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When performing a set of successive repetitions, fatigue ensues and the quality of performance during subsequent repetitions contained in the set decreases. Oftentimes, this response may be beneficial, as fatigue may stimulate the neuromuscular system to adapt, resulting in a super-compensatory response. However, there are instances in which accumulated fatigue may be detrimental to training or performance adaptations (i.e. power development). In these instances, the ability to recover and maintain repetition performance would be considered essential. By providing intermittent rest between individual repetitions or groups of repetitions within a set, an athlete is able to acutely alleviate fatigue, allowing performance to remain relatively constant throughout an exercise session. Within the scientific literature, a set that includes intermittent rest between individual repetitions or groups of repetitions within a set is defined as a cluster set. Recently, cluster sets have received more attention as researchers have begun to examine the acute and chronic responses to this relatively novel set structure. However, much of the rest-period terminology within the literature lacks uniformity and many authors attempt to compare largely different protocols with the same terminology. Additionally, the present body of scientific literature has mainly focused on the effects of cluster sets on power output, leaving the effects of cluster sets on strength and hypertrophy relatively unexplored. Therefore, the purpose of this review is to further delineate cluster set terminology, describe the acute and chronic responses of cluster sets, and explain the need for further investigation of the effects of cluster sets.
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BRIEF REVIEW
THEORETICAL AND PRACTICAL ASPECTS OF DIFFERENT
CLUSTER SET STRUCTURES:ASYSTEMATIC REVIEW
JAMES J. TUFANO,
1,2
LEE E. BROWN,
3
AND G. GREGORY HAFF
1
1
Center for Exercise and Sport Science Research, Edith Cowan University, Joondalup, Australia;
2
Faculty of Physical
Education and Sport, Charles University, Prague, Czech Republic; and
3
Center for Sport Performance, Department of
Kinesiology, California State University, Fullerton, California
ABSTRACT
Tufano, JJ, Brown, LE, and Haff, GG. Theoretical and practical
aspects of different cluster set structures: a systematic review.
J Strength Cond Res 31(3): 848–867, 2017—When performing
a set of successive repetitions, fatigue ensues and the quality of
performance during subsequent repetitions contained in the set
decreases. Oftentimes, this response may be beneficial because
fatigue may stimulate the neuromuscular system to adapt, result-
ing in a super-compensatory response. However, there are in-
stances in which accumulated fatigue may be detrimental to
training or performance adaptations (i.e., power development).
In these instances, the ability to recover and maintain repetition
performance would be considered essential. By providing inter-
mittent rest between individual repetitions or groups of repeti-
tions within a set, an athlete is able to acutely alleviate fatigue,
allowing performance to remain relatively constant throughout an
exercise session. Within the scientific literature, a set that in-
cludes intermittent rest between individual repetitions or groups
of repetitions within a set is defined as a cluster set. Recently,
cluster sets (CS) have received more attention as researchers
have begun to examine the acute and chronic responses to this
relatively novel set structure. However, much of the rest period
terminology within the literature lacks uniformity and many authors
attempt to compare largely different protocols with the same
terminology. Additionally, the present body of scientific literature
has mainly focused on the effects of CS on power output, leaving
the effects of CS on strength and hypertrophy relatively unex-
plored. Therefore, the purpose of this review was to further delin-
eate cluster set terminology, describe the acute and chronic
responses of CS, and explain the need for further investigation
of the effects of CS.
KEY WORDS rest-pause, periodization, rest intervals, intraset,
interrepetition
INTRODUCTION
When designing a resistance training program,
several factors such as the choice of exercise,
training load, number of repetitions and sets
performed, the exercise order, frequency, and
length of designated rest periods must be considered to opti-
mize the targeted training outcomes. Once all these program
variables have been established, the strength and condi-
tioning professional can effectively define and implement
a training program. Ultimately, these decisions are made to
construct a periodized resistance training program in accor-
dance with the individual athlete’s training goals. However,
a largely overlooked and underused aspect of developing
a resistance training program is the ability to alter the struc-
ture of individual sets (34). For example, the number of rep-
etitions, training load, and rest periods contained within a set
can be manipulated to alter the training stimulus. When
conceptualizing a set, 2 types of general set structures can
be used: traditional sets (TS) and cluster sets (CS) (34). To
effectively use both types of set structure, the strength and
conditioning professional must understand the fundamentals
that underpin each type.
Traditional Sets
Traditionally, the completion of a set occurs without any
rest being taken between repetitions that are contained
within the set. Once the set is completed, a predetermined
rest interval is provided to allow recovery before the
initiation of a subsequent set, and this basic set configura-
tion is repeated for the targeted number of sets prescribed
in the training session. This traditional method of resis-
tance training set prescription can be described as training
using TS.
Regardless of set structure, the manner in which repe-
titions are performed can largely affect the resultant
training adaptations stimulated by a resistance training
program. For example, strength and conditioning profes-
sionals often instruct athletes to perform concentric muscle
actions as quickly as possible because explosive concentric
muscle actions result in enhanced recruitment of type II
muscle fibers (77) and result in greater training effects
compared with intentionally slower concentric muscle
Address correspondence to James J. Tufano, James.J.Tufano@gmail.com.
31(3)/848–867
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actions (41,77). Unfortunately, fatigue can quickly manifest
itself when repeatedly performing explosive movements
under externally loaded conditions using TS training struc-
tures (21,33,37,44,45,82,89).
One of the most widely accepted causes of muscular fatigue
is the reduced availability of phosphocreatine (PCr) and rate
of adenosine triphosphate (ATP) resynthesis within the
working muscles (8–10). Sahlin and Ren (81) showed that
after a sustained fatiguing isometric muscle action, maximal
force production during a subsequent isometric action can be
met, but the subsequent force endurance capacity is
decreased, credited to an inability to continually regenerate
ATP. Building on this idea, the classic works of Bogdanis et al.
(8–10) indicate that ATP and PCr stores are significantly
reduced after an initial cycle sprint of 10–30 seconds and do
not fully recover after 90–240 seconds of recovery (i.e., similar
work-to-rest ratios of many common resistance training pro-
grams), indicated by a decrease in power output during a sub-
sequent cycle sprint. More recently, the work of Gorostiaga
et al. (29–31) has confirmed that when performing the leg
press exercise at maximal effort, the accumulation of meta-
bolic byproducts and decreased energy availability are accom-
panied with decreases in power output. The decrease in
power output noted in these studies is the basis of the hypoth-
esis that impairments in high velocity movements may occur
when TS are chronically used without sufficient replenish-
ment of ATP and PCr within the active muscles, especially
when high volumes of work are completed (7,32,34).
Although a fatigue-induced decrease in movement
velocity reduces power output (33,35,39,82) especially as
the number of repetitions performed in the set increases
(29–31,48), such fatigue may be useful in inducing hyper-
trophic responses or strength gains because a decrease in
concentric velocity results in an increase in the overall time
under tension (TUT) (13,67,90) and increased myoelectri-
cal activity toward the end of a set (50,93,95), both of
which have been suggested to be prerequisites for the
development of strength (2,3,23). Additionally, when
fatigue ensues and the energy availability from the ATP-
PCr energy pathways becomes reduced, an increase in
glycolytic dependence results in an accumulation of metab-
olites within the muscle, decreasing the pH level and
subsequently, decreasing performance (9,10,29–31,72).
Although an increase in metabolites such as lactate is asso-
ciated with a decrease in acute performance (3,45), some
researchers have explained that resistance training using TS
encourages neuromuscular fatigue, which may be war-
ranted for long-term strength development (2,3,54).
Considering the relationship between metabolites and
hormonal responses to fatigue and resistance training, TS
structures seem to be ideal for promoting skeletal muscle
hypertrophy (23,60,64). For these reasons, the recommen-
dations for hypertrophic development set forth by the
American College of Sports Medicine (1) and the National
Strength and Conditioning Association (6) favor shorter
rest periods between TS to promote muscle growth. In
line with these recommendations, resistance training using
TS has resulted in skeletal muscle hypertrophy, especially
in high-volume programs (13,16,42). Based on this reason-
ing, some strength and conditioning professionals suggest
that the intentional use of slow movement velocities in-
creases the TUT and thus may positively impact hypertro-
phic responses and strength gains. However, critical
analysis of the scientific literature reveals that there is
a paucity of conclusive data to support this claim and that
the opposite may be true (28,78,83) because recent
research has revealed that faster concentric movement
velocities have the potential to stimulate greater gains in
strength and hypertrophy compared with slower concen-
tric movements (41,70).
To support this contention, Hatfield et al. (41) indicated
that intentionally slow movement velocities performed
with TS result in fewer repetitions being performed, lower
peak force production, reduced peak power output, and
less total training volume when compared with the same
exercise performed at quicker movement velocities. Con-
tinuing on the cross-sectional work of Hatfield et al. (41),
Gonzalez-Badillo et al. (28) found that performing the
bench press exercise at maximal intended concentric
velocities for 6 weeks resulted in greater strength gains
when compared with performing the bench press with
intentionally slower velocities. Similarly, Padulo et al.
(77) reported that maximal velocity bench press training
(80–100% maximal attainable velocity using 85% 1 repeti-
tion maximum [1RM]) resulted in greater strength gains
and greater peak velocity at maximal loads when com-
pared with self-selected velocities after 3 weeks of training.
Ultimately, these authors (28,77) concluded that lifting
a load at maximal concentric velocities may be more
important than intentionally slow movements that aim to
induce maximal strength gains by increasing TUT.
To determine the influence of maximal velocity resistance
training on athletic performance, Pareja-Blanco et al. (78)
investigated the effects of 6 weeks of maximal concentric
velocity vs. half-maximal concentric velocity back squat
training using TS on sprinting and jumping movements.
Ultimately, the authors determined that maximal velocity
resistance training may be more beneficial for improving
powerful athletic movements, such as sprinting and jumping,
when compared with slower velocity training with equiva-
lent loads (78). Additionally, the authors specifically stated
that a fast concentric movement velocity seemed to be of
greater importance than increasing TUT when aiming to
develop maximal strength.
Collectively, these studies (28,41,77,78) shed light on the
importance of training at maximal concentric velocities to
maximize strength, power output, and performance gains.
Therefore, it may be warranted to implement strategies that
limit the typical fatigue-induced reductions in movement
velocity seen during TS.
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One potential strategy for offsetting the fatigue-induced
performance decrements associated with TS could be the use
of CS (33). Based on the work of Gorostiaga et al. (29–31),
using CS structures to provide more frequent rest periods
should result in enhanced recovery via a greater maintenance
of PCr stores and increased metabolite clearance compared
with TS training (19,27,75). By using CS structures, there may
be an increase in substrate availability (i.e., PCr and ATP) that
could result in the maintenance of movement velocity
throughout an entire set and, ultimately, an entire training
session.
Cluster Sets
Set structures inclusive of normal interset rest periods
accompanied by preplanned rest intervals within a set are
referred to as CS structures (11,33,37–39,91). Conceptu-
ally, the addition of short rest periods within a set while
maintaining normal rest periods between sets may offer
a methodology for maximizing individual repetition per-
formance while reducing accumulated fatigue seen during
TS (27,32–35,39,91). However, because of the wide range
of protocols using the CS terminology (further discussed in
the “Set Structure Terminology” section of this article), CS
have simply become a set structure in which rest periods
aremorefrequentthanTS.
Previous research has indicated that force production
remains relatively constant throughout TS and CS
(19,35,68,91), but the movement velocity and power output
across multiple sets seems to decrease to a greater extent
during TS when compared with CS (33,37,39,91). Therefore,
it has been hypothesized that a greater training stimulus for
power development may be generated in response to the
increased movement velocity noted in several studies com-
paring CS with TS (33,34,38,39,45,76). Fundamentally, train-
ing with CS in a “recovered” state may be more beneficial
than TS for movements that require large amounts of mus-
cular power output at high velocities (7,32,34).
As previously mentioned, fatigue is oftentimes thought to
be of paramount importance for the development of
muscular strength (42,55). However, it has been observed
that training to maximal fatigue (i.e., training to failure) is
not a prerequisite for the development of maximal strength
(20,24), and resistance training at maximal velocities may be
more effective at developing strength when compared with
slower training velocities (28,41). Because velocity is better
maintained using CS than TS, CS structures may play a role
in enhancing maximal strength (46,74). Additionally, CS
allow for a greater number of repetitions to be performed
with a given load (19,44), resulting in a greater volume load,
which may also result in a greater stimulus for the develop-
ment of maximal strength (55,79,87).
Finally, research investigating the hypertrophic effects of
CS is scant, but evidence supports the idea of using CS to
develop skeletal muscle growth. In particular, it has been
shown that after 12 weeks of resistance training, CS
resulted in similar gains in lean mass when compared with
TS (74). Moreover, the use of CS seems to allow for
a greater number of repetitions to be performed when com-
pared with TS (19,44), which may ultimately lead to an
increase in the amount of total work (i.e., volume load),
providing a stimulus for increasing muscle hypertrophy
(56,61,87). Alternatively, if the number of repetitions is kept
constant, CS may allow for the use of greater training inten-
sities, which may also increase the hypertrophic stimulus
(25,101). Therefore, the overall volume load may be
increased when using CS compared with TS, possibly re-
sulting in a greater stimulus for skeletal muscle hypertrophy
(25,42,65,87,97).
Although TS have been the longstanding set structure for
resistance training programs, the alteration of TS to CS
provides a different training stimulus that may benefit certain
training goals. Even though there is a growing body of
literature that explores the use of CS structures, the current
definitions of CS are inconsistent and the applications of CS
in a training environment remain inadequate. Therefore, the
purposes of this review were to (a) define the CS terminol-
ogy, (b) describe the acute and chronic responses to CS, and
(c) explain the need for further investigation of the effects of
CS on strength and hypertrophy.
DEFINING REST PERIODS
Before discussing the CS literature in detail, it is important to
understand the rest period terminology that is used to
describe set structures within the scientific literature. Defin-
ing rest periods using prefixes such as intra-(within) and
inter-(between) describes the location of the rest interval in
relation to the remainder of the set.
Interset Rest
It would be most appropriate to describe the rest interval
between sets (i.e., multiple repetitions performed in
sequence) as the “interset” rest period. Often, interset rest
periods are established as part of the training program to
facilitate recovery between sets and target-specific training
adaptations (98–100). For instance, when attempting to
achieve maximal strength gains, it is recommended that an
interset rest interval of 2–3 minutes is used (18). To provide
an example, an athlete aiming to increase maximal strength
could perform 2 sets of 4 repetitions with 120 seconds of
interset rest allocated between each set (Figure 1A).
Intraset Rest
The term “intraset” would be most appropriate when
describing rest periods between groups of repetitions within
CS structures. For example, if 2 sets of 4 repetitions are pre-
scribed using clusters of 2 repetitions, each cluster of 2 could
be separated by a short intraset rest interval of 15 seconds
with 120 seconds of interset rest (Figure 1B). Although the
number of repetitions within each cluster and the intraset
rest times can largely vary, Figure 1B shows that intraset rest
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intervals apply to rest periods that occur within a set but not
between sets and not between individual repetitions.
Interrepetition Rest
Rest periods that occur between individual repetitions of
a set could be best described as “interrepetition” rest periods
(Figure 1C). Based on this line of reasoning, it could be
advised that the use of the interrepetition rest (IRR) termi-
nology should be limited to rest intervals that are applied
only between individual repetitions within a single set but
not groups of repetitions within a set (i.e., clusters) or sets of
single repetitions (i.e., TS). For example, if IRR is prescribed
for 2 sets of 4 repetitions, each repetition within each set of
4 could be separated by a short 15-second IRR interval in
addition to 120 seconds of interset rest (Figure 1C). To con-
clude, the term intrarepetition should never be used because
it is impossible to rest within a single repetition.
SET STRUCTURE TERMINOLOGY
Since the emergence of sport science, there has been a need
for standardized terminology (53). In a field where scientists
and practitioners work side-by-side, it becomes increasingly
important for coaches to understand the jargon used in exer-
cise science in addition to the scientists understanding the
nomenclature used in practice. In today’s world, the Internet
increases the availability of information, allowing for rapid
dissemination of ideas and the inability to regulate the com-
municative process.
At times, a minor tweak to a simple concept opens the door
for various interpretations and other amendments. Consis-
tency of terminology can help eliminate confusion between
professionals or between disciplines. For example, even simple
barbell exercises such as the squat and bench press leave room
for interpretation that can sometimes be misconstrued (49,73).
Numerous attempts have been made to standardize the
nomenclature used in sport science (40,49,52,53,57,73) and
the need still exists because concepts are continuously being
compared and contrasted. For this article, understanding set
structure terminology is of great importance.
Specifically, the use of the umbrella term “cluster set” has
evolved to include many different types of set structures that
simply describe a manner in which repetitions are performed
which diverges from the TS structure. Although Byrd et al.
(17), Rooney et al. (80), and Keogh et al. (51) used protocols
inclusive of various IRR periods, the first use of the term
“cluster set” in the scientific literature, to our knowledge,
was used in 2003 (33). That article created a CS by breaking
a single TS of 5 repetitions into a single CS of 5 repetitions
with short IRR periods. However, they did not mention any
terminology for performing a CS over multiple sets, leaving
interset rest periods unmentioned and open for interpreta-
tion. As a result, the term “cluster set” has evolved to include
many different types of protocols that do not necessarily
follow a TS structure.
In theory and practice, there are 2 main things that can
happen to the interset rest when using CS structures. The
Figure 1. Two sets of 4 repetitions with 120 seconds of interset rest using 3 different set configurations. Arrows indicate number of repetitions performed in
sequence, triangles indicate intraset or interrepetition rest periods, and quadrilateral shapes indicate interset rest periods. (A) Traditional sets with neither
intraset nor interrepetition rest. (B) Cluster sets doubles with intraset rest periods. (C) Cluster sets singles with interrepetition rest periods.
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interset rest periods can remain unchanged, resulting in
greater total rest times within the protocol, or the intraset
rest/IRR can be subtracted from the interset rest to result
in the same total rest time within the protocol. Careful
examination of the scientific and non–peer-reviewed litera-
ture reveals that there is a great deal of disconnect when
defining “cluster set” terminology since 2003.
Some authors have created CS structures by equalizing
the work-to-rest ratio (35,44,63), dividing interset rest peri-
ods into shorter but more frequent intraset rest periods
(19,36,50,58,59,69,74,102), or using the rest-pause method
(51,62). Therefore, it is important to examine the different
methods of altering a set structure and how these relate to
each other. Ultimately, the purpose of the nomenclature set
forth in this article is to illuminate fundamental differences
between protocols that use different forms of CS and to
create more appropriate subclassifications of CS. If adopted,
these subclasses will allow researchers and practitioners to
compare and contrast various set structure designs with
more accuracy and less confusion.
Basic Cluster Sets
Training using the basic CS in which the interset rest periods
remain unchanged requires a longer training duration to
achieve a desired number of repetitions when compared
with a TS structure because the intraset rest or IRR periods
are added to the total rest time (Figure 2B) (4,11,26,33,37–
39,47,68,71,80,91,92). For example, Verkoshansky and Siff
(94) explained that “extensive cluster training” involves 4–6
repetitions with one’s 4–6RM, with 10 seconds of IRR and
1–3 minutes of interset rest. By maintaining the interset rest
interval, recovery between sets is facilitated as normal, but
now with the addition of partial recovery within each set,
the quality of repetitions within each set may be elevated
across all sets performed. To simplify, a basic CS structure is
essentially a TS with additional short rest periods of typically
15–45 seconds inserted within each set (34). Although it is
possible to add short IRR periods of 1 to 4 seconds (4,17),
the majority of basic CS structures include a minimum of
about 10–15 seconds of IRR or intraset rest.
An example of basic CS structures is present in the work of
Hardee et al. (37–39), where 3 sets of 6 power cleans using TS
with 3 minutes of interset rest were compared with 2 different
basic CS structures in which the interset rest intervals re-
mained constant at 3 minutes. The 2 basic CS structures
differed to the TS structure by adding either 20 or 40 seconds
of IRR within each set. Additionally, Tufano et al. (91) used
basic CS structures by comparing 3 sets of 12 with 2 minutes
of interset rest with 3 sets of 12 with 30 seconds of intraset rest
without adjusting the 2-minute interset rest periods. In this
manner, each basic CS protocol included a greater amount of
total rest time when compared with the TS protocol.
Interset Rest Redistribution
One type of CS subclass is created when the redistribution of
interset rest intervals occurs (5,19,27,36,50,58,69,74–76,102).
In these scenarios, long interset rest intervals are often
divided in to shorter but more frequent interset rest intervals,
keeping the total rest time equal (Figure 2D). For example,
Oliver et al. (74) compared 4 sets of 10 with 2 minutes of
interset rest with 8 sets of 5 with 1 minute of interset rest. In
this manner, each set of 10 was split in to 2 sets of 5 and each
2-minute interset rest period was reduced to 1 minute. Fun-
damentally, each set of 10 repetitions was split into smaller
but more frequent sets of 5, keeping the total rest period
between groups the same. Similarly, Moreno et al. (69) used
3 jump squat protocols in which each prescribed set and
repetition scheme contained equal total rest. Specifically,
the set structures were broken into 2 sets of 10, 4 sets of 5,
and 10 sets of 2, with 90, 30, and 10 seconds of interset rest,
respectively. Later, Oliver et al. (76) compared 4 sets of 10
with 2 minutes of interset rest with 4 sets of 10 with 90
seconds of interset rest and 30 seconds of intraset rest. In
all these cases, the investigators increased the frequency but
decreased the duration of rest periods while keeping the
total rest time equal between sets.
Specific terminology such as “rest redistribution” (RR)
could be adapted for CS structures that equate and rearrange
rest periods instead of adding additional rest periods as basic
CS structures do. Therefore, an RR protocol differs from
a basic CS design in that the interset rest periods during
RR are shortened, the time subtracted from the interset rest
is redistributed within the protocol, and extra rest is not
provided.
Equal Work-to-Rest Ratio
Some studies have equated the work-to-rest ratio (EW:R)
for the entire exercise session and described it as CS training
(35,43–46,59,63). In these cases, the protocols cannot be
randomized because the TS serves as the “standard” from
which the work-to-rest ratio is calculated (Figure 2C). For
example, the protocols of Iglesias-Soler et al. (44) included
the following 2 protocols: (a) 3 sets of TS to failure (4, 4, and
3 repetitions per set for example; 11 total repetitions) with
3 minutes of interset rest for a total of 360-second rest and
(b) repetitions to failure with 36 seconds of IRR to ensure an
equal work-to-rest ratio for the first 11 repetitions in this
example (360 seconds divided by 10 rest periods). It is
important to note that these ratios will mostly be subject
dependent and that subjects may be able to complete far
more repetitions in the equal work-to-rest ratio protocol
(i.e., 11 repetitions during TS vs. 45 during the equal work-
to-rest protocol (44)). In this manner, these CS structures
may be most accurately described as EW:R protocols in
which the total number of repetitions was not controlled
and the total number of repetitions performed could vary
between subjects. Practically, an EW:R protocol of this
nature (i.e., performed to failure) could take up to 20 minutes
if 30 seconds of IRR was to be provided for 40 repetitions.
Hansen et al. (35) also used EW:R set structures but kept the
number of repetitions in each protocol constant. Unlike
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Iglesias-Soler et al. (44), subjects in this study (35) always per-
formed the same number of repetitions using the following
4 protocols with a work-to-rest ratio of 15 seconds of work
to 3 minutes of rest: 4 sets of 6 with 3 minutes of interset rest;
4 sets of 6 with 12 seconds of IRR and 2 minutes of interset
rest; 4 sets of 6 with 30 seconds of intraset rest after every
2 repetitions and 2 minutes of interset rest; and 4 sets of 6 with
60 seconds of intraset rest after every 3 repetitions and 2 mi-
nutes of interset rest. In this case, the same number of repeti-
tions was used in each protocol, but no additional rest periods
were supplied, and the work-to-rest ratio remained constant.
At first glance, RR and EW:R protocols seem to be similar
because they both take the total rest time and divide it by
a certain number of repetitions. However, RR protocols only
take the rest time into consideration, whereas EW:R
protocols take the time spent lifting the load into consider-
ation as well. By specifically using the EW:R terminology,
researchers and practitioners can understand that the total
amount of rest is divided by the number of repetitions
performed per unit of time, allowing a seemingly countless
number of set manipulation variations that can be used to
target various training goals.
Rest-Pause Method
Another method of varying a set structure is what can be
termed as the “rest-pause” method (Figure 2E) (4,17,23,51,62).
Verkoshansky and Siff (94) define “intensive cluster training” as
a method of performing single repetitions of an exercise with
short rest periods between each repetition for 4 to 6 repeti-
tions, allowing a near-maximal load to be lifted multiple times:
a method which has alternatively been described as the rest-
pause method (12,23). Other definitions of the rest-pause
method include performing a single set of an exercise with
short rest intervals of increasing duration between every cou-
ple of repetitions, hoping to increase total volume load (96); an
Figure 2. Schematic differences between various set structures. Arrows indicate number of repetitions performed in sequence, triangles indicate intraset or
interrepetition rest periods, and quadrilateral shapes indicate interset rest periods. Although not identical, the following studies have used set structures that can
be represented by the conceptual ideas presented in (B) (4,11,26,33,37–39,47,68,71,80,91,92), (C) (35,43–46,59,63), (D) (5,19,27,36,50,58,69,74–
76,102), and (E) (4,17,51,62), whereas (A) represents a traditional set structure that is commonly used as a control, or reference, set structure. Please note,
protocols (C) and (E) do not have to be performed to failure as shown in this diagram, but some studies adopt such designs.
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initial set to failure with subsequent sets to failure performed
with 20 seconds of interset rest (62); and 1–4 seconds of un-
loaded rest between repetitions within an otherwise TS
(4,17,51). Although the rest-pause method has not been
described as CS in the scientific peer-reviewed literature, many
text books (as described above) and online training blogs syn-
onymously refer to the rest-pause method as a CS structure,
making it important to discuss in this article.
Careful inspection of this method reveals that its applica-
tion is different from the previously mentioned basic CS,
EW:R, and RR subclassifications. Specifically, the aforemen-
tioned definitions of the rest-pause method describe
a method in which training to failure often occurs, then
a short rest period is applied to encourage recovery, allowing
for additional repetitions to be completed until volitional
failure or a predetermined number of repetitions are
completed (23,62). When compared with a basic CS, EW:
R, or RR protocol, the rest-pause method does not allow for
ad hoc programming of repetitions or rest periods because of
the rest-pause method’s general reliance on training to fail-
ure, creating variable sequences of repetitions that change
based on the athlete’s daily fatigue level. In contrast, other
subclasses of CS can allow for a consistent set structure
across training days, facilitating the periodization process.
Although the rest-pause method is similar to the other sub-
classifications of CS training in that short rest intervals are
included, its lack of a constantly defined structure highlights
its uniqueness among the CS subclasses.
Summary of Different Set Structures
The ability to infinitely manipulate training variables, such as
the number of repetitions, sets, and rest periods, make exercise
prescription difficult to describe without providing extremely
detailed information. Because of this, specific terminology
may help describe subtle differences between types of set
structures that otherwise may be difficult to differentiate. After
elucidating the differences between the basic CS, RR, EW:R,
and the rest-pause method, it may be recommended that they
should not all be classified under a single CS description.
Nonetheless, the investigation of basic CS, RR, EW:R, and the
rest-pause method provide valuable insight regarding the
effects of rest periods and intraworkout training density on
acute and chronic adaptations to resistance training. A
simplified visual representation of TS, basic CS, EW:R, RR,
and the rest-pause method is presented in Figure 2. Addition-
ally, references are provided for studies that fit into each sub-
classification. It is important to note that the referenced
studies do not use the exact protocols listed in Figure 2, but
the main idea of the set structures in each study generally
agrees with the designated examples in Figure 2.
CLUSTER SET LITERATURE
To date, the majority of CS research focuses on the acute
responses to various intraset rest and IRR intervals, frequently
comparing acute power-related variables between different
types of CS and TS (33,37,39,50,68,76,91). The body of
literature examining the acute effects of CS is consistently
growing, but the number of studies investigating the use of
CS training as part of a chronic training program has received
significantly less attention. To date, only 9 studies have
investigated the chronic effects of CS subclasses but show
inconsistent results most likely because of heterogeneous
populations and protocol designs. The following sections will
discuss key acute studies that focus on variables related to
power, strength, and hypertrophic development. Then, each
training study will be discussed in detail.
Acute Power
There is a plethora of evidence supporting the use of CS
variations to maintain power production during acute bouts
of exercise (19,27,35,37,39,59,75,76,91). As mentioned pre-
viously, concentric movement velocities decrease during
TS (21,45,82,89), significantly reducing power output
(33,35,39,76,91). With the addition of intraset rest intervals,
the velocity of repetitions toward the end of various CS
protocols is maintained, resulting in the preservation of
acute power output (35,39,45,91).
For example, Lawton et al. (59) reported that power out-
put was maintained when an EW:R protocol was compared
with TS. Subjects in this study performed 6 repetitions of the
bench press with a 6RM load using TS and 3 different EW:R
strategies. The EW:R protocols consisted of 6 sets of 1 with
20-second rest between sets, 3 sets of 2 with 50-second rest
between sets, and 2 sets of 3 with 100-second rest between
sets. By using these set structures, each protocol contained
100 seconds of rest and the final repetition of all 3 protocols
was completed 118 seconds after the start of the first repe-
tition, assuming 3 seconds was needed to complete each
repetition. The authors concluded that the 3 EW:R proto-
cols resulted in equally greater total power output than TS.
This study (59) showed that various EW:R protocols con-
taining shorter but more frequent rest intervals equally main-
tained power output during 6 repetitions of heavy bench
press (i.e., about 21–25% greater total power output than
TS) when compared with a single TS structure of 6 repeti-
tions during which power output significantly decreased by
approximately 50% in a near-linear fashion.
To compare the effects of RR and TS across multiple sets,
Moreno et al. (69) investigated the effect of RR throughout
a series of bodyweight jump squats. Total rest time was
equalized between groups, but it was observed that an RR
protocol consisting of 10 sets of 2 jumps with 10 seconds of
interset rest better maintained power output, takeoff velocity,
and jump height when compared with 2 sets of 10 jumps
with 90 seconds of interset rest (TS). Building on the study
by Lawton et al. (59) who examined EW:R during a single
set of the bench press, these authors (69) showed that RR
structures alleviate fatigue-induced decreases in movement
velocity during multiple sets of bodyweight jump squats
when compared with TS.
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In comparison with the study by Moreno et al. (69) where
bodyweight jump squats were used, Hansen et al. (35) inves-
tigated the effects of EW:R with more frequent rest periods
during loaded jump squats (40 kg) in semiprofessional rugby
players. The players experienced a decline in peak velocity
and peak power output during 4 sets of 6 using TS. How-
ever, when EW:R protocols were used, peak velocity and
power output were better maintained during the latter rep-
etitions of each set. The authors concluded that because
individual repetition peak force was not different between
protocols, the maintenance of peak velocity during loaded
jump squats was responsible for the maintenance of power
output in the EW:R protocols when compared with TS.
As a whole, the literature shows that it is clear that
power output can be maintained when using more frequent
rest intervals during exercises that begin with eccentric
muscle actions, use the stretch-shortening cycle (SSC), and
finish with concentric muscle actions (i.e., bench press, jump
squats, and back squats) (35,50,59,69,76,91). However,
Hardee et al. (39) investigated the effect of CS on power
during 3 sets of 6 power cleans, which are considered to be
predominately concentric in nature. Using 80% 1RM, subjects
performed a TS protocol (3 sets of 6 with no intraset rest) and
2 CS protocols with IRR intervals of either 20 or 40 seconds.
When averaged across all 18 repetitions, peak power output,
peak velocity, and peak force decreased more in TS than the
2 CS protocols. In contrast to the bench press, jump squats,
and back squats (35,59,69), power cleans begin with concentric
muscle actions. During the power clean, peak velocity is usu-
ally obtained during the second pull, which is preceded by the
double knee bend (22,66). Therefore, the velocity of the sec-
ond pull may be affected by the involvement of the SSC during
the double knee bend. Although the authors did not report
exactly when peak velocity occurred (39), it is likely that peak
velocity occurred during the second pull, partially relying on
the SSC during the double knee bend. Therefore, when com-
pared with TS, CS using IRR intervals of 20–40 seconds main-
tained peak power even when using an exercise that begins
with concentric muscle actions but still uses the SSC (39).
To further elaborate on this phenomenon, it seems that
CS structures may be beneficial for increasing power output
only for exercises that use the SSC at some point during the
lift (68). Moir et al. (68) showed that greater reductions in
power output were observed when a single set of 4 deadlifts
was performed using CS compared with TS. The authors
concluded that when implementing 30-second IRR periods,
the SSC did not play a major role and the impulse of the
deadlifts was greater than that of TS. When performing
clusters of 2 repetitions (using an intraset rest period of 30
seconds between the second and third repetitions), the sec-
ond and fourth repetitions were performed quicker and re-
sulted in greater power output than the first and third
repetitions. Force remained unchanged during all protocols
meaning that, mathematically, a decrease in velocity (i.e., an
increase in time) was responsible for the greater impulse
observed when using IRR periods. Therefore, if maintaining
power output is important, CS structures that use IRR peri-
ods may not be warranted when performing exercises that
begin with a concentric muscle action and lack SSC involve-
ment, such as the deadlift. However, if multiple repetitions
are performed in sequence using the SSC at some point,
intraset rest intervals may be useful.
In summary, EW:R, RR, and basic CS set structures seem
to be beneficial for attenuating the acute decline in power
output that occurs when using TS in exercises that include
some kind of SSC component. Additionally, the mainte-
nance of concentric movement velocity seems to be largely
responsible for the maintenance of power output during an
acute exercise bout. However, further investigation is
necessary to determine the effect of CS on acute power-
based variables using different exercises, rest periods, and
number of repetitions.
Acute Strength
Previous authors have hypothesized that TS should be
chosen over CS when training to develop maximal strength
because CS alleviate fatigue, and fatigue is sometimes
warranted when aiming to develop muscular strength
(32,34,50). However, these claims remain relatively unex-
plored. Although the investigation of various types of CS
on power output is more common in the literature, there
are some studies that have explored the effects of CS on
acute variables that are considered to be indicative of
strength development, specifically force production, training
volume, and muscle activity. It must be noted that acute
studies cannot determine the chronic effect of a protocol
on maximal strength, but the results from the following acute
studies can be used to extrapolate hypotheses about the
effects of CS on strength development.
In a study conducted by Denton and Cronin (19), subjects
completed the bench press using 3 different protocols. The TS
structure included 4 sets of 6 with 302 seconds of interset rest.
One RR protocol was matched for training volume and total
rest time and included 8 sets of 3 with 130 seconds of interset
rest, whereas a different RR protocol was matched for total
rest time and included 8 sets with 130 seconds of interset rest,
but the odd-numbered sets contained 3 repetitions and even-
numbered sets were performed to failure. The load in all set
structures was the same (6RM load). The results of this study
showed that the RR protocol that was performed to failure
during the odd-numbered sets resulted in a significantly
greater number of repetitions performed than the TS or RR
protocol that was not performed to failure. In theory, an RR
protocol that allows for the performance of more repetitions
should increase training volume and, in turn, result in greater
maximal strength gains (55).
Similarly, Iglesias et al. (47) showed that by using a basic
CS configuration, training volume can be increased by
increasing the load and number of repetitions performed.
In this study, subjects completed as many repetitions as
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possible during a single TS of the bench press and bicep curl
using 70% 1RM. Subjects then completed as many repeti-
tions as possible of each exercise with 90% 1RM, but with 30
seconds of IRR. The protocol with IRR resulted in a greater
number of repetitions performed with a greater load, indi-
cating that CS allowed for a greater load to be used for
a greater number of repetitions, increasing training volume.
Although a most of the literature shows that compared
with TS, CS allow for greater volume load by increasing the
number of repetitions, training load, or both, there is one
study that does not show this and in fact shows that CS
decrease the number of repetitions performed (4). In this
study, subjects performed 4 sets of leg press and bench press
to failure using 75% 1RM on 3 separate visits. Each of the 3
visits included either zero, 2, or 4 seconds of IRR. Unique to
this study, the subjects continued to support the load in the
extended position during the IRR periods (i.e., elbows
extended during the bench press and knees extended during
the leg press). As a result, subjects were able to perform more
repetitions during the bench press and leg press when there
was no IRR (TS) compared to the 2 protocols in which IRR
periods were used (CS). Therefore, it can be concluded that
when using any type of CS structure to maintain acute
exercise performance or increase the number of repetitions
performed, it is imperative that the lifter be unloaded and
fully relaxed during the intraset rest or IRR periods.
Hansen et al. (35) determined that rugby players were able
to maintain loaded jump squat peak force better when using
EW:R compared with TS. Four sets of 6 jump squats were
performed with a standard load of 40 kg to assess the per-
cent change in peak force from the first repetition of each set
to all subsequent repetitions per set. The absolute peak force
was not different between protocols when repetitions were
collapsed across sets, but the percent change from the first
repetition did exhibit differences between protocols.
Although the EW:R set structures did not fully maintain
peak force when latter repetitions were compared with the
first repetition of each set, there was a greater reduction in
force across the set with the TS. Therefore, based on these
data, it seems that EW:R may help attenuate the declines in
peak force observed during the latter repetitions of TS struc-
tures. Although jump squats are generally not assigned to
a resistance training program to increase maximal strength,
the principle of force maintenance may be applied to other
exercises that do focus on strength development.
To date, one study has investigated the effect of RR on
muscle activity by comparing TS with RR using the back
squat exercise at 75% 1RM (50). The TS protocol consisted
of 4 sets of 10 with 2 minutes of interset rest, whereas the RR
protocol included 8 sets of 5 with 1 minute of interset rest.
To assess muscle activity, the authors reported the root-
mean-square electromyography (EMG) values for the entire
repetition (eccentric, amortization, and concentric phases) in
the vastus lateralis and biceps femoris. When collapsed
across 10 repetitions (i.e., the first TS set and the first
2 RR sets), muscle activity increased in a near-linear fashion
during TS and followed the same pattern for the first 5
repetitions during RR. However, the muscle activity of the
next repetition (sixth) of the RR set structure returned to the
value of the first repetition and followed the same trend as
repetitions 1–5. Therefore, TS resulted in greater total mus-
cle activity when compared with RR because the muscle
activity during the final 5 repetitions of each TS was greater
than the muscle activity during the even-numbered sets in
RR. The authors concluded that TS, rather than RR, should
be used when an increase in muscle activity is desired. These
conclusions display merit because various CS set structures
are less fatiguing than TS when using the same load (37,63).
However, because CS structures are less fatiguing (37,63),
greater loads may have been used during the RR structure
to match the effort of TS, and muscle activity may have been
equivalent or greater in the RR protocol. However, the inter-
action between muscle activity, load, fatigue, and training
volume is complex, resulting in only speculative claims when
using EMG data to make inferences about maximal strength
development.
In summary, various types of CS may help maintain peak
force throughout a training session, and the duration of the
IRR or intraset rest interval seems to impact the ability to
attenuate force loss, with longer rest intervals resulting in
a greater maintenance of peak force. Because of the capacity
to maintain peak force using CS, it is possible that more
force can be applied during later portions of a set, allowing
the athlete to perform the set with overall higher movement
velocities, which are also indicative of strength gains (28,77).
However, current data (50) do not support the use of CS to
increase muscle activity, and research should investigate the
effects of greater loads during CS structures to match fatigue
observed during TS structures. It has also been shown that
greater training volumes result in greater strength adapta-
tions (55), meaning that when designed appropriately, var-
iations of CS structures may be used to increase training
volume (19,47) and possibly maximal strength.
Acute Hypertrophy
As with maximal strength development, acute studies cannot
directly determine the effectiveness of a protocol to induce
muscle hypertrophy over time. However, it is possible to
examine the existing body of CS research that can link
specific acute variables with an increased potential for
inducing hypertrophy. Specifically, the following acute CS
studies incorporate large training volumes that are indicative
of classical hypertrophic training and other variables that
have previously been linked to skeletal muscle growth.
Although not designed as a study to investigate the
hypertrophic potential of CS, Hardee et al. (37,38) noted
that the rating of perceived exertion (RPE) was significantly
lower during power cleans using CS when compared with
TS and that barbell displacement was greater during CS.
Because fatigue is a determinant of training volume, set
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structures that are less fatiguing may enable greater volumes
of work to be accomplished (38) by allowing the lifter
to perform more sets or more repetitions. The idea of
greater training volumes resulting in greater skeletal muscle
hypertrophy (56,87,88) supports the idea that CS may
allow for greater training loads or training volumes and
may serve as an alternative method to achieve muscular
anabolism.
Building on this, Iglesias-Soler et al. (44) examined the
maximal number of repetitions that could be performed using
EW:R and TS. Subjects performed 3 sets of squats to failure
using a 4RM load using TS with 3 minutes of interset rest. By
using an EW:R protocol, subjects performed single squats
with IRR periods until muscular failure was achieved. The
EW:R protocol allowed subjects to complete about 5 times
as many repetitions as the TS protocol (EW:R = 45.5; TS =
9.3 repetitions). These data indicate that EW:R training allows
for a greater number of repetitions to be performed with the
same load when compared with TS, increasing training vol-
ume and the amount of external work accomplished: key
aspects of hypertrophy training (56,85,88). Therefore, accord-
ing to the hypothesis that performing more repetitions with
the same load results in greater amounts of work, suggesting
greater hypertrophy over time (14,15,56), the results from this
study (44) suggest that CS may have the ability to result in
greater hypertrophy than TS.
Other authors have also showed that CS allow for
greater training volumes than TS (19) and that RPE is
lower during CS than TS when training volume, intensity,
and work-to-rest ratios are equated (63). However, all the
studies accomplished greater training volumes by increas-
ing the number of repetitions performed, sometimes result-
ing in inefficient protocols in a practical strength and
conditioning realm because of the time needed to complete
the protocols (44). Despite the option for CS to result in
greater training volumes, and in turn greater external work,
the current body of CS literature has not attempted to
address this possibility by increasing the load lifted for an
equal number of repetitions.
Rather, studies by Girman et al. (27) and Oliver et al. (75)
chose to equalize training volumes (sets 3repetitions)
between TS and CS protocols and investigate the effect
of set structure on physiological markers of hypertrophy
(84–86), such as lactate and hormonal responses. Together,
these studies show that CS protocols result in less lactate
and a blunted hormonal response when compared with TS
(27,75). Therefore, both groups of researchers concluded
that CS should not be used in place of TS when trying to
induce skeletal muscle hypertrophy (27,75). However, it
should be noted that the process of muscle growth is a com-
plex phenomenon that includes both physiological and
mechanical factors. Therefore, one area of future research
could focus on the ability of CS to increase mechanical
factors such as external work, subsequently effecting phy-
siological markers.
In summary, the body of CS literature shows that CS
loading can allow for greater training volumes than TS in an
acute setting, which may result in greater hypertrophy over
time (56,85,86). However, this idea is purely hypothetical
because such study designs do not exist regarding the direct
effects of CS on hypertrophy.
Chronic Responses
Although the body of evidence regarding the acute re-
sponses of CS structures is vast and continually growing, few
studies have chronically implemented CS in a training
environment. Therefore, the relatively small number of
studies allows the following section to discuss each study,
to our knowledge, that has used various CS protocols
inclusive of different loads, sets, repetitions, and rest periods.
Because of the nature of training studies that target multiple
training adaptations simultaneously, each study will be
chronologically discussed as a whole rather than dividing
the responses into power, strength, and hypertrophy sub-
categories as in the acute sections of this article.
Lawton et al. (58) compared TS and RR set structures
over a 6-week training period in elite junior basketball and
soccer players (n= 26) using a 6RM load during the bench
press exercise. The subjects performed either 4 sets of 6 (TS)
or 8 sets of 3 (RR) in the same amount of time in an attempt
to equalize the work-to-rest ratio between groups. However,
the TS group actually experienced greater TUT (36.03 sec-
onds) than the RR group (31.74 seconds) despite the re-
searchers trying to equate the work-to-rest ratios. Hence,
RR would be considered as the most appropriate subclass
of CS for this study because the total rest time was equal
between groups. After the 6-week training period, subjects in
both groups increased bench press throw peak power output
against 20-, 40-, and 60-kg loads, but no differences were
present between groups. However, training with TS resulted
in significantly greater bench press strength gains when
compared with RR (increases of 9.7 and 4.9% for TS and
RR, respectively). Because subjects in this study used the
same relative intensity across the various set structures for
the duration of the training program, it is possible that im-
plementing RR structures using the same load as TS may
have resulted in a decrease in perceived effort during the RR
training sessions, as seen in other studies (37,46,63). Decreas-
ing the level of perceived effort may have allowed the ath-
letes to increase the resistance used, resulting in an increased
stimulus for the physiological adaptations that underpin the
development of muscular strength. However, because no
data were reported on the RPE and training loads were kept
constant in this study (39), further research is warranted to
determine if RR can allow for an increased training load
while producing a similar RPE as in TS. Nonetheless, these
data suggest that the strategic use of RR structures may serve
as an alternate method for developing strength and power
output but that TS may result in greater increases in strength
when all training variables are equal.
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Hansen et al. (36) compared RR with TS during the
8-week preseason period of elite rugby players. The team
(n= 18) was split into a TS group and an RR group, with
both groups completing the same lower-body resistance
training program consisting of squat and clean variations.
The only difference between groups was the redistribution
of total rest time for the RR group, which included intraset
rest intervals throughout the training program that were
subtracted from the interset rest periods (exact times varied
per week and are too complex to be summarized here). The
total rest time, training load, and training volume were not
different between groups at any time during the study. After
8 weeks of training, effect sizes showed that RR may have
had a greater effect on power output, but neither peak
velocity nor peak power assessed during loaded jump squats
significantly increased for either group. Additionally, the use
of TS resulted in significantly greater gains in back squat
1RM strength when compared with RR (an 18.3% increase
from 203 to 240 kg, and a 14.6% increase from 191 to 216 kg
for TS and RR, respectively). The greater increase in strength
in the TS group shows that RR protocols may not be ideal
when both groups use the same training loads, training vol-
umes, and total rest time. Similar to the previously discussed
study (58), it is possible that if the RR group experienced less
fatigue (37,46,63), its subjects may have been able to tolerate
greater training loads, leading to greater strength increases
when compared with TS. Additionally, the authors also ex-
plained that players participated in supplementary concur-
rent training during the time of the study, which may have
interfered with power adaptations. Therefore, the results of
this study (36) show that the specific RR protocol used did
not result in significant increases in power output during
loaded jump squats but did result in increased back squat
1RM (although a lesser increase than TS) in rugby players
participating in concurrent training during the off-season.
Zarezadeh-Mehrizi et al. (102) investigated the effect of
RR and TS training in 22 male soccer players. After a stan-
dardized 4-week block of hypertrophy training, subjects in
this study were assigned to an RR or TS group and per-
formed 3 weeks of strength training (3 sets of 5 with 85%
1RM) followed by 3 weeks of power training (5 sets of 5 with
30–80% 1RM depending on the exercise) with the total rest
time equal between groups. A lack of detail regarding the
methods of this training program creates uncertainty of
whether rest periods were controlled, evidenced by IRR
ranging from 10 to 30 seconds in the RR group. To add to
the lack of methodological clarity, 1RM squat strength was
not directly assessed and an RM estimation technique was
used, but the article did not specify how many repetitions
were used in the estimation protocol. According to the 1RM
estimations, both groups increased maximal strength (from
130 to 165 kg and 130–147 kg for TS and RR, respectively),
with the TS group experiencing a significantly greater
increase compared with the RR group. To assess power out-
put, the velocity was calculated by dividing vertical displace-
ment by time during 6 jump squats with 30% 1RM, and force
was calculated using mass, gravity, and acceleration. Unfor-
tunately, the authors did not state which mass was included
in the calculation (barbell, body, or both) and the accelera-
tion calculation was not provided. Ultimately, the estimated
power output was determined by multiplying an estimated
force and estimated velocity. With that in mind, the authors
reported that the RR group experienced increases in power
output (2,236–2,665 W), whereas the TS group did not
(1,857–1,890 W). Although the results from this study indi-
cate preferable power adaptations resulting from RR train-
ing, it is important to interpret these results with caution
because the training methodology was not clearly reported,
the TS group displayed an average 25 kg increase in back
squat strength with no concomitant increase in power out-
put, and power measurements were estimated and not
directly measured.
Oliver et al. (74) investigated the effect of RR and TS
throughout a 12-week total-body hypertrophy-oriented
training program in resistance-trained men (n= 22). The
TS group trained with 4 sets of 10 repetitions for all com-
pound lifts with 120 seconds of interset rest, whereas the RR
group performed 8 sets of 5 repetitions with 60 seconds of
interset rest, meaning the total rest time was equalized
between groups. After 12 weeks, both groups improved
bench press, back squat, and vertical jump power output,
but the RR group experienced greater increases in bench
press and vertical jump power output compared with TS.
The authors also observed similar gains in lean mass between
groups, but neither group experienced shifts in myosin heavy
chain isoform percentage. However, when both groups
were collapsed together, the percentage of IIx (13.9–8.9%)
and slow (51.1–47.5%) isoforms decreased while IIa (35.0–
43.6%) increased, indicating a typical shift in fiber type result-
ing from resistance training. It was also noted that RR and TS
increased bench press and back squat strength, but in con-
trast to the previously discussed studies (37,52,84), the RR
group in this study experienced greater increases in strength
when compared with the TS group. This anomaly may partly
be explained by the inclusion of repeated 1RM tests through-
out the study period. Although the relative intensities of the
exercises were kept the same for each group (% 1RM), sub-
jects were allowed to adjust their absolute load according to
changes in 1RM strength, which was tested every 4 weeks. In
this manner, training residuals from a previous block of train-
ing could have been translated into the subsequent training
block, indicative of a typical sequential periodized training
program that takes advantage of delayed training effects.
Although not significantly different, the RR group trained
with a greater total training volume compared with TS (effect
size range of 0.42–0.71; not reported by the authors, but
calculated by the authors of the present article using the
effect size calculator found at www.uccs.edu/;lbecker/) for
compound exercises. Therefore, it is possible that the contin-
uous increases in strength may have allowed for greater
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absolute loads to be lifted, but the authors did not focus on
this aspect. This study provides compelling evidence that
different types of CS structures may allow for greater training
loads for the same number of repetitions, resulting in greater
training volumes, which may favor strength development
when compared with TS.
Iglesias-Soler et al. (46) investigated the effects of a TS
and an EW:R protocol over a 5-week period using unilat-
eral knee extensions in sport science students of both gen-
ders (n= 13). Subjects were assigned to either the TS
group (4 sets of 8, 10RM load, 180 seconds of interset rest)
or RR group (32 repetitions, 10RM load, 17.4 seconds of
IRR). Data collected during the training sessions showed
that TS resulted in slower mean propulsive velocities
(0.48 vs. 0.54 m$s
21
) and greater RPE (8.3 vs. 6.6) than
EW:R, respectively. Following the 5 weeks of training,
subjects in the EW:R and TS groups experienced an equal
increase in isometric strength, dynamic 1RM, mean pro-
pulsive power, and total work completed with the original
10RM load. The results of this study indicate that an EW:
R unilateral knee extension protocol felt easier but resulted
in similar increases in strength and power output com-
pared with TS after 5 weeks of training in university
students of both genders.
Asadi and Ramirez-Campillo (5) investigated the effects
of TS and RR plyometric training in college-aged students
(n= 13) who were familiar with plyometric training but had
not participated in such training for at least 6 months. The
TS group consisted of 5 sets of 20 maximal depth jumps
from a 45-cm box with 120 seconds of interset rest. The
RR group completed 5 sets of 20 but with 30 seconds of
intraset rest after the first 10 repetitions of each set and 90
seconds of interset rest. After training twice per week for
6 weeks, both groups increased countermovement jump
height, standing long jump distance, and decreased t-test
and 20- and 40-m sprint times. Although there were no
significant interactions between groups, the effect sizes were
greater in the RR group for countermovement jump height,
long jump distance, and t-test time, whereas the effect sizes
were greater for the TS group for 20- and 40-m sprint times.
Therefore, in untrained college students, plyometric training
using TS and RR resulted in increased jumping, sprinting,
and agility performance.
In summary, 4 studies show that TS and CS result in
similar increases in power output (5,36,46,58), whereas 2
studies show that CS protocols may be favorable over TS
(74,102). Differences in study designs may explain these
unequivocal findings. The studies that reported similar in-
creases in power output in TS and CS protocols equated
training intensity, volume, and total rest time between pro-
tocols, not taking full advantage of the ability of CS struc-
tures to increase training volume (44). However, the 2
studies that showed preferable power output adaptations
from CS structures also equated total rest time between
groups (74,102), but unique to the study by Oliver et al.
(74), the 12-week duration allowed for 1RM measurements
every 4 weeks and possibly greater absolute loads in the RR
group. Therefore, CS structures may be more beneficial than
TS for the development of muscular power output, but more
research must be conducted in this area to make conclusive
recommendations.
To date, some studies have reported that strength gains
are generally greater in TS set structures than CS
(36,58,102), with only one study reporting that CS structures
produce superior strength gains (74) and one study showing
similar increases in strength (46). At first glance, the collec-
tive body of RR literature suggests that different CS struc-
tures may have a limited application for the development of
maximal strength. However, it is important to carefully
examine these studies and determine why TS resulted in
greater strength development compared with RR training
in these instances. Two of the main commonalities within
studies that investigate RR are the equalization of the total
rest time for RR and TS protocols and the lack of training
load variation and systematic progression between the RR
and TS set structures (36,58,102). Similar to matching total
rest time, the equalization of training loads between groups
is a sound scientific method. However, if RR and TS set
structures are performed using the same training intensities,
it is likely that the TS group will experience greater acute
fatigue, a greater compensatory response, and possibly
greater increases in strength. Therefore, to determine the
effects of CS on chronic strength adaptations, it is necessary
to determine how the RR protocols used in these studies can
be reformed to create CS that may elicit strength gains equal
to or greater than TS, similar but not limited to the strategy
used by Oliver et al. (74).
Only one study has directly measured skeletal muscle
hypertrophy after CS and TS training, showing that neither
set structure is superior to the other (74). One of the advan-
tages of CS loading is that greater training intensities can be
used for the same training volume, possibly magnifying neu-
romuscular and morphological training adaptations
(25,34,55,56). Therefore, future research should address the
effects of greater total rest times, training loads, training vol-
umes, and total external work in CS training protocols.
Finally, it is important to not neglect the periodization pro-
cess during training studies to elicit progressive adaptations
over time in a systematic manner.
SUMMARY
A summary of studies investigating CS, RR, and EW:R is
included in Table 1. Because of the large degree of variability
of protocols between studies and even within studies, the
results of each study have been summarized and do not
include results for individual repetitions or sets but include
the global response to each protocol as a whole.
Collectively, researchers have compiled a large body
of evidence that supports the use of CS to maintain or
increase acute power-related variables, such as jump height,
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TABLE 1. Studies listed by cluster set subclass, followed by duration (acute or chronic), and author’s last name.
Author
Cluster set
subclass Duration Subjects Protocols Response
Boullosa
et al. (11)
Basic CS Acute 12 resistance-
trained men, 5RM
half squat 2.333
BM
Countermovement jump
height measured before
and 1, 3, 6, 9, and 12 min
after squats with 5RM
load; TS: 5 reps; CS: 5
reps with 30-s IRR
Vertical jump postactivation
potentiation occurred
after 1 min using CS
compared with 9 min
using TS
Garcı
´a-
Ramos
et al. (26)
Basic CS Acute 34 active college-
aged men, 1RM
bench press
1.023BM
Bench press throws at 30,
40, and 50% 1RM; TS:
15 reps; CS1: 15 reps
with 6-s IRR; CS2: 15
reps with 12-s IRR
Peak velocity was
maintained best in CS2,
followed by CS1, both of
which maintained velocity
better than TS
Haff et al.
(33)
Basic CS Acute 8 male track and
field athletes, 5
male weightlifters,
1RM power clean
1.323BM
Clean pulls at 90 and 120%
1RM; TS: 5 reps; CS: 5
reps with 30-s IRR
On average, peak velocity
was greater during CS
compared with TS
Hardee
et al. (37)
Basic CS Acute 10 male
recreational
weightlifters, 1RM
power clean
1.393BM
Power cleans at 80% 1RM;
TS: 3 36 with 180-s
interset rest; CS1: same
as TS with 20-s IRR;
CS2: same as TS with
40-s IRR
CS resulted in greater
power output and less
exertion than TS; CS with
longer rest periods
maintained power output
and decreased exertion
more than when CS rest
periods were shorter
Hardee
et al. (39)
Basic CS Acute 10 male
recreational
weightlifters, 1RM
power clean
1.393BM
Power cleans at 80% 1RM;
TS: 3 36 with 180-s
interset rest; CS1: same
as TS with 20-s IRR;
CS2: same as TS with
40-s IRR
Force, velocity, and power
were better maintained
during CS than TS; CS
with longer rest periods
maintained these
variables better than when
CS rest periods were
shorter
Hardee
et al. (38)
Basic CS Acute 10 male
recreational
weightlifters, 1RM
power clean
1.393BM
Power cleans at 80% 1RM;
TS: 3 36 with 180-s
interset rest; CS1: same
as TS with 20-s IRR;
CS2: same as TS with
40-s IRR
Vertical displacement was
greater during CS,
resulting in greater
external work than TS
Iglesias
et al. (47)
Basic CS Acute 13 men; bench
press 1RM 1.23
BM; bicep curl
1RM 0.253BM
Bench press and biceps
curl with different loads;
TS: reps to failure using
70% 1RM; CS: reps to
failure using 90% 1RM
with 30-s IRR
CS resulted in a greater
number of repetitions
performed with a greater
load compared with the
greatest number of
repetitions performed
using TS with a lighter
load
Moir et al.
(68)
Basic CS Acute 11 resistance-
trained men,
deadlift 1RM
1.953BM
Deadlifts using 90% 1RM;
TS: 4 reps; CS1: 4 reps
with 30-s IRR; CS2: 4
reps with 30-s intraset
rest after second rep
Force was similar between
CS1, CS2, and TS, but
CS1 resulted in greater
TUT, less power output
and greater impulse than
TS
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Tufano et al.
(91)
Basic CS Acute 12 resistance-
trained men, back
squat 1RM 1.93
BM
Squats using 60% 1RM;
TS: 3 312 with 120-s
interset rest; CS1: 3 312
with 120-s interset rest
and 30-s intraset rest after
every 2 reps; CS2: 3 3
12 with 120-s interset rest
and 30-s intraset rest after
ever 4 reps
CS1 and CS2 maintained
velocity and power output
better than TS; more
frequent intraset rest
(CS1) resulted in greater
maintenance of velocity
and power output (CS2)
Valverde-
Esteve
et al. (92)
Basic CS Acute 16 physical
education men,
bench press 1RM
1.153BM
Bench press using subject-
dependent “optimal load”
of about 49% 1RM; TS:
1315; CS1: 1 315 with
5-s IRR; CS2: 1 315
with 10-s IRR
Peak power output was
maintained best in CS2,
followed by CS1, both of
which maintained power
output better than TS
Nicholson
et al. (71)
Basic CS 6 wk 46 trained college
men, no baseline
data provided
TS Strength: 4 36, 85%
1RM, 900-s total rest; TS
hypertrophy: 5 310, 70%
1RM, 360-s total rest;
CS1: 4 36, 85% 1RM,
1,400-s total rest; CS2:
436, 90% 1RM, 1,400-s
total rest
All CS and TS groups
resulted in similar increases
in isometric force, muscle
activity, and jump height;
CS2 and TS strength
resulted in greater strength
gains compared with TS
hypertrophy and CS1
Rooney
et al. (80)
Basic CS 6 wk 18 men and 24
untrained women,
bicep curl 1RM
11–14 kg
TS: 6–10 reps at 6 RM; CS:
6–10 reps at 6RM with
30-s IRR
TS resulted in greater gains
in strength compared with
CS
Hansen
et al. (35)
EW:R Acute 20 (semi) and
professional male
rugby players,
strength level not
provided
TS: 4 36 with 180-s
interset rest; CS1: 4 36
with 120-s interset rest
and 12-s IRR; CS2: 4 36
with 120-s interset rest
and 30-s intraset rest after
every 2 reps; CS3: 4 36
with 120-s interset rest
and 60-s intraset rest after
every 3 reps
Power and velocity were
greater during CS than
TS, with no differences in
force between the
protocols
Iglesias-
Soler
et al. (45)
EW:R Acute 10 male judoists,
back squat 1RM
1.583BM
Back squats with 4RM load;
TS: 3 sets to failure, 180-s
interset rest; CS: same
volume as TS with
subject-dependent IRR
with same EW:R as TS
CS resulted in greater
movement velocity during
the protocol and less
lactate after compared
with TS
Iglesias-
Soler
et al. (44)
EW:R Acute 9 male judoists,
back squat 1RM
1.573BM
Back squats with 4RM load;
TS: 3 sets to failure, 180-s
interset rest; CS: same
volume as TS with
subject-dependent IRR
with same EW:R as TS
CS resulted in a greater
number of repetitions
while also resulting in
greater movement velocity
than TS
Iglesias-
Soler
et al. (43)
EW:R Acute 10 male judoists,
back squat 1RM
1.583BM
Back squats with 4RM load;
TS: 3 sets to failure, 180-s
interset rest; CS: same
volume as TS with
subject-dependent IRR
with same EW:R as TS
CS resulted in lower
exercise heart rates,
systolic blood pressure,
and rate pressure product
compared with TS
Lawton et al.
(59)
EW:R Acute 26 elite junior, male
basketball and
soccer players,
bench press 6RM
0.83BM
Bench press with 6RM load;
TS: 6 reps; CS1: 6 31
with 20-s IRR; CS2: 3 3
2 with 50-s interset rest;
CS3: 2 33 with 100-s
interset rest
Power output was greater
during CS compared with
TS
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Mayo et al.
(63)
EW:R Acute 7 male and 1 female
sport science
students, bench
press 10RM
0.713BM; back
squat 10RM
1.293BM
Bench press and back
squats with 10RM load;
TS: 5 sets to failure with
180-s interset rest; CS:
same volume as TS with
subject-dependent IRR
with same EW:R as TS
CS resulted in greater
movement velocity and
less exertion compared
with TS
Iglesias-
Soler
et al. (46)
EW:R 5 wk 6 and 7 female and
male sport
science students,
respectively;
strength level not
provided for each
gender
Unilateral knee extensions
with 10RM load; TS: 4 3
8 with 180-s interset rest;
CS: 32 reps with 17.4-s
IRR
CS and TS resulted in
similar increases in 1RM,
power output, and
muscular endurance
Denton et al.
(19)
RR Acute 9 healthy men,
bench press 6RM
1.013BM
TS: 4 36, 302-s interset
rest; CS1: 8 33, 130
interset rest; CS2: 8 sets,
130 interset rest* (3 reps
during odd sets, reps to
failure during even sets)*
CS1 resulted in similar
power output, force, and
work compared with TS;
CS2 resulted in a greater
number of repetitions,
work, and lactate than
CS1 and TS
Girman
et al.,
2014 (27)
RR Acute 11 resistance-
trained men,
strength level not
provided
TS: 1 36 clean pull 75%
and 1 310 back squat
70% with 2-min interset
rest; CS: same as TS, but
15-s intraset rest and 90-s
interset rest
Blood lactate was lower and
jump performance was
greater after CS
compared with TS; both
protocols resulted in
similar growth hormone
and cortisol responses
Joy et al.
(50)
RR Acute 9 resistance-trained
men, back squat
1RM 1.763BM
Back squats with 75%
1RM; TS: 4 310 with
120-s interset rest; CS: 8
34 with 60-s interset rest
CS resulted in greater
power output but less
muscle activity compared
with TS
Moreno
et al. (69)
RR Acute 26 recreationally
trained college
men, strength
levels not
reported
Plyometric bodyweight jump
squats; TS: 2 310 with
90-s interset rest; CS1: 4
35 with 30-s interset
rest; CS2: 10 32 with
10-s interset rest
CS1 and CS2 resulted in
similar force but greater
jump height, power
output, and take off
velocity compared with TS
Oliver et al.
(76)
RR Acute 12 resistance-
trained men, back
squat 1RM 1.73
BM 12 untrained
men, back squat
1RM 1.13BM
Back squats with 70%
1RM; TS: 4 310 with
120-s interset rest; CS: 4
310 with 90-s interset
rest and 30-s intraset rest
Velocity and power output
were better maintained
during CS compared to
TS
Oliver et al.
(75)
RR Acute 12 resistance-
trained men, back
squat 1RM
1.753BM; 11
untrained men,
back squat 1RM
1.073BM
Back squats with 70%
1RM; TS: 4 310 with
120-s interset rest; CS: 4
310 with 90-s interset
rest and 30-s intraset rest
CS resulted in greater
volume load and power
output than TS, while CS
also resulted in less TUT,
less lactate, and similar
hormonal responses
Asadi and
Ramirez-
Campillo
(5)
RR 6 wk 13 college men,
40-m sprint 6.31
s;
countermovement
jump 43 cm
Depth jumps from a 45-cm
box; TS: 5 320 with 120-
s interset rest; CS: 5 3
20 with 90-s interset rest
and 30-s intraset rest
Both groups improved
countermovement jump
height, standing long jump
distance, and t-test agility,
20- and 40-m sprint times;
sprinting effect sizes were
greater in TS, but jumping
effect sizes were greater
in CS
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Hansen
et al. (36)
RR 8 wk 18 elite rugby union
men, 1RM back
squat 1.93BM
Squat and pull variations,
80–95% 1RM; TS: 3–5
sets of 3–8 with 180-s
interset rest; CS: same as
TS but with 120-s interset
rest and 10- to 30-s IRR
CS and TS both resulted in
increases in strength, but
a greater increase after
TS; neither protocol had
a significant change in
jump squat force, velocity,
or power
Lawton et al.
(58)
RR 6 wk 26 men, elite junior
basketball and
soccer players;
strength levels
not reported
Bench press using 80–
105% 6RM load; TS: 4 3
6 with 260-s interset rest;
CS: 8 33 with similar
work-to-rest ratios as TS
(but not controlled,
making this RR, not EW:
R)
Increases in power and
strength were present
after both CS and TS, but
strength increases were
greater after TS; TUT
during training was
greater during TS
Oliver et al.
(74)
RR 12 wk 22 men in the
military; bench
press 1RM
1.673BM; back
squat 1RM
2.093BM
Total body workout using
60–75% 1RM; TS: 4 3
10 with 120-s interset
rest; CS: 8 35 with 60-s
interset rest
CS and TS resulted in
similar increases in lean
mass, but CS resulted in
greater gains in strength
and power
Zarazadeh-
Mehrizi
et al.
(102)
RR 6 wk 22 male soccer
players; back
squat 1RM
1.833BM
Total body workout using
85% 1RM during strength
phase and 30–80% 1RM
during power phase; TS:
333–5 with 180-s
interset rest; CS: 3 33–5
with 120-s interset rest
and 10- to 30-s IRR
CS and TS resulted in
increased strength, but
increases were greater
after TS; CS resulted in
increases in power output,
whereas TS did not
Arazi et al.
