the psychological factors that influ-
ence the apnea periods interruption. There may be tools to assist
technical and physical coaches and sports psychologists in meet-
ing alternatives to enhance and increase the athletes’ apnea
capability, mainly for base athletes.
Other important physiological factor is HR. Rodrıguez-
Zamora et al. (2012) observed that after a period of anticipa-
tory pre-activation, the HR increases rapidly and progressively
to high levels of tachycardia interspersed with periods of
intense bradycardia during intense exercise in apnea. The pat-
tern of HR response during the performance of six routines
was similar in all swimmers. On the other hand, there was a
significant difference in the HR recovery (after 30and 50)
between the technical solo routines compared to free team
(FT). The findings about the HR in the study by Rodrıguez-
Zamora et al. (2012) corroborate those of Alentejano et al.
(2010), reporting that the HR anticipatory response occurred
at an early stage in all swimmers at high intensities and the
cardiovascular demands are also increased with the HR and
their approach to maximal levels, interspersed with periods of
11Physiological responses during the practice, K. Ponciano et al.
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd

bradycardia during intense movements in apnea. These find-
ings may lead to training alternatives to apnea and intensifica-
tion of bradycardia even in the beginning of routines, what
may minimize tachycardia in the initial periods.
With respect to ventilatory responses, different protocols
were used. Naranjo et al. (2006) observed a significant increase
in ventilation (V
E
), oxygen uptake (VO
2
) and carbon dioxide
production (VCO
2
) without significant difference of HR and
blood lactate for the SS group in test two compared with test
one. Regarding the CG, the observed values of ventilation (V
E
),
oxygen uptake (VO
2
) and carbon dioxide production (VCO
2
)
were considerably higher and showed significant difference in
HR and blood lactate in test two compared with test one. Bante
et al. (2007) observed similar VO
2
peak values in senior and
youth synchronized swimmers at the end of the routine. Again
in this study, Naranjo et al. (2006) observed an adaptive meta-
bolic response to this sport when compared with other groups.
Evaluating the O
2
saturation, Alentejano et al. (2010) found
no significant changes during the apnea periods; however, the
arterial blood saturation (S
a
O
2
) values of synchronized swim-
mers were lower compared to the CG, even though their oxy-
gen (O
2
) consumption was higher during apnea. The
mechanism underneath this response is directly related to the
ability of synchronized swimmers to remain in apnea. During
BH, there is a decrease in HR and, consequently, in cardiac
output, causing the blood flow to be led to essential demands,
that is heart and brain (Alentejano et al., 2010).
Rodrıguez-Zamora et al. (2012) mention that cardiovascular
demands of all SS competitive routines are better described during
actual competitions with a large number of subjects. Since the HR
responses are largely related to BH responses, it seems logical to
assume that non-specific laboratory tests would not accurately
reproduce specific cardiovascular loading and thus miss an impor-
tant feature of specific adaptation to SS performance.
Regarding blood lactate, Rodrıguez-Zamora et al. (2012)
found lactate peaks in all subjects in the free solo (FS) perfor-
mances when compared to the technical duet (TD) as well as
the FT executions. The examination of blood lactate response
in free trials showed higher values in free duet (FD) than in
the FT performances. Thus, considering the lactate values pre-
sented in the studies (Rodrıguez-Zamora et al., 2012, 2013;
Schaal et al., 2013), it is possible to consider that the SS per-
formance has anaerobic predominance regardless of the anal-
ysed routine. According to Rodrıguez-Zamora et al. (2012),
the high levels of lactate peaks obtained in FS and FD demon-
strate that there is a specific effect of the apnea periods, as
well as a glycolytic metabolic activation in the muscles used,
besides the training adaptations.
It is known that the rates of perceived exertion are consid-
ered an important variable, resulting in the integration of
afferent signals from the skeletal muscles (peripheral) and the
central cardiorespiratory system (Borg, 1982). In addition, it
can help quantify the internal training load (Rodrıguez-
Zamora et al., 2014; Schaal et al., 2015), considering that few
studies (Rodrıguez-Zamora et al., 2012, 2013; Schaal et al.,
2013, 2015; Rodrıguez-Zamora et al., 2014) have investigated
the rates of perceived exertion responses during the practice
of SS.
