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Abstract and Figures

Physical exercise, particularly resistance training (RT), is presently the only proven means to reduce the accelerated decline in muscle strength exhibited by older adults, but its effect is hindered by low adherence rate, even under well-structured programs. Here we investigate the efficacy of circuit resistance training (CRT) on muscle strength, lean mass and aerobic capacity in older adults. MEDLINE (Ovid), EMBASE, ClinicalTrials.gov, Cochrane electronic databases were systematically searched including references of pertinent articles up to August 2016. The search yielded a total of 237 articles, 106 of which did not meet the inclusion criteria. Sensitivity analysis was conducted using studies with higher likelihood for bias. Ten articles were included with a total of 362 patients (average age of 64.51 ± 7.39 years). The intervention programs averaged 3 ± 1.15 sessions/week and 41.78 ± 15.89 minutes/session. Upper body strength modestly increased, by 1.14 kg (95% CI; 0.28–2.00), whereas larger increment was seen in lower body strength (11.99; 1.02–2.61). A subgroup analysis revealed that higher program volume (>24 sessions) positively influenced upper body strength and aerobic capacity. CRT is a valid alternative to conventional RT. Because of its shorter duration and lower intensity relative to traditional RT, it may increase adherence to training in older adults.
Content may be subject to copyright.
Ageing
Research
Reviews
37
(2017)
16–27
Contents
lists
available
at
ScienceDirect
Ageing
Research
Reviews
jou
rn
al
hom
epage:
www.elsevier.com/locate/arr
Review
Circuit
resistance
training
is
an
effective
means
to
enhance
muscle
strength
in
older
and
middle
aged
adults
A
systematic
review
and
meta-analysis
Assaf
Bucha,b,c,,
Ofer
Kisa,
Eli
Carmelia,d,
Lital
Keinan-Bokere,f,
Yitshal
Bernerb,g,
Yael
Barerb,
Gabi
Shefera,
Yonit
Marcusa,b,
Naftali
Sterna,b
aInstitute
of
Endocrinology,
Metabolism
and
Hypertension,
Tel
Aviv
Sourasky
Medical
Center,
Tel-Aviv,
Israel
bThe
Sackler
Faculty
of
Medicine
Tel-Aviv
University,
Israel
cRobert
H
Smith
Faculty
of
Agriculture,
Food
and
Environment,
The
Hebrew
University
of
Jerusalem,
Rehovot,
Israel
dThe
Department
of
Physical
Therapy,
University
of
Haifa,
Haifa,
Israel
eSchool
of
Public
Health,
University
of
Haifa,
Haifa,
Israel
fIsrael
Center
for
Disease
Control,
Israel
Ministry
of
Health,
Ramat
Gan,
Israel
gGeriatric
Medicine,
Meir
Medical
Center,
Kfar
Saba,
Israel
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
29
January
2017
Received
in
revised
form
18
April
2017
Accepted
19
April
2017
Available
online
27
April
2017
Keywords:
Circuit
resistance
training
Muscle
strength
Lean
body
mass
Aerobic
capacity
a
b
s
t
r
a
c
t
Background:
Physical
exercise,
particularly
resistance
training
(RT),
is
proven
treatment
to
reduce
the
accelerated
decline
in
muscle
strength
exhibited
by
older
adults,
but
its
effect
is
hindered
by
low
adher-
ence
rate,
even
under
well-structured
programs.
Objective
and
data
sources:
We
investigated
the
efficacy
of
circuit
resistance
training
(CRT)
on
muscle
strength,
lean
mass
and
aerobic
capacity
in
older
adults
based
on
report
in
MEDLINE,
EMBASE,
Clini-
calTrials.gov
and
Cochrane
electronic
(through
8/2016).
Study
eligibility
criteria:
middle
and
older
aged
men
and/or
women
who
followed
a
structured
program,
assigned
to
CRT.
Study
appraisal
and
synthesis
methods:
Out
of
237
originally
identified
articles,
10
articles
were
included
with
a
total
of
362
patients
with
mean:
age
64.5
±
7.4
years;
3
±
1.15
sessions/week;
session
duration
41.8
±
15.9
min.
Results:
Upper
body
strength
modestly
increased,
by
1.14
kg
(95%
CI;
0.28–2.00),
whereas
larger
increment
was
seen
in
lower
body
strength
(11.99;
2.92–21.06).
Higher
program
volume
(>24
sessions)
positively
influenced
upper
body
strength
and
aerobic
capacity.
Limitations:
(1)
variability
in
the
studies’
validity;
(2)
relatively
low
number
of
studies.
Conclusion:
CRT
is
a
valid
alternative
to
conventional
RT.