(4)
Rest-
pause/
basic CS
Acute 20 resistance-
trained men;
strength level not
reported
Bench press and leg press
with 75% 1RM; TS: 4
sets to failure with 3-min
interset rest; CS1: same
as TS but with 2-s IRR;
CS2: same as TS but with
4-s IRR
The only study to show that
TS resulted in a greater
number of repetitions than
CS, most likely because
of the subjects supporting
the load at full elbow
(bench press) or knee (leg
press) extension during
the IRR periods; possible
that CS where subjects
support the load during
IRR is more fatiguing than
TS
Keogh et al.
(51)
Rest-
pause/
basic CS
Acute 12 weight-trained
men; bench press
1RM 1.413BM
Bench press using 6RM
load; TS: 6 reps; CS: 6
reps with 2-s IRR
Concentric pectoralis major
muscle activity was less
during CS compared with
TS, whereas power
output, triceps muscle
activity, TUT, blood
lactate, and force were
not different between
protocols
Marshall
et al. (62)
Rest-pause Acute 14 resistance-
trained men; back
squat 1RM
2.083BM
Back squats using 80%
1RM; TS1: 5 34 with
180-s interset rest; TS2: 5
34 with 20-s interset
rest; CS: sets to failure
with 20-s interset rest until
20 reps completed
CS resulted in greater
muscle activity than TS1
and TS2 with similar
amounts of postexercise
fatigue
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force, velocity, and power. Additionally, there is compelling
evidence that CS structures acutely allow for a greater
volume load, and in turn greater external work, by increasing
the number of repetitions performed at a given load or
increasing the load for a given number of repetitions.
In a training context, researchers have used various
protocols inclusive of different exercises on a variety of
subjects, but future research should continue to explore the
possibilities of different CS structures on hypertrophy,
strength, power, and sport-specific performance. Further-
more, research is needed to determine the effects of CS
protocols that use different total rest periods and loads
compared with TS. Finally, because of various protocol
designs that possibly play a role in the development of
inconsistent data within the body of CS literature, the need
for consistent terminology when explaining basic CS, RR,
and EW:R set structures is of utmost importance.
PRACTICAL APPLICATIONS
According to the present scientific literature, CS structures
should be used when:
Velocity and power maintenance are warranted
(26,33,35,39,44,45,47,50,59,69,75,76,91,92).
Aiming to increase the total volume load and total work
within a session (19,44,47,75).
Aiming to increase vertical jump performance
(27,69,74).
Aiming to decrease an athlete’s RPE (37,46,63).
Technique and displacement of an exercises is to be
maintained (33,38).
The SSC plays a large role in the designated movement
(68).
Aiming to acutely decrease cardiovascular stress during
resistance training (43).
Using post-activation potentiation (PAP) under strict
time constraints (11).
ACKNOWLEDGMENTS
The time spent writing this manuscript was partly funded by
a postgraduate research scholarship from Edith Cowan
University and partly by a PRVOUK P38 biological aspect of
human movement grant in association with Charles University.
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... Traditionally, resistance training is performed with repetitions that are completed continuously with no rest period within the set and a period of rest is then applied at the end of the set to facilitate recovery (53). When sets are prescribed in this manner, they are known in the literature as traditional-set structures (53). ...
... Traditionally, resistance training is performed with repetitions that are completed continuously with no rest period within the set and a period of rest is then applied at the end of the set to facilitate recovery (53). When sets are prescribed in this manner, they are known in the literature as traditional-set structures (53). Traditional-set structures have been clearly demonstrated to accumulate large amounts of mechanical and metabolic fatigue during sets (12,54). ...
... In contrast to traditional-set structures, cluster-set structures reduce the fatigue experienced during sets by including intraset rest periods in addition to traditional interset rest periods (14,53,54). More specifically, cluster-set structures facilitate greater maintenance of velocity and power output (54) while reducing metabolic stress (39) and consequently, reduced neuromuscular fatigue for a given training volume (46). ...
Article
Davies, TB, Halaki, M, Orr, R, Mitchell, L, Helms, ER, Clarke, J, and Hackett, DA. Effect of set structure on upper-body muscular hypertrophy and performance in recreationally trained men and women. J Strength Cond Res 36(8): 2176–2185, 2022—This study explored the effect of volume-equated traditional-set and cluster-set structures on muscular hypertrophy and performance after high-load resistance training manipulating the bench press exercise. Twenty-one recreationally trained subjects (12 men and 9 women) performed a 3-week familiarization phase and were then randomized into one of two 8-week upper-body and lower-body split programs occurring over 3 and then progressing to 4 sessions per week. Subjects performed 4 sets of 5 repetitions at 85% one repetition maximum (1RM) using a traditional-set structure (TRAD, n = 10), which involved 5 minutes of interset rest only, or a cluster-set structure, which included 30-second inter-repetition rest and 3 minutes of interset rest (CLUS, n = 11). A 1RM bench press, repetitions to failure at 70% 1RM, regional muscle thickness, and dual-energy x-ray absorptiometry were used to estimate changes in muscular strength, local muscular endurance, regional muscular hypertrophy, and body composition, respectively. Velocity loss was assessed using a linear position transducer at the intervention midpoint. TRAD demonstrated a significantly greater velocity loss magnitude (g = 1.50) and muscle thickness of the proximal pectoralis major (g = −0.34) compared with CLUS. There were no significant differences between groups for the remaining outcomes, although a small effect size favoring TRAD was observed for the middle region of the pectoralis major (g = −0.25). It seems that the greater velocity losses during sets observed in traditional-set compared with cluster-set structures may promote superior muscular hypertrophy within specific regions of the pectoralis major in recreationally trained subjects.
... In a CS, all the repetitions were divided into small clusters of repetitions separated by brief rest periods. Compared with traditional sets (TS) training, CS could improve training quality (12), decrease fatigue by allowing better recovery of ATP and CP storage and metabolite clearance (13,14). ...
... Although the same training volume (765) for both groups was applied in the current study, CS showed greater DLP effects. Resistance training with CS con guration was proved to induce less fatigue compared with TS by the same training volume (13,22). It might explain that better DLP effects observed in the study. ...
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Background: The aim of the study was to compare the delayed potentiation (DLP) effects induced by cluster sets (CS) versus traditional sets (TS) resistance training. Methods: Sixteen male collegiate athletes were recruited for the study in a crossover design. All the subjects performed a CS (30 s interval between reps, 4 minutes interval between sets) and a TS (no rest between reps, 4 minutes interval between sets) resistance training sessions (3 sets of 3 repetitions of barbell back squat at 85% 1RM) in random order separated by 72 hours. Countermovement jump (CMJ), 20-meter sprint and T-test performance were evaluated at baseline and 6 hours after the resistance training sessions. Results: 6 hours after the resistance training sessions, both the CS and TS significantly improved the CMJ height (CS: ES = 0.48, P < 0.001; TS: ES = 0.23, P = 0.006), CMJ take-off velocity (CS: ES = 0.56, P < 0.001; TS: ES = 0.38, P = 0.004), CMJ push-off impulse (CS: ES = 0.38, P < 0.001; TS: ES = 0.26, P = 0.006), 20-meter sprint (CS: ES = 0.85, P < 0.001; TS: ES = 0.58, P = 0.006) and T-test (CS: ES = 0.99, P < 0.001; TS: ES = 0.73, P = 0.003) performance compared with baseline values. Following the CS, CMJ height (ES = 0.25, P = 0.007), CMJ peak power (ES = 0.2, P = 0.034) and 20-meter sprint performance (ES = 0.31, P = 0.019) were significantly better compared with that following TS. Conclusions: Both TS and CS configurations could induce DLP at 6 hours following the training. CS is a better strategy to induce DLP compared with TS training.
... For the trained limb, both experimental groups showed significant improvements in the 1RM test. These results are similar to those observed in previous studies, which obtained comparable strength gains after training programs with different set configurations but equated in volume and work-to-rest ratio 14,16,18 . Furthermore, in agreement with previous research 18 , these 1RM improvements were accompanied by increases in the levels of MPP, regardless of the set configuration that was used. ...
Article
Full-text available
Objectives: The main aim of this study was to determine the effects of set configuration during five weeks of unilateral knee extension resistance training on untrained knee extensors performance. Methods: Thirty-five subjects were randomly assigned to traditional training (TTG; n=14), rest-redistribution (RRG; n=10) and control group (CON; n=11). TTG and RRG groups trained the dominant knee extensors twice a week with the 10-repetition maximum (RM) load. TTG performed four sets of eight repetitions with three min-rest between sets and RRG 32 repetitions with 17.4 seconds of rest between each one. Before and after interventions, anthropometry, muscle thickness (MT), pennation angle (PA), 1RM, number of repetitions with 10RM pretest load (N10RM), maximum propulsive power (MPP) and maximum voluntary isometric contraction (MVIC) were measured. Results: 1RM of the untrained leg increased only in the TTG group (p<0.001, 10.3% compared with Pre-test). 1RM, MPP and N10RM increased in the trained leg in both TTG (p<0.001) and RRG (p<0.001). No changes occurred in MT or PA. Conclusions: These results suggest that, when it is not possible to perform bilateral exercises (e.g., leg injury), traditional set configurations should be recommended to improve maximal voluntary force in the untrained leg.
... Considering the potential of some recovery strategies on athletic performance [100], this would be a relevant area for future research. Similarly, the configuration of recovery time (e.g., cluster vs. traditional set) would also be a relevant area of further research inquiry [101][102][103]. For example, the use of inter-repetition recovery might reduce the need for prolonged inter-set rest intervals, although this has not been previously explored in soccer. ...
Article
Full-text available
The aim of this review was to describe and summarize the scientific literature on programming parameters related to jump or plyometric training in male and female soccer players of different age and fitness levels. A literature search was conducted in the electronic databases PubMed, Web of Science and SCOPUS, using keywords related to the main topic of the study (e.g., “ballis-tic”, “plyometric”). According to the PICOS framework, the population for the review was re-stricted to soccer players, involved in jump or plyometric training. Among 7,556 identified studies, 90 were eligible for inclusion. Only 12 studies were found for females. Most studies (n=52) were conducted with youth male players. Moreover, only 35 studies determined the effec-tiveness of a given jump training programming factor. Based on the limited available research, it seems that a dose of 7 weeks (1-2 sessions per week), with ~80 jumps (specific of combined types) per session, using near-maximal or maximal intensity, with adequate recovery between repetitions (<15 s), sets (≥30 s) and sessions (≥24-48 h), using progressive overload and taper strategies, using appropriate surfaces (e.g., grass), and applied in a well-rested state when com-bined with other training methods, would increase chances for effective and safe plyome-tric-jump training interventions aimed at improving soccer players physical fitness. In conclu-sion, jump training is effective, and an easy-to-administer training approach for youth, adult, male and female soccer players. However, optimal programming for plyometric-jump training in soccer is yet to be determined in future research.
... While cluster sets are an effective method for maintaining movement velocity across a series of sets, one often noted issue with this programming strategy is that the total time of the session can be extended (119). Due to the reality that the time allotted for strength training is often limited in many applied settings, several researchers have recommended an alternative that they refer to as the rest-redistribution method (117). The rest-redistribution method can be applied by 1) redistributing the rest time between sets to include the intra-set or inter-repetition (Insert Figure 1 here) ...
