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A quantitative observational laboratory study was conducted to characterize and classify core training exercises executed in a suspension modality on the base of muscle activation. In a prospective single-group repeated measures design, seventeen active male participants performed four suspension exercises typically associated with core training (roll-out, bodysaw, pike and knee-tuck). Surface electromyographic signals were recorded from lower and upper parts of rectus abdominis, external oblique, internal oblique, lower and upper parts of erector spinae muscles using concentric bipolar electrodes. The average rectified values of electromyographic signals were normalized with respect to individual maximum voluntary isometric contraction of each muscle. Roll-out exercise showed the highest activation of rectus abdominis and oblique muscles compared to the other exercises. The rectus abdominis and external oblique reached an activation higher than 60% of the maximal voluntary contraction (or very close to that threshold, 55%) in roll-out and bodysaw exercises. Findings from this study allow the selection of suspension core training exercises on the basis of quantitative information about the activation of muscles of interest. Roll-out and bodysaw exercises can be considered as suitable for strength training of rectus abdominis and external oblique muscles.
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Journal of Human Kinetics volume 56/2017, 61-71 DOI: 10.1515/hukin-2017-0023 61
Section I – Kinesiology
1 - Department of Brain and Behavioral Sciences, Unit of Medical and Genomic Statistics, University of Pavia, Italy..
2 - Department of Medical Sciences, University of Torino, Torino, Italy.
3 - CeRiSM Research Center “Sport, Mountain, and Health”, Rovereto, (TN), Italy.
4 - Motor Science Research Center, School of Exercise & Sport Sciences, SUISM, Department of Medical Sciences, University of
Turin. 12, Torino, Italy.
.
Authors submitted their contribution to the article to the editorial board.
Accepted for printing in the Journal of Human Kinetics vol. 56/2017 in March 2017.
Core Muscle Activation in Suspension Training Exercises
by
Giovanni Cugliari1,2, Gennaro Boccia3,4
A quantitative observational laboratory study was conducted to characterize and classify core training
exercises executed in a suspension modality on the base of muscle activation. In a prospective single-group repeated-
measures design, seventeen active male participants performed four suspension exercises typically associated with core
training (roll-out, bodysaw, pike and knee-tuck). Surface electromyographic signals were recorded from lower and
upper parts of rectus abdominis, external oblique, internal oblique, lower and upper parts of erector spinae muscles
using concentric bipolar electrodes. The average rectified values of electromyographic signals were normalized with
respect to individual maximum voluntary isometric contraction of each muscle. Roll-out exercise showed the highest
activation of rectus abdominis and oblique muscles compared to the other exercises. The rectus abdominis and external
oblique reached an activation higher than 60% of the maximal voluntary contraction (or very close to that threshold,
55%) in roll-out and bodysaw exercises. Findings from this study allow the selection of suspension core training
exercises on the basis of quantitative information about the activation of muscles of interest. Roll-out and bodysaw
exercises can be considered as suitable for strength training of rectus abdominis and external oblique muscles.
Key words: core stability, core strength, electromyography, abdominal muscles.
Introduction
In recent years, core training has been
widely studied since it has been considered a
pivotal issue in health, rehabilitation and sports
performance (Hibbs et al., 2008). However, the
definition of the core varies with the
interpretation of the literature (Hibbs and
Thompson, 2008). Anatomically, the core region
has been described as the area bounded by the
abdominal muscles in the front, by paraspinal and
gluteal muscles in the back, by diaphragm on the
top and by pelvic floor and girdle musculature at
the bottom (Richardson et al., 1999). The core
represents the connection between lower and
upper limbs and should be considered as a
functional unit in which different muscles
interact, even if not located in the thoraco-lumbar
region (such as shoulders and pelvic muscles).
However, literature concerning core training
sometimes fails to distinguish between concepts
of core stability and core strength. Faries and
Greenwood (in Hibbs and Thompson, 2008)
formulated the following clear definitions: core
stability refers to the ability to stabilize the spine
as a result of muscle activity, while core strength
refers to the ability of muscles’ contractions to
produce and transfer force as a result of muscle
activity. Since strength and motor control are
complementary qualities, the core training
programmes can target mainly, but not
exclusively, at muscle strengthening and/or motor
control of core musculature. Motor control
training seems to require low intensity
62 Core Muscle Activation in Suspension Training Exercises
Journal of Human Kinetics - volume 56/2017 http://www.johk.pl
stabilization exercises focused on efficient
integration of low threshold recruitment of local
and global muscle systems. Conversely, core
strength training seems to require high intensity
and overload training of the global muscle
system. Vezina and Hubley-Kozey (2000)
suggested that core stability programmes should
include muscle activation below 25% of maximum
voluntary contraction (MVC), while core strength
training should include activation higher than
60% of MVC to result in strength benefits.
The available evidence suggests that to
adequately train the core muscles in athletes,
strength and conditioning specialists should focus
on implementing multi-joint full body exercises,
rather than core-specific exercises (Martuscello et
al., 2013). Exercises involving the full body
linkage such as plank exercises, have been
advocated to enhance the capacity of transmitting
force through the body linkage (Schoenfeld et al.,
2014). Training with labile systems has been
documented to offer unique opportunities for
linkage training challenges (McGill et al., 2015).
Several studies examined core muscle activation
during the execution of various exercises on stable
and unstable surfaces (for a review see: Behm et
al., 2010). The use of unstable surfaces contacting
the subject’s feet or hands is becoming popular in
strength training. Instability can be obtained
through the use of many devices and techniques
including, but not limited to, unstable platforms
such as Bosu or Swiss balls. More recently,
suspension training systems have been added to
the list of instability training devices.
In suspension training, lower or upper
limbs are hung with straps free to oscillate. Many
core directed exercises are designed with such a
device, creating a wide variety of challenges.
These exercises consist of multi-planar and multi-
joint movements, and are executed with complex
techniques. It is important to quantify the muscle
contraction intensity since it is a key factor in
establishing training effects induced by this sort of
exercises. Although considerable research has
examined more traditional means of instability
training (Behm and Drinkwater, 2010), little
previous research has evaluated the effects of
suspension training on muscle activation. In
particular, some studies focused on core-directed
exercises (Atkins, 2014; Byrne et al., 2014;
Czaprowski et al., 2014; Mok et al., 2014; Snarr
and Esco, 2014), whereas others investigated the
effect of the application of suspension system on
core muscle activity in push exercises (Calatayud
et al., 2014; McGill et al., 2014; Snarr and Esco,
2013). Further investigation of these exercise
approaches is needed to understand their
influence on muscle activation and joint load
levels.
The primary purpose of this study
therefore, was to examine differences in core
muscle activation across four full-body linkage
exercises using a suspension training system.
These exercises were chosen from a spectrum of
whole body linkage exercises focused on the
anterior core musculature executed in instable
conditions, including a roll-out, bodysaw, pike,
and knee-up. Although the selected exercises
were mainly focused on anterior slings, we
wanted to provide a comprehensive view of core
muscle activation by monitoring rectus
abdominis, internal and external oblique, and
paraspinal muscles. It was hypothesized that
significant differences would be found in core
muscles among exercises. The second aim of the
study was to determine which of these exercises
would reach the threshold of 60% of MVC,
expected to be high enough to increase muscle
strength. It was hypothesized that the four
exercises would elicit muscle activity in excess of
60% of MVC in the rectus abdominis, i.e. the
muscle on which the main focus was put
considering the selected exercises.
Material and Methods
Seventeen healthy participants were
recruited (age 27.3±2.4 years, body height 172±5
cm, body mass 69.2±9.3 kg). All participants were
physically active, declaring three practice sessions
per week of resistance training. The participants
had no prior experience with suspension training
exercises. Inclusion criteria for study participation
were as follows: no past or present neurological or
musculoskeletal trunk or limb pathology, no
cardiorespiratory disease, no history of
abdominal, shoulder or back surgery, and no
psychological problems. Participants were
instructed to refrain from performing strenuous
physical activity in the 24 hours preceding all
experimental sessions. All participants signed a
written informed consent form. The study was
previously approved by the research ethics
by Giovanni Cugliari and Gennaro Boccia 63
© Editorial Committee of Journal of Human Kinetics
committee of the Department of Medical Sciences,
University of Turin.
The surface electromyographic (EMG)
signals were obtained from six trunk muscles with
concentric bipolar electrodes (CoDe, Spes Medica,
Battipaglia, Italy). Before the placement of the
electrodes, the skin was slightly abraded with
adhesive paste and cleaned with water in
accordance to SENIAM recommendation for skin
preparation (Hermens et al., 2000). The electrodes
were placed according to the instructions
described in previous methodological works
(Beretta Piccoli et al., 2014; Boccia and Rainoldi,
2014) – lower rectus abdominis: on the lower part
of the rectus abdominis, 3 cm lateral to the
midline; upper rectus abdominis: on the upper
part of the rectus abdominis, 3 cm lateral to the
midline; external oblique: 14 cm lateral to the
umbilicus, above the anterior superior iliac spine
(ASIS); internal oblique: 2 cm lower with respect
to the most prominent point of the ASIS, just
medial and superior to the inguinal ligament;
lower erector spinae: 2 cm lateral to the L5-S1;
upper erector spinae: 6 cm lateral to the L1-L2.
The electrodes were placed only on the left
(randomly chosen) side of the body; the reference
electrode was positioned on the wrist.
The signal of a biaxial electrogoniometer
(SG 150, Biometrics Ltd, Gwent, UK) positioned at
the level of the shoulders (for the roll-out and
bodysaw) or the hips (for the pike and knee-tuck),
depending on which joint was more involved
during the exercise, was used as a trigger to
highlight exercise repetitions. The electrodes were
fixed using extensible dressing (Fixomull®,
Beiersdorf). The EMG signals were synchronized
with the electrogoniometer signal, amplified
(EMG-USB, OT Bioelettronica, Torino, Italy),
sampled at 2048 Hz, bandpass filtered (3-dB
bandwidth, 10- 450 Hz, 12 dB/oct slope on each
side), and converted to digital data by a 12-bit
A/D converter. Samples were visualized during
acquisition and then stored in a personal
computer using OT BioLab software (version 1.8,
OT Bioelettronica, Torino, Italy) for further
analysis.
The participants recruited were instructed
with regard to the correct technique of suspension
exercise and the MVC procedure during the first
experimental session conducted one week before
the measurement session. The participants were
asked to refrain from physical activity 24 hours
before the measurements. During the
measurement session, participants performed 4
exercises with the use of suspension straps (TRX®
suspension trainer; Fitness Anywhere LCC, San
Francisco, CA, USA) in random order. The
exercises were selected based on a previous study
(Behm and Drinkwater, 2010) that indicated them
as important in developing core strength.
At the beginning of the measurement
session, three MVC exercises were performed
twice for 5 s, with 2 min rest between them. The
following standardized exercises (Ng et al., 2002)
were used to activate maximally the trunk
muscles (Figure 1):
1. Upper rectus abdominis (URA)
and lower rectus abdominis (LRA): body supine
with hips and knees flexed 90°, with feet locked.
Participants flexed the trunk (i.e. crunch
execution) against resistance at the level of the
shoulders;
2. External oblique (EO) and internal
oblique (IO): side-lying with the hip at the edge of
the bench and feet locked by a second operator.
Participants performed side-bend exercise against
resistance at the level of the shoulder;
3. Lower erector spinae (LES) and
upper erector spinae (UES): prone position with
ASIS at the edge of the bench and feet locked by a
second operator. Participants performed a back
extension against resistance at the level of the
shoulders.
The suspension system handles were
positioned 15 cm from the ground. Participants
were required to achieve a range of motion
with the correct technique execution and to
maintain a neutral position of the spine and pelvis
in each exercise. A certified strength and
conditioning coach monitored the exercise
performance to ensure that the exercise was
properly executed considering its technique. Each
exercise was repeated three times and lasted 6 s. A
metronome set at 30 beats per minute was used to
ensure proper timing (with 4 beats for each
repetition): 2 s from the initial position to the final
position (concentric phase); 2 s of maintenance
(isometric phase); and 2 s returning to the starting
position (eccentric phase). The exercises were
performed with 3 min of rest in-between to allow
complete recovery. The random order of the
exercises allowed to mitigate the effects of
64 Core Muscle Activation in Suspension Training Exercises
Journal of Human Kinetics - volume 56/2017 http://www.johk.pl
cumulative fatigue on EMG estimates. Each
session lasted approximately 90 min. The
following exercises were used (Figure 2):
1) Roll-out: participants assumed an
inclined standing position while placing each
hand on the strap handles, with elbows and wrists
placed below the shoulders, arms perpendicular
to the floor and shoulders flexed approximately
45°; they then performed a shoulder flexion
moving the hands forward;
2) Bodysaw: participants assumed a prone
position, they placed elbows below the shoulders,
both forearms touching the floor, while placing
each foot on the strap handle; participants then
flexed the shoulders and extended the elbows
pushing the body backwards;
3) Pike: participants assumed a push-up
position with the feet in strap handles, then they
flexed hips to approximately 90°, while keeping
the knees fully extended;
4) Knee-tuck: participants assumed a push-
up position while placing each foot in the strap
handle, then they flexed both hips and knees to
approximately 90°, bringing the knees forward.
The average rectified value (ARV) of EMG
signals was computed off-line with numerical
algorithms using non-overlapping signal epochs
of 0.5 s (Hibbs et al., 2011). The epoch with the
highest ARV was chosen as reference in the
MVCs. The second and third repetitions of each
exercise were analyzed. The mean value of ARV
over the two repetitions was calculated for each
muscle and normalized with respect to the
maximum ARV obtained during the
correspondent MVC.
The normality assumption of the data was
evaluated with the Shapiro-Wilk test;
homoscedasticity and autocorrelation of the
variables were assessed using the Breusch-Pagan
and Durbin-Watson tests. The differences
between exercises (pike – bodysaw – knee-tuck –
roll-out) and between muscles (LRA – URA – EO
– IO – LES – UES) were compared with the 2-way
analysis of variance (ANOVA). For the purpose of
this report, only the results concerning differences
between exercises were presented. For multiple
comparisons, the Tukey test was used. The level
of significance was set at p < 0.01. Statistical
analyses were conducted using the R statistical
package (version 3.0.3, R Core Team, Foundation
for Statistical Computing, Vienna, Austria).
Results are expressed as medians (Interquartile
Range, IR).
Results
All participants managed to complete
each exercise trial and thus, were included in the
data analysis. Figure 3 shows the box plots of the
activation values (% of MVC) of each muscle
during the four exercises. Muscle activation
(Median, IR) expressed as percentage values of
ARV normalized to MVCs is reported in Table 1.
The normalized LRA activity was 140%
(IR, 89%) of MVC during the roll-out, 100% (IR,
42%) of MVC during the bodysaw, 57% (IR, 36%)
of MVC during the pike and 54% (IR, 50%) of
MVC during the knee-tuck. The normalized LRA
values were significantly higher (p < 0.01) during
the roll-out and bodysaw compared to the pike
and knee-tuck. The roll-out exercise showed
significantly greater activation (p < 0.01) than the
bodysaw.
The normalized URA activity was 67%
(IR, 78%) of MVC during the roll-out, 57% (IR,
52%) of MVC during the bodysaw, 41% (IR, 48%)
of MVC during the pike and 44% (IR, 41%) of
MVC during the knee-tuck. The normalized URA
values were significantly higher (p < 0.01) during
the roll-out compared to the pike and knee-tuck.
The normalized EO activity was 71% (IR,
44%) of MVC during the roll-out, 59% (IR, 33%) of
MVC during the bodysaw, 55% (IR, 21%) of MVC
during the pike and 42% (IR, 7%) of MVC during
the knee-tuck. The normalized EO values were
significantly higher (p < 0.01) during the roll-out
compared to the knee-tuck.
The normalized IO activity was 40% (IR,
31%) of MVC during the roll-out, 32% (IR, 20%) of
MVC during the bodysaw, 23% (IR, 20%) of MVC
during the pike and 18% (IR, 26%) of MVC during
the knee-tuck. During all exercises the normalized
IO values were not significantly higher (p < 0.01).
The normalized LES activity was 9% (IR,
5%) of MVC during the roll-out, 4% (IR, 3%) of
MVC during the bodysaw, 12% (IR, 7%) of MVC
during the pike and 8% (IR, 5%) of MVC during
the knee-tuck. During all exercises the normalized
LES values were not significantly higher (p < 0.01).
The normalized UES activity was 11% (IR,
6%) of MVC during the roll-out, 8% (IR, 6%) of
MVC during the bodysaw, 9% (IR, 4%) of MVC
during the pike and 6% (IR, 5%) of MVC during
by Giovanni Cugliari and Gennaro Boccia 65
© Editorial Committee of Journal of Human Kinetics
the knee-tuck. During all exercises the normalized
UES values were not significantly higher (p <
0.01).
Table 2 shows the estimate (difference of
means) at 95% of the confidence interval after
Tukey multiple comparisons; in this case only
"exercise factor" was considered.
The roll-out exercise showed significantly
(p < 0.01) higher activation compared to the
bodysaw (16%, CI 8-23%), pike (26%, CI 18-33%)
and knee-tuck (29%, CI 21-37%). Pike and knee-
tuck exercises showed significantly higher
activation compared to the bodysaw of 10% (2-
8%) and 13% (6-21%).
Figure 1
Standardized exercises used to maximally activate trunk muscles:
Lower rectus abdominis and upper rectus abdominis (left);
Internal oblique and external oblique (middle);
Lower erector spinae and upper erector spinae (right).
Figure 2
Initial and final positions of each exercise: 1) Roll-out; 2) Bodysaw; 3) Pike; 4) Knee-tuck.
66 Core Muscle Activation in Suspension Training Exercises
Journal of Human Kinetics - volume 56/2017 http://www.johk.pl
Figure 3
Each box plot shows the muscle activation (as percentage of maximum
voluntary contraction) during exercise.
Whiskers indicate variability outside the upper and lower quartiles.
Table 1
Muscle activation (Median, IR) expressed as percentage values
of electromyographic amplitude normalized to maximum voluntary contraction.
Results of the two-way ANOVA after Tukey multiple comparisons
are reported as symbols; p<0.01.
Lower rectus
abdominis
Upper rectus
abdominis
External
oblique
Internal
oblique
Lower erector
spinae
Upper erector
spinae
Pike 57 (36) ǂ § 41 (48) ǂ 55 (21) 23 (20) 12 (7) 9 (4)
Bodysaw 100 (42) ǂ Ф Ψ 57 (52) 59 (33) 32 (20) 4 (3) 8 (6)
Knee-tuck 54 (50) ǂ § 44 (41) ǂ 42 (7) ǂ 18 (26) 8 (5) 6 (5)
Roll-out 140 (89) § Ф Ψ 67 (78) Ф Ψ 71 (44) Ψ 40 (31) 9 (5) 11 (6)
Ф indicates statistically significant difference between
the indicated exercise (explained in row) with respect to the pike
§ indicates statistically significant difference between
the indicated exercise (explained in row) with respect to the bodysaw
Ψ indicates statistically significant difference between
the indicated exercise (explained in row) with respect to the knee-tuck
ǂ indicates statistically significant difference between
the indicated exercise (explained in row) with respect to the roll-out
by Giovanni Cugliari and Gennaro Boccia 67
© Editorial Committee of Journal of Human Kinetics
Table 2
Estimate at 95% of the confidence interval after Tukey multiple comparisons
with the "exercise factor" considered. The estimate shows
the difference of means (% of maximum voluntary contraction).
* indicates the statistical significance of the adjusted p-value.
Exercises Estimate Lower CI (95%) Upper CI (95%)
Bodysaw – Roll-out -16 * -23 -8
Pike – Roll-out -26 * -33 -18
Knee-tuck – roll-out -29 * -37 -21
Pike – Bodysaw -10 * -18 -2
Knee-tuck – Bodysaw -13 * -21 -6
Knee-tuck – Pike -3 -11 4
Discussion
Suspension training has become
increasingly popular as a training tool. Despite
this popularity, relatively little research exists on
the effects of such training on muscle activation
magnitude. The first objective of the study was to
investigate the activation differences of four
exercises (roll-out, bodysaw, pike and knee-tuck)
to better characterize suspension training. Our
findings indicate that suspension exercises could
be an effective strategy to reach high to very high
activation of abdominal muscles such as the
rectus abdominis and external oblique.
To facilitate comparisons between
exercises and previous studies, we categorized
muscle activation into four levels according to
previous studies, with <21% as low, 21–40% as
moderate, 41–60% as high, and >60% as very high
(Escamilla et al., 2010). Exercises used in the
present study provide a range of medium to high
intensity exercises through which participants or
athletes can progress during a training or
rehabilitation programme (Blanchard and
Glasgow, 2014) (Figure 2). Roll-out exercise was
the most challenging for core musculature,
followed by bodysaw, pike and knee-tuck
exercises (Table 2). The roll-out showed the
highest activation of rectus abdominis and
oblique muscles compared to other exercises.
However, not all muscles responded in the same
way across exercises. Although LRA showed
much greater activation in roll-out and bodysaw
compared to pike and knee-tuck exercises, the
other muscles showed smaller differences. These
findings could suggest that in the exercises
characterized by shoulder flexion (such as roll-out
and bodysaw), the increased requirement of core
stability was reflected more by the lower rectus
abdominis.
According to Vezina and Hubley-Kozey
(2000), the exercises that generate muscle activity
greater than 60% of MVC might be more
conducive to developing muscular strength. The
rectus abdominis (both parts) and EO reached
activation higher than 60% of MVC (or very close
to that threshold, 55%) in the roll-out and
bodysaw; consequently these exercises can be
considered suitable for strength training of these
muscles. Although in the knee-tuck and pike, the
rectus abdominis and EO did not reach the
threshold of 60%, they presented high activation
68 Core Muscle Activation in Suspension Training Exercises
Journal of Human Kinetics - volume 56/2017 http://www.johk.pl
levels (41-60% MVC). While strengthening of the
core is important, an activation level below 60%
might be beneficial in increasing muscle
endurance within the core. Since the core muscles
are primarily composed of type I fibres
(Haggmark and Thorstensson, 1979), muscular
endurance should also be a major concern when
designing strength and conditioning programmes
(Vezina and Hubley-Kozey, 2000). Due to large
demand for muscle activation, all the proposed
exercises might be appropriate for extremely fit
individuals in the latter stages of a progressive
abdominal strengthening or rehabilitation
programme.
Erector spinae muscles resulted in being
activated at low and very low intensity. This is an
expected result as all exercises focused on anterior
abdominal wall muscles. This finding confirms
that in the herein selected whole-body linkage
exercises, the activation of core muscles can be
mainly focused on abdominal muscles while
keeping the paraspinal muscles involved with low
intensity.
Although no direct comparison can be
made between the selected suspension exercises
compared to previously reported similar
exercises, it is possible to highlight the following
differences. We can compare only the activation of
the rectus abdominis, since for oblique muscles
we used a different normalization exercise than
the other three studies. Plank exercises are
frequently included in spine stabilization
programmes as a means of improving motor
control for spine stabilization. When plank
exercises are performed on stable or unstable
support surfaces, the reported activation level of
the rectus abdominis and EO ranges from low to
moderate (Garcia-Vaquero et al., 2012). When
executed in suspension condition, rectus
abdominis muscles also showed moderate
activation (Byrne and Bishop, 2014). Only when
the planks were performed with a similar
technique (instability on lower limb and shoulder
flexion) was the activation similar to that reported
here, which was very high for the rectus
abdominis (McGill and Andersen, 2015).
Therefore, we can assume that our exercises were
more challenging than an isometric plank in a
stable condition.
In the roll-out, we found very high
activation of LRA (140%) and URA (67%). These
levels were higher than previously reported
values obtained during the execution of the roll-
out with the Swiss-ball (about 50-60% for rectus
abdominis) (Escamilla and Lewis, 2010; Marshall
and Desai, 2010) and similar to the values
reported with the use of the Power Wheel, being
very high for URA (76%) and LRA (81%)
(Escamilla et al., 2006). In the pike, we found high
activation of LRA (57%) and URA (41%). The
values reported for the pike executed with the
Swiss ball (Escamilla and Lewis, 2010) and Power
Wheel (Escamilla and Babb, 2006) were similar for
URA (Swiss ball 47%; Power Wheel 41%) and
LRA (Swiss ball 55%; Power Wheel 53%). In the
knee-tuck, we observed high activation of LRA
(54%) and URA (44%). Otherwise, the values
reported for the knee-tuck executed with the
Swiss ball (Escamilla and Lewis, 2010) and Power
Wheel (Escamilla and Babb, 2006) were lower for
both URA (Swiss ball 32%; Power Wheel 41%)
and LRA (Swiss ball 35%; Power Wheel 45%).
Our findings suggest that the two parts of
the rectus abdominis can be activated differently
according to the needs of the motor task (Kibler et
al., 2006). This finding could be explained by the
possibility to (voluntary or involuntary) modulate
the activation ratio between rectus abdominis
parts in order to achieve the best control of the
core region. This could be justified by the
metameric innervation of rectus abdominis
muscles (Duchateau et al., 1988), although this
issue is still controversial (Monfort-Panego et al.,
2009). However, LRA muscles were generally
more active than URA because of confounding
methodological factors. MVCs of the LRA and
URA in fact were estimated by a standardized
exercise to activate maximally the trunk muscles:
it could be argued that the same exercise fully
activated URA whereas it failed to fully activate
LRA. Hence, the EMG amplitude recorded during
MVC was not the maximum achievable.
Consequently, throughout experimental exercises,
LRA seemed relatively more active than URA
because its reference value of MVC was
underestimated.
A few methodological limitations of our
study warrant further consideration. In some
cases, ARV estimates of EMG signals exceeded the
MVC reference values (ARV higher than 100%).
This inconsistency might be due to incomplete
activation during MVC (as in the case of the lower
by Giovanni Cugliari and Gennaro Boccia 69
© Editorial Committee of Journal of Human Kinetics
rectus abdominis) and other confounding factors
related to EMG technique (relative shift of muscle
belly with respect to electrodes occurring in
dynamic tasks and different activation between
isometric and dynamic tasks, among others).
As widely reported, variability of
muscular activation between participants was
high. This suggests that performing these
exercises, some individuals might produce more
or less activation than the average activity
indicated here. Although 17 individuals
participated in this research, the differences in
their fitness level and exercise experience could
have affected the performance of the exercises and
the resulting activation levels.
Crosstalk between muscles was
minimized by using an innovative detection
system based on concentric-ring electrodes which
had been reported as having higher spatial
selectivity compared to the traditional detection
systems and reducing the problem of crosstalk
from nearby muscles (Farina and Cescon, 2001).
Conclusions
Findings from this study, based on
electromyographic analysis, showed that roll-out
exercise was the most challenging. Moreover, roll-
out and bodysaw exercises executed in
suspension activated the rectus abdominis and
external oblique muscles at intensities higher
than, or very close to, 60% of the maximum
voluntary contraction. Based on these findings,
we can assume that roll-out and bodysaw
exercises can be used to adequately strengthen the
antero-lateral, superficial aspect of the core
region, and thus they can be considered core
strength exercises. These findings appear to have
particular relevance for well-trained individuals
given the high demand imposed by these
exercises.
Acknowledgements
This work was supported by Funding for Innovation Projects under grant Project HExEC, PQR FESR
2007/1013
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by Giovanni Cugliari and Gennaro Boccia 71
© Editorial Committee of Journal of Human Kinetics
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Corresponding author:
Gennaro Boccia,
1) CeRiSM Research Center “Sport, Mountain, and Health”, via del Ben 5/b, 38068, Rovereto, (TN), Italy.
2) Motor Science Research Center, School of Exercise & Sport Sciences, SUISM, Department of Medical
Sciences, University of Turin. 12, piazza Bernini, 10143, Torino, Italy.
Address: 12, piazza Bernini, 10143, Torino, Italy;
Telephone: +39 0117764708
Fax: +39 011748251
E-mail gennaro.boccia@unito.it
... De tal maneira, a proposta do teste prancha também é relevante por mensurar a força de grupos musculares distintos aos avaliados no Teste Sit-up. Nesse sentido, cabe ressaltar que a força dinâmica está associada aos processos neuromotores dos grandes grupos musculares em processos de exercícios físicos com contrações concêntricas e excêntricas 4,11,23 . A força isométrica aplicada no teste prancha parece depender, em maior proporção, de processos metabólicos localizados nas fibras musculares 4,6,11,23,26 . ...
... Nesse sentido, cabe ressaltar que a força dinâmica está associada aos processos neuromotores dos grandes grupos musculares em processos de exercícios físicos com contrações concêntricas e excêntricas 4,11,23 . A força isométrica aplicada no teste prancha parece depender, em maior proporção, de processos metabólicos localizados nas fibras musculares 4,6,11,23,26 . Além disso, deve-se considerar que ambos os testes podem apresentar relação com os processos maturacionais, o crescimento, idade e o sexo 26,27 , fatos que podem ser considerados em futuros estudos, para a proposição de normas e critérios relacionados ao desempenho esportivo e à saúde 16 . ...
... Adicionalmente, as medidas em testes isométricos de força muscular na posição de prancha, bem como suas variações, e as medidas em testes como o Sit-up e o Curl-up, podem relacionar-se em até 63% com a força muscular abdominal avaliada por eletromiografia, revelando uma validade de medida adequada no que se refere ao conceito geral de força 4,11,23 . Por outro lado, como limitação da pesquisa, observa-se a amostra conveniente. ...