Its
shorter
duration
and
lower
intensity
relative
to
traditional
RT,
may
increase
adherence
to
training
in
older
adults.
©
2017
Elsevier
B.V.
All
rights
reserved.
Contents
1.
Introduction
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2.2.
Eligibility
criteria
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18
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extraction
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18
2.4.
Risk
of
bias
in
individual
studies
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18
2.5.
Data
analyses
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18
2.6.
Risk
of
bias
across
studies
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19
3.
Results.
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.19
3.1.
Study
selection
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19
Corresponding
author
at:
The
Institute
of
Endocrinology
Metabolism
and
Hypertension
Tel
Aviv-Sourasky
Medical
Center,
6
Weizmann
St.,
Tel-Aviv
64239,
Israel.
E-mail
address:
buchasaf@gmail.com
(A.
Buch).
http://dx.doi.org/10.1016/j.arr.2017.04.003
1568-1637/©
2017
Elsevier
B.V.
All
rights
reserved.
A.
Buch
et
al.
/
Ageing
Research
Reviews
37
(2017)
16–27
17
3.2.
Study
characteristics
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19
3.3.
Quality
(risk
of
Bias)
and
publication
bias
assessment
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19
3.4.
Effect
of
circuit
resistance
training
on
muscle
strength
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19
3.5.
Effect
of
circuit
resistance
training
on
lean
body
mass
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19
3.6.
Effect
of
circuit
resistance
training
on
aerobic
capacity
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22
3.7.
Sensitivity
analyses.
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.22
3.8.
Sub-group
analyses.
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.22
3.9.
Assessment
of
publication
bias
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22
4.
Discussion
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22
4.1.
Special
populations.
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.23
5.
Conclusions
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24
Funding
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25
Conflicts
of
interest
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26
Acknowledgements.
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.26
Appendix
A.
Supplementary
data
.
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26
References
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26
1.
Introduction
Aging
is
characterized
by
accelerated
decline
in
muscle
mass
and
function
(strength
or
performance)
termed
sarcopenia
(Cruz-
Jentoft
et
al.,
2010),
a
syndrome
of
multifactorial
etiology
including
contributors
such
inactivity,
changes
in
nutrition
and
protein
metabolism,
oxidative
stress,
and
hormonal
imbalance
and
insen-
sitivity
(Budui
et
al.,
2015).
The
progressive
decline
in
muscle
strength
(Manini
and
Clark,
2012)
especially
in
the
lower
extrem-
ities
(Nogueira
et
al.,
2013),
that
potentially
impacts
mobility
and
translates
into
frailty
and
functional
disability.
With
advancing
age,
old
adults
often
perform
their
activities
of
daily
living
(ADLs)
close
to
their
maximal
capabilities,
leading
to
further
reduction
in
daily
activity
(Hortobágyi
et
al.,
2003),
increased
risk
of
falls
(Trombetti
et
al.,
2016)
and
eventually,
dependency
(Shin
et
al.,
2011).
The
best
prevention
of
the
accelerated
decline
in
muscle
strength
and
mass
in
older
adults
is
through
resistance
train-
ing
(RT)
(Rolland
et
al.,
2008),
which
has
been
an
integral
part
of
the
American
College
of
Sport
Medicine
(ACSM)
exercise
pre-
scription
guidelines
for
older
adults
since
1998
(American
College
of
Sports
Medicine
Position
Stand,
1998;
American
College
of
Sports
Medicine
et
al.,
2009).
Unfortunately,
older
adults’
adher-
ence
to
exercise
programs
is
low,
even
during
highly
supervised
RT
programs
(Van
Roie
et
al.,
2013a):
only
22%
of
older
adults
engage
in
muscle-strengthening
activities
at
least
twice
weekly
and
participation
decreases
further
with
age
(Centers
for
Disease
Control
and
Prevention,
2013),
particularly
in
women
(Kruger
et
al.,
2007).
Factors
such
as
awareness,
availability
and
accessibility
to
programs
as
well
as
program
features
such
as
frequency,
inten-
sity,
duration,
consistency
of
instruction
and
cost
(Moschny
et
al.,
2011;
Jancey
et
al.,
2006
Dec),
all
play
some
role
in
adherence
rates.
In
search
for
a
shorter
form
of
exercise
training
which
is
also
less
physically
challenging
but
still
improves
muscular
strength,
aerobic
fitness
and
body
composition,
circuit
resistance
training
(CRT)
has
emerged
as
a
viable
alternative
for
the
elderly
population
(Brentano
et
al.,
2008;
Kelemen
et
al.,
1986;
Maiorana
et
al.,
1997).
CRT
became
very
popular
during
the
early
eighties
(then
called
“circuit
weight
training”)
and
showed
positive
effects
on
muscle
strength,
fat
mass
and
lean
body
mass
in
healthy
adults
(American
College
of
Sports
Medicine
et
al.,
2009;
Brentano
et
al.,
2008).
CRT
is
comprised
of
10
exercises,
each
activating
a
different
muscle
group
via
12–15
repetitions.
The
trainee
moves
quickly
from
one
exercise
to
the
next
with
little
(15–30
s)
or
no
rest.
One
to
three
cycles
of
such
exercises
can
be
performed
in
a
CRT
session.
The
intensity
of
exercises
is
usually
modest
[40–60%
of
the
maxi-
mal
load
achieved
in
one
repetition
of
an
exercise
(RM1)].
Because
of
shorter
inter-exercise
resting
periods
compared
to
conventional
RT
(typically
only
1–2
min),
the
entire
session
may
requires
only
30–45
min
(American
College
of
Sports
Medicine
et
al.,
2009;
Brentano
et
al.,
2008;
Romero-Arenas
et
al.,
2013a),
well
below
the
time
needed
to
perform
a
conventional
RT
program
(45–90
min)
(Romero-Arenas
et
al.,
2013b).
Although
CRT
has
been
studied
in
diverse
populations
(Paoli
et
al.,
2013;
Shabani
et
al.,
2015;
Wilmore
et
al.,
1978;
Butler
et
al.,
1992)
the
efficacy
and
safety
of
CRT
in
older
subjects
is
presently
not
well
defined
and
this
form
of
exercise
is
therefore
not
routinely
recommended
for
subjects
older
than
65y.
The
primary
aim
of
this
first
systematic
review
and
meta-analysis
of
CRT
in
older
adults
was
to
evaluate
the
effect
of
CRT
on
muscle
strength.
Secondary
aims
were
to
evaluate
the
effect
of
CRT
on
lean
body
mass
(LBM)
and
on
cardiovascular
function
(aerobic
capacity);
and
assess
the
feasibility
and
safety
of
CRT
in
the
independent
elderly
population.
The
full
protocol
of
this
study
includes
this
manuscript
as
well
as
the
online
supplementary
data
and
was
not
a
priori
published.
2.
Methods
2.1.
Study
selection
We
systematically
searched
the
following
electronic
databases:
MEDLINE
(Ovid),
EMBASE,
ClinicalTrials.gov
and
Cochrane
from
their
initial
covered
date
(1946,1947,
2000
and
1999,
respectively)
up
to
August
2015.
Reference
lists
of
the
included
trials
were
also
searched
manually.
The
same
was
applied
to
the
search
for
sys-
tematic
reviews
and
meta-analyses.
The
search
was
comprised
of
the
following
terms:
circuit
training
or
exercise,
circuit
classes
and
cyclic
exercise
or
training
with
limitations
to
middle
age
or
elderly
population.
Language
was
not
limited
but
all
trials
found
were
in
English
(Box
1).
Contact
with
researchers
was
made
if
the
article
was
not
available.
The
analysis
process
required
a
full
year
fol-
lowing
the
initial
literature
search,
thus
we
have
re-searched
the
databases
to
race
relevant
additional
publications
(up
to
August
2016).
In
this
new
search,
we
found
23
articles
in
Medline
(Ovid)
and
21
in
EMBASE.
Out
of
these
44
new
articles,
4
duplicates
were
found,
12
were
not
relevant
to
topic,
4
did
not
report
relevant
outcomes,
6
did
not
match
the
age
criterion,
1
did
not
report
suf-
ficient
duration
of
intervention,
5
reported
on
concurrent
training,
11
studies
were
not
eligible
by
their
type
and
one
did
not
provide
sufficient
data
(data
not
shown).
Results
are
presented
in
accor-
dance
with
the
Preferred
Reporting
Items
for
Systematic
Reviews
and
Meta-Analyses
(PRISMA)
statement
11
(Liberati
et
al.,
2009)
and
the
Cochrane
Handbook
for
Systematic
Reviews
(Higgins
and
Green,
2011).
18
A.
Buch
et
al.
/
Ageing
Research
Reviews
37
(2017)
16–27
Box
1:
Medline
search
strategy.
Database: Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations <August
18, 2015
>, Ovid MEDLINE(R) <1946
to Augu
st Week 1 2015>
Search Strategy:
--------------------------------------------------------------------------------
1 (circuit adj2 (training or exercise*)).mp. [mp=title, abstract, original title, name of
sub
stance
word, sub
jec
t hea
ding
word, keyword heading word, protocol
supplementary concept word, rare disease supplementary concept word, unique
identifie r] (316)
2 (circuit adj1 (class or classes)).mp. [mp=title, abstract, original title, name of
substance word, subject heading word, keyword heading word, protocol
supplementary concept word, rare disease supplementary concept word, unique
identifie r]
(28)
3 (cyclic adj2 (exercise or training)).mp. [mp=title, abstract, original title, name of
sub
stance
word, sub
jec
t hea
ding
word, keyword heading word, protocol
sup
plementary conce
pt word, rare disease sup
plementary conce
pt word, un
iqu
e
identifie r]
(25)
4 1 or 2 or 3 (360)
5 exp aged/ or mi
ddle aged/ (4098433)
6 (elder* or older).ti. (149106)
7 5 or 6 (4118173)
8 4 and 7 (12
7)
_____________________________________________________________________
2.2.
Eligibility
criteria
A
priori
structured
criteria
were
developed
based
on
the
“Participants,
Intervention,
Comparison
and
Outcome”
approach
(PICO)
(Liberati
et
al.,
2009).
Intervention
studies
with
partici-
pants
in
middle
age
and
older
(45
years
by
range
or
mean
50
years
with
SD
10)
with
any
medical
condition
and
a
moderate
background
of
physical
activity
(PA;
3
times
a
week
of
moderate
exercise,
excluding
RT)
were
eligible.
The
intervention
had
to
be
a
structured,
such
that
patients
were
engaged
in
a
planned,
individualized
program
of
CRT
lasting
8
weeks,
at
least
once
weekly,
performed
at
any
intensity,
with
any
equipment
(weights,
bands,
body
weight,
etc.),
with
or
without
supervision.
Concurrent
aerobic
workout
was
allowed
only
if
a
parallel
aerobic
workout
was
performed
in
the
control
group.
Due
to
the
novelty
and
limited
data,
eligible
intervention
studies
were
included,
with
or
without
a
control
group
(active
control
or
follow
up).
We
did
not
exclude
studies
based
on
a
validity
assessment
(risk
of
bias),
but
referred
to
this
issue
in
the
sensitivity
analysis
(therefore,
uncontrolled
trials
were
included,
but
not
in
the
main
analysis).
To
be
included,
studies
had
to
report
at
least
one
of
the
following
outcomes:
measured
strength,
body
composition,
and/or
cardiac
capacity.
For
duplicate
publications
or
sub
studies,
only
the
article
with
the
most
extractable
information
was
used.
Attempts
to
retrieve
missing
data
were
made
by
contacting
the
authors.
2.3.
Data
extraction
Both
titles
and
abstracts
were
evaluated
by
two
of
the
study’s
investigators
together
(one
methodologist-
Buch
A
and
one
expert
Kis
O).
Based
on
eligibility
criteria,
the
“first
no”
response
was
documented
as
the
main
reason
for
excluding
the
study.
Abstracts
that
did
not
provide
sufficient
information
regarding
the
inclusion
and
exclusion
criteria
were
retrieved
for
full
text
evaluation.
Poten-
tially
eligible
full
text
papers
were
reviewed
independently
by
two
investigators
(AB,
OK).
A
detailed
data
extraction
file
was
devel-
oped
and
was
then
pilot-tested
on
two
random
studies
(Kelemen
et
al.,
1986;
Romero-Arenas
et
al.,
2013b).
Contact
with
authors
was
made
to
complete
missing
results
(e.g.,
weight
at
baseline,
but
not
at
the
end
of
study).
However,
if
there
was
no
mention
of
a
prede-
fined
parameter,
such
as
adverse
events,
compliance
and
adherence
we
considered
it
as
missing
data
and
referred
to
it
in
the
validity
(bias)
assessment.
In
all
we
have
contacted
the
authors
of
6
publi-
cations
(Brentano
et
al.,
2008;
Kelemen
et
al.,
1986;
Romero-Arenas
et
al.,
2013b;
Bocalini
et
al.,
2012;
Stibrant
Sunnerhagen,
2007;
Yoshitake
et
al.,
2011),
and
received
replies
from
four
(Brentano
et
al.,
2008;
Romero-Arenas
et
al.,
2013b;
Stibrant
Sunnerhagen,
2007;
Yoshitake
et
al.,
2011).
For
further
information
see
online
supplementary
data
(eMethods
1).
2.4.
Risk
of
bias
in
individual
studies
was
evaluated
according
to
the
“Cochrane
collaboration’s
tool
for
assessing
risk
of
bias”
(Higgins
et
al.,
2011a)
and
followed
by
the
PRISMA
statement
11
(Liberati
et
al.,
2009).
The
process
of