Article
Altering set configurations during a resistance training program can provide a novel training variation that can be used to modify the external and internal training loads that induce specific training outcomes. To design training programs that better target the defined goal(s) of a specific training phase, strength and conditioning professionals need to better understand how different set configurations impact the training adaptations that result from resistance training. Traditional and cluster set structures are commonly implemented by strength and conditioning. The purpose of this review is to offer examples of the practical implementation of traditional and cluster sets that can be integrated into a periodized resistance training program.
... 1-5 minutes rest). 6 These set configurations are referred to in the literature as a 'traditional set'. 7 During traditional set-structures as a lifter performs repetitions and approaches concentric muscular failure and fatigue increases, there is a reduction in movement velocity. ...
Article
Background: Similar muscle performance adaptations have been shown following volume-equated resistance training using cluster (CLUS) versus traditional (TRAD) set structures. This study aimed to examine the effects of higher-volume CLUS compared to lower-volume TRAD set structures on muscle performance. Methods: Twenty resistance-trained males (age 20.9 ± 4.3 y) were randomized into one of two bench press training routines performed for six weeks. Subjects in CLUS (n = 10), performed six sets of five repetitions at 85% 1RM with 30 seconds inter-repetition rest and three minutes of inter-set rest. In contrast, subjects in TRAD (n = 10) performed three sets of five repetitions at 85% 1RM with five minutes of inter-set rest. Muscular strength (one repetition maximum - 1RM), concentric velocity, power, local muscular endurance and maintenance muscle performance (in training sessions) were assessed. Results: For 1RM there was a significant time effect (p < 0.001) with moderate effect sizes (ES) within each group (CLUS: ES = 0.48; TRAD: ES = 0.67). A trend towards significance was found for concentric velocity (p = 0.05; CLUS: ES =-0.36; TRAD (ES = -0.96). There were no other significant time or group effects nor group × time interactions. Greater maintenance of concentric velocity and power (sets 1-3) was found for CLUS compared to TRAD at week one (p <0.05) but not at week six. Conclusions: High load resistance training in the bench press exercise, utilizing intra-set rest periods to increase the training volume, does not yield any muscular performance benefits compared to traditional set structures.
... Instead, the contractions are spread more evenly over the whole time horizon to allow a greater accumulation of training volume, i.e., force-time integral. This is a similar approach to variants of so-called cluster sets [50], which allow to increase training volume by breaking up the traditional set-repetition structure. Here, the algorithmic optimization of durations of contractions and rests provides a clear advantage over intuitive planning. ...
Article
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Individualized resistance training is necessary to optimize training results. A model-based optimization of loading schemes could provide valuable impulses for practitioners and complement the predominant manual program design by customizing the loading schemes to the trainee and the training goals. We compile a literature overview of model-based approaches used to simulate or optimize the response to single resistance training sessions or to long-term resistance training plans in terms of strength, power, muscle mass, or local muscular endurance by varying the loading scheme. To the best of our knowledge, contributions employing a predictive model to algorithmically optimize loading schemes for different training goals are nonexistent in the literature. Thus, we propose to set up optimal control problems as follows. For the underlying dynamics, we use a phenomenological model of the time course of maximum voluntary isometric contraction force. Then, we provide mathematical formulations of key performance indicators for loading schemes identified in sport science and use those as objective functionals or constraints. We then solve those optimal control problems using previously obtained parameter estimates for the elbow flexors. We discuss our choice of training goals, analyze the structure of the computed solutions, and give evidence of their real-life feasibility. The proposed optimization methodology is independent from the underlying model and can be transferred to more elaborate physiological models once suitable ones become available.
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In traditional sets (TRD) repetitions are performed continuously, whereas cluster sets (CLU) allow a brief rest between groups of repetitions. We investigated the acute mechanical, metabolic, and hormonal response to CLU in men. Twelve resistance-trained (RT) and 11 untrained (UT) men performed TRD (4 × 10 repetitions with 2 min rest) and CLU [4 × (2 × 5) with 1.5 min rest between sets 30 s rest between clusters] at 70 % 1RM back squat in random order. Seven days separated trials. Average power and time under tension (TUT) were calculated. Blood was sampled pre, sets 1, 2, and 3; immediate post-exercise, 5, 15, 30, 60 min post-exercise for blood lactate, total testosterone (TT), free testosterone (FT), growth hormone (GH), and cortisol. CLU produced greater average power at an increasing number of repetitions over each set with greater total volume load. TUT was shorter for RT and lower for CLU in repetitions 1, 6, 7, 8. Blood lactate was higher Set 2 through 30 min in TRD. RT had higher TT; however, the time course was similar between RT and UT. TT and FT increased immediate post-exercise and remained elevated 30 min in both conditions. GH was significantly greater during TRD with a similar pattern observed in both conditions. Cortisol was significantly lower at 30 min in CLU. CLU allowed greater total volume load, shorter TUT, greater average power, similar anabolic hormonal response, and less metabolic stress. The acute response was similar despite training status.
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Introduction: It is widely believed that ‘strength-type’ (STR) resistance training (RT) is a more effective way of improving maximal strength than ‘hypertrophy-type’ RT (HYP) however, research comparing these training methods is far from unequivocal (Nicholson et al., 2014). Furthermore, cluster training (CL) challenges the traditional way in which strength training sessions are designed although there is a paucity of research into this approach. Our main objective was to compare the adaptations resulting from STR, HYP and CL training over a 6 week period involving the back squat. Methods: 46 trained males (age: 21.8 ± 2.6 years; height: 178.0 ± 6.3cm; mass: 81.1 ± 8.8kg) were matched according to one repetition maximum [1RM] strength before being randomly assigned to one of 4 groups: a) STR: 4x6 reps, 85% 1RM, 900s total rest; b) HYP: 5x10 reps, 70% 1RM, 360s total rest; c) CL-1 4x6 reps, 85% 1RM, 1400s total rest; d) CL-2: 4x6 reps, 90% 1RM, 1400s total rest. Physiological and mechanical variables were measured before, during and after the workouts to investigate the acute training stimulus whilst similar techniques were employed before, during and after a 6 week intervention (2 sessions per week) to investigate the training effects. The findings were analysed using a two-way mixed ANOVA with significance set at p<0.05. Results: From an acute perspective, the STR and HYP workouts resulted in significantly greater reductions in repetition quality than the CL workouts (p<0.05). Furthermore, the STR and HYP workouts showed significant post-exercise elevations in blood lactate concentration (p<0.001). In terms of chronic responses, all four groups elicited significant increases (8-13%; p<0.001) in 1RM strength after training; however, the 1RM improvements were significantly greater for the STR (12.1 ± 2.8%; p<0.05) and CL-2 (13.2 ± 2.2%; p<0.001) groups than the HYP group (8.1 ± 2.5%). Increases in isometric peak force, rate of force development, muscle activity and jump height were not significantly different between groups. Discussion: The STR and CL-2 regimens represented the most favorable means of improving maximal strength. The effectiveness of the STR and CL-2 regimens underlines the importance of longer time under tension and greater impulse generation for strength development but does not support the importance of higher velocities which are often used to signify repetition quality. The findings highlight that CL regimens can offer similar performance enhancements to STR regimens so the decision as to which approach should be use lies with coaches.
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This study investigated the effect of introducing different interrepetition rest (IRR) periods on the ability to sustain maximum bench press throw velocity with a range of loads commonly used to develop upper-body power. Thirty-four physically active collegiate men (age: 21.5 ± 2.8 years; body mass: 75.2 ± 7.2 kg; height: 176.9 ± 4.9 cm) were tested during 2 consecutive weeks. During the first week, the maximum dynamic strength (repetition maximum [RM]) in bench press exercise was determined (RM = 76.7 ± 13.2 kg). The following week, 3 testing sessions were conducted with 48 hours apart in random order. In each day of evaluation, only 1 load (30%RM, 40%RM, or 50%RM) was assessed in the bench press throw exercise. With each load, subjects performed 3 single sets of 15 repetitions (15-minute interset rest) with 3 different sets configurations: continuous repetitions (CR), 6 seconds of IRR (IRR6), and 12 seconds of IRR (IRR12). The decrease of peak velocity (PV) was significantly lower for IRR12 compared with CR and IRR6 at least since the repetition 4. No differences between CR and IRR6 protocols were found until the repetition 7 at 30%RM and 40%RM and until the repetition 5 at 50%RM. The decrease of PV during the CR protocol was virtually linear for the 3 loads analyzed (r2 > 0.99); however, this linear relationship became weaker for IRR6 (r2 = 0.79–0.95) and IRR12 (r2 = 0.35–0.87). These results demonstrate that IRR periods allow increasing the number of repetitions before the onset of significant velocity losses.
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Current recommendations for training protocols aimed at increasing muscle mass are commonly based on a percentage of the concentric one repetition maximum (1RM) for a particular exercise. However, research utilizing lower exercise intensities (20- 30% 1RM) has been observed to result in skeletal muscle hypertrophy similar to that of higher intensity resistance training. These findings appear to question the overall importance of exercise intensity for increasing muscle mass. Objectives: The purpose of this manuscript is to discuss the skeletal muscle hypertrophy exercise intensity recommendations and provide discussion on overall exercise volume, which is likely more important for stimulating skeletal muscle hypertrophy than exercise intensity per se. Design and Methods: Non-systematic review Results: It appears that a large portion of the exercise recommendations for skeletal muscle hypertrophy appear to be based on protocols that elicit short term changes in systemic ‘anabolic&apos; hormones; although little conclusive evidence exists to support that ‘anabolic&apos; hormone hypothesis. Exercise volume may be of much more importance for stimulating and maximizing the duration of the muscle protein synthesis (MPS) response than exercise intensity per se. In addition,chronic training studies confirm the acute findings that volume, not exercise intensity is the mediating factor for skeletal muscle hypertrophy. Conclusion: The data suggests that skeletal muscle hypertrophy recommendations on the basis of exercise intensity are too simplistic and more focus should instead be placed on total exercise volume. The current recommendations for muscle hypertrophy do not reflect current science.
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Limited research exists on the language associated with resistance training. The purpose of this study was to identify the ways in which resistance training exercises are named. Names of 57 exercises were obtained from the National Strength and Conditioning Association's Exercise Technique Manual for Resistance Training. The analysis consisted of categorizing into themes all the words of the exercise names, and then identifying naming patterns. The 57 exercises names were comprised of 188 total words. Seven percent of the words described body position (e.g., "seated"); 1.1% described body position direction (e.g., "over"); 19.1% described a body part (e.g., "shoulder"); 1.1% were body part adjectives ("stiff"); 30.3% described action (e.g., "row"); 5.9% described action direction (e.g., "lateral"); 23.4% described equipment (e.g., "barbell"); 8% described equipment position (e.g., "incline"); and 4.3% were considered miscellaneous (e.g., "power"). Of the 57 exercises names, 22.8% contained a body position word; 3.5% contained a body position direction word; 54.4% contained a body part word; 3.5% contained a body part adjective word; 94.7% contained an action word; 19.3% contained an action direction word; 61.4% contained an equipment word; 26.3% contained an equipment position word; and 12.3% contained a miscellaneous word. These types of words were used inconsistently. Additionally, 35 different naming patterns were discovered among the 57 exercise names. Overall, the findings reveal that current strategies for naming exercises are inconsistent. The strength and conditioning field can use this information to move toward standardizing the way in which resistance training exercises are named.