Rodrıguez-Zamora et al. (2012) showed higher rating per-
ceived exertion values in athletes during the performance of FS
and FD routines compared to the technical and FT ones possibly
due to the longer apnea periods and duration of the solo routi-
nes (Rodrıguez-Zamora et al., 2013). Rates of perceived exer-
tion were significantly higher in juniors when compared with
seniors, hence indicating that seniors perceived their perfor-
mance to be less strenuous. These findings may suggest that the
use of rating perceived exertion can be an important tool in
training the SS athletes, mainly base athletes.
Rodrıguez-Zamora et al. (2014) used rates of perceived exer-
tion to find that the internal load used in duets was the same dur-
ing training and competition. Additionally, Rodrıguez-Zamora
et al. (2012) demonstrated that lower rates of perceived exertion
values in senior athletes compared to junior athletes can be
understood as more experience in the modality, higher levels of
automaticity in the performance of the task, lower levels of prec-
ompetitive anxiety and more attention during the execution of
the routine. Motor changes and psychological changes can be
related to the apnea periods of the athletes. In addition to the
artistic development and demonstration, technical and acrobatic
skills demand long and high intensity of training, improving
thus strength, flexibility and aerobic and anaerobic exercise
capacity (Liang et al., 2005; Mountjoy, 2009).
Limitations of this study
In the present study, two main limitations must be consid-
ered. The total papers analysed in this study used different
methodological strategies, that is some studies from this
review used laboratory tests and others used real competition
situation. Additionally, the majority of the studies have inves-
tigated senior athletes, disregarding other categories.
Conclusion
More investigations should be done to encourage the clarifica-
tion of physiological responses in different competitions on SS
in different categories. A standardization of tools and similar
methodological settings in the studies is necessary in both
competitive environment and laboratory. Only two studies in
this review (Alentejano et al., 2008; Rodrıguez-Zamora et al.,
2012) correlated the apnoea periods with the scores in
the performance routines using the manual of rules of the last
quadrennium. New studies are necessary once the rules were
modified in 2013. This review also brought other important
information related to the anaerobic predominance in this
modality, considering the lactate values presented in the stud-
ies (Rodrıguez-Zamora et al., 2012, 2013; Schaal et al., 2013).
This review may also suggest to SS athletes different alterna-
tives of training to improve and increase apnoea periods, since
apnoea was the study focus of the present review and it is a
12 Physiological responses during the practice, K. Ponciano et al.
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd

characteristic of the SS modality. Therefore, it is important to
highlight that the apnoea training may contribute to intensify
bradycardia periods in the beginning of the routine and possi-
bly minimize tachycardia. It would be interesting to study ath-
letes from other categories of synchronized swimming and
athletes who are starting in the modality in the future.
Besides, new investigations should be proposed to the male
genre. Men already practice synchronized swimming for years
and had their first official participation in the 16 FINA World
Championship Kazan –2015 mixed duet.
References
Alentejano TC, Marshall D, Bell GJ. A time-
motion analysis of elite solo synchronized
swimming. Int J Sports Physiol Perform (2008);
3:31–40.
Alentejano TC, Marshall D, Bell GJ. Breath
holding with water immersion in synchro-
nized swimmers and untrained women. Res
Sports Med (2010); 18:97–114.
Alentejano TC, Bell G, Marshall DA. Compar-
ison of the physiological responses to
underwater arm cranking and breath hold-
ing between synchronized swimmers and
breath holding untrained women. J Hum
Kinet (2012); 32: 147–156.
Bante C, Bogdanis GC, Chairopoulou C, et al.
Cardiorespiratory and metabolic responses
to a simulated synchronized swimming rou-
tine in s^enior (>18 years) and comen (13-
15 years) national levels athletes. J Sports Med
Phys Fitness (2007); 47: 291–299.
Borg GAV. Phychophysical bases of perceived
exertion. Med Sci Exerc (1982); 14: 377–381.
Chatard JC, Mujika I, Chantegraille MC, et al.
Performance and physiological responses to
a 5-week synchronized swimming technical
training programme in humans. Eur J Appl
Physiol (1999); 79: 479–483.
Chu DA. Athletic training issues in synchronized
swimming. Clinic Sports Med (1999); 18:437–445.
Davies BN, Donaldson GC, Joels N. Do the
competition rules of synchronized swim-
ming encourage undesirable levels of hypox-
ia? Braz J Sports Med (1995); 29:16–19.
