July 2021. Volume 11. Number 3
Research Paper: The Effect of Three Methods of Kinesthetic Imagery, Active, and Combined Exercises on
Electromyographic Pattern of Hip Hyperextension
and the Muscle Strength of Gluteus Maximus and
Abdominal in Women With Lumbar Hyperlordosis
Maryam Ghorbani1*
, Mohammed Husain Alizadeh2*
, Mehdi Shahbazi3
, Hooman Minoonejad2
1. Department of Sports Injury and Corrective Exercise, Pardis Alborz of University of Tehran, Tehran, Iran.
2. Department of Sports Injury and Corrective Exercise, Faculty of Physical Education, University of Tehran, Tehran, Iran.
3. Department of Motor Behavior, Faculty of Physical Education, University of Tehran, Tehran, Iran.
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Citation Ghorbani M, Alizadeh MH, Shahbazi M, Minoonejad H. The Effect of Three Methods of Kinesthetic Imagery, Active,
and Combined Exercises on Electromyographic Pattern of Hip Hyperextension and the Muscle Strength of Gluteus Maximus and Abdominal in Women With Lumbar Hyperlordosis. Physical Treatments. 2021; 11(3):145-156. http://dx.doi.org/10.32598/ptj.11.3.36.3
:
http://dx.doi.org/10.32598/ptj.11.3.36.3
AB STRACT
Article info:
Received: 27 Jun 2020
Accepted: 14 Feb 2021
Available Online: 01 Jul 2021
Keywords:
Lumbar hyperlordosis,
Mental training,
Electromyography,
Lumbopelvic muscles
Purpose: Mental exercise uses the same neuronal pathways involved in physical exercise to modify
the pattern and function without stress caused by physical exercise. This study investigates the effect
of kinesthetic imagery, active, and combined exercises (imagery and active) on the hip hyperextension
and the power of selected lumbopelvic muscles in women suffering from lumbar hyperlordosis.
Methods: In this quasi-experimental study, 36 women with lumbar hyperlordosis (age range: 30-40
years, non-athlete and without injury and surgery in the lumbar region) were selected and divided into
three groups. The groups practiced three sessions per week for six weeks. We assessed the lumbar
lordosis by a flexible ruler and the electromyographic (EMG) activity of the lumbopelvic muscles
during hip hyperextension in the prone position by surface electromyogram. We also measured the
power of the gluteus maximus using a dynamometer during hip hyperextension and the abdominal
muscles using a goniometer during the double leg lowering test. All of the measurements were done
before and after the intervention. The normality of the data was checked by The Shapiro-Wilk test, and
the obtained data were analyzed by repeated-measures ANOVA test at the significant level of 0.05.
Results: The variables of lumbar lordosis were significantly reduced in the active and combined
groups in the post-test compared to the pre-test, and the strength of gluteus and abdominal muscles
in the active and combined groups in the post-test significantly increased compared to the pre-test.
However, the lumbar lordosis and strength of gluteus and abdominal muscles in the post-test were
not significantly changed compared to the pre-test. Gluteus maximus and abdominis transverse
muscle activity rates in the combined group increased significantly in the post-test compared to the
pre-test, and gluteus maximus muscle activity rate in the active group increased significantly in the
post-test compared to the pre-test. Gluteus maximus muscle activity in the imagery group increased
significantly in the post-test compared to the pre-test. The activity of lumbar erector spinae and
rectus femoris muscles decreased significantly in the active and combined groups in the post-test
compared to the pre-test. However, the activity of the rectus femoris muscle decreased significantly
in the image group in the post-test compared to the pre-test (P≤0.05). The results showed a significant
difference between the three methods of kinesthetic imagery, active, and combined (P=0.001). There
was a significant difference between the method of the imagery exercise and the active and combined
exercise methods but no significant difference between methods of the active and combined exercise.
Conclusion: Imagery exercises effectively modified the EMG of some lumbopelvic muscles (gluteus
maximus and rectus femoris muscles). However, it had no significant effect on the strength and degree
of lumbar lordosis. The combined exercise was as effective as active exercise in modifying the EMG
activity of the lumbopelvic muscles and the strength of the abdominal and gluteus maximus muscles.
* Corresponding Author:
Mohammed Husain Alizadeh, PhD.
Address: Department of Sports Injury and Corrective Exercise, Faculty of Physical Education, University of Tehran, Tehran, Iran.
Phone: +98 (912) 8092567
E-mail: maryamghorbani@ut.ac