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The objectives of this study are to verify the reproducibility and reliability of the "Plank" test in schoolchildren aged 6 to 12 years and to identify the association between isometric strength measurement in the plank test and abdominal resistance strength in the sit-up test. That is a cross-sectional study with a quantitative approach, performed with 221 students, 58.8% of the male gender, selected by convenience at a school in southern Santa Catarina, Brazil. Abdominal isometric strength was assessed by the plank test, it adapted from the Mckenzie. The sit-up test was evaluated following the PROESP-BR protocol. Reproducibility and reliability were measured with intraclass correlation test (IC) and Bland and Altmann graph. The correlation of the strength in the plank test with the sit-up abdominal test was measured according to the determination coefficient (R2), Cronbach's Alpha and McDonald Omega estimate. The IC between plank test measurements showed high agreement (> 0.70; p = 0.001). There was a moderate relationship between test, retest plank with the number of sit-ups in one minute (R2 = 0.43 male; R2 = 0.33 female). The Cronbach's alpha and McDonald's Omega are elevated between the three measures (> 0.80). It concluded that the proposed isometric plank test presents a high level of reproducibility, reliability, and a high relationship with sit-up abdominal strength. It indicates that Plank can be used as an alternative measure for isometric abdominal strength in schoolchildren of present study.
... The other characteristic of TRX training is core muscle engagement, in which muscles in the abdomen, trunk, lower back, and hips maintain body stability. Instability resistance training through more motor unit recruitment can be more effective than training under stable conditions [11]. ...
... Stronger core muscles with improvements in the upper and lower body strength can contribute to better stability and postural control. Furthermore, increased blood flow to the brain, especially the cerebellum (body's balance control center), facilitates information processing and thus improved balance ability [11]. In this study, better balance performance in the TRX training seems to be related to greater muscle strength (LB, UB) in this group. ...
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... One of possible mechanisms of suspension exercises effect on motor control is that suspension exercises have increased control of body position through simultaneous contractions of agonist and antagonist muscles. Therefore, the used exercises probably increase proprioceptive and improve function of muscles around the spine by increasing tonic activity and ability to maintain contraction in the agonist muscle and increase the peripheral inputs [45]. One of the characteristics of instability training is that exercises begin the process of learning new movement patterns and using these exercises may increase muscle recall due to unstable surface [16]. ...
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Information about comparing the effectiveness of exercise methods on management of disk herniation is limited. The aim of this study was to compare the effect of two programs of suspension and core stability exercises on some electromyography (EMG) coordinates, pain and range of motion of patients with disk herniation. Thirty-two men with disk herniation participated in this clinical trial study which was randomly divided into three groups of suspension exercises (n: 12, age: 34.25 ± 8.81, BMI: 24.01 ± 2.7), core stability exercises (n: 10, age: 35 ± 10.3, BMI: 25 ± 2.27) and control (n: 10, age: 34.4 ± 6.67, BMI: 23.76 ± 1.45). Electrical activity of rectus abdominis, internal and external oblique and erector spinae muscles was masured by superficial EMG, back pain by McGill Pain Questionnaire and range of motion by Modified Schober test, one day before and immediately after of intervention period. The experimental groups performed an 8-week training period while the control group was only followed up. Data were analyzed using paired sample t test and analysis of covariance test and statistical significance was set at 0.05. Suspension group showed significant improvement in EMG of rectus abdominis, internal and external oblique muscles (respectively, p = 0.030, p = 0.017, p = 0.022) and pain (p = 0.001) compared to core stability group; but there was no significant difference between two groups in EMG of erector spinae muscle and range of motion. Changes in both training groups were significant in all variables compared to control groups (p ˂ 0.05). Our findings showed that although both exercises were effective in patients with lumbar disk herniation, but the effectiveness of suspension exercises in increasing muscle activation and reducing pain was more pronounced than core stability exercises. Iranian Registry of Clinical Trials (IRCT): IRCT20191016045136N1.
... Abdominal/core strengthening has been widely studied, as it is considered a key factor for health, rehabilitation and athletic performance (Cugliari & Boccia, 2017). In the present study, it was found that SU performance improved significantly. ...
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Introduction: Recent research data show a significant decline in youth's muscle strength. Purpose: The purpose of the present study was to assess the efficacy of a suspension training intervention during physical education (PE) lessons on strength parameters in adolescents, compared with a control group. Methods: The sample of the study included 321 adolescents (158 boys and 163 girls, M age = 16.54, SD = .91). The intervention group followed a suspension training program twice a week for a total of eight weeks during the PE lesson, while the control group attended the regular PE class throughout the intervention. A pre-intervention, a post-intervention and a detraining test were conducted. Field tests that measure muscle strength and endurance were used to assess lower body, core, upper body and handgrip strength (standing long jump, sit-up, push-up, handgrip). A two-way (2 groups X 3 measurements) analysis of variance (ANOVA) was used to test the efficacy of the intervention. Results: The results showed that students in the intervention group improved performance significantly from pre-to post-intervention in all tests compared to control participants. Regarding retention, the performance of the students in the intervention group, although decreased, remained significantly higher than that of the participants in the control group. Conclusions: These results suggest that suspension training is an effective and feasible resistance training method that can be integrated in PE lessons. Furthermore, due to the promptly observed improvements in strength, the suspension training program could lead to an increase in motivation to participate in the PE lesson and consequently, integrating strength training into the PE lesson throughout the school year could increase the academic learning time.
... For the exercises of the upper part of the trunk and the stabilising muscles, they have been studied with the performance of the Push-up exercise. It has been shown that greater muscular activation in the core, rectus abdominis and external oblique muscles [69,73], however, the stable situation reported greater activation for the pectoral and deltoid muscles [65,69,71] the brachial triceps [65] and the clavicular portion of the pectoralis [71]. However, for the frontal plate exercise, Byrne et al. [70] reported no significant differences when studying exercise with suspension devices. ...
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The usefulness of leaving lateral strips of the rectus abdominis muscle in place during a transverse rectus abdominis musculocutaneous (TRAM) flap procedure is questioned. Since textbooks do not agree on the course of the intercostal nerves in the rectus fascia and no precise description is given of the exact site of penetration of the nerves in the rectus muscle, six fresh cadavers were dissected. It has been observed that the nerves enter the deep face of the muscle in its middle portion. Lateral parts of the muscle are consequently denervated during a transverse rectus abdominis musculocutaneous flap, which preserves them. This has been confirmed by CT scan of the abdominal wall in 10 patients 2 to 37 months after a transverse rectus abdominis musculocutaneous flap. In these patients, a progressive fibrosis and disappearance of the remaining muscle could be demonstrated. It is concluded that a partial taking of the rectus abdominis muscle does not preserve its muscular function. (C)1988American Society of Plastic Surgeons
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Core stability training traditionally uses stable base techniques. Less is known as to the use of unstable base techniques, such as suspension training, to activate core musculature. This study sought to assess the neuromuscular activation of global core stabilisers when using suspension training techniques, compared to more traditional forms of isometric exercise. Eighteen elite level, male youth swimmers (Age 15.5yrs ± 2.3yrs; Stature - 163.3cm ± 12.7cm; Body Mass 62.2kg ± 11.9 kg) participated in the current study. Surface electromyography (sEMG) was used to determine the rate of muscle contraction in postural musculature, associated with core stability and torso bracing (rectus abdominus-RA, external oblique's-EO, erector spinae-ES). A maximal voluntary contraction (MVC) test was used to determine peak amplitude for all muscles. Static bracing of the core was achieved using a modified 'plank' position, with and without a Swiss ball, and held for 30 seconds. A mechanically similar 'plank' was then held using suspension straps. Analysis of sEMG revealed that suspension produced higher peak amplitude in the RA than using a prone or Swiss Ball 'plank' (p=0.04). This difference was not replicated in either the EO or ES musculature. We conclude that suspension training noticeably improves engagement of anterior core musculature when compared to both lateral and posterior muscles. Further research is required to determine how best to activate both posterior and lateral musculature when using all forms of core stability training.
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Abstract This study examined anterior chain whole body linkage exercises, namely the body saw, hanging leg raise and walkout from a push-up. Investigation of these exercises focused on which particular muscles were challenged and the magnitude of the resulting spine load. Fourteen males performed the exercises while muscle activity, external force and 3D body segment motion were recorded. A sophisticated and anatomically detailed 3D model used muscle activity and body segment kinematics to estimate muscle force, and thus sensitivity to each individual's choice of motor control for each task. Gradations of muscle activity and spine load characteristics were observed across tasks. On average, the hanging straight leg raise created approximately 3000 N of spine compression while the body saw created less than 2500 N. The hanging straight leg raise created the highest challenge to the abdominal wall (>130% MVC in rectus abdominis, 88% MVC in external oblique). The body saw resulted in almost 140% MVC activation of the serratus anterior. All other exercises produced substantial abdominal challenge, although the body saw did so in the most spine conserving way. These findings, along with consideration of an individual's injury history, training goals and current fitness level, should assist in exercise choice and programme design.
Article
: The objective of the study was to examine the effect of suspension training on muscle activation during performance of variations of the plank exercise. Twenty-one participants took part. All individuals completed two repetitions each of four different plank exercises that consisted of a floor based plank, or planks with arms suspended, feet suspended, or feet and arms suspended using a TRX® Suspension System. During plank performance, muscle activation was recorded from rectus abdominis, external oblique, rectus femoris and serratus anterior muscles using electromyography. All planks were performed for a total of three seconds. Resulting muscle activation data was amplitude normalized and root mean square activation was then determined over the full three second duration of the exercise. A significant main effect of plank type was found for all muscles. Post-hoc analysis and effect size examination indicated that abdominal muscle activation was higher in all suspended conditions compared to the floor based plank. The highest level of abdominal muscle activation occurred in the arms suspended and arms/feet suspended conditions, which did not differ from one another. Rectus femoris activation was greatest during the arms suspended condition, while serratus anterior activity peaked during normal and feet suspended planks. These results indicate that suspension training as performed in the present study appears to be an effective means of increasing muscle activation during the plank exercise. Contrary to expectations, the additional instability created by suspending both the arms and feet did not result in any additional abdominal muscle activation. These findings have implications in prescription and progression of core muscle training programs.