Dujic Z, Breskovic T. Impact of breath hold-
ing on cardiovascular respiratory and cere-
brovascular health. Int J Sports Med (2012);
42: 459–472.
Ebine N, Feng JY, Homma M, et al. Total
energy expenditure of elite synchronized
swimmers measured by the doubly labeled
water method. Eur J Appl Physiol (2000); 86:
1–6.
FINA (Federation Internationale the Natation).
Manual for Synchronized Swimming, Judges, Coaches
& Referees (2013). Fina Office, Lausanne –
Switzerland.
Fugita M, Ponciano K. Nado sincronizado: carac-
terısticas da modalidade e aspectos para ensino.
Rev Acta Bras Mov Hum (2013); 3:99–116.
Gemma KE, Wells CL. Heart rates of elite syn-
chronized swimmers. Phys Sportsmed (1987);
15:99–107.
Homma M. The components and the time of
‘face in’ of the routines in synchronized
swimming. Med Sport Sci (1994); 39: 149–
154.
Homma M, Takahashi G. Heart rate response
during exercise with breath holding in syn-
chronized swimming. SuieiSuichu Undo Kagaku
(1999); 11:27–38.
Liang MTC, Arnaud SB, Steele CR, et al. Ulnar
and tibial bending stiffeness as an index of
bone strength in synchronized swimmers
and gymnasts. Eur J Appl Physiol (2005); 90:
400–407.
Liberati A, Altman DG, Tetzlaff J, et al. The
PRISMA statement for reporting systematic
reviews and meta-analyses of studies that
evaluate health care interventions: explana-
tion and elaboration. BMJ (2009); 339:
b2700.
Mountjoy M. The basics of synchronized
swimming and its injuries. Aquat Sports Inj
Rehabil (1999); 18: 321–336.
Mountjoy M. Injuries and Medical Issues in
Synchronized Olympic Sports. American Col-
lege of Sports Medicine. (2009); 8(5): 255–
261.
Naranjo J, Centeno RA, Carranza MD, et al. A
test for evaluation of exercise with apneic
episodes in synchronized swimming. Int J
Sports Med (2006); 27: 1000–1004.
Pazikas MGA, Curi A, Aoki MS. Behaviour of
physiological variables in synchronized
swimming athletes during a training session
preparing for the Athens 2004 Olympic
Games. Rev Bras Med Esporte (2005); 11: 357–
362.
Rodrıguez-Zamora L, Iglesias X, Barrero A,
et al. Physiological responses in relation to
performance during competition in elite
synchronized swimmers PLoS One (2012); 7:
1–10. www.plosone.org.
Rodrıguez-Zamora L, Iglesias X, Barrero A,
et al. Perceived exertion, time of immersion
and physiological correlates in synchronized
swimming. Int J Sports Med (2013); 35: 403–
411.
Rodrı
´guez-Zamora L, Iglesias X, Barrero A,
Torres L, Chaverri D, Rodrı
´guez FA. Moni-
toring internal load parameters during com-
petitive synchronized swimming duet
routines in elite athletes. The Journal of Strength
and Conditioning Research. (2014); 28(3): 742–
751.
Schaal K, Le Meur Y, Louis J, et al. Effect of
recovery mode on postexercise vagal reac-
tivation in elite synchronized swimmers.
Appl Physiol Nutr Metab (2013); 38: 126–
133.
Schaal K, Le Meur Y, Louis J, et al. Whole-
body cryostimulation limits overreachinh in
elite synchronized swimmer. Med Sci Sports
Exerc (2015); 47: 1416–1425.
Schagatay E, Kampen M, Emanuelsson S, et al.
Effects of physical and apnea training on apneic
time and the diving response in humans. Eur J
Appl Physiol (2000); 82: 161–169.
Shamseer L, Moher D, Clarke M, et al. Pre-
ferred reporting items for systematic review
and meta-analysis protocols (PRISMA-P)
2015: elaboration and explanation. BMJ
(2015); 349:1–25.
Yamamura C, Zushi S, Takata K, et al. Physio-
logicalcharacteristics of well-trained syn-
chronized swimmers in relation to
performance scores. Int J Sports Med (1999);
20: 246–251.
Yamamura C, Matsui N, Kitagawa K. Physio-
logical loads in the team technical and free
routines of synchronized swimmers. Med Sci
Sports Exerc (2000); 06: 1171–1174.
13Physiological responses during the practice, K. Ponciano et al.
©2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd