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Maximal Strength, Number of Repetitions, and Total Volume Are Differently Affected by Static-, Ballistic-, and Proprioceptive Neuromuscular Facilitation Stretching

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Stretching exercises have been traditionally incorporated into warm-up routines before training sessions and sport events. However, the effects of stretching on maximal strength and strength endurance performance seem to depend on the type of stretching employed. The objective of this study was to compare the effects of static stretching (SS), ballistic stretching (BS), and proprioceptive neuromuscular facilitation (PNF) stretching on maximal strength, number of repetitions at a submaximal load, and total volume (i.e., number of repetitions × external load) in a multiple-set resistance training bout. Twelve strength-trained men (20.4 ± 4.5 years, 67.9 ± 6.3 kg, 173.3 ± 8.5 cm) volunteered to participate in this study. All of the subjects completed 8 experimental sessions. Four experimental sessions were designed to test maximal strength in the leg press (i.e., 1 repetition maximum [1RM]) after each stretching condition (SS, BS, PNF, or no-stretching [NS]). During the other 4 sessions, the number of repetitions performed at 80% 1RM was assessed after each stretching condition. All of the stretching protocols significantly improved the range of motion in the sit-and-reach test when compared with NS. Further, PNF induced greater changes in the sit-and-reach test than BS did (4.7 ± 1.6, 2.9 ± 1.5, and 1.9 ± 1.4 cm for PNF, SS, and BS, respectively). Leg press 1RM values were decreased only after the PNF condition (5.5%, p < 0.001). All the stretching protocols significantly reduced the number of repetitions (SS: 20.8%, p < 0.001; BS: 17.8%, p = 0.01; PNF: 22.7%, p < 0.001) and total volume (SS: 20.4%, p < 0.001; BS: 17.9%, p = 0.01; PNF: 22.4%, p < 0.001) when compared with NS. The results from this study suggest that, to avoid a decrease in both the number of repetitions and total volume, stretching exercises should not be performed before a resistance training session. Additionally, strength-trained individuals may experience reduced maximal dynamic strength after PNF stretching.
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MAXIMAL STRENGTH,NUMBER OF REPETITIONS,
AND TOTAL VOLUME ARE DIFFERENTLY AFFECTED
BY STATIC-, BALLISTIC-, AND PROPRIOCEPTIVE
NEUROMUSCULAR FACILITATION STRETCHING
RENATO BARROSO,
1,2
VALMOR TRICOLI,
1
SAULO DOS SANTOS GIL,
1
CARLOS UGRINOWITSCH,
1
AND HAMILTON ROSCHEL
1
1
Laboratory of Neuromuscular Adaptations to Strength Training, School of Physical Education and Sport, University of Sa˜o
Paulo, Sa˜o Paulo, Brazil; and
2
Department of Physical Education, University of Ribeira˜o Preto—UNAERP, Sa˜o Paulo, Brazil
ABSTRACT
Barroso, R, Tricoli, V, dos Santos Gil, S, Ugrinowitsch, C, and
Roschel, H. Maximal strength, number of repetitions, and total
volume are differently affected by static-, ballistic-, and pro-
prioceptive neuromuscular facilitation stretching. J Strength
Cond Res 26(9): 2432–2437, 2012—Stretching exercises
have been traditionally incorporated into warm-up routines
before training sessions and sport events. However, the effects
of stretching on maximal strength and strength endurance
performance seem to depend on the type of stretching
employed. The objective of this study was to compare the
effects of static stretching (SS), ballistic stretching (BS), and
proprioceptive neuromuscular facilitation (PNF) stretching on
maximal strength, number of repetitions at a submaximal load,
and total volume (i.e., number of repetitions 3external load) in a
multiple-set resistance training bout. Twelve strength-trained
men (20.4 64.5 years, 67.9 66.3 kg, 173.3 68.5 cm)
volunteered to participate in this study. All of the subjects
completed 8 experimental sessions. Four experimental ses-
sions were designed to test maximal strength in the leg press
(i.e., 1 repetition maximum [1RM]) after each stretching condi-
tion (SS, BS, PNF, or no-stretching [NS]). During the other
4 sessions, the number of repetitions performed at 80% 1RM
was assessed after each stretching condition. All of the
stretching protocols significantly improved the range of
motion in the sit-and-reach test when compared with NS.
Further, PNF induced greater changes in the sit-and-reach
test than BS did (4.7 61.6, 2.9 61.5, and 1.9 61.4 cm for
PNF, SS, and BS, respectively). Leg press 1RM values were
decreased only after the PNF condition (5.5%, p,0.001).
All the stretching protocols significantly reduced the number of
repetitions (SS: 20.8%, p,0.001; BS: 17.8%, p= 0.01; PNF:
22.7%, p,0.001) and total volume (SS: 20.4%, p,0.001;
BS: 17.9%, p= 0.01; PNF: 22.4%, p,0.001) when compared
with NS. The results from this study suggest that, to avoid
a decrease in both the number of repetitions and total volume,
stretching exercises should not be performed before a resis-
tance training session. Additionally, strength-trained individuals
may experience reduced maximal dynamic strength after PNF
stretching.
KEY WORDS training, skeletal muscle, range of motion
INTRODUCTION
Stretching exercises have traditionally been incor-
porated into warm-up routines before training
sessions and sport events. Its practice has been
associated with performance improvements,
decreased risk of injuries, and even reduced delayed onset
of muscle soreness (35).
However, recent research indicates that the effects of
stretching on performance seem to depend on the mode
of stretching employed (2,3,12,13,27,28,37). For instance,
it has been demonstrated that both the static and the
proprioceptive neuromuscular facilitation (PNF) stretching
may reduce not only maximal strength production
(2,3,12,27,37) but also the number of repetitions performed
with a submaximal load (12,13,28). Conversely, the literature
has shown that sprinting and agility performance (23),
isokinetic power (24), and vertical jump height (6) seem to
be acutely improved after a ballistic-stretching (BS) protocol.
These findings are difficult to reconcile. Nevertheless, data
from previous studies suggest that BS might result in different
neuromuscular adaptations than those of static stretching
(SS) and PNF stretching. In fact, it has been demonstrated
that SS and PNF may negatively affect the motor unit
activation and the structural properties of soft tissues
Address for correspondence to Renato Barroso, barroso@usp.br.
26(9)/2432–2437
Journal of Strength and Conditioning Research
Ó2012 National Strength and Conditioning Association
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Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
(i.e., muscles and tendons), which may, at least partially,
explain performance decrements after SS and PNF (18,21).
Despite the increasing number of research studies dedi-
cated to investigate the effects of different stretching protocols
on several parameters of neuromuscular performance
(6,12,13,18,21,27,28), not much attention has been given to
the evaluation of the effects of stretching protocols on the
number of repetitions performed at a submaximal load.
Further, the few studies (12,13,28) that investigated the acute
effects of stretching on such a parameter adopted single-set
experimental designs. However, there seems to be a consen-
sus that multiple sets are necessary to maximize training
adaptations throughout a resistance training program (31).
Considering that the negative effects of stretching are
transient (11), there is a gap in the knowledge regarding
the effects of stretching on the number o repetitions
performed with a submaximal load in a more realistic
multiple-set training program design.
Additionally, stretching may affect the total volume
performed during a resistance training bout. The term total
volume takes into account both the number of repetitions
performed and the weight lifted (i.e., repetitions 3load
[kilograms]). Moreover, total volume is thought to affect
long-term adaptations to resistance training (i.e., hypertrophy
and strength gains) (15,16,19,29,32), which warrants further
studies on the effects of stretching not only on the number of
repetitions but also on the total volume performed.
Therefore, the aim of this study was to compare the acute
effects of SS, BS, and PNF stretching on maximal strength,
number of repetitions, and total volume performed during
a multiple-set resistance training bout. We hypothesized
that the SS and PNF would greatly affect neuromuscular
performance when compared with the BS protocol.
METHODS
Experimental Approach to the Problem
To evaluate the effects of 3 different stretching protocols
on neuromuscular performance, all the subjects underwent
3 familiarization sessions. Afterward, each subject attended
the laboratory on 8 separate occasions, all at the same time of
the day. The subjects were also instructed to ingest a light
meal and fluids before the experimental sessions. Each session
comprised an evaluation of the range of motion (ROM) using
the sit-and-reach test followed by a general warm-up (i.e.,
5 minutes of treadmill running at 9 kmh
21
). Then, 1 of the
3 stretching protocols (i.e., SS, BS, or PNF) or a control
no-stretching condition (NS) took place. After treatment
(i.e., stretching), an additional evaluation of the ROM was
performed to determine the efficacy of the stretching
protocol employed. Finally, 1 of the 2 neuromuscular tests
was performed (i.e., a maximal strength test [1 repetition
maximum (1RM)] or a number of repetitions test performed
at 80% of 1RM). Figure 1 gives a pictorial view of the
experimental design.
Four of the experimental sessions included a 1RM
assessment after the 3 different stretching protocols (i.e.,
1RM-SS, 1RM-B S, 1RM-PNF) and a control session with no
stretching applied (1RM-NS). The remaining 4 experimen-
tal sessions consisted of a test to obtain the maximal number
of repetitions performed with 80% of 1RM after the same
stretching protocols (i.e., REP-SS, REP-BS, REP-PNF, and
REP-NS). Except for the 1RM-NS session, which was
always performed first, all the other experimental sessions
were performed in a randomized order at least 72 hours
apart. This design was adopted because we needed a baseline
1RM value (1RM-NS) to determine the external load
applied to the number of repetitions tests. During the NS
conditions, the participants sat for 10 minutes between the
end of the general warm-up and the sit-and-reach test,
which corresponded to the time necessary to perform the
stretching protocols.
Subjects
Twelve young strength-trained men (20.4 64.5 years, 67.9 6
6.3 kg, 173.3 68.5 cm) volunteered to participate in this study.
All the subjects were currently engaged in upper and lower-
limb strength training for at least 12 months before the
investigation (16.2 64.9 months). Training frequency varied
between 3 and 5 workout sessions a week. They were free
from any lower-limb musculoskeletal injuries and neuromus-
cular disorders. The investigation was approved by an
institutional review board for use of human subjects, and all
the participants signed an informed consent form before
participation.
Familiarization
Before the experimental procedures, all the subjects
completed 3 familiarization sessions on separate days at
least 72 hours apart from each other. During the
familiarization sessions, the subjects performed a general
warm-up consisting of 5 minutes of running at 9 kmh
21
on
a treadmill followed by 3 minutes of whole-body light
stretching exercises. After warming-up, the subjects were
familiarized with the leg-press
1RM testing and with the 3
different stretching protocols
(SS,BS,andPNF).Body
position and foot placement
were recorded and reproduced
throughout the study. The
subjects were also familiarized
to the sit-and-reach test.
Figure 1. Pictorial view of the experimental design.
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Maximum Strength Test (1 Repetition Maximum)
Three days after the last familiarization session, the 1RM test
for the lower limbs was assessed using a conventional inclined
(45°) leg-press machine (Nakagym model NK5070, Sa
˜o
Paulo, Brazil). The testing protocol followed the guidelines
proposed by Brown and Weir (7). In brief, the subjects ran for
5 minutes on a treadmill at 9 kmh
21
followed by 2 leg-press
warm-up sets. During the first set, the subjects performed
8 repetitions with 50% of the estimated 1RM (obtained
during familiarization sessions). After a 2-minute interval, the
participants performed the second set with 3 repetitions
with 70% of the estimated 1RM. The subjects then rested
for 3 minutes and had up to 5 trials to achieve the 1RM load
(i.e., maximum weight that could be lifted once with the
proper technique), with a 3-minute interval between trials.
The tests were conducted by 2 experienced researchers, and
strong verbal encouragement was provided during the lifts.
The same testing procedure was used during the 1RM-NS,
1RM-SS, 1RM-BS, and 1RM-PNF experimental conditions.
Number of Repetition Test
A multiple-set resistance training bout was used to obtain the
number of repetitions. The test consisted of 3 sets until failure
in the leg press using a submaximal load (80% of 1RM). Body
positioning, knee and hip angles, and foot placement were
reproduced according to the records made during the
familiarization sessions. The number of repetitions performed
in each set was recorded, and a 2-minute interval was allowed
between sets. The sum of the repetitions performed in the
3 sets was used for statistical purposes. Total volume was
calculated as the product of the number of repetitions
completed and the load lifted (number of repetitions [no] 3
weight [kilograms]). Only repetitions performed with the
proper technique were considered valid.
Sit-and-Reach Test
The subjects sat with their heels pressed against the testing
board. The knees were extended, and the right hand was
placed over the left. Then, the participants were asked to
reach and hold as far as possible along the measuring board,
on the fourth bobbing movement (3). Three trials were
performed, and the best result was used for statistical analysis.
Stretching Protocols
During stretching sessions, the participants stretched the
main muscle groups used during the leg-press exercise
(gluteus maximum and quadriceps), and the hamstring
muscles. The stretching exercises used included the supine
knee flex, the side quadriceps stretch, and the sitting toe
touch. Baechle and Earle (4) offer a more detailed explanation
of the stretches. During the stretching exercises, the subjects
were assisted by an experienced researcher.
Three sets of each stretching exercise were performed. The
SS was performed by holding the stretching position for
30 seconds followed by a 30-second interval before the next
set. For the BS protocol, the same procedures were followed,
but instead of holding the stretching positions for 30 seconds,
the subjects had to bob in 1:1-second cycles for 1 minute.
For the PNF protocol, the hold-relax technique was used.
The subjects performed a passive stretch and held the
stretching position for approximately 5 seconds. Then, they
performed a 5-second near-maximal isometric contraction
(34), relaxed, and passively held the stretching position for
another 20 seconds.
Statistical Analyses
Data are presented according to descriptive statistics (mean
and SD). Normality was assured by a Shapiro-Wilk test. The
ROM data (pretest to posttest absolute change) were
analyzed by a 1-way analysis of variance (ANOVA)
TABLE 1. Acute changes in flexibility after the
stretching protocols in each neuromuscular test.*
Test day Acute changes in flexibility (cm)
1RM-NS 0.5 60.8
1RM-SS3.9 61.7§
1RM-PNF,4.7 61.6§
1RM-BS2.9 61.5§
REP-NS 0.6 60.7
REP-SS3.8 61.6
REP-PNF,4.5 61.5§
REP-BS3.3 61.7§
*NS = no-stretching condition; SS = static-stretching
condition; PNF = proprioceptive neuromuscular facilita-
tion stretching condition; BS = ballistic-stretching condi-
tion; 1RM = 1 repetition maximum.
p,0.05 compared with NS.
p,0.05 when compared with BS.
§p,0.05 when compared with prevalues.
Figure 2. Acute changes (pretest to posttest) inthe range of motion(ROM)
and difference in the leg-press 1 repetition maximum (1RM; mean 6SD)
between the 3 stretching protocols and the control (no-stretching [NS])
condition. *p,0.05 when compared with NS for both ROM and 1RM.
#
p,0.05 when compared with ballistic stretching (BS).
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procedure. Changes between the control condition (NS) and
the other stretching protocols (i.e., BS, SS, and PNF) for all
of the remaining variables (i.e., maximal strength [1RM],
number of repetitions, and total volume) were compared
using a 1-way ANOVA. Whenever a significant Fvalue
was obtained, a Tukey post hoc test was performed for
multiple comparison purposes. The significance level was set
at p#0.05. Further, intraclass correlation coefficient values
were calculated for 1RM and sit-and-reach tests with values
of 0.92 and 0.96, respectively.
RESULTS
Range of Motion
The results are presented in Table 1. No differences were
observed between prestretching values across the experi-
mental conditions (data not shown). As expected, no changes
were observed in the sit-and-reach scores in the NS
conditions. The PNF significantly improved ROM when
compared with either SS or BS as measured by delta changes
in ROM before the 1RM and the maximal number of
repetitions tests.
Maximal Strength, Number of Repetitions, and Total Volume
Leg-press 1RM values significantly decreased after the PNF
stretching protocol (233.3 640.5 kg) when compared with
NS (246.7 640.8, p= 0.01) but were similar to those of SS
(241.7 640.0 kg, p= 0.81) and BS (240.8 642.3 kg, p= 0.82).
Figure 2 shows SS, PNF, and BS leg-press 1RM changes
compared with NS and ROM delta change data.
In regard to the number of repetitions test, all the 3
stretching protocols negatively affected performance when
compared with NS (Figure 3). The subjects performed 36 6
4.2 repetitions during NS; 27.8 64.1 during PNF (p,0.001);
28.5 65.7 during SS (p,0.001); and 29.6 64.9 during BS
(p= 0.001). Total volume was also negatively affected by all
the 3 stretching protocols (5,702.7 61,784.1 kg, p,0.001;
5,535.3 61,456.6 kg, p,0.001; 5,860 61,536.4 kg, p,0.001
for SS, PNF, and BS, respectively) when compared with
NS (7,137.3 61,698.5 kg) (Figure 4).
DISCUSSION
The objective of this study was to compare the acute effects
of different lower-limb stretching protocols on maximal
strength, number of repetitions, and total volume performed
in the leg-press exercise. The main and novel finding of this
study is that not only SS and PNF but also BS impaired
the number of repetitions and the total volume (i.e., number
of repetitions 3external load) performed after stretching
when compared with NS. Additionally, we demonstrated that
in strength-trained individuals, only the PNF stretching mode
impaired the maximal strength production.
Reports on the acute effects of different stretching
protocols on the number of repetitions are scarce. Nonethe-
less, previous studies have shown that either SS or PNF
significantly reduces the number of repetitions performed in
a single set of a resistance exercise (12,13,27). Our results
extend this knowledge to BS protocols as well (Figure 3) and
to multiple-set resistance training bouts. Despite evidence
showing that BS does not affect maximal strength (3) and
may even improve sprinting and agility (23) and vertical jump
performance (6), our investigation is the first to investigate
the acute effects of BS on the number of repetitions,
demonstrating that a BS protocol significantly reduces the
number of repetitions performed in the leg-press exercise at
a submaximal load (80% of 1RM).
Total volume, which affects short- and long-term responses
to strength training (3,14–16,32), is positively related to
myofibrillar protein synthesis (8), anabolic hormones release
(14,15,36), strength gains, and skeletal muscle hypertrophy
(15,16,19,29,32). Our results demonstrated that total volume
was reduced after the 3 proposed stretching protocols.
Figure 3. Acute changes (pretest to posttest) in the range of motion
(ROM) and difference in the maximal number of repetitions (mean 6SD)
performed at a submaximal load between the 3 stretching protocols and
the control (no-stretching [NS]) condition. *p,0.05 when compared
with NS for both ROM and the maximal number of repetitions.
#
p,0.05
when compared with ballistic stretching (BS).
Figure 4. Acute changes (pretest to posttest) in the range of motion
(ROM) and difference in the total volume (i.e., number of repetitions 3
external load) (mean 6SD) between the 3 stretching protocols in relation
to the control (no-stretching [NS]) condition. *p,0.05 when compared
with NS for both flexibility and 1 repetition maximum (1RM) and
#
p,0.05
when compared with ballistic stretching (BS).
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It suggests that stretching before training may negatively
impact resistance training-induced adaptations in strength
and muscle mass. However, caution should be exercised
when interpreting and generalizing these findings because we
have not evaluated the effects of stretching on long-term
adaptations to resistance training.
In regard to the 1RM data, it is important to note that
the scores obtained in the sit-and-reach test indicate that all
the stretching protocols were effective in increasing ROM.
Despite the previous reports associating acute increments in
ROM (through SS and PNF stretching) with decreased
maximal strength performance (3), our data show that only
the PNF protocol significantly affected 1RM. In fact, the
literature is still controversial regarding the acute effects of SS
and PNF stretching on neuromuscular performance. For
instance, Molacek et al. (26) and Egan et al. (9) reported no
effect of SS and PNF stretching on the maximal torque
and muscle power output. Conversely, SS and PNF have
been shown to decrease vertical jump (6) and maximal
strength (2,25,26,28).
Interestingly, Molacek et al. (26) and Egan et al. (9)
suggested that training status could affect individual suscep-
tibility to the detrimental effects of stretching on maximal
strength performance. In accordance with this suggestion,
Beedle et al. (5) showed that in highly trained subjects,
neither BS nor SS affected maximal strength performance.
Our results support this concept, because the strength-trained
subjects of our study were not affected by either SS or BS. On
the other hand, PNF induced an approximately 5.5%
decrease in the 1RM in our study, supporting previous
suggestions (9,26) that stretching should be of greater
intensity (i.e., PNF) to affect strength in trained subjects.
The mechanisms underlying maximal strength decrements
after stretching are based on reduced musculotendinous
stiffness (1,11,33) and decreased motor unit activation
(10,18,21,22). Our sit-and-reach scores indicate that despite
improvements in the ROM after any of the stretching
protocols, PNF was more effective in acutely augmenting
ROM (Table 1), thus suggesting that PNF may greatly affect
musculotendinous stiffness (18). It is important to note that
sit-and-reach tests were used to evaluate changes in ROM
but the muscles assessed (hamstrings) were different from
those used during leg-press lifts (quadriceps and gluteus), but
this test was used to evaluate stretching protocol efficacy.
Because 1RM was reduced only by the PNF protocol, it is
tempting to speculate that there might be a threshold
in stiffness reduction to affect maximal strength. Additionally,
it is also possible that autogenic inhibition was greater after
PNF thus reducing neuromuscular activation and muscle
strength.
At the moment, the events related to stretching that act
upon the maximal number of repetitions are unknown. It is
interesting to note that both the SS and BS protocols did not
affect maximal strength but induced a decrease in the number
of repetitions performed with a submaximal load. This
suggests that mechanisms other than the viscoelastic
properties of the musculotendineous unit and the reduced
motor unit activation might play a role. It has been suggested
that blood flow through a muscle can be reduced during
stretching (20,30,38), which could at least partially explain
the results. The partial ischemia-induced reduction in
strength is attributed to a low-oxygen supply and impaired
removal of metabolic by-products (17). The number of
repetitions test was performed after the stretching protocol,
so one may argue that blood flow was likely back to normal
by then. However, it is possible that ischemia during
stretching could have elevated the concentration of metab-
olites, which may have impaired testing performance.
Despite the lack of data regarding mechanical properties,
motor unit activation, and metabolic parameters regarding
different stretching protocols, our results warrant further
investigations evaluating such parameters and their relation
to the number of repetitions performed.
In summary, the 3 stretching protocols acutely increased
ROM and decreased the number of repetitions and the total
volume performed, demonstrating for the first time that BS
can also compromise neuromuscular performance. Addition-
ally, we demonstrated that in strength-trained individuals,
only PNF reduced the maximal dynamic strength.
PRACTICAL APPLICATIONS
Stretching exercises as part of a warm-up routine are
a common practice among trainers and athletes. Trainers
should be aware that not only the stretching protocol
performed but also the training statuses of the athletes play
a role in its effect upon the neuromuscular performance.
Strength-trained athletes are less prone to the negative effects
of acute stretching on maximal strength and hence should
avoid high-intensity protocols such as the PNF in their
maximum strength training sessions.
However, when the training session includes multiple sets
of resistance exercise (i.e., hypertrophy-oriented training
sessions), trainers should avoid any stretching protocol,
including the BS because stretching may result in a reduced
number of repetitions performed with a submaximal load and
lower total volume (i.e., number of repetitions 3external
load), thus affecting long-term resistance training adaptations.
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... Por outro lado, no efeito crônico, é observado o remodelamento da estrutura muscular adaptativa, ocorrendo a ampliação do número dos sarcômeros em série, resultando no aumento do comprimento muscular, onde permanecem por períodos determinados quando não ocorre a interrupção das atividades físicas 8,9 . Barroso et al. (2012) 10 sugerem que a flexibilidade treinada antes do exercício resistido pode reduzir adaptações neuromusculares importantes, tais como força e resistência. A interferência negativa do treinamento de flexibilidade na força e hipertrofia muscular, podem estar relacionadas a diminuição do número de repetições e o volume total de treinamento de resistência [10][11][12][13] , portanto, torna-se fundamental avaliar o efeito da aplicação da técnica de alongamento estático ativo crônico no desempenho de potência e de força máxima para auxiliar os profissionais na prescrição de exercícios 14,15 . ...
... Por outro lado, no efeito crônico, é observado o remodelamento da estrutura muscular adaptativa, ocorrendo a ampliação do número dos sarcômeros em série, resultando no aumento do comprimento muscular, onde permanecem por períodos determinados quando não ocorre a interrupção das atividades físicas 8,9 . Barroso et al. (2012) 10 sugerem que a flexibilidade treinada antes do exercício resistido pode reduzir adaptações neuromusculares importantes, tais como força e resistência. A interferência negativa do treinamento de flexibilidade na força e hipertrofia muscular, podem estar relacionadas a diminuição do número de repetições e o volume total de treinamento de resistência [10][11][12][13] , portanto, torna-se fundamental avaliar o efeito da aplicação da técnica de alongamento estático ativo crônico no desempenho de potência e de força máxima para auxiliar os profissionais na prescrição de exercícios 14,15 . ...
... Barroso et al. (2012) 10 sugerem que a flexibilidade treinada antes do exercício resistido pode reduzir adaptações neuromusculares importantes, tais como força e resistência. A interferência negativa do treinamento de flexibilidade na força e hipertrofia muscular, podem estar relacionadas a diminuição do número de repetições e o volume total de treinamento de resistência [10][11][12][13] , portanto, torna-se fundamental avaliar o efeito da aplicação da técnica de alongamento estático ativo crônico no desempenho de potência e de força máxima para auxiliar os profissionais na prescrição de exercícios 14,15 . Consequentemente, alguns pesquisadores investigaram os efeitos crônicos de programas específicos de alongamento estático no desempenho, apresentando resultados mistos. ...
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Nos últimos anos, muitos estudos foram realizados com o intuito de comprovar a eficácia de protocolos de alongamentos agudos sobre as habilidadesmotoras de força e potência muscular, no entanto seus efeitos crônicos ainda não foram totalmente elucidados na literatura. O objetivo do presente estudo foiverificar a influência de um protocolo de alongamento ativo estático crônico dos músculos quadríceps e isquiostibiais sobre a flexibilidade e as variáveis isocinéticasde força e potência em adultos praticantes de musculação, durante 12 semanas. Trata-se de um ensaio clínico randomizado (parecer número: 2.697.277), no qual aamostra foi composta por 20 adultos do sexo masculino, praticantes de musculação há no mínimo três meses. Os participantes foram avaliados quanto ao peso ealtura, força muscular da articulação do joelho (utilizando dinamômetro isocinético Biodex Multi-Joint Pro), teste de flexibilidade e avaliação de composiçãocorporal. A intervenção foi aplicada após a realização do treinamento muscular e consistiu em um programa de alongamentos estáticos ativos para os músculosisquiotibiais e quadríceps, após o treinamento de força, durante um período de 12 semanas. Observou-se um aumento para todas as variáveis de flexibilidade dogrupo intervenção, além de promover um aumento significativo das variáveis de pico de torque do membro dominante e não dominante na extensão e de potênciado membro dominante e não dominante na extensão e do membro dominante na flexão. Conclui-se que os exercícios de alongamento foram benéficos para o ganhode flexibilidade, além de constatar uma melhora nas variáveis isocinéticas do grupo intervenção nos membros dominante e não dominante em relação ao grupo controle.
... However, a recent meta-analysis reported greater ROMs achieved with SS over PNF training [27]. On the other hand, a number of studies report that a session of DS induced similar [28][29][30] or even greater [31,32] ROM improvements than SS, while other articles show that an acute bout of SS is superior to DS [20,[33][34][35][36]. Thus, there is still no consistent clarity on whether there is a superior form of stretching to produce acute changes in ROM. ...
... There are diverse reports indicating greater [83][84][85] or similar ROM increases with PNF vs. SS [86,87] as well as similar [28,29] or greater [31,32] increases in flexibility with DS vs. SS. These findings contrast with other studies reporting that DS was not as effective for increasing ROM as SS [20,[33][34][35][36]. When examining 55 effect sizes (SS: 36, ballistic/ DS: 10, PNF: 9 studies) with disparate stretch intensities, durations and other prescription components, the main message from this review is that all forms of stretching are similarly effective in promoting acute increases in joint ROM within a general population. ...
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Background Although stretching can acutely increase joint range of motion (ROM), there are a variety of factors which could influence the extent of stretch-induced flexibility such as participant characteristics, stretching intensities, durations, type (technique), and muscle or joint tested. Objective The objective of this systematic review and meta-analysis was to investigate the acute effects of stretching on ROM including moderating variables such as muscles tested, stretch techniques, intensity, sex, and trained state. Methods A random-effect meta-analysis was performed from 47 eligible studies (110 effect sizes). A mixed-effect meta-analysis subgroup analysis was also performed on the moderating variables. A meta-regression was also performed between age and stretch duration. GRADE analysis was used to assess the quality of evidence obtained from this meta-analysis. Results The meta-analysis revealed a small ROM standard mean difference in favor of an acute bout of stretching compared to non-active control condition (ES = −0.555; Z = −8.939; CI (95%) −0.677 to −0.434; p < 0.001; I2 = 33.32). While there were ROM increases with sit and reach (P = 0.038), hamstrings (P < 0.001), and triceps surae (P = 0.002) tests, there was no change with the hip adductor test (P = 0.403). Further subgroup analyses revealed no significant difference in stretch intensity (P = 0.76), trained state (P = 0.99), stretching techniques (P = 0.72), and sex (P = 0.89). Finally, meta-regression showed no relationship between the ROM standard mean differences to age (R2 = −0.03; P = 0.56) and stretch duration (R2 = 0.00; P = 0.39), respectively. GRADE analysis indicated that we can be moderately confident in the effect estimates. Conclusion A single bout of stretching can be considered effective for providing acute small magnitude ROM improvements for most ROM tests, which are not significantly affected by stretch intensity, participants’ trained state, stretching techniques, and sex.
... These effects are attributed to changes in tissue viscoelasticity and the speed of nerve impulse transmission [2]. While static stretching has been shown to improve the flexibility [3,4], its immediate effects tend to diminish within a few hours [5,6]. Conversely, some studies have reported medium-and long-term improvements in flexibility with stretching, although the results vary depending on the type of stretching and the parameters applied [7]. ...
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(1) Background: Stretching has been shown to improve flexibility, muscle activation, and coordination, but its effects may depend on neural tension during the stretch. This study evaluated the short- and medium-term effects of hamstring stretching with and without neural load on flexibility, tibial nerve pressure pain threshold, and maximum isometric strength. (2) Methods: Seventy-eight healthy participants (mean age: 24.96 ± 6.11 years) were randomly assigned to stretching programs with (n = 39) or without neural load (n = 39). Flexibility, pressure pain threshold, and maximum isometric strength were assessed at baseline, after the first session, at the end of the intervention, and one month later. (3) Results: The group using neural load showed significant flexibility improvements after the first session (MD = −5.2; p < 0.001), which were maintained at two months (MD = −8.6; p < 0.001) and follow-up (MD = −6.4; p < 0.001). In the control group, flexibility gains diminished at follow-up (MD = −3.9; p = 0.052). Other variables showed no significant changes across time points. (4) Conclusions: Since neither treatment showed superior efficacy, no specific stretching type could be recommended.
... However, a single session of static stretching could cause acute decreases in maximal muscular strength (43-45). Moreover, such stretch-induced decreases in muscle force could reduce the total training volume during the intervention period and thus may attenuate the training effects on muscle hypertrophy (46) and maximal muscle strength (47). Meanwhile, our study revealed a training modality to chronically decrease the passive stiffness of a specific muscle while simultaneously increasing muscle strength and size. ...
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Purpose Resistance training may be empirically believed to increase passive muscle stiffness. Meanwhile, a recent study showed that the passive stiffness of a specific hamstring muscle acutely decreased after eccentric-only resistance exercise at long muscle lengths with a long contraction duration (LL). To extend this finding, the present study investigated the chronic effects of eccentric-only resistance training with LL at different weekly frequencies on the passive stiffness of the biarticular hamstring muscles. Methods Thirty-six healthy young males were assigned into two training groups with two and three weekly sessions (W2 and W3, n = 12, respectively) and a control group (CON, n = 12). The participants in both training groups performed eccentric-only stiff-leg deadlift at 50–100% of exercise range of motion (0% = upright position) with 5 s per repetition for 10 weeks. Before and after the intervention period, the shear moduli of the biarticular hamstring muscles, maximal voluntary isometric torque of knee flexion, and volumes of the individual hamstring muscles were measured. Results In W3, the shear modulus of the semimembranosus (−11.4%) significantly decreased, whereas those of the other biarticular muscles did not change. There were no significant changes in the shear moduli of the biarticular hamstring muscles in W2 or CON. The isometric torque (20.3 and 26.2%, respectively) and semimembranosus volume (5.7% and 7.4%, respectively) were significantly increased in W2 and W3. Conclusions Passive stiffness of a specific muscle could be chronically decreased when eccentric-only resistance training with LL is performed at a relatively high weekly frequency with a high total training volume. Our training modality may be a promising strategy for decreasing passive muscle stiffness while increasing muscular strength and size.
... In this sense, our results align with Barroso et al. (27) , who demonstrated a significant reduction in strength when PNF stretching was previously developed. Fowles et al. (28) explain that the decrease in strength obtained after stretching may be related to the lengthtension change of the muscle, plastic deformation of the connective tissue, and changes in viscoelastic properties (29) . ...
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Background: Numerous strategies can be implemented as preconditioning preparation to increase strength production, including PNF and MFR strategies, however there are still contradictions in the literature regarding competing effects between preconditioning actions and strength perfor- mance, which it becomes plausible to look for the impact is effect on strength resistance perfor- mance. Objective: of the study was to evaluate the acute effects of series of PNF, myofascial release (MFR), or the sum of the methods, on the development of resistance strength in subsequent series of deadlifts. Methods: Eight adults of both sexes (25.4 ± 4.1 years) participated in the study, attend- ing the gym on 7 visits. The first visit consisted of a sample characterization. On the second and third visits, participants performed the maximum repetition Deadlift procedure, from the fourth to seventh visits, they were randomly divided into: a) CTL; b) PNF; c) MFR; d) PNF + MFR. All sessions followed three sets of the Deadlift exercise with 80% RM. Results: The repeated measures ANOVA showed significant differences between the control condition (no intervention) and the PNF inter- vention (p = 0.034) and MFR + PNF (p = 0.047). However, the Control vs. MFR there were no signif- icant differences (p = 0.07), as well as PNF vs. MFR (p = 0.585), and PNF vs. PNF+MFR (p = 0.382). Conclusion: Strength performance was influenced by the PNF method, or associated with MFR, both reducing total work.
... In the SS technique, the hamstrings were passively stretched by the examiner, with the knee extended, for 30 s. Based on previous studies (Barroso et al. 2012;Kay et al. 2015;Oliveira et al. 2018), the PNF was performed with the hold-relax technique as follows: hamstrings were passively stretched with a straight leg raise for 5 s, followed by a 5-s submaximal isometric contraction at 50% of perceived maximal effort against a manual resistance applied on the distal part of the tibia and then stretched for additional 20 s, resulting in the same total duration as in SS. Three sets of each technique were performed with a 30-s rest period between each set. ...
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This study aimed to compare the acute effects of static stretching (SS) and proprioceptive neuromuscular facilitation (PNF) stretching on hamstrings flexibility and shear modulus. Sixteen recreationally active young volunteers participated in a rand-omized cross-over study. Participants underwent an aerobic warm-up (WU), followed by either SS or PNF stretching. Range of motion (RoM) during passive straight leg raise and active knee extension, as well as shear modulus of the biceps femoris (BF) and semitendinosus (ST) muscles, were measured at baseline, post-WU, and post-stretching. Both stretching techniques significantly increased RoM, with no differences observed between SS and PNF (p < 0.001; η 2 = 0.59-0.68). However, only PNF stretching resulted in a significant decrease in BF shear modulus (time×stretching type interaction: p = 0.045; η 2 = 0.19), indicating reduced muscle stiffness. No changes in ST shear modulus were observed after either stretching technique. There was no significant correlation between changes in RoM and shear modulus, suggesting that the increase in RoM was predominantly due to changes in stretch tolerance rather than mechanical properties of the muscles. These findings suggest that both SS and PNF stretching can effectively improve hamstring flexibility, but PNF stretching may additionally reduce BF muscle stiffness. The study highlights the importance of considering individual muscle-specific responses to stretching techniques and provides insights into the mechanisms underpinning acute increases in RoM.
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The present study aimed to compare the effect of 24 sessions of stretching exercises performed before resistance exercises versus resistance exercise sessions on the hemodynamic responses of sedentary individuals. Thirty volunteers (26.76±6.29 years old, 81.56±10.66 kg body weight, 1.74±0.07 m height, and 26.74 ±.82 kg/m2 body mass index) participated in this study. After performing the test and retest of 10 maximum repetitions (10RM), the volunteers were divided into 3 groups: a) stretching exercise + resistance exercise (SE+RE); b) resistance exercise (RE) and c) control group (CG). The RE was composed of 3 sets of 10 repetitions at 80% of 10RM with a 2-minute interval between sets of RE preceded or not by 3 sets of 30 seconds of SE. Blood pressure (BP) was assessed using an automatic oscillometric device at session 0, session 12 and session 24 of training. Systolic BP (SBP), diastolic BP (DBP), mean BP (MAP), heart rate (HR), double product (DP) and oxygen saturation (SpO2) were measured after 10 minutes of rest. Comparison between groups was performed by Kruskal Wallis test with Bonferroni correction and 5% significance (p < 0.05). DBP showed significant difference when comparing session 0 vs. session 24 (p = 0.006) for the RE protocol. MAP decreased significantly after session 24 for the RE protocol compared to the other protocols (p = 0.016) and difference between session 0 vs. session 24 (p = 0.022). Significant difference was found in SE + RE protocol (p = 0.029) compared to session 0 vs. session 24 GC. This study showed that RE improved the DBP and MAP response and that the combination of SE+RE improved the SpO2 response after 24 training sessions. Keywords: stretching, strength training, cardiovascular system, blood pressure, heart rate
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The present study aimed to compare the effect of 24 sessions of stretching exercises performed before resistance exercises versus resistance exercise sessions on the hemodynamic responses of sedentary individuals. Thirty volunteers (26.76±6.29 years old, 81.56±10.66 kg body weight, 1.74±0.07 m height, and 26.74 ±.82 kg/m2 body mass index) participated in this study. After performing the test and retest of 10 maximum repetitions (10RM), the volunteers were divided into 3 groups: a) stretching exercise + resistance exercise (SE+RE); b) resistance exercise (RE) and c) control group (CG). The RE was composed of 3 sets of 10 repetitions at 80% of 10RM with a 2-minute interval between sets of RE preceded or not by 3 sets of 30 seconds of SE. Blood pressure (BP) was assessed using an automatic oscillometric device at session 0, session 12 and session 24 of training. Systolic BP (SBP), dias-tolic BP (DBP), mean BP (MAP), heart rate (HR), double product (DP) and oxygen saturation (SpO2) were measured after 10 minutes of rest. Comparison between groups was performed by Kruskal Wallis test with Bonferroni correction and 5% significance (p < 0.05). DBP showed significant difference when comparing session 0 vs. session 24 (p = 0.006) for the RE protocol. MAP decreased significantly after session 24 for the RE protocol compared to the other protocols (p = 0.016) and difference between session 0 vs. session 24 (p = 0.022). Significant difference was found in SE + RE protocol (p = 0.029) compared to session 0 vs. session 24 GC. This study showed that RE improved the DBP and MAP response and that the combination of SE+RE improved the SpO2 response after 24 training sessions. Resumen. El presente estudio tuvo como objetivo comparar el efecto de 24 sesiones de ejercicios de estiramiento realizados antes de ejercicios de resistencia versus sesiones de ejercicios de resistencia sobre las respuestas hemodinámicas de individuos sedentarios. Treinta voluntarios (26.76±6.29 años de edad, 81.56±10.66 kg de peso corporal, 1.74±0.07 m de altura y 26.74±.82 kg/m2 de índice de masa corporal) participaron en este estudio. Después de realizar la prueba y la retest de 10 repeticiones máximas (10RM), los voluntarios se dividieron en 3 grupos: a) ejercicios de estiramiento + ejercicios de resistencia (EE+ER); b) ejercicios de resisten-cia (ER) y c) grupo de control (GC). El ER se compuso de 3 series de 10 repeticiones al 80% de 10RM con un intervalo de 2 minutos entre series de ER precedidas o no por 3 series de 30 segundos de EE. La presión arterial (PA) se evaluó utilizando un dispositivo oscilométrico automático en la sesión 0, sesión 12 y sesión 24 de entrenamiento. La presión arterial sistólica (PAS), la presión arterial diastólica (PAD), la presión arterial media (PAM), la frecuencia cardíaca (FC), el doble producto (DP) y la saturación de oxígeno (SpO2) se midieron después de 10 minutos de reposo. La comparación entre grupos se realizó mediante la prueba de Kruskal Wallis con corrección de Bonferroni y un 5% de significancia (p < 0.05). La PAD mostró una diferencia significativa al comparar la sesión 0 vs. la sesión 24 (p = 0.006) para el protocolo ER. La PAM disminuyó significativamente después de la sesión 24 para el protocolo ER en comparación con los otros protocolos (p = 0.016) y la diferencia entre la sesión 0 vs. la sesión 24 (p = 0.022). Se encontró una diferencia significativa en el protocolo EE+ER (p = 0.029) en comparación con la sesión 0 vs. la sesión 24 del GC. Este estudio mostró que el ER mejoró la respuesta de la PAD y la PAM, y que la combinación de EE+ER mejoró la respuesta de SpO2 después de 24 sesiones de entrenamiento. Palabras clave: estiramiento, entrenamiento de fuerza, sistema cardiovascular, presión arterial, frecuencia cardíaca. Fecha recepción: 26-09-23. Fecha de aceptación: 03-05-24 Rodrigo Rodrigues da Conçeição
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This study aims to investigate the acute effects of hip mobility exercises applied before anaerobic activities on vertical jump, 1 repetition maximum (1RM), and isometric strength performances. For this purpose, 12 male athletes with a high level of training (age = 21 ± 1.2 years; height = 180 ± 0.05 m; body weight = 88.08 ± 9.17 kg) voluntarily participated in the study. Before starting the study, an approval report was obtained from the Sakarya University of Applied Sciences Ethics Committee and all athletes signed a voluntary consent form before the study. All participants were asked to perform a standard 15-minute dynamic warm-up procedure (dynamic stretching exercises related to cycling and tests) on the first measurement day. Then, in order to avoid fatigue in the athletes, 1 RM (1 Repetition Maximum) strength tests were applied. On the second measurement day, the subjects performed 8 different hip mobility exercises (2 sets x 20 seconds for each exercise) with the same 15-minute dynamic warm-up protocol and reapplied the tests applied on the first measurement day. When the findings were examined, it was found that there was no significant difference in the 1RM strength values of the deadlift exercise in the 1st and 2nd measurement sessions (p = 0.596). However, a significant difference was found between the 1RM strength, Isometric back-leg strength, Counter Movement Jump (CMJ), and Squat Jump (SJ) values of the squat exercise (p = 0.003, p = 0.002, p = 0.002, p = 0.002). In conclusion, this study shows that a dynamic warm-up protocol that includes hip mobility positively affects vertical jump, maximal, and isometric strength parameters. Bu çalışmanın amacı anaerobik aktiviteler öncesinde uygulanan kalça hareketliliği egzersizlerinin dikey sıçrama, 1 tekrar maksimum (1TM) ve izometrik kuvvet performansları üzerindeki akut etkilerini araştırmaktır. Bu amaç için 12 antrenman geçmişi düzeyi yüksek erkek sporcu (yaş = 21 ± 1.2 yıl; boy = 180 ± 0.05 m; vücut ağırlığı = 88.08 ± 9.17 kg) gönüllü olarak çalışmaya katılmıştır. Araştırmaya başlanılmadan önce Sakarya Uygulamalı Bilimler Üniversitesi Etik Kurulundan onay raporu alındı ve tüm sporculara çalışma öncesinde gönüllü onam formu imzalatılmıştır. Tüm katılımcılardan ilk ölçüm gününde 15 dakikalık standart bir dinamik ısınma prosedürü (bisiklet ve testler ile ilgili dinamik esneme egzersizleri) uygulamaları istenmiş ve daha sonra sporcularda yorgunluk meydana gelmemesi için sırasıyla dikey sıçrama, izometrik sırt bacak kuvveti ve alt ekstremiteye yönelik iki temel egzersizde 1TM (1 Tekrar Maksimum) kuvvet testleri uygulatılmıştır. İkinci ölçüm gününde ise denekler aynı 15 dakikalık dinamik ısınma protokolü ile 8 farklı kalça hareketliliği egzersizini (her egzersiz için 2 set x 20 saniye) gerçekleştirmişler ve ilk ölçüm gününde uygulanan testleri tekrar uygulamışlardır. Bulgular incelendiğinde 1. ve 2. ölçüm seanslarında deadlift egzersizinin 1TM kuvvet değerlerinde anlamlı bir fark olmadığı bulunmuştur (p = 0.596). Bununla birlikte squat egzersizinin 1TM kuvvet, İzometrik sırt-bacak kuvveti, Counter Movement Jump (CMJ) ve Squat Jump (SJ) değerleri arasında anlamlı bir fark olduğu bulunmuştur (p = 0.003, p = 0.002, p = 0.002, p = 0.002). Sonuç olarak, bu çalışma kalça hareketliliği içeren bir dinamik ısınma protokolünün dikey sıçrama, maksimal ve izometrik kuvvet parametreleri üzerinde olumlu bir etkiye sahip olduğunu göstermektedir.
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