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Dose–Response Relationships of Resistance Training in Healthy Old Adults: A Systematic Review and Meta-Analysis

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Background: Resistance training (RT) is an intervention frequently used to improve muscle strength and morphology in old age. However, evidence-based, dose-response relationships regarding specific RT variables (e.g., training period, frequency, intensity, volume) are unclear in healthy old adults. Objectives: The aims of this systematic review and meta-analysis were to determine the general effects of RT on measures of muscle strength and morphology and to provide dose-response relationships of RT variables through an analysis of randomized controlled trials (RCTs) that could improve muscle strength and morphology in healthy old adults. Data sources: A computerized, systematic literature search was performed in the electronic databases PubMed, Web of Science, and The Cochrane Library from January 1984 up to June 2015 to identify all RCTs related to RT in healthy old adults. Study eligibility criteria: The initial search identified 506 studies, with a final yield of 25 studies. Only RCTs that examined the effects of RT in adults with a mean age of 65 and older were included. The 25 studies quantified at least one measure of muscle strength or morphology and sufficiently described training variables (e.g., training period, frequency, volume, intensity). Study appraisal and synthesis methods: We quantified the overall effects of RT on measures of muscle strength and morphology by computing weighted between-subject standardized mean differences (SMDbs) between intervention and control groups. We analyzed the data for the main outcomes of one-repetition maximum (1RM), maximum voluntary contraction under isometric conditions (MVC), and muscle morphology (i.e., cross-sectional area or volume or thickness of muscles) and assessed the methodological study quality by Physiotherapy Evidence Database (PEDro) scale. Heterogeneity between studies was assessed using I (2) and χ (2) statistics. A random effects meta-regression was calculated to explain the influence of key training variables on the effectiveness of RT in terms of muscle strength and morphology. For meta-regression, training variables were divided into the following subcategories: volume, intensity, and rest. In addition to meta-regression, dose-response relationships were calculated independently for single training variables (e.g., training frequency). Results: RT improved muscle strength substantially (mean SMDbs = 1.57; 25 studies), but had small effects on measures of muscle morphology (mean SMDbs = 0.42; nine studies). Specifically, RT produced large effects in both 1RM of upper (mean SMDbs = 1.61; 11 studies) and lower (mean SMDbs = 1.76; 19 studies) extremities and a medium effect in MVC of lower (mean SMDbs = 0.76; four studies) extremities. Results of the meta-regression revealed that the variables "training period" (p = 0.04) and "intensity" (p < 0.01) as well as "total time under tension" (p < 0.01) had significant effects on muscle strength, with the largest effect sizes for the longest training periods (mean SMDbs = 2.34; 50-53 weeks), intensities of 70-79 % of the 1RM (mean SMDbs = 1.89), and total time under tension of 6.0 s (mean SMDbs = 3.61). A tendency towards significance was found for rest in between sets (p = 0.06), with 60 s showing the largest effect on muscle strength (mean SMDbs = 4.68; two studies). We also determined the independent effects of the remaining training variables on muscle strength. The following independently computed training variables are most effective in improving measures of muscle strength: a training frequency of two sessions per week (mean SMDbs = 2.13), a training volume of two to three sets per exercise (mean SMDbs = 2.99), seven to nine repetitions per set (mean SMDbs = 1.98), and a rest of 4.0 s between repetitions (SMDbs = 3.72). With regard to measures of muscle morphology, the small number of identified studies allowed us to calculate meta-regression for the subcategory training volume only. No single training volume variable significantly predicted RT effects on measures of muscle morphology. Additional training variables were independently computed to detect the largest effect for the single training variable. A training period of 50-53 weeks, a training frequency of three sessions per week, a training volume of two to three sets per exercise, seven to nine repetitions per set, a training intensity from 51 to 69 % of the 1RM, a total time under tension of 6.0 s, a rest of 120 s between sets, and a rest of 2.5 s between repetitions turned out to be most effective. Limitations: The current results must be interpreted with caution because of the poor overall methodological study quality (mean PEDro score 4.6 points) and the considerable large heterogeneity (I (2) = 80 %, χ (2) = 163.1, df = 32, p < 0.01) for muscle strength. In terms of muscle morphology, our search identified nine studies only, which is why we consider our findings preliminary. While we were able to determine a dose-response relationship based on specific individual training variables with respect to muscle strength and morphology, it was not possible to ascertain any potential interactions between these variables. We recognize the limitation that the results may not represent one general dose-response relationship. Conclusions: This systematic literature review and meta-analysis confirmed the effectiveness of RT on specific measures of upper and lower extremity muscle strength and muscle morphology in healthy old adults. In addition, we were able to extract dose-response relationships for key training variables (i.e., volume, intensity, rest), informing clinicians and practitioners to design effective RTs for muscle strength and morphology. Training period, intensity, time under tension, and rest in between sets play an important role in improving muscle strength and morphology and should be implemented in exercise training programs targeting healthy old adults. Still, further research is needed to reveal optimal dose-response relationships following RT in healthy as well as mobility limited and/or frail old adults.
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SYSTEMATIC REVIEW
Dose–Response Relationships of Resistance Training in Healthy
Old Adults: A Systematic Review and Meta-Analysis
Ron Borde
1
Tibor Hortoba
´gyi
2,3
Urs Granacher
1
Published online: 29 September 2015
ÓThe Author(s) 2015. This article is published with open access at Springerlink.com
Abstract
Background Resistance training (RT) is an intervention
frequently used to improve muscle strength and morphol-
ogy in old age. However, evidence-based, dose–response
relationships regarding specific RT variables (e.g., training
period, frequency, intensity, volume) are unclear in healthy
old adults.
Objectives The aims of this systematic review and meta-
analysis were to determine the general effects of RT on
measures of muscle strength and morphology and to pro-
vide dose–response relationships of RT variables through
an analysis of randomized controlled trials (RCTs) that
could improve muscle strength and morphology in healthy
old adults.
Data Sources A computerized, systematic literature
search was performed in the electronic databases PubMed,
Web of Science, and The Cochrane Library from January
1984 up to June 2015 to identify all RCTs related to RT in
healthy old adults.
Study Eligibility Criteria The initial search identified 506
studies, with a final yield of 25 studies. Only RCTs that
examined the effects of RT in adults with a mean age of 65
and older were included. The 25 studies quantified at least
one measure of muscle strength or morphology and suffi-
ciently described training variables (e.g., training period,
frequency, volume, intensity).
Study Appraisal and Synthesis Methods We quantified
the overall effects of RT on measures of muscle strength
and morphology by computing weighted between-subject
standardized mean differences (SMD
bs
) between interven-
tion and control groups. We analyzed the data for the main
outcomes of one-repetition maximum (1RM), maximum
voluntary contraction under isometric conditions (MVC),
and muscle morphology (i.e., cross-sectional area or vol-
ume or thickness of muscles) and assessed the method-
ological study quality by Physiotherapy Evidence Database
(PEDro) scale. Heterogeneity between studies was assessed
using I
2
and v
2
statistics. A random effects meta-regression
was calculated to explain the influence of key training
variables on the effectiveness of RT in terms of muscle
strength and morphology. For meta-regression, training
variables were divided into the following subcategories:
volume, intensity, and rest. In addition to meta-regression,
dose–response relationships were calculated independently
for single training variables (e.g., training frequency).
Results RT improved muscle strength substantially (mean
SMD
bs
=1.57; 25 studies), but had small effects on
measures of muscle morphology (mean SMD
bs
=0.42;
nine studies). Specifically, RT produced large effects in
both 1RM of upper (mean SMD
bs
=1.61; 11 studies) and
lower (mean SMD
bs
=1.76; 19 studies) extremities and a
medium effect in MVC of lower (mean SMD
bs
=0.76;
four studies) extremities. Results of the meta-regression
revealed that the variables ‘‘training period’’ (p=0.04)
This article is part of the Topical Collection on Exercise to improve
mobility in healthy aging.
&Ron Borde
rborde@uni-potsdam.de
Urs Granacher
urs.granacher@uni-potsdam.de
1
Division of Training and Movement Sciences, Research
Focus Cognition Sciences, University of Potsdam, Am Neuen
Palais 10, Building 12, 14469 Potsdam, Germany
2
Center for Human Movement Sciences, University Medical
Center Groningen, University of Groningen, Groningen,
The Netherlands
3
Faculty of Health and Life Sciences, Northumbria University,
Newcastle Upon Tyne, UK
123
Sports Med (2015) 45:1693–1720
DOI 10.1007/s40279-015-0385-9
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
and ‘‘intensity’’ (p\0.01) as well as ‘‘total time under
tension’’ (p\0.01) had significant effects on muscle
strength, with the largest effect sizes for the longest
training periods (mean SMD
bs
=2.34; 50–53 weeks),
intensities of 70–79 % of the 1RM (mean SMD
bs
=1.89),
and total time under tension of 6.0 s (mean
SMD
bs
=3.61). A tendency towards significance was
found for rest in between sets (p=0.06), with 60 s
showing the largest effect on muscle strength (mean
SMD
bs
=4.68; two studies). We also determined the
independent effects of the remaining training variables on
muscle strength. The following independently computed
training variables are most effective in improving measures
of muscle strength: a training frequency of two sessions per
week (mean SMD
bs
=2.13), a training volume of two to
three sets per exercise (mean SMD
bs
=2.99), seven to nine
repetitions per set (mean SMD
bs
=1.98), and a rest of
4.0 s between repetitions (SMD
bs
=3.72). With regard to
measures of muscle morphology, the small number of
identified studies allowed us to calculate meta-regression
for the subcategory training volume only. No single
training volume variable significantly predicted RT effects
on measures of muscle morphology. Additional training
variables were independently computed to detect the lar-
gest effect for the single training variable. A training period
of 50–53 weeks, a training frequency of three sessions per
week, a training volume of two to three sets per exercise,
seven to nine repetitions per set, a training intensity from
51 to 69 % of the 1RM, a total time under tension of 6.0 s,
a rest of 120 s between sets, and a rest of 2.5 s between
repetitions turned out to be most effective.
Limitations The current results must be interpreted with
caution because of the poor overall methodological study
quality (mean PEDro score 4.6 points) and the considerable
large heterogeneity (I
2
=80 %, v
2
=163.1, df =32,
p\0.01) for muscle strength. In terms of muscle mor-
phology, our search identified nine studies only, which is
why we consider our findings preliminary. While we were
able to determine a dose–response relationship based on
specific individual training variables with respect to muscle
strength and morphology, it was not possible to ascertain
any potential interactions between these variables. We
recognize the limitation that the results may not represent
one general dose–response relationship.
Conclusions This systematic literature review and meta-
analysis confirmed the effectiveness of RT on specific
measures of upper and lower extremity muscle strength and
muscle morphology in healthy old adults. In addition, we
were able to extract dose–response relationships for key
training variables (i.e., volume, intensity, rest), informing
clinicians and practitioners to design effective RTs for
muscle strength and morphology. Training period, inten-
sity, time under tension, and rest in between sets play an
important role in improving muscle strength and mor-
phology and should be implemented in exercise training
programs targeting healthy old adults. Still, further
research is needed to reveal optimal dose–response rela-
tionships following RT in healthy as well as mobility
limited and/or frail old adults.
Key Points
Meta-regression of data from 25 studies revealed that
a resistance training (RT) program with the goal to
increase healthy old adults’ muscle strength is
characterized by a training period of 50–53 weeks, a
training intensity of 70–79 % of the one-repetition
maximum (1RM), a time under tension of 6 s per
repetition, and a rest in between sets of 60 s.
Selecting a training frequency of two sessions per
week, a training volume of two to three sets per
exercise, seven to nine repetitions per set, and a rest
of 4.0 s between repetitions could also improve
efficacy of training.
The meta-regression revealed that none of the
examined training variables of volume (e.g., period,
frequency, number of sets, number of repetitions)
predicted the effects of RT on measures of muscle
morphology. Yet, RT to improve muscle
morphology seems to be effective using the
following independently computed training
variables: a training period of 50–53 weeks, a
training frequency of three sessions per week, a
training volume of two to three sets per exercise,
seven to nine repetitions per set, a training intensity
from 51 to 69 % of the 1RM, a total time under
tension of 6.0 s, a rest of 120 s between sets, and a
2.5-s rest between repetitions.
This meta-analysis provides preliminary data for
therapists, practitioners, and clinicians regarding
relevant RT variables and their dose–response
relationships to improve muscle strength and
morphology in healthy old adults.
1 Introduction
With the onset of the sixth decade in life, degenerative
processes affect the neuromuscular system in terms of
losses in muscle strength (dynapenia) and muscle mass
(sarcopenia) [13]. Neural (e.g., numerical loss of alpha
motoneurons) and morphological factors (e.g., reduced
1694 R. Borde et al.
123
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number and size of particularly type-II muscle fibers) as
well as their interaction are responsible for age-related
declines in muscle strength and mass [4]. There is evidence
that muscular weakness is highly associated with impaired
mobility and an increased risk for falls [5]. Moreover,
lower extremity muscle weakness was identified as the
dominant intrinsic fall-risk factor with a five-fold increase
in risk of falling [5]. Although the age-related decline in
muscle strength is associated with the loss in muscle size
(r=0.66–0.83, p\0.001) [6], longitudinal studies found
a 1.5 to five times greater decline in muscle strength
compared with muscle size [2,7]. In addition, there was a
stronger relationship between muscle strength and physical
performance or disability compared with the relationship
between muscle strength and mass [3].
Even though exercise cannot fully prevent aging of the
neuromuscular system, resistance training (RT) has a great
potential to mitigate age-related changes. Over the past
25–30 years, numerous studies have examined the effects
of RT on measures of muscle strength and morphology in
old adults. Frontera and Bigard [8] reviewed RT’s potential
to improve old adults’ muscle strength and morphology [6].
The review highlighted two studies that examined (a) the
impact of aging on muscle strength (i.e., maximal isoki-
netic knee extensor torque) and muscle size [i.e., cross-
sectional area (CSA) of the knee extensors] in elderly men
with a mean age of 65 years, followed over a 12-year
period [7], and (b) the effects of a 12-week RT program
(three sessions/week) on the same variables of muscle
strength and size in a cohort of 60- to 72-year-old men [9].
Findings from the 12-year longitudinal study revealed a
loss in isokinetic knee extensor torque of -24 % and in
quadriceps CSA of -16 %. In contrast, 12 weeks of RT at
80 % of the one-repetition maximum (1RM) resulted in an
increase in isokinetic torque of 16 % and in knee extensor
CSA of 11 %. Even though different cohorts were inves-
tigated in the two studies, the reported percentage rates are
impressive and may allow a cautious and preliminary
conclusion that biological aging of the neuromuscular
system can be mitigated or even reversed to a certain extent
[8].
Relying on an extensive database comprising individual
experimental studies and reviews, the American College of
Sports Medicine (ACSM) issued what is considered as the
gold standard of RT exercise prescription for healthy old
adults [10]. However, a careful examination of this position
stand suggests that the position stand was based on cate-
gory 4 or ‘expert level’ evidence on the evidence pyramid,
the lowest compared with evidence level 1 provided by
systematic reviews and meta-analyses [11]. Considering
that the already published meta-analyses are methodolog-
ically limited in terms of study selection criteria {inclusion
of non-randomized controlled trials (RCTs) [12,13] }, the
number of included training variables (e.g., traditional
variables such as training period, frequency, volume,
intensity only) [1416], and by focusing only on direct
comparisons of intervention groups (e.g., high- vs. low-
intensity) [14], it seems imperative and timely to quantify
the dose–response relationships through a systematic
review and meta-analysis. To the best of our knowledge, a
meta-analysis that only includes RCTs and is based on a
comparison between an intervention group and a physically
inactive control group is currently missing in the literature.
In contrast to direct comparisons (high- vs. low-intensity
intervention groups), we investigate the effects of RT in
sedentary older adults when starting RT compared with
physically inactive control groups to mitigate the age-re-
lated loss of muscle strength and morphology. A review of
existing data concerning so far overlooked variables such
as time under tension and rest time would more compre-
hensively inform clinicians and practitioners on how to
standardize RT. Finally, potential influences of the inclu-
ded training variables on the investigated effects of RT on
muscle strength and morphology will be examined using
meta-regression. Meta-regression will be performed for
relevant subcategories of training variables (i.e., volume,
intensity, rest). Thus, the purpose of the present systematic
review and meta-analysis is to determine the general
effects of RT on measures of muscle strength and mor-
phology. Furthermore, the present meta-analysis, using
meta-regression, examines how specific training variables
affect muscle strength and morphology. We constructed
dose–response relationships for key RT variables [17]
through the analysis of RCTs that have clearly improved
measures of muscle strength and morphology in healthy
old adults.
2 Methods
The present meta-analysis follows the recommendations of
the ‘Preferred Reporting Items for Systematic Reviews and
Meta-Analyses’ (PRISMA) [18].
2.1 Search Strategy
A systematic literature search was conducted from January
1984 to June 2015 in the online databases PubMed, Web of
Science, and The Cochrane Library. The following Medi-
cal Subject Headings (MeSH) of the United States National
Library of Medicine (NLM) and search terms were inclu-
ded in our Boolean search syntax: (‘‘resistance training’
OR ‘‘strength training’’ OR ‘‘weight training’’ OR ‘‘weight-
Resistance Training in Old Age 1695
123
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bearing exercise program’’) AND (old* OR elderly) AND
(sarcopenia OR dynapenia OR ‘‘muscle strength’’ OR
‘muscle morphology’). The search was limited to English
language, human species, age 65?years, full text avail-
ability, and RCTs.
2.2 Selection Criteria/Study Eligibility
Inclusion criteria were decided by the consensus state-
ments of two reviewers (RB, UG). In cases where RB and
UG did not reach agreement on inclusion of an article, TH
was contacted. In accordance with the PICOS approach
[18], inclusion criteria were selected by (a) population:
healthy subjects who were aged C60 years, with a study
mean age C65 years; (b) intervention: machine-based RT
containing a description of at least one training variable
(e.g., training intensity); (c) comparator: non-physically
active (e.g., health education, no intervention) control
groups; (d) outcome: at least one proxy of muscle strength
[e.g., 1RM, maximum voluntary contraction under iso-
metric conditions (MVC)] and/or muscle morphology
[e.g., CSA (cm
2
, mm), volume (kg, cm
3
), thickness (mm)];
and (e) study design: RCTs [18]. Studies were excluded if
they (a) did not meet the minimum requirements regarding
the description of training variables (e.g., period, fre-
quency, volume, intensity); (b) tested multiple repetition
maximum (e.g., 3RM); (c) did not report results ade-
quately (mean and standard deviation); (d) included frail,
mobility and/or cognitively limited and/or ill subjects;
(e) examined the effects of concurrent training (i.e.,
combined RT and endurance training); and (f) investigated
the effects of nutritional supplements in combination with
RT. If multiple outcomes (e.g., strength properties of
different muscle groups) were recorded within one study,
we chose the outcome with the highest functional rele-
vance for mobility in old age. In other words, (a) lower
extremity muscle strength tests were preferred over upper
extremity muscle strength tests; (b) isokinetic or dynamic
muscle strength tests were preferred over isometric tests;
and (c) multi-joint tests (e.g., leg press) were chosen rather
than single-joint strength tests (e.g., leg extension/curl). In
terms of muscle groups, sub-analyses were computed for
muscles of upper and lower extremities. Tests for the
assessment of muscle strength were analyzed separately
for the 1RM and MVC. Measures of muscle morphology
were included if one of the following devices was used:
magnetic resonance imaging, computed tomography, dual
x-ray absorptiometry, ultrasound, or BOD POD (air dis-
placement plethysmograph for whole-body densitometry).
In addition, one representative part of the respective
muscle (e.g., vastus lateralis) had to be assessed either by
muscle CSA, volume, or thickness when more than one
muscle was tested.
2.3 Coding of Studies
The studies were coded for the following variables:
(a) cohort; (b) age; (c) training variables [i.e., period, fre-
quency, volume (i.e., number of sets per exercise, number
of repetitions per set), intensity, time under tension (total,
isometric, concentric, eccentric), and rest (rest in between
sets and repetitions)]; (d) strength tests (i.e., 1RM, MVC);
(e) body region (i.e., upper limbs, lower limbs); and
(f) assessment of muscle morphology (i.e., CSA, muscle
volume, muscle thickness). The RT groups were subdi-
vided according to the applied training intensity: high-in-
tensity RT: C70 % 1RM; moderate-intensity RT:
51 % C1RM B69 %; and low-intensity RT: B50 %
1RM [16]. In the dose–response relationship figures pre-
sented in the ‘‘Results’’ section, diamonds, circles, and
triangles symbolize high- (C70 % 1RM), moderate-
(51 % C1RM B69 %), and low- (B50 % 1RM) intensity
RT groups. If exercise progression was realized over the
course of the intervention or if training variables were
reported, the average of these variables was calculated. If
results of pre- and post-tests were not conclusively repor-
ted, the authors of the respective studies were contacted via
email. Six out of 12 authors responded to our queries and
subsequently sent the missing data to calculate SMD
bs
.
2.4 Data Extraction
The main study characteristics (i.e., cohort, age, interven-
tion program, training variables, relevant outcomes) were
extracted in an Excel template/spreadsheet.
2.5 Assessment of Methodological Study Quality
Evaluation of methodological study quality was conducted
by two independent reviewers using the Physiotherapy
Evidence Database (PEDro) scale [19]. The PEDro scale
includes 11 items with three items from the Jadad scale
[20] and nine items from the Delphi list [21]. PEDro rates
RCTs on a scale from 0 (low quality) to 10 (high quality),
with a score of C6 representing a cut-off for high-quality
studies [19]. The first item of the PEDro scale (eligibility
criteria were specified) is used to establish external validity
and is therefore not included in the overall score. Maher
et al. [19] demonstrated fair-to-good inter-rater reliability,
with an intra-class correlation coefficient of 0.68 when
using consensus ratings generated by two or three inde-
pendent raters.
2.6 Statistical Analyses
To determine overall effects of RT on measures of muscle
strength and morphology and to establish dose–response
1696 R. Borde et al.
123
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relationships following RT in old adults, the between-sub-
ject standardized mean differences (SMD
bs
) were calcu-
lated according to the following formula: SMDi¼m1im2i
si
[22], where SMD
i
is the standardized mean difference of
one reported parameter (e.g., strength properties of
quadriceps muscle), m
1i
and m
2i
correspond to the mean of
the intervention and the control groups, respectively and s
i
is the pooled standard deviation. In accordance with Hedges
and Olkin, this formula was adjusted for sample size: g¼
13
4Ni9

[23], where N
i
is the total sample size of the
intervention group and control group. SMD
bs
is defined as
the difference between the post-test treatment and the
control means divided by the pooled standard deviation,
with 95 % confidence intervals (CIs). If two or more studies
reported the same training variable (e.g., training volume,
intensity, rest), weighted mean SMD
bs
over the studies was
calculated and presented as filled squares in the dose–re-
sponse relationship figures presented in the Sect. 3. Each
unfilled symbol illustrates SMD
bs
per single training group.
Within-subject standardized mean difference (SMD
ws
) was
calculated as follows: ±(mean of post-test -mean of pre-
test)/SD pre-value, where SD is the standard deviation.
Positive SMD values indicate a favorable effect of RT as
compared with the control condition. Our meta-analysis
was conducted using Review Manager version 5.3.4
(Copenhagen: The Nordic Cochrane Centre, The Cochrane
Collaboration, 2008). The included studies were weighted
by the standard error: SE SMDi
fg
¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
Ni
n1in2iþSMD2
i
2ðNi3:94Þ
r[22],
where n
1i
is the sample size of the intervention group and n
2i
is the sample size of the control group. Given that vari-
ability (e.g., different age and muscle groups) between
studies was large, we decided to compute a random-effects
model to estimate the effects of RT interventions [18,24].
According to Cohen, effect size values of 0.00 to B0.49
indicate small, values of 0.50 to B0.79 indicate medium,
and values C0.80 indicate large effects [25]. Heterogeneity
was assessed using I
2
and v
2
statistics. Furthermore, a
random effects meta-regression was performed to examine
whether the effects of RT on measures of muscle strength
and morphology are predicted according to the combined
values of the different training variables using the valid
software Comprehensive Meta-analysis version 3.3.070
(Biostat Inc., NJ, USA) [2628]. Subcategories were cre-
ated to extract the most important training variables of the
following combinations: training volume (i.e., period, fre-
quency, number of sets per exercise, number of repetitions
per set); training intensity (i.e., intensity, time under ten-
sion) and rest (rest in between sets and repetitions) [29,30].
For each subcategory, random-effects meta-regression was
performed to identify variables that best predict the
differences in the effect sizes of improvements in measures
of muscle strength and morphology. According to Toigo
and Boutellier [17], RT variables were previously reported
insufficiently in the literature. Thus, we decided to report
dose–response relationships of each RT variable that could
maximize improvements in measures of muscle strength
and morphology [17].
3 Results
Our systematic literature search identified 506 potentially
relevant studies (Fig. 1). A screening of the titles excluded
287 studies and then 109 duplicates were removed. The
remaining 110 studies were analyzed concerning the pre-de-
fined eligibility criteria, and 85 of these were removed.
Finally, 25 studies with a total of 819 participants (mean
sample size 33 subjects) and a mean age of 70.4 years (age
range 60–90 years) were included in the quantitative syn-
thesis (Table 1). Furthermore, four out of 25 studies investi-
gated the effects of high-intensity RT compared with low-
intensity RT (i.e., B50 % 1RM) [3134]. Three studies [31,
33,35] analyzed the effects of high-intensity RT compared
with RT at moderate intensities (i.e., 51 % C1RM B69 %).
3.1 Overall Findings
3.1.1 Effects of Resistance Training (RT) on Measures
of Muscle Strength
All 25 studies reported a favorable effect of RT on upper
and lower extremity muscle strength. Weighted mean
SMD
bs
for the effects of RT on muscle strength amounted
to mean SMD
bs
=1.57 (95 % CI 1.20–1.94; I
2
=80 %,
v
2
=163.10, df =32, p\0.01) (Fig. 2), which is
indicative of a large effect. In addition, in sub-analyses, we
determined the effects of RT on upper and lower body
strength tested by the 1RM. The analyses revealed
weighted mean SMD
bs
for the upper (mean SMD
bs
=1.61;
95 % CI 0.95–2.27; I
2
=86 %, v
2
=88.52, df =12,
p\0.01) and lower extremities (mean SMD
bs
=1.76;
95 % CI 1.20–2.31; I
2
=87 %, v
2
=144.47, df =19,
p\0.01), corresponding to large effects. There were no
studies that tested MVC in upper extremity muscles. Only
four studies measured leg muscle MVCs [34,3638]. A
medium effect (mean SMD
bs
=0.76; 95 % CI 0.40–1.31)
was found for MVC of lower limbs, with non-significant
heterogeneity (I
2
=0%,v
2
=2.89, df =4, p=0.58).
3.1.2 Effects of RT on Measures of Muscle Morphology
Nine studies examined the effects of RT on measures of
muscle morphology. An I
2
value of 0 % (v
2
=7.18,
Resistance Training in Old Age 1697
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
df =10, p=0.71) is indicative of non-existent hetero-
geneity, which is why no further sub-analyses were com-
puted (Fig. 3). We pooled weighted mean SMD
bs
across
the nine studies and observed a small effect (mean
SMD
bs
=0.42; 95 % CI 0.18–0.66) of RT on measures of
muscle morphology.
3.2 Methodological Study Quality
Table 2shows that the quality scores averaged 4.6 ±1.2
points (range 2–7). This is indicative of low method-
ological study quality even though only RCTs were
included. Three studies [35,41,43] were identified that
exceeded the pre-determined cut-off score [19] of 6 points
or higher.
3.3 Dose–Response Relationships of RT
on Measures of Muscle Strength
To improve the generalizability and external validity of our
study findings, we combined the results from 25 studies
that examined lower/upper extremity muscle strength
based on 1RM or MVC tests. Such pooling of data was
done to explore the effects of training variables on muscle
strength using meta-regression (Table 3). In addition to
meta-regression, dose–response relationships were
calculated independently using the effect size of charac-
teristics of each training variable (Table 4).
3.3.1 Meta-Regression Analysis for Training Variables
of Muscle Strength
Table 3shows the results of the meta-regression for three
subcategories: training volume, training intensity, and rest.
Concerning training volume, only training period predicted
(p=0.04) the effects of RT on muscle strength. In the
subcategory training intensity, the best predictors for the
explanation of effects of RT on muscle strength were
intensity (p\0.05) and time under tension (p\0.01). The
mode of muscle action (i.e., isometric, concentric, eccen-
tric) did not influence the effects of RT (p=0.41–0.91).
Rest in between sets (p=0.06, trend) and in between
repetitions did not predict strength gains.
3.3.2 Training Period
On average, the training period in the 25 studies lasted
21.2 weeks (range 6–52 weeks). Figure 4demonstrates
dose–response relationships for the training variable
‘training period’’. Mean SMD
bs
amounted to 1.57 (95 %
CI 1.20–1.94; I
2
=81 %, v
2
=163.10, df =32,
p\0.01). The longest training intervention lasted
Results of literature search
PubMed (n= 138), Web of Science (n= 185), Cochrane Library (n= 183)
(N= 506)
Potentially relevant papers remaining (n= 219)
Papers excluded on basis of eligibility criteria (n= 85)
no RCT (n = 32)
inadequate training description (n = 17)
no relevant outcome (n = 16)
no healthy subjects (n = 11)
mean age < 65 years (n = 9)
Included papers (n= 25)
Duplicate papers excluded (n= 109)
Papers excluded on basis of title (n= 287)
IdentificationScreening
EligibilityIncluded
Potentially relevant papers remaining (n= 110)
Fig. 1 Flow chart presenting the different steps of search and study selection. RCT randomized controlled trial
1698 R. Borde et al.
123
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Table 1 Studies examining the effects of RT on variables of muscle strength and muscle morphology in healthy old adults
Study Sex Age
(years)
NMuscles/functional
movement
Period
(weeks)
Strength
gain (%)
Gain in measure of
muscle morphology (%)
Within subject
SMD (SMD
ws
)
Between subject
SMD (SMD
bs
)
Training variables
Beneka et al.
[31]
M/
F
66–72
Mean
age:
69
M: 8/8/
8/8
HI/MI/
LI/
CG
F: 8/8/
8/8
HI/MI/
LI/
CG
Knee extension 16 1RM male
HI: 11
MI: 8
LI: 4
CG: -2 n.s.
1RM
female
HI: 15
MI: 7
LI: 3
CG: -1 n.s.
1RM male
HI: 1.36
MI: 1.14
LI: 0.43
CG: -0.16
1RM female
HI: 3.58
MI: 0.71
LI: 0.69
CG: -0.13
1RM male
HI vs. CG: 1.17
MI vs. CG: 0.77
LI vs. CG: 0.25
HI vs. MI: 0.33
HI vs. LI: 1.03
MI vs. LI: 0.60
1RM female
HI vs. CG: 1.92
MI vs. CG: 0.62
LI vs. CG: 0.83
n.s.
HI vs. MI: 3.18
HI vs. LI: 3.49
MI vs. LI: -0.10
RT: 39/week; 3 sets
HI: 4–6 reps; 90 % 1RM
MI: 8–10 reps; 70 % 1RM
LI: 12–14 reps; 50 % 1RM;
TUT: 6 s; 2 s con, 2–3 s
iso, 2–3 s ecc; RIS: 120 s;
RIR: 5 s; weight
machines
CG: no intervention
Charette et al.
[92]
F 64–86
Mean
age:
68
13/6 Leg press 12 1RM
RT: 27–106
CG: -2to
11 n.s.
1RM
RT: 5.92–11.00
CG: -0.12 to
1.17
1RM
RT vs. CG:
1.98–7.42
RT: 39/week; 3–6 sets; 6
reps;
1–5 weeks: 65 % 1RM
6–9 weeks: 70 % 1RM
10–12 weeks: 75 % 1RM;
TUT: 5 s; 2 s con, 3 s ecc;
weight machines
CG: no intervention
Daly et al. [93]M/
F
Mean
age:
75
8/8 Upper extremity 6 1RM
RT: -33 to
14 NPA
CG: -19 to
28 NPA
MRI/MV
RT: 1–4 NPA
CG:
-3to-1 NPA
1RM
RT: -0.07 to
1.00
CG: -0.41 to
0.11
MV
RT: -0.11 to
0.13
CG: -0.02 to
-0.08
1RM
RT vs. CG: -0.17
to 0.50
MV
RT vs. CG:
0.36–0.52
RT: 39/week;
1 week: 3 sets; 8 reps; 60 %
1RM
2 weeks: 3 sets; 8 reps;
70 % 1RM
3–6 weeks: 2 sets; 8 reps;
75 % 1RM;
RIS: 60–90 s; weight
machines and free weight
CG: no intervention
Resistance Training in Old Age 1699
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Table 1 continued
Study Sex Age
(years)
NMuscles/functional
movement
Period
(weeks)
Strength
gain (%)
Gain in measure of
muscle morphology (%)
Within subject
SMD (SMD
ws
)
Between subject
SMD (SMD
bs
)
Training variables
DeBeliso et al.
[94]
M/
F
63–83
Mean
age:
72
13/17/
13
FR/
PER/
CG
Lower extremity 18 1RM
FR: 50–67
PER: 70–81
CG: -5to
25
1RM
FR: 1.40–2.33
PER: 1.08–2.09
CG: -0.10 to
0.72
1RM
FR vs. CG:
1.33–1.80
PER vs. CG:
1.22–1.37
FR vs. PER:
0.07–0.21
RT: 29/week;
FR: 3 sets; 9RM
PER: 1–6 weeks; 2 sets;
15RM
7–12 weeks; 3 sets; 9RM
13–18 weeks; 4 sets; 6RM;
60 min; RIS: 120–180 s;
weight machines
CG: no intervention
Fatouros et al.
[95]
M 65–78
Mean
age:
70
8/8 Upper/lower
extremity
16 IS
RT: 14
CG: -1 n.s.
1RM upper
RT: 114
CG: 1 n.s.
1RM lower
RT: 77
CG: 3 n.s.
IS
RT: 1.71
CG: -0.08
1RM upper
RT: 6.65
CG: 0.02
1RM lower
RT: 7.23
CG: 0.20
IS
RT vs. CG: 1.38
1RM upper
RT vs. CG: 3.65
1RM lower
RT vs. CG: 4.88
RT: 39/week;
1–4 weeks: 2 sets; 13 reps;
55–60 % 1RM
5–8 weeks: 3 sets; 12 reps;
60–70 % 1RM
9–12 weeks: 3 sets; 10 reps;
70–80 % 1RM
13–16 weeks; 3 sets; 8 reps;
80 % 1RM; 45–50 min;
TUT: 7.5 s; 2–3 s con, 2 s
iso, 2–3 s ecc; RIS: 120 s;
RIR: 5 s; weight
machines
CG: no intervention
Fatouros et al.
[33]
M 65–78
Mean
age:
71
14/12/
14/
10
HI/MI/
LI/
CG
Upper/lower
extremities
24 1RM upper
HI: 73
MI: 48
LI: 34
CG: 2 n.s.
1RM lower
HI: 63
MI: 53
LI: 38
CG: -2 n.s.
1RM upper
HI: 3.52
MI: 2.25
LI: 1.77
C: 0.10
1RM lower
HI: 4.94
MI: 5.45
LI: 4.86
C: -0.18
1RM upper
HI vs. CG: 2.71
MI vs. CG: 1.93
LI vs. CG: 1.38
HI vs. MI: 0.78
HI vs. LI: 1.44
MI vs. LI: 0.63
1RM lower
HI vs. CG: 4.10
MI vs. CG: 3.75
LI vs. CG: 3.34
HI vs. MI: 0.62
HI vs. LI: 1.81
MI vs. LI: 1.22
RT: 39/week; 2–3 sets;
8–15 reps
HI: 80 % 1RM
MI: 60 % 1RM
LI: 40 % 1RM;
TUT: 7.5 s; 2–3 s con,
2–3 s iso, 2–3 s ecc;
HI RIS: 360 s
MI RIS: 240 s
LI RIS: 120 s;
RIR: 3–5 s; weight
machines
CG: no intervention
1700 R. Borde et al.
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Table 1 continued
Study Sex Age
(years)
NMuscles/functional
movement
Period
(weeks)
Strength
gain (%)
Gain in measure of
muscle morphology (%)
Within subject
SMD (SMD
ws
)
Between subject
SMD (SMD
bs
)
Training variables
Granacher et al.
[36]
M/
F
60–80
Mean
age:
67
20/20 Lower extremity 13 MVC
RT: 27
CG: -4 n.s.
MVC
RT: 1.24
CG: -0.16
MVC
RT vs. CG: 1.15
RT: 39/week; 3 sets; 10
reps; 80 % 1 RM; 60-min
sessions; RIS: 120 s;
weight machines;
CG: no intervention
Henwood and
Taaffe [40]
M/
F
65–84
Mean
age:
70
22/22 Upper/lower
extremities
8 1RM upper
RT: 2 n.s. –
25
CG: -3to
-14 n.s.
1RM lower
RT: 11–27
CG: -10 to
3 n.s.
1RM upper
RT: 0.06–0.54
CG: -0.30 to -
0.09
1RM lower
RT: 0.35–1.06
CG: -0.22 to
0.07
1RM upper
RT vs. CG:
3.62–5.02
1RM lower
RT vs. CG:
4.30–7.66
RT: 29/week; 3 sets; 8
reps; 75 % 1RM; 60-min
sessions; RIS: 60 s; TUT:
6 s; con: 3 s, ecc: 3 s;
weight machines
CG: no intervention
Hortobagyi
et al. [34]
M/
F
66–83
Mean
age:
72
9/9/9
HI/LI/
CG
Leg press 10 MVC
HI: 24 n.s.
LI: 28 n.s.
CG: 2 n.s.
IS
HI: 38 n.s.
LI: 29 n.s.
CG: 1 n.s.
1RM
HI: 35 n.s.
LI: 33 n.s.
CG: 3 n.s.
MVC
HI: 1.06
LI: 1.00
CG: -0.10
IS
HI: 1.17
LI: 0.84
CG: -0.02
1RM
HI: 1.05
LI: 0.78
CG: -0.10
MVC
HI vs. CG: 0.89
LI vs. CG: 0.67
HI vs. LI: 0.03
n.s.
IS
HI vs. CG: 0.86
LI vs. CG: 0.37
HI vs. LI: 0.45
n.s.
1RM
HI vs. CG: 1.05
LI vs. CG: 0.52
HI vs. LI: 0.41
n.s.
RT: 3 9/week;
HI: 5 sets; 4–6 reps; 80 %
1RM
LI: 5 sets; 8–12 reps; 40 %
1RM;
TUT: 3 s; 1–2 s con, 1–2 s
ecc; RIS:
120 s; weight machines
CG: no intervention
Resistance Training in Old Age 1701
123
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Table 1 continued
Study Sex Age
(years)
NMuscles/functional
movement
Period
(weeks)
Strength
gain (%)
Gain in measure of
muscle morphology (%)
Within subject
SMD (SMD
ws
)
Between subject
SMD (SMD
bs
)
Training variables
Hunter et al.
[96]
M/
F
61–77
Mean
age:
66
14/14/
14
HI/VI/
CG
Knee extension/
elbow flexion
25 1RM
HI: 13–24
VI: 10–28
CG: -6to
-2 n.s.
BP/FFM
HI: 4
VI: 4
CG: 1 n.s.
1RM
HI: 0.43–0.74
VI: 0.21–0.75
CG: -0.18 to -
0.04
FFM
HI: 0.19
VI: 0.17
CG: 0.03
1RM
HI vs. CG:
0.85–1.13
VI vs. CG:
0.05–0.67
HI vs. VI:
0.61–0.96 n.s.
FFM
HI vs. CG: 0.38
VI vs. CG: -0.23
HI vs. CG: 0.71
n.s.
RT: 3 9/week; 2 sets; 10
reps; 45-min session;
RIS: 120 s; weight
machines
HI: 80 % 1RM
VI: 50, 65, 80 % 1RM
across the 3 sessions per
week
CG: no intervention
Judge et al. [43]M/
F
C75
Mean
age:
80
28/27 Lower extremity 13 1RM
RT: 12
CG: -3 n.s.
1RM
RT: 0.64
CG: -0.05
1RM
RT vs. CG: 0.11
RT: 39/week; 3 sets; 12
reps; 75 % RM; 45-min
session; TUT: 4 s; 2 s
con, 2 s ecc; RIS:
120–180 s; RIR: 1–2 s;
weight machines
CG: no intervention
Kalapotharakos
et al. [35]
M/
F
60–74
Mean
age:
65
11/12/
10
HI/MI/
CG
Upper/lower
extremities
12 1RM upper
HI: 66
MI: 43
CG: -1 n.s.
1RM lower
HI: 78
MI: 44
CG: 0 n.s
CT/CSA
HI: 10
MI: 7
CG: -1 n.s.
1RM upper
HI: 2.73
MI: 1.62
CG: -0.04
1RM lower
HI: 3.13
MI: 1.45
CG: 0.02
CSA
HI: 0.34
MI: 0.37
CG: -0.02
1RM upper
HI vs. CG: 2.11
MI vs. CG: 1.47
HI vs. MI: 0.50
1RM lower
HI vs. CG: 2.51
MI vs. CG: 1.51
HI vs. MI: 0.97
CSA
HI vs. CG: 0.38
MI vs. CG: 0.34
HI vs. MI: 0.10
RT: 39/week; 3 sets;
HI: 8 reps; 80 % 1RM
MI: 15 reps; 60 % 1RM;
TUT: 6 s; 2 s con, 2 s iso,
2 s ecc; RIS: 120 s; RIR:
2–3 s; weight machines
CG: no intervention
Kalapotharakos
et al. [71]
M 61–75
Mean
age:
68
9/9 Lower extremity 10 1RM
RT: 24
CG: 0 n.s.
1RM
RT: 0.83
CG: 0.01
1RM
RT vs. CG: 1.50
RT: 39/week; 3 sets; 15
reps; 60 % 1RM; 60-min
session; RIS: 120 s;
weight machines
CG: no intervention
1702 R. Borde et al.
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Table 1 continued
Study Sex Age
(years)
NMuscles/functional
movement
Period
(weeks)
Strength
gain (%)
Gain in measure of
muscle morphology (%)
Within subject
SMD (SMD
ws
)
Between subject
SMD (SMD
bs
)
Training variables
Lovell et al.
[97]
M/
F
70–80
Mean
age:
74
12/12 Leg extension 16 1RM
RT: 90
CG: -1 n.s.
CT/LM
RT: 7
CG: 1 n.s.
1RM
RT: 5.97
CG: -0.07
LM
RT: 0.14
CG: 0.03
1RM
RT vs. CG: 4.33
LM
RT vs. CG: 0.10
RT: 39/week; 3 sets; 6–10
reps; 70–90 % 1RM;
RIS: 120 s; weight
machines
CG: no intervention
Miszko et al.
[98]
M/
F
65–90
Mean
age:
72
13/15 Lower extremity 16 1RM upper
RT: 14
CG: -1 n.s.
1RM lower
RT: 23
CG: 5 n.s.
1RM upper
RT: 0.28
CG: 0.01
1RM lower
RT: 0.43
CG: 0.11
1RM upper
RT vs. CG: 0.33
1RM lower
RT vs. CG: 0.53
RT: 39/week; 3 sets; 6–8
reps;
1–8 weeks: 50–70 % 1RM
9–16 weeks: 80 % 1RM;
TUT: 4 s; 4 s con; weight
machines ?free weights
CG: no intervention
Morse et al.
[99]
M 70–82
Mean
age:
74
13/8 Lower extremity
(ankle)
52 MVC
RT: 0 n.s.
-25
CG: -2to
5 n.s.
MRI/MV
RT: 15
CG: 2 n.s.
MVC
RT: 0.00–1.29
CG: -0.09 to
0.35
MV
RT: 1.53
CG: 0.22
MVC
RT vs. CG: 0.89
BD-1.51
MV
RT vs. CG: 1.03
RT: 39/week (2 9group
based, 1 9home based);
2-3 sets; 8 -10 reps;
80 % 1RM; rubber
bands, weight machines
CG: no intervention
Pinto et al. [41] F 60–69
Mean
age:
66
19/17 Lower extremity 6 1RM
RT: 22
CG: -1 n.s.
US/MT
RT: 11–21
CG: -5 to 7 n.s.
1RM
RT: 1.16
CG: -0.04
MT
RT: 0.59–0.90
CG: -0.38 to
0.24
1RM
RT vs. CG: 1.33
MT
RT vs. CG:
0.52–0.99
RT: 29/week;
1–3 weeks: 2 sets; 15–20
reps
4–6 weeks: 3 sets; 12–15
reps;
RIS: 120 s
CG: no intervention
Pyka et al. [39]M/
F
61–78
Mean
age:
68
8/6 Upper/lower
extremities
52 1RM upper
RT: 23–51
CG: -4to
-12 n.s.
1RM lower
RT: 27–62
CG: -3to
-12 n.s.
1RM upper
RT: 3.30–5.38
CG: -1.35 to
-0.63
1RM lower
RT: 4.50–9.51
CG: -1.45 to
-0.32
1RM upper
RT vs. CG:
4.69–6.12
1RM lower
RT vs. CG:
5.87–7.67
RT: 39/week; 3 sets; 8
reps; 65–75 % 1RM;
60-min sessions; TUT:
5 s; 2 s con, 3 s ecc; RIS:
60 s; weight machines
CG: no intervention
Resistance Training in Old Age 1703
123
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Table 1 continued
Study Sex Age
(years)
NMuscles/functional
movement
Period
(weeks)
Strength
gain (%)
Gain in measure of
muscle morphology (%)
Within subject
SMD (SMD
ws
)
Between subject
SMD (SMD
bs
)
Training variables
Raso et al. [42] F 60–77
Mean
age:
68
14/9 Trunk/lower
extremity
52 1RM
RT: 48
CG: 5 n.s.
N/A/FFM
RT: -3 n.s
CG: -2 n.s.
1RM
RT: 4.73
CG: 0.67
FFM
RT: -0.22
CG: -0.20
1RM
RT vs. CG: 2.20
FFM
RT vs. CG: 0.20
RT: 39/week; 3 sets; 12
reps; 55 % 1RM; 60-min
sessions; TUT: 4 s; 1–2 s
con, 2–3 s ecc; RIS:
120 s; weight machines
CG: no intervention
Reeves et al.
[37]
M/
F
65–79
Mean
age:
71
9/9 Lower extremity 14 MVC
RT: 15
CG: -12
n.s.
MVC
RT: 0.32
CG: -0.45
MVC
RT vs. CG: 0.52
NPA
RT: 39/week; 2 sets; 10
reps; 70–75 % 1RM;
TUT: 5 s; 2 s con, 3 s
ecc; RIS: 180 s; weight
machines
CG: no intervention
Rhodes et al.
[100]
F 65–75
Mean
age:
69
20/18 Upper/lower
extremity
52 1RM upper
RT: 9 n.s. –
25
CG: 0–2
n.s.
1RM lower
RT: 19–54
CG: -4to
1 n.s.
1RM upper
RT: 0.55–1.70
CG: 0.02–0.09
1RM lower
RT: 0.83–2.62
CG: -0.21 to
0.06
1RM upper
RT vs. CG:
0.60–1.25
1RM lower
RT vs. CG:
1.28–2.85
RT: 3 9/week; 3 sets; 8
reps; 75 % 1RM; 60-min
sessions; TUT: 6 s; 2–3 s
con, 3–4 s ecc
CG: no intervention
Strasser et al.
[72]
M/
F
C70
Mean
age:
74
15/14 Upper/lower
extremities
26 1RM upper
RT: 24–31
CG: 3 n.s.
1RM lower
RT: 15
CG: 9 n.s.
1RM upper
RT: 0.61–0.76
CG: 0.10–0.12
1RM lower
RT: 0.47
CG: 0.35
1RM upper
RT vs. CG:
1.00–1.40
1RM lower
RT vs. CG: 0.77
BD
RT: 39/week; 3–6 sets;
10–15 reps; 60–70 %
1RM
CG: no intervention
Tracy et al. [38]M/
F
65–80
Mean
age:
74
11/9 Knee extension 16 MVC
RT: 26
CG: -1 n.s.
1RM
RT: 27
CG: 2 n.s.
MVC
RT: 0.81
CG: -0.05
1RM
RT: 0.67
CG: 0.05
MVC
RT vs. CG: 0.27
1RM
RT vs. CG: 0.53
RT: 39/week; 3 sets; 10
reps; 80 % 1RM
CG: no intervention
1704 R. Borde et al.
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Table 1 continued
Study Sex Age
(years)
NMuscles/functional
movement
Period
(weeks)
Strength
gain (%)
Gain in measure of
muscle morphology (%)
Within subject
SMD (SMD
ws
)
Between subject
SMD (SMD
bs
)
Training variables
Vincent et al.
[32]
M/
F
60–83
Mean
age:
68
22/24/
16
HI/LI/
CG
Upper/lower
extremities,
trunk
(total strength)
24 1RM
HI: 18
LI: 17
CG: -1 n.s.
CT/FFM
HI: 0.4 n.s.
LI: -3.6 n.s.
CG: -1 n.s.
1RM
HI: 0.42
LI: 0.45
CG: -0.04
FFM
HI: 0.02
LI: -0.12
CG: -0.05
1RM
HI vs. CG: 0.66
LI vs. CG: 0.49
HI vs. LI: 0.25
n.s.
FFM
HI vs. C: 0.17
LI vs. C: 0.22
HI vs. LI: -0.06
NPA
RT: 39/week; 1 set;
HI: 8 reps; 80 % 1RM
LI: 13 reps; 50 % 1RM;
RIS: 120 s; weight
machines
CG: no intervention
Vincent et al.
[73]
M/
F
60–72
Mean
age:
69
10/10 Total body strength 24 1RM
RT: 16
CG: -2 n.s.
CT/FFM
RT: 4 n.s.
CG: 1 n.s.
1RM
RT: 1.35
CG: -0.15
FFM
RT: 0.57
CG: 0.13
1RM
RT vs. CG: 0.08
FFM
RT vs. CG: 1.30
RT: 39/week; 1 set; 8–13
reps; 50–80 % 1RM;
weight machines
CG: no intervention
1RM one-repetition maximum, BD baseline differences (p[0.05), BP BOD POD (air displacement plethysmograph for whole-body densitometry), CG control group, con concentric, CSA
cross-sectional area, CT computed tomography, ecc eccentric, Ffemale, FFM fat-free mass, FR fixed repetitions, HI high-intensity, IS isokinetic strength, iso isometric, LI low-intensity, LM
lean mass, Mmale, MI moderate-intensity, MRI magnetic resonance imaging, MT muscle thickness, MV muscle volume, MVC maximal voluntary contraction, N/A not available, NPA no
pvalues available, n.s. not significant, PER periodized repetitions, reps repetitions, RIR rest in between repetitions, RIS rest in between sets, RT resistance training, SMD
bs
difference between
the post-test treatment and the control means divided by the pooled standard deviation with 95 % confidence intervals, SMD
ws
difference of mean of post-test and mean of pre-test divided by
standard deviation of pre-value, TUT total time under tension, US ultrasonography, VI variable intensity
Resistance Training in Old Age 1705
123
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Fig. 2 Effects of RT on measures of muscle strength. CG control
group, CI confidence interval, FR fixed repetition training group, HI
high-intensity training group, IV inverse variance, LI low-intensity
training group, MI moderate-intensity training group, PER periodized
repetition training group, Random random effects model, RT resis-
tance training, SE standard error, SMD standardized mean difference,
Weight weight attributed to each study due to its statistical power
Fig. 3 Effects of RT on measures of muscle morphology. CG control
group, CI confidence interval, HI high-intensity training group, IV
inverse variance, LI low-intensity training group, MI moderate-
intensity training group, Random random effects model, RT resistance
training, SE standard error, SMD standardized mean difference,
Weight weight attributed to each study due to its statistical power
1706 R. Borde et al.
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Table 2 Physiotherapy Evidence Database (PEDro) scores of the 25 included studies
Authors Eligibility
criteria
Random
allocation
Concealed
allocation
Baseline
comparability
Blind
subjects
Blind
therapists
Blind
assessor
Adequate follow-up
dropout \15 %
Intention-to-
treat analysis
Between-group
comparisons
Point estimates
and variability
Score
Beneka et al.
[31]
-?- ? ---? - ? ? 5
Charette et al.
[92]
??- ? ---- - ? ? 4
Daly et al. [93]-?? - --?? - ? - 5
DeBeliso et al.
[94]
-?- ? ---- - ? ? 4
Fatouros et al.
[95]
-?- ? ---? - ? ? 5
Fatouros et al.
[33]
-?- ? ---? - ? ? 5
Granacher et al.
[36]
-?- - ---- - - ? 2
Henwood and
Taaffe [40]
??- ? ---? - ? ? 5
Hortobagyi
et al. [34]
-?- ? ---? - ? ? 5
Hunter et al.
[96]
??- ? ---? - ? ? 5
Judge et al.
[101]
??- ? --?? ? ? ? 7
Kalapotharakos
et al. [71]
-?- ? ---- - ? ? 4
Kalapotharakos
et al. [35]
-?- ? --?? - ? ? 6
Lovell et al.
[97]
??- ? ---? - ? ? 5
Miszko et al.
[98]
-?- - ---- - ? ? 3
Morse et al.
[99]
-?- - ---- - ? ? 3
Pinto et al. [41]??- ? --?? ? ? ? 7
Pyka et al. [39]-?- ? ---? - ? ? 5
Raso et al. [42]??- ? ---- - ? ? 4
Reeves et al.
[37]
-?- ? ---- - - ? 3
Rhodes et al.
[100]
??- ? ---? - ? ? 5
Resistance Training in Old Age 1707
123
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50–53 weeks and revealed the largest mean SMD
bs
, with a
value of 2.34.
3.3.3 Training Frequency
Twenty-five studies were included in this sub-analysis, and
the mean training frequency was 2.9 sessions per week,
with a mean SMD
bs
of 1.57 (range two to three sessions per
week; 95 % CI 1.20–1.94; I
2
=79 %, v
2
=163.10,
df =32, p\0.01). That is, two and three training sessions
per week produced large effects on measures of muscle
strength, with mean SMD
bs
of 2.13 (two sessions) and 1.49
(three sessions).
3.3.4 Number of Sets and Repetitions
In the 25 studies included in this sub-analysis, the number
of sets per exercise averaged 2.9 (range one to five sets)
and the number of repetitions per set averaged 10.0 (range
five to 16 repetitions). Mean SMD
bs
for number of sets and
repetitions per exercise were 1.57 (95 % CI 1.20–1.94;
I
2
=80 %, v
2
=163.10, df =32, p\0.001) and 1.61
(95 % CI 1.22–1.99; I
2
=81 %, v
2
=161.71, df =31,
p\0.01), indicative of large effects. Two to three sets per
exercise (mean SMD
bs
=2.99) and seven to nine repeti-
tions (mean SMD
bs
=1.98) resulted in the largest
improvements in muscle strength.
3.3.5 Training Intensity
Twenty-four studies were included in this sub-analysis, and
training intensity was classified as high (C70 % 1RM),
moderate (51 % C1RM B69 %), and low (B50 % 1RM)
[16]. The sub-analysis revealed a mean intensity of 69 % of
the 1RM (range 40–90 % 1RM) across studies. Figure 5
illustrates dose–response relationships for training inten-
sity, with a mean SMD
bs
of 1.63 (95 % CI 1.21–2.05;
I
2
=82 %, v
2
=157.81, df =28, p\0.01). The largest
effects on measures of muscle strength were found for
intensities of 70–79 % of the 1RM (mean SMD
bs
=1.89).
3.3.6 Time Under Tension per Repetition
Time under tension is an important variable to induce
adaptations in muscle strength and morphology [17]. In 14
studies, the total time under tension averaged 5.7 s per
repetition (range 3–7.5 s; mean SMD
bs
=1.60; 95 % CI
1.09–2.10; I
2
=82 %, v
2
=102.65, df =18, p\0.01).
The largest effect was shown for 6 s, with a mean SMD
bs
of 3.61. Figure 6shows the dose–response relationships for
the training variable ‘‘time under tension’’. In addition, the
mean time under tension was 2.3 s for isometric (range
2–2.5 s; SMD
bs
=2.48; 95 % CI 1.36–3.32; I
2
=83 %,
Table 2 continued
Authors Eligibility
criteria
Random
allocation
Concealed
allocation
Baseline
comparability
Blind
subjects
Blind
therapists
Blind
assessor
Adequate follow-up
dropout \15 %
Intention-to-
treat analysis
Between-group
comparisons
Point estimates
and variability
Score
Strasser et al.
[72]
??- ? ---- - ? ? 4
Tracy et al. [38]-?- ? --?- - ? ? 5
Vincent et al.
[73]
-?- ? ---? - ? ? 5
Vincent et al.
[32]
-?- ? ---- - ? ? 4
Mean score 4.6
?indicates a ‘‘yes’’ score, -indicates a ‘‘no’’ score
1708 R. Borde et al.
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v
2
=47.19, df =8, p\0.01), 2.2 s for concentric (range
1.5–4.0 s; SMD
bs
=2.18; 95 % CI 1.26–2.54; I
2
=84 %,
v
2
=101.94, df =16, p\0.01), and 2.5 s for eccentric
actions (range 1.5–3.5 s; SMD
bs
=2.28; 95 % CI
1.36–2.79; I
2
=87 %, v
2
=123.06, df =16, p\0.01).
During the isometric mode, a time under tension of 2.0 s
with a mean SMD
bs
of 2.70 appears most effective. In the
concentric and eccentric modes, times under tension of
2.5 s (mean SMD
bs
=3.44) and 3.0 s (mean
SMD
bs
=2.98) seem to be most effective.
3.3.7 Rest Time (Rest in Between Sets and Repetitions)
Based on data from 17 studies, we computed dose–re-
sponse relationships regarding rest time between sets and/
or repetitions. The mean rest time between sets was 132 s
(range 60–360 s; mean SMD
bs
=1.87; 95 % CI
1.35–2.38; I
2
=84 %, v
2
=138.61, df =22, p\0.01),
and between repetitions (five studies) it was 3.9 s (range
1.5–5 s; mean SMD
bs
=2.24; 95 % CI 1.52–2.31;
I
2
=83 %, v
2
=47.19, df =8, p\0.01). Figure 7
shows the dose–response relationships for the training
variable ‘‘rest in between sets’’. Eleven out of 17 studies
used 120 s of rest in between sets, resulting in a mean
SMD
bs
of 1.57. With reference to the results of two
studies [39,40], a rest in between sets of 60 s appears to
be most effective to increase muscle strength (mean
SMD
bs
=4.68) (Fig. 7). A rest time between repetitions
of 4.0 s seems to be most effective, coupled with a mean
SMD
bs
of 3.72.
Table 3 Meta-regression for training variables of different subcategories to predict RT effects on muscle strength
Coefficient Standard error 95 % lower CI 95 % upper CI Z value Pvalue
Training volume
Training period 0.0316 0.0155 0.0012 0.0619 2.04 0.04
Training frequency 0.0900 0.3315 -0.5598 0.7397 0.27 0.79
Number of sets 0.1142 0.1810 -0.2406 0.4690 0.63 0.53
Number of repetitions per set 0.0219 0.0585 -0.0927 0.1366 0.37 0.71
Training intensity
Training intensity 0.0182 0.0052 0.0084 0.0288 3.57 0.01
Time under tension 0.3154 0.1094 0.1010 0.5297 2.88 0.01
Rest
Rest in between sets 0.0095 0.0051 -0.0006 0.0196 1.85 0.06
Rest in between repetitions 0.1600 0.2255 -0.282 0.6019 0.71 0.48
CI confidence interval, RT resistance training
Table 4 Training variables with largest mean SMD
bs
Training variables Measures of muscle strength Measures of muscle morphology
Highest value Mean SMD
bs
Highest value Mean SMD
bs
Training period [weeks] 50–53 2.34 50–53 0.59
a
Training frequency [sessions per week] 2 2.13 3 0.38
Number of sets per exercise 2–3 2.99 2–3 0.78
a
Number of repetitions [per set] 7–9 1.98 7–9 0.49
Training intensity [% of 1RM] 70–79 1.89 51–69 0.43
Time under tension (total) [s] 6.0 3.61 6 0.36
a
Time under tension (isometric mode) [s] 2.0 2.70
a
2.0 0.36
a
Time under tension (concentric mode) [s] 2.5 3.44 2.0 0.36
a
Time under tension (eccentric mode) [s] 3.0 2.98 2.0 0.36
a
Rest in between sets [s] 60 4.68
a
120 0.30
Rest in between repetitions [s] 4 3.72
a
2.5 0.36
a
The content of this table is based on individual training variables with no respect for interaction between training variables
SMD
bs
between-subject standardized mean difference, 1RM one-repetition maximum
a
Based on less than three studies
Resistance Training in Old Age 1709
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0
1
2
3
4
5
6
7
5 6 7 8 9 10111213
Standardized mean difference
Training period (weeks)
0 6-9 10-13 14-17 18-21 … 24-27 … 50-53
Fig. 4 Dose-response
relationships for training period
and measures of muscle strength
following resistance training.
Each unfilled symbol illustrates
the SMD
bs
per single study.
Filled black squares represent
the weighted mean SMD
bs
of all
studies. Diamonds,circles, and
triangles symbolize high-,
moderate-, and low-intensity
resistance training groups,
respectively. SMD
bs
between-
subject standardized mean
difference
0
1
2
3
4
5
6
7
Standardized mean difference
Training intensity (%)
0 ≤ 50 51-69 70-79 80-89 ≥ 90
Fig. 5 Dose-response
relationships for training
intensity and measures of
muscle strength following
resistance training. Each
unfilled symbol illustrates the
SMD
bs
per single study. Filled
black squares represent the
weighted mean SMD
bs
of all
studies. Diamonds,circles, and
triangles symbolize high-,
moderate-, and low-intensity
resistance training groups,
respectively. SMD
bs
between-
subject standardized mean
difference
1710 R. Borde et al.
123
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0
1
2
3
4
5
6
7
8
765
43
Standardized mean difference
Time under tension (s)
0
Fig. 6 Dose-response
relationships for total time
under tension and measures of
muscle strength following
resistance training. Each
unfilled symbol illustrates the
SMD
bs
per single study. Filled
black squares represent the
weighted mean SMD
bs
of all
studies. Diamonds,circles, and
triangles symbolize high-,
moderate-, and low-intensity
resistance training groups,
respectively. SMD
bs
between-
subject standardized mean
difference
0
1
2
3
4
5
6
7
0 50 100 150 200 250 300 350 400
Standardized mean difference
Rest in-between sets (s)
Fig. 7 Dose-response
relationships for rest in between
sets and measures of muscle
strength following resistance
training. Each unfilled symbol
illustrates the SMD
bs
per single
study. Filled black squares
represent the weighted mean
SMD
bs
of all studies. Diamonds,
circles, and triangles symbolize
high-, moderate-, and low-
intensity resistance training
groups, respectively. SMD
bs
between-subject standardized
mean difference
Resistance Training in Old Age 1711
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3.4 Dose–Response Relationships of RT
on Measures of Muscle Morphology
3.4.1 Meta-Regression Analyses for Training Variables
of Muscle Morphology
Due to the low number of studies, we performed meta-re-
gression only for the subcategory ‘‘training volume’’. The
regression analysis revealed that no variable within the
training volume subcategory (i.e., period, frequency, num-
ber of sets, number of repetitions) produced significant
effects (p=0.52–0.94) on measures of muscle morphology.
3.4.2 Training Period
Pooled data from nine studies revealed a mean training period
of 24.0 weeks (range 6–52 weeks), with a mean SMD
bs
of 0.42
(95 % CI 0.18–0.66; I
2
=0%, v
2
=7.18, df =10,
p=0.71). With reference to the results of one study [41], a
training period of 6 weeks appeared to be most effective to
improve measures of muscle morphology, with an SMD
bs
of
0.66. Of note, the results of the two studies that used
50–53 weeks as a training period showed a slightly lower effect
on measures of muscle morphology (mean SMD
bs
=0.59).
3.4.3 Training Frequency
Our sub-analysis included nine studies and revealed a mean
training frequency of 2.9 training sessions per week (range
two to three sessions per week), with a mean SMD
bs
of 0.42
(95 % CI 0.18–0.66; I
2
=0%, v
2
=7.18, df =10,
p=0.71). The results of one study [41] suggested the largest
improvement in measures of muscle morphology with two
(SMD
bs
=0.66) compared with three sessions per week
(mean SMD
bs
=0.38). Of note, eight out of nine studies
examined the effects of three training sessions per week.
3.4.4 Number of Sets and Repetitions
Based on nine studies, the average number of sets per
exercise was 2.3 (range one to three sets). On average, 10.6
repetitions (range eight to 16 repetitions) were performed
per set. The mean SMD
bs
for number of sets as well as
repetitions per exercise was 0.54 (95 % CI 0.30–0.78;
I
2
=0%,v
2
=7.25, df =10, p=0.70) and 0.42 (95 %
CI -0.32–0.90; I
2
=0%,v
2
=0.08, df =1, p=0.77),
indicative of moderate and small effects, respectively. Two
to three sets per exercise (mean SMD
bs
including two
studies =0.78) and seven to nine repetitions (mean
SMD
bs
=0.49; six studies) resulted in the largest
improvements in measures of muscle morphology based on
findings of more than one study. One study conducting RT
with 16–18 repetitions per set reported an SMD
bs
of 0.66.
3.4.5 Training Intensity
Eight studies that reported training intensities were classified as
high (C70 % 1RM), moderate (51 % C1RM B69 %), and
low (B50 % 1RM) [16]. Mean intensity across studies was
71 % of the 1RM (range 50–80 % of 1RM), with a mean
SMD
bs
of 0.38 (95 % CI 0.13–0.64; I
2
=0%, v
2
=6.61,
df =9, p=0.68). Exercise at a moderate intensity between 51
and 60 % of the 1RM produced the greatest effects on measures
of muscle morphology, with a mean SMD
bs
of 0.43 (four
studies). One study showed the same effect (SMD
bs
=0.43) on
muscle volume using an intensity of 70–79 % of 1RM.
3.4.6 Time Under Tension per Repetition
Based on two studies, the total time under tension averaged
5.3 s, with a mean SMD
bs
of 0.31 (range 4–6 s; 95 % CI -
0.18 to 0.80; I
2
=0%,v
2
=0.10, df =2, p=0.95). The
largest effect occurred at 6 s, with a mean SMD
bs
of 0.36
(one study). Considering specific muscle action modes,
only one study [35] reported time under tension during
isometric muscle actions and two studies [35,42] reported
time under tension for concentric and eccentric muscle
actions. The mean time under tension was 2.0 s for the
isometric mode (SMD
bs
=0.36; 95 % CI 1.13–4.27;
I
2
=75 %, v
2
=7.98, df =2, p=0.02), 1.8 s for the
concentric mode (range 1.5–2 s; SMD
bs
=0.31; 95 % CI
-0.18 to 0.80; I
2
=0%, v
2
=0.10, df =2, p=0.95),
and 2.2 s for the eccentric mode (SMD
bs
=0.31; 95 % CI
-0.18 to 0.80; I
2
=0%, v
2
=0.10, df =2, p=0.95).
The most effective time under tension appears to be 2.0 s
for isometric, concentric, and eccentric muscle actions
(SMD
bs
=0.36; one study), respectively.
3.4.7 Rest Time (Rest in Between Sets and Repetitions)
In each of the six studies, the mean rest time was 120 s
between sets. Only one study [35] provided detailed
information regarding rest time between repetitions (2.5 s).
The mean SMD
bs
was 0.30 for rest in between sets (95 %
CI 0.04–0.57; I
2
=0%,v
2
=1.74, df =7, p=0.97) and
0.36 for rest in between repetitions (95 % CI -0.24 to
0.96; I
2
=0%,v
2
=0.00, df =1, p=0.95).
4 Discussion
To the best of our knowledge, this is the first systematic
literature review and meta-analysis that provides an inte-
grated overview of the general effectiveness of RT on
measures of muscle strength and morphology in healthy
old adults. The results from the 25 eligible RCTs suggest a
large and systematic training effect of RT on muscle
1712 R. Borde et al.
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strength (Fig. 2) and a small effect on measures of muscle
morphology (Fig. 3). We also performed a meta-regression
analysis to determine how such training variables as vol-
ume, intensity and rest modify the RT effects on measures
of muscle strength and morphology. Additional dose–re-
sponse relationships of each training variable were com-
puted independently from the other training variables
(Table 4). Moreover, we discuss the findings with refer-
ence to the relevant literature concerning the general
effects and dose–response relationships following RT in
healthy old adults. If no age-group specific information was
available in the literature, we extended our search and
discussion to findings regarding the effects of RT in heal-
thy young adults.
4.1 Effects of RT on Measures of Muscle Strength
and Morphology in Healthy Old Adults
In healthy old adults, RT improved muscle strength sub-
stantially (13–90 %; 25 studies) and measures of muscle
morphology to a smaller extent (1–21 %; nine studies). The
results seem to suggest that the various forms of RT
reviewed here have a greater potential to improve healthy
old adults’ ability to generate maximal voluntary force
compared with the potential to improve measures of mus-
cle morphology (mean SMD
bs
=1.57 vs. 0.42). These
findings are in line with the results of two meta-analyses,
which examined the effects of RT on muscle strength [12]
and size [44] in healthy as well as frail and/or disabled
middle-aged and/or old adults (range 50–95 years) and
reported increases in muscle strength and size of 24–33 %
and 1.5–16 %, respectively [1316]. Recent imaging,
magnetic brain stimulation, and peripheral nerve stimula-
tion studies seem to lend support to the emerging hypoth-
esis that life-long RT could be an important non-
pharmaceutical intervention to slow the age-related neural
dysfunction through which muscle strength loss can be
reduced [4554]. This prediction is corroborated by in vitro
evidence suggesting that age and disuse do not affect
intrinsic upper- and lower-limb skeletal muscle function
even in the oldest-old. While age does affect in vivo whole
muscle function, which is exacerbated by disuse [55], RT
could effectively counteract the age-related strength loss.
The effectiveness of RT was investigated by the present
and several previous reviews [1216]. Further, Delmonico
et al. [2] conducted a 5-year longitudinal study with well-
functioning men and women (N=1678) between the ages
of 70 and 79 years at baseline and measured knee extensor
torque using an isokinetic device and mid-femur CSA
using computer tomography at the beginning of the study
and after 6 years. It was found that decreases in isokinetic
leg muscle torque were two to five times greater than losses
in CSA with aging and that the change in quadriceps
muscle area only explains about 6–8 % of the between-
subject variability in the change in knee extensor torque.
This implies that the loss in muscle strength with age
(dynapenia) is more related to impairments in neural acti-
vation and/or reductions in the intrinsic force-generating
capacity of skeletal muscle [3]. Based on these findings, it
seems plausible to argue that primarily neural adaptations
account for training induced improvements in muscle
strength, with improvements in measures of muscle mor-
phology playing a minor role, particularly during the early
phase of RT [56]. This may explain the observed larger
gains in muscle strength compared with measures of
muscle morphology [2,7].
Despite the large effect of RT on muscle strength, there
was still considerable variation in the magnitude of adap-
tations between studies. Methodological issues may also
contribute to the large variability. For example, the mag-
nitude of response varies between body regions (upper vs.
lower limbs) or muscle groups. Adaptations to RT can be
highly specific, as training-induced changes in CSA can
differ between vastus lateralis and vastus medialis and can
also be muscle-length specific [57]. Another factor con-
tributing to the large variation in the response to RT is the
age of the subjects, which ranged widely, between 60 and
90 years. Spontaneous physical activity is much higher for
seniors at age 65 vs. 85, with some older individuals
making as few as 100–200 steps per day [58]. The obser-
vations from a large cross-sectional study that in some
healthy old cohorts there could be accelerated muscle
strength loss even as early as age 60–69 just further
strengthen the argument for prescribing RT for old adults
aging healthily [1].
4.2 Dose–Response Relationships of RT to Increase
Muscle Strength
The previous section established a large overall effect of
RT on maximal voluntary strength in healthy old adults.
We further performed meta-regression to identify training
variables that affected strength gains after conducting RT.
To specify the characteristic of each training variable with
the largest effect on muscle strength, we conducted addi-
tional analyses of independently computed dose–response
relationships.
4.2.1 Training Volume (Period, Frequency, Number
of Sets, Number of Repetitions)
Of the four training variables within training volume, meta-
regression identified training period only to have a signif-
icant effect on muscle strength. The longest training period
produced the largest increases in voluntary muscle strength
Resistance Training in Old Age 1713
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(mean SMD
bs
=2.34; 50–53 weeks). This result is based
on only four studies, as in the majority of the studies the
intervention duration ranged from 6 to 26 weeks. Curi-
ously, RT as short as 6–9 weeks was only slightly less
effective than RT of 50–53 weeks to improve muscle
strength (mean SMD
bs
=2.27; two studies). This obser-
vation suggests that RT is a suitable intervention to combat
weakness in healthy old adults because the nervous system
exhibits a rapid responsiveness to mechanical overload [4,
30,49,51,59]. In agreement with our findings, a current
meta-analysis that included 15 studies confirmed the out-
come of the general analysis that ‘‘training period’’ is the
only significant variable (p\0.01) to improve muscle
strength based on results of meta-regression [15]. These
authors reported that long (24–52 weeks) versus short
training periods (8–18 weeks) are more effective. In
addition, Kennis et al. [60] investigated detraining effects
following 1 year of RT on different variables of muscle
strength in old adults (60–80 years). After 7 years of
detraining, initially strength-trained participants still
exhibited improved muscle strength characteristics com-
pared with the control group. However, the authors pointed
out that RT cannot attenuate the age-related decline in
muscle strength and therefore suggested the application of
lifelong RT. These findings are in accordance with ACSM
recommendations [61].
In contrast to the results of meta-regression, additional
analyses of dose–response relationships indicated large
differences between two training sessions per week (mean
SMD
bs
=2.13) and three training sessions per week (mean
SMD
bs
=1.49). Because studies that administered two
sessions per week were also of short duration (6–9 weeks),
learning effects and neuronal adaptions must have con-
tributed strongly to the effects associated with two versus
three sessions per week [4,30,49,51,59]. In support of
our meta-regression data, DiFrancisco-Donoghue et al. [62]
reported similar increases in muscle strength after 9-week-
long programs consisting of one and two weekly sessions
in healthy old adults age 65–79. Furthermore, Taaffe et al.
[63] conducted a 24-week RT intervention with three dif-
ferent training frequencies (one to three sessions per week)
in old adults aged 65–79 years. The authors concluded that
a weekly or biweekly RT is equally effective to enhance
muscle strength as compared with three sessions per week.
Of note, our findings must be interpreted with caution
because the range of training frequencies was narrow (two
to three sessions per week). Finally, the current meta-
analysis confirms the conclusion reached by expert opinion
in the ACSM position stand that recommended RT fre-
quencies of at least two sessions per week [61].
Our analyses revealed little or no effect of the training
variables ‘‘number of sets per exercise’’ and ‘‘number of
repetitions per set’’ on strength gains. The additional
analyses of dose–response relationships of the number of
sets per exercise revealed an inverse U-shape, with the
largest effect (mean SMD
bs
=2.99) being prevalent in RT
protocols that applied two to three sets. However, it seems
that there is no difference between single versus multiple
sets in short-term RT (6 weeks) in old adults [64]. More-
over, these results suggested that during the early phase of
RT, number of sets was not the primary variable respon-
sible for increases in muscle strength and thickness in old
adults [64]. In addition, ‘‘number of sets’’ appears not to
result in neural adaptations because no differences were
found in electromyography activation of quadriceps mus-
cles between groups of old women (60–74 years) that
trained using single or multiple sets [64]. But although the
musculoskeletal system is adapted through the stimulus of
a single set to failure, multiple sets appear to be required to
add continued strength gains [65]. Multiple versus single
number of sets seemingly has a higher impact on muscle
strength in combination with longer training periods. In this
context, Radaelli et al. [66] examined the effects of one set,
three sets, and five sets of RT applied over a period of
6 months (three sessions per week) on measures of upper-
and lower-limb muscle strength and muscle thickness in
young untrained men age 24 years. Multiple versus single
sets improved muscle strength and muscle thickness par-
ticularly of the upper body more effectively, especially
with five sets of RT. In addition, two non-RCTs investi-
gated the impact of one set or three sets per exercise on
measures of muscle strength in old adults aged 60–80 years
[67,68]. Only the study examining a longer training period
(20 vs. 12 weeks) found a significant effect of three-set
versus one-set training on peak torque and maximum vol-
untary contraction of the knee extensors in elderly subjects
aged 65–78 years [68]. Together, there is a paucity of data
from high-quality RCTs concerning the effects of training
frequency on muscle strength, especially in the elderly.
Finally, concerning the training variable ‘‘number of
repetitions’’, the largest effects in strength gains occurred
when old adults used seven to nine repetitions per set
(mean SMD
bs
=1.98). Despite that the ‘‘number of repe-
titions’’ within a set in RT could provide a distinct physi-
ological stimulus for strength gains—with lower repetitions
predicted to be more effective [69]—our systematic search
identified no study that specifically examined the effects of
different repetitions per set on variables of muscle strength.
This can most likely be explained by the fact that the
variable ‘‘number of repetitions’’ is often used as an indi-
cator of training intensity, which is why previous research
efforts focused on ‘‘training intensity’’ rather than ‘‘number
of repetitions’’. In fact, it has been reported that a given
percentage of the 1RM determines the realized number of
repetitions within a set until failure [15]. For that reason,
lower repetitions resulted in higher training intensity that
1714 R. Borde et al.
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Content courtesy of Springer Nature, terms of use apply. Rights reserved.
induced greater acute neuromuscular fatigue accompanied
by greater hormonal responses [70].
4.2.2 Training Intensity (Intensity, Time Under Tension)
In support of the meta-regression results that training
intensity (p\0.01) predicted the effects of RT on muscle
strength, the largest effect of RT (intensity mean
SMD
bs
=1.89) on 1RM strength occurred when strength
training intensity was set at 70–79 % of 1RM (range
40–90 % 1RM, Fig. 5). Our systematic search identified
six studies that directly compared RT protocols of different
intensities [3135]. This analysis showed that high-inten-
sity RT produced the largest effects on muscle strength in
comparison to moderate- (high vs. moderate mean
SMD
bs
=0.60) or low-intensity (high vs. low mean
SMD
bs
=0.88) training regimes. Also, moderate-intensity
RT produced a larger effect on muscle strength compared
with low-intensity RT (moderate vs. low mean
SMD
bs
=0.93). The effects of moderate- and low-inten-
sity RT compared with a passive control group had a mean
SMD
bs
of 1.75 and 1.02 in favor of RT [31,3335,42,71
73].
Previous meta-analyses suggested similar effects of
high-intensity RT (C70 % 1RM) compared with moderate-
[e.g., mean SMD
bs
(high vs. moderate) =0.62] and low-
intensity [e.g., mean SMD
bs
(high vs. low) =0.88] RTs
[12,14,15] on muscle strength in healthy old adults. These
findings are in accordance with the ACSM position stand
that states higher intensities result in greater strength gain
in old adults [61]. Nevertheless, recent reviews rated the
importance of training intensity as a training variable to be
of minor relevance if no other training variables (i.e., time
under tension, rest time) were considered [15,74]. Training
intensity defined as the individual percentage of 1RM,
appears not to be as sensitive as the rate of perceived
exertion using, for instance, the OMNI resistance exercise
scale [75]. In other words, the number of repetitions con-
ducted at a given percentage of 1RM differs inter-indi-
vidually because of training status, and intra-individually
because of the muscle groups trained [75]. Therefore, the
1RM represents a method to regulate training intensity that
should always be combined with information about the
time under tension [17,74].
Total time under tension had a strong effect (p\0.01)
on strength gains, with 6 s per repetition producing the
largest effect size (mean SMD
bs
=3.61; 14 studies, range
3–7.5 s). The time under tension is an important variable
for mechano-biological adaptations, because different
times under tension affect different metabolic changes as
well as motor unit (MU) recruitment and MU firing rates
occurring during RT [17]. Furthermore, temporal distri-
bution of isometric, concentric, and eccentric muscle action
per repetition seemed to be also important [17]. However,
the mode of muscle action (isometric, concentric, eccen-
tric) had no effect on strength gains (p=0.41–0.91). Our
search identified 14 studies that reported information on
muscle action-specific time under tension per repetition
during RT (isometric: four studies, range 2.0–2.5 s; con-
centric: 14 studies, range 1.5–4 s; eccentric: 13 studies,
range 1.5–3.5 s). The most effective time under tension
amounted to 2.0 s (mean SMD
bs
=2.70), 2.5 s (mean
SMD
bs
=3.44), and 3.0 s (mean SMD
bs
=2.98) for iso-
metric, concentric, and eccentric muscle actions, respec-
tively. But to the best of our knowledge, there is no study
that compared the effects of contraction duration on
strength gains. The meta-analysis of Roig et al. [76] allows
us at least some insight into muscle action-specific adaptive
processes in healthy adults aged 18–65 years. These
authors stated that separate eccentric muscle actions pro-
duce larger gains in muscle strength and morphology
compared with concentric muscle actions. However, these
findings have to be interpreted with caution because in
several cases, isotonic RT is applied, which consists of
concentric and eccentric muscle actions, so that informa-
tion on muscle action-specific time under tension is needed.
It has previously been hypothesized that a longer eccentric
phase results in improved training efficiency because
eccentric loads affect the protein synthesis and muscle
activation and thus muscle hypertrophy and strength [77,
78]. The results concerning time under tension are limited
by the low number of studies and by a lack of direct
determination of the muscle action duration effects on
strength gains. For example, no study has performed RT
with longer contraction duration than 7.5 s per muscle
action. Based on our and previous findings [17], we rec-
ommend that authors report time under tension, measured
or estimated, as this seems an important variable underly-
ing gains in muscle strength and muscle morphology.
4.2.3 Rest (Rest in Between Sets and Repetitions)
Meta-regression revealed that rest between sets (p=0.06)
and repetitions did not modify the effects of RT on muscle
strength. Of the two specific studies that examined dose–
response relationship with respect to rest in between sets,
one using 60 s produced the largest mean SMD
bs
of 4.68 in
healthy old adults. The overall analysis is limited by a
uniform use of 120-s rest in between sets, resulting in a
mean SMD
bs
of 1.57 (Fig. 7). The recent study of Vil-
lanueva et al. [79] investigated the effects of short (60-s)
vs. long (240-s) rest intervals between sets on muscle
strength and lean body mass after 8-week RT (39/week,
2–3 sets, 4–6RM) in 22 old men aged 66 years. The find-
ings revealed that short rest intervals between sets resulted
in significant greater increases in leg press 1RM
Resistance Training in Old Age 1715
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
(p\0.001) and in lean body mass (p=0.001). Moreover,
it is suggested that less rest times produced greater levels of
fatigue, providing a stimulus which resulted in increases in
muscle strength [17,79,80]. Furthermore, Willardson [81]
hypothesized in a narrative review that shorter rests in
between sets are associated with a more prominent
hypertrophic effect. In addition, there is information in the
literature stating that the duration of rest in between sets
has to be configured to the training goal. Based on different
metabolic and hormonal loads, a narrative review sug-
gested that rest in between sets of 180–300 s is suitable for
improvements in maximal strength, 1–2 min for gains in
hypertrophy and 30–60 s for improvements in muscle
endurance [30,82].
The training variable ‘‘rest time between repetitions’
was computed independently to elucidate dose–response
relationships, and the results indicated that a 4.0-s rest in
between repetitions seems to be most effective to increase
muscle strength (mean SMD
bs
=3.72). However, this
finding is preliminary because it is based on one study with
three training groups only. Nevertheless, the variable ‘‘rest
in between repetitions’’ seems to be a significant mechano-
biological determinant of myocellular oxygen homeostasis
[17]. Therefore, it needs to be specified in RT protocols.
None of the five included studies reported the reason for
the duration of rest used between repetitions. Furthermore,
no other study compared the effects of in between repeti-
tions rest on strength gains at any age. Basically, the effi-
ciency of RT (i.e., duration of a single training session) is
influenced by the amount of rest in between repetitions.
However, longer rest times between repetitions prolong the
time of a single training session and may thus make
training less efficient. On the other hand, longer rest times
between repetitions might be particularly beneficial in old
adults because acute deteriorations in postural control were
reported following one bout of high-intensity RT exercise
(four sets) [83]. Longer rest times during RT exercises may
affect postural control to a lesser extent by reducing the
acute risk of falling during training [83]. This review
provided for the first time information on how to effec-
tively implement rest in between repetitions in RT proto-
cols for old adults. Based on the low number of studies
(five studies) and the results of meta-regression, these
findings should be interpreted with caution and further
studies are needed.
4.3 Dose–Response Relationships of RT to Improve
Measures of Muscle Morphology
To the best of our knowledge, no systematic review or
meta-analysis has examined whether changes in muscle
morphology would scale according to RT dose in healthy
old adults. Due to a low number of studies, we could only
examine the effects of training volume on measures of
muscle morphology. We found that variation in the volume
of RT had no effect on measures of muscle morphology. A
training period of 6 weeks and using 16–18 repetitions per
set during RT is ineffective for muscle hypertrophy. We
interpret this unexpected result [41] as an abnormality
caused by the choice of unusual training variables (6 weeks
of training; 16–18 repetitions per set), producing an SMD
bs
of 0.66 [41]. Nevertheless, a cumulative analysis of the
remainder of the studies revealed the following specific
effects on healthy old adults’ muscle morphology when
conducting RT with a training period of 50–53 weeks
(mean SMD
bs
=0.59), a training frequency of three ses-
sions per week (mean SMD
bs
=0.38), a training volume of
two to three sets per exercise (mean SMD
bs
=0.78), seven
to nine repetitions per set (mean SMD
bs
=0.49), a training
intensity of 51–69 % of the 1RM (mean SMD
bs
=0.43), a
total time under tension of 6 s (mean SMD
bs
=0.36), a
time under tension of 2.0 s for isometric, concentric, and
eccentric muscle actions (mean SMD
bs
=0.36 each),
respectively, a rest between sets of 120 s (mean
SMD
bs
=0.30), and a rest between repetitions of 2.5 s
(mean SMD
bs
=0.36). In general, our findings agree with
results reported previously [13,84,85]. The meta-analysis
of Peterson et al. [13] suggested that RT with a mean
training period of 21 weeks (three training sessions per
week), an intensity of 75 % of the 1RM, two to three sets
and ten repetitions with a 110-s rest in between sets was
effective to significantly increase lean body mass in old
adults (weighted pooled estimate 1.1 kg; 95 % CI 0.9–1.2).
The narrative reviews of Mayer et al. [84] and Petrella and
Chudyk [85] also illustrated dosage of training variables to
prevent the loss of muscle mass. These authors recom-
mended the following RT variables to prevent the loss of
muscle mass in old age: training period of 8–12 weeks,
three training sessions per week, training intensities of
60–80 % of the 1RM, three to four sets and eight to 12
repetitions per exercise. These recommendations are con-
sistent with the results of the present meta-analysis. How-
ever, we consider our findings preliminary with regard to
the effects of RT on measures of muscle morphology
because our systematic search identified only nine eligible
studies for inclusion in our quantitative sub-analyses and
meta-regression could not be performed for all
subcategories.
4.4 Limitations and Strengths of this Review
Even though the present review has identified the numer-
ical characteristics of the dose–response relationships, it is
a major limitation that such analyses fail to provide insights
into the physiological stimulus for increasing old adults’
muscle strength and muscle size. This is a particularly
1716 R. Borde et al.
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
relevant issue because the number of theories concerning
the stimulus for strength gains involves fatigue [80], total
work [34,59,86], hypoxia [87,88], and time under tension
[89] and these factors are often also cited as concurrently
acting as stimulus for muscle hypertrophy [3,90].
The ultimate aim was to establish a possible combina-
tion of a set of RT variables that provides an effective
training stimulus for slowing age-related muscle strength
and muscle mass loss. To investigate the effects of training
variables on muscle strength and morphology, subcate-
gories were created on the basis of best applicability for
practitioners and clinicians. Afterwards, a meta-regression
was performed to find best predictors for effects of RT on
measures of muscle strength and muscle morphology.
Indeed, we constructed a dose–response relationship from
individual RT variables as additional analyses. The vari-
ables may be most effective in improving measures of
muscle strength and morphology, but it is unclear if the
interaction between the so-specified variables would still
remain ‘optimal’. We recognize the limitation that our
results may not represent one such general dose–response
relationship. Modeling of training variables can, however,
address this issue; holding a set of RT variables constant
while changing the effects of one specific variable could
determine the unique effects of each training variable [91].
With regard to training volume, the training effects have to
be interpreted with caution because of the difficulty in
quantifying training volume if more than one exercise per
muscle is performed (e.g., leg press and knee extension/
curl). Furthermore, due to the nature of meta-analysis, we
focused on those strength outcomes with the highest
functional relevance (e.g., dynamic before isometric
strength tests). Thus, our findings are outcome specific and
cannot necessarily be transferred to different strength out-
comes that were not computed in the present study.
The methodological quality of the included studies is
rather low because only three out of 25 studies reached the
pre-determined cut-off score of 6 points on the PEDro scale
that stands for high-quality studies. Of note, possible sys-
tematic errors cannot be eliminated because important
points (e.g., blinding of subjects or therapists) for internal
validity were not considered in all included studies. Fur-
thermore, our findings of effects of RT on measures of
muscle morphology have to be considered as preliminary
because our systematic search identified only nine studies
based on our selected inclusion criteria. Another limitation
is that many studies failed to report the training variables.
Further, information regarding subject characteristics were
often incomplete (e.g., training status, age, health status)
and results were inconclusively reported (e.g., means and
standard deviation) so that in several cases we were not
able to compute SMDs. Future studies should present
detailed information and data sets on the investigated
cohorts, RT protocols, and study findings. In addition, large
heterogeneity was found across studies, which implies a
large variability in the tested muscle strength variables
(i.e., tests for upper- and lower-extremity muscles) and the
investigated cohorts (i.e., large age ranges from 60 to
90 years).
Despite these limitations, this systematic review and
meta-analysis is the first to provide an adequate overview
of RT effects on measures of muscle strength and muscle
morphology in one meta-analysis. The present meta-anal-
ysis analyzed sedentary old adults who commenced RT to
mitigate the age-related loss of muscle strength and mass.
In addition, we were able to extract crucial training vari-
ables, such as volume, intensity, and rest, and their dose–
response relationships for clinicians and practitioners
seeking to implement an effective RT in healthy old adults.
Furthermore, we undertook the first attempt to provide
dose–response relationships for other important training
variables such as time under tension and rest in between
sets and repetitions, albeit these were calculated indepen-
dently of other training variables.
5 Conclusion
This systematic literature review and meta-analysis showed
that the effects of RT on measures of muscle morphology
(mean SMD
bs
=0.42) were much smaller compared with
the effects on muscle strength (mean SMD
bs
=1.57) in
healthy old adults. The dose–response relationship analyses
showed that training period (50–53 weeks, p=0.04),
intensity (70–79 % 1RM, p\0.01), and time under ten-
sion (6 s, p\0.01) can significantly and independently
modify the RT effects on muscle strength in healthy old
adults. Data for other variables were insufficient to draw
firm conclusions. It seems that 60 s of rest between sets
(p=0.06; two studies), a training frequency of two ses-
sions per week, a training volume of two to three sets per
exercise, seven to nine repetitions per set, and 4.0 s
between repetitions appear to be the training variables that
could have the greatest and most rapid effects on improv-
ing maximal voluntary strength in healthy old adults.
RT with the following parameters seems to be effective
to improve measures of muscle morphology: a training
period of 50–53 weeks, a training frequency of three ses-
sions per week, a training volume of two to three sets per
exercise, seven to nine repetitions per set, a training
intensity from 51 to 69 % of the 1RM, a total time under
tension of 6.0 s, a rest of 120 s between sets and 2.5 s
between repetitions. Practitioners, clinicians, and therapists
should consult these findings with caution and only as an
initial attempt for a comprehensive analysis to characterize
RT variables for improving healthy old adults’ muscle
Resistance Training in Old Age 1717
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
morphology. Future studies should particularly focus on
the detailed description of training variables (e.g., time
under tension) to allow in-depth analysis of dose–response
relationships following RT in healthy, mobility limited,
and/or frail old adults.
Compliance with Ethical Standards
This work was supported by a grant from the German Research
Foundation (MU 3327/2-1). Ron Borde, Tibor Hortoba
´gyi, and Urs
Granacher declare that they have no conflicts of interest.
Open Access This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License (http://
creativecommons.org/licenses/by/4.0/), which permits unrestricted
use, distribution, and reproduction in any medium, provided you give
appropriate credit to the original author(s) and the source, provide a
link to the Creative Commons license, and indicate if changes were
made.
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... The aging process is associated with changes in older women affecting their daily routine, quality of life (QoL) and health. Sarcopenia is a syndrome that occurs after 60 years and is characterized by a progressive loss of muscle mass and strength that are associated with declines in functional capacity and loss of balance, and increases in the risk of falling [3][4][5]. ...
... RT is an effective method to increase fat-free mass, bone strength, muscle strength and functional capacity, and reduce risk factors for several diseases such as cardiovascular and metabolic diseases [3,4,6,7,9]. Filho et al. [10] reported that older women, after twenty weeks of strength training, improved functional capacity, strength and the ability to perform activities of daily life (ADL). ...
... The volunteers of the CG did not perform any systematic PA during the 16 weeks and maintained their daily routine. During the study, five older women dropped out (one from CG and TRT; three from PWT) due to illness (3) or not attending at least 85% of the sessions (2). ...
Article
Full-text available
Background: Physical activity (PA) and physical fitness are key factors for quality of life (QoL) for older women. The aging process promotes the decrease in some capacities such as strength, which affect the activities of daily life. This loss of strength leads to a reduction in balance and an increased risk of falls as well as a sedentary lifestyle. Resistance Training (RT) is an effective method to improve balance and strength but different RT protocols can promote different responses. Power training has a higher impact on the performance of activities of daily life. Therefore, our study aimed to analyze if different RT protocols promote individual responses in balance, QoL and PA levels of older women and which are more effective for the older women. Methods: Ninety-four older women were divided into four RT groups (relative strength endurance training, SET; Traditional strength training, TRT; absolute strength training, AST; power training, PWT) and one control group (CG). Each RT group performed a specific protocol for 16 weeks. At baseline and after 8 and 16 weeks, we assessed balance through the Berg balance scale; PA levels with a modified Baecke questionnaire and QoL with World Health Organization Quality of Life-BREF (WHOQOL-BREF) and World Health Organization Quality of Life-OLD module (WHOQOL-OLD). Results: Balance improved after 16 weeks (baseline vs. 16 weeks; p < 0.05) without differences between all RT groups. PWT (2.82%) and TRT (3.48%) improved balance in the first 8 weeks (baseline vs. 8 weeks; p < 0.05). PA levels increased in PWT, TRT and AST after 16 weeks (baseline vs. 16 weeks; p < 0.05). Conclusion: All RT protocols improved PA levels and QoL after 16 weeks of training. For the improvement of balance, QoL and PA, older women can be subjected to PWT, AST and SET, and not be restricted to TRT.
... Physical activity and nutrition play a crucial role in muscle strength [19,20]. The effectiveness of resistance training in muscle strength across different age and sex groups has been confirmed in several meta-analyses [21][22][23][24][25]. The effect of nutrition, especially protein intake, on muscle strength has been extensively investigated in many studies [26]. ...
... Thus, long-term maintenance/improvement of muscle strength is recommended not only for individuals with active lifestyles, such as athletes, but also for those with normal physical activity. Several meta-analyses have confirmed the effectiveness of resistance training in increasing muscle strength across age and sex groups [21][22][23][24][25]. There have also been several meta-analyses on the effect of protein intake on muscle strength [31][32][33][34][35][36][37]. ...
... This may be one of the reasons that protein intake alone could not effectively improve muscle strength. The idea that muscle mass alone cannot account for all the changes in muscle strength is supported by previous reviews and meta-analyses, which reported that resistance training has a more profound effect on muscle strength than on muscle mass [24,25,78]. Further, a cross-sectional study showed that muscle mass accounts for only 11-40% of muscle strength in older adults [79] and longitudinal studies have shown that muscle strength declined faster than did muscle mass in older adults [40,80]. ...
Article
Full-text available
Background Protein supplementation augments muscle strength gain during resistance training. Although some studies focus on the dose-response relationship of total protein intake to muscle mass or strength, the detailed dose-response relationship between total protein intake and muscle strength increase is yet to be clarified, especially in the absence of resistance training. Objective We aimed to assess the detailed dose-response relationship between protein supplementation and muscle strength, with and without resistance training. Design Systematic review with meta-analysis. Data Sources PubMed and Ichushi-Web (last accessed on March 23, 2022). Eligibility Criteria Randomized controlled trials investigating the effects of protein intake on muscle strength. Synthesis Methods A random-effects model and a spline model. Results A total of 82 articles were obtained for meta-analyses, and data from 69 articles were used to create spline curves. Muscle strength increase was significantly augmented only with resistance training (MD 2.01%, 95% CI 1.09–2.93) and was not augmented if resistance training was absent (MD 0.13%, 95% CI − 1.53 to 1.79). In the dose-response analysis using a spline model, muscle strength increase with resistance training showed a dose-dependent positive association with total protein intake, which is 0.72% (95% CI 0.40–1.04%) increase in muscle strength per 0.1 g/kg body weight [BW]/d increase in total protein intake up to 1.5 g/kg BW/d, but no further gains were observed thereafter. Conclusion Concurrent use of resistance training is essential for protein supplementation to improve muscle strength. This study indicates that 1.5 g/kg BW/d may be the most appropriate amount of total protein intake for maintaining and augmenting muscle strength along with resistance training.
... Mechanical tension is an important stimulus to achieving an increase in maximal strength (MSt), which is commonly induced by strength training [4][5][6]. While low intensities seem to be sufficient to induce hypertrophy [7,8], a load intensity of 60-80% of the one-repetition maximum (1RM) is generally recommended as an appropriate method to achieve both MSt and muscle hypertrophy [4,9]. From this, it can be hypothesized that high intensities seem to be more beneficial to achieve improvements in MSt [8,10]. ...
Article
Full-text available
Rebuilding strength capacity is of crucial importance in rehabilitation since significant atrophy due to immobilization after injury and/or surgery can be assumed. To increase maximal strength (MSt) strength training is commonly used. Literature from animal studies shows that long-lasting static stretching (LStr) interventions can also produce significant improvements in MSt with a dose-response relationship with stretching times from 30 min to 24 hours per day, however, there is limited evidence in human studies. Consequently, the aim of this study is to investigate the dose-response relationship of long-lasting static stretching on MSt. 70 active participants (f=30, m=39; age: 27.4±4.4years, height: 175.8±2.1cm, and weight: 79.5±5.9kg) were divided into three groups: IG1 and IG 2 both performed unilateral stretching continuously for one (IG1) or two hours (IG2) respectively per day for six weeks, while CG served as non-intervened control. MSt was determined in the plantar flexors in the intervened as well as in the non-intervened control leg to investigate the contralateral force transfer. Two-way ANOVA showed significant interaction ef-fects for MSt in the intervened leg (ƞ²=0.325, p<0.001) and in the contralateral control leg (ƞ²=0.123, p=0.009) dependent upon stretching time. From this, it can be hypothesized that the stretching duration has an influence on MSt increases but both durations were sufficient to induce significant enhancements in MSt. Thus, possible applications in rehabilitation can be assumed, e. g. if no strength training can be performed meaning atrophy could be reduced by performing long-lasting static stretching training.
... Although, there was a continuous increase in strength load in all exercises throughout the 16 weeks of exercise program [22], the maximum strength tests detected only small strength improvements. The small increase might be due to the low volume and frequency of strength training used in this study compared to others [23,24]. It is doubtful that the exercise prescription method per se, using the rate of perceived exertion (RPE [0 to 10]), influenced our findings considering other studies have shown improvements with RPE prescription. ...
Article
Full-text available
The aim was to identify whether 16 weeks of combined training (Training) reduces blood pressure of hypertensive older adults and what the key fitness, hemodynamic, autonomic, inflammatory, oxidative, glucose and/or lipid mediators of this intervention would be. Fifty-two individuals were randomized to either 16 weeks of Training or control group who remained physically inactive (Control). Training included walking/running at 63% of V˙O2max, three times per week, and strength training, consisting of one set of fifteen repetitions (seven exercises) at moderate intensity, twice per week. Both groups underwent a comprehensive health assessment at baseline (W0) and every four weeks, for 16 weeks total. p-value ≤ 0.05 was set as significant. Training did not reduce blood pressure. It increased V˙O2max after eight weeks and again after 16 weeks (~18%), differently from the Control group. At 16 weeks, Training increased strength (~8%), slightly reduced body mass (~1%), and reduced the number of individuals with metabolic syndrome (~7%). No other changes were observed (heart rate, carotid compliance, body composition, glycemic and lipid profile, inflammatory markers and oxidative profile, vasoactive substances, heart rate variability indices). Although Training increased cardiorespiratory fitness and strength, Training was able to reduce neither blood pressure nor a wide range of mediators in hypertensive older adults, suggesting other exercise interventions might be necessary to improve overall health in this population. The novelty of this study was the time-course characterization of Training effects, surprisingly demonstrating stability among a comprehensive number of health outcomes in hypertensive older adults, including blood pressure.
... Progressive resistance training (PRT)-Participants randomly assigned to the PRT group performed three sessions per week of supervised resistance exercise, during 12-weeks, following the recommendations for PRT for older adults (Borde, Hortobágyi, & Granacher, 2015). The training program was composed of nine whole-body exercises: vertical chest press (pectoralis major), horizontal leg press (quadriceps , hamstrings, glutes and hip adductors), seated row (trapezius, latissimus dorsi and deltoids.), ...
Article
This study aimed to analyze the effects of 12 weeks of a progressive resistance training (PRT) intervention on postural balance and concerns about falling in older adults. This study is a randomized controlled trial. Fifty men and women, community-dwelling older adults (aged 60 and older), were randomly assigned to a PRT (n= 25) or control group (n= 25). Participants allocated to the PRT performed a supervised RT program for 12-weeks (three times per week; three sets of 10-15 repetition maximum of nine whole-body exercises). Control group participants did not perform any structured exercise. Outcomes were obtained at baseline and follow-up and included postural balance assessment using the centre of pressure (CoP) variables. Concerns about falling and leg extension muscle strength were also evaluated using the falls efficacy scale international (FESI) and 1-RM, respectively. At the end of the intervention, PRT did not improve anteroposterior and mediolateral amplitude and velocity, and total velocity and area of CoP in any condition (bipodal, with eyes open and closed — p> 0.05 for all) or concerns about falling (mean difference: +1 point; 95%CI −2; +5). Conversely, compared with the control group, participants in the PRT demonstrated muscle strength gains in the leg extension exercise (+19 kg; 95%CI +3; +35) after the intervention. In summary, 12-weeks of PRT did not improve postural balance or concerns about falling in healthy older adults.
... On the other hand, resistance training has been proposed as the gold-standard treatment to counteract the age-associated wasting of muscle mass, neuromuscular performance and cellular adaptations [162][163][164][165]. In a recent study comparing different strength training frequencies (3 days a week vs. 2) and different intensities (low-load vs. high-load) in adults over 65, it was shown that high-load exercise 3 days per week over a 2-year period of supervised training significantly increased appendicular lean mass when compared to those subjects who performed only 2 days of exercise at light loads. ...
Article
Full-text available
Functional status is considered the main determinant of healthy aging. Impairment in skeletal muscle and the cardiovascular system, two interrelated systems, results in compromised functional status in aging. Increased oxidative stress and inflammation in older subjects constitute the background for skeletal muscle and cardiovascular system alterations. Aged skeletal muscle mass and strength impairment is related to anabolic resistance, mitochondrial dysfunction, increased oxidative stress and inflammation as well as a reduced antioxidant response and myokine profile. Arterial stiffness and endothelial function stand out as the main cardiovascular alterations related to aging, where increased systemic and vascular oxidative stress and inflammation play a key role. Physical activity and exercise training arise as modifiable determinants of functional outcomes in older persons. Exercise enhances antioxidant response, decreases age-related oxidative stress and pro-inflammatory signals, and promotes the activation of anabolic and mitochondrial biogenesis pathways in skeletal muscle. Additionally, exercise improves endothelial function and arterial stiffness by reducing inflammatory and oxidative damage signaling in vascular tissue together with an increase in antioxidant enzymes and nitric oxide availability, globally promoting functional performance and healthy aging. This review focuses on the role of oxidative stress and inflammation in aged musculoskeletal and vascular systems and how physical activity/exercise influences functional status in the elderly.
... Finally, and most importantly, the exercise volume and intensity could be more in the intervention group than the comparative group. As a dose-response relationship [41], the participants in the intervention group performed nearly 90 min of multi-component exercise, including flexibility, resistance and balance, contrasting to throwing and kicking ball(s) or the recreational activity in the comparative group. ...
Article
Full-text available
The Community Care Station (CCS) service was initiated by the Taiwanese government as a part of its elderly social services programs. This study aimed to investigate the effects of using an inexpensive exercise toolkit, containing a stick, theraband, sandbag and a small ball, led by a physical therapist among community-dwelling older adults participating in CCS. A total of 90 participants (aged 77.0 ± 6.8 years) were recruited and divided into an intervention group (n = 45) and a comparison group (n = 45). The intervention group regularly participated in a health promotion program with the exercise toolkit for approximately 90 min per twice-weekly session for 3 months, and the comparison group maintained their usual CCS activity program. Both groups were assessed before and after the 3-month intervention period. Outcome measures included the Short Physical Performance Battery (SPPB), one-leg stance, functional reach (FR), Timed Up and Go (TUG), and 10 m walk tests; 83 participants completed the study. No significant between-group differences were found at baseline in general characteristics or outcome variables. After 3 months, the intervention group showed the significant group x time interaction effects in SPPB, one-leg stance, FR, TUG and 10 m walk tests compared to the comparison group (p < 0.05).; A structured group-based health promotion program using a low-cost exercise toolkit could be effective in improving the physical performances, balance, and walking ability of community-dwelling older adults receiving CCS program services. Furthermore, the comparison group maintained most of their physical performances, even showing significant progress on FR.
Article
Sarcopenia is an age-related neuromuscular disease characterized by substantial muscle atrophy, dynapenia and/or loss of physical function. Sarcopenia progression increases the risk for numerous negative events, including falls, disability, hospitalization, nursing home placement, and death. As such, this condition is recognized as an important topic in gerontology and geriatrics. The best approach to counteract the development and progression of sarcopenia is actively debated. Resistance training (RT) has received special attention in this context, owing to large number of studies showing its ability to produce significant improvements in sarcopenia-related parameters. Recommendations to guide RT prescription for older adults with different conditions, including people who have traits of sarcopenia, have been published. Some authors have argued that RT guidelines for older adults are similar to one another, which may indicate that the presence of sarcopenia does not require specific physical exercise programs. However, older people with sarcopenia might present with peculiar physical, biomechanical, physiological, and psychosocial characteristics that, in our view, are not taken into adequate consideration in existing exercise guidelines. Here, we present evidence to support the view that RT prescription for older adults with sarcopenia is complex, multifactorial, and still needs more evidence.
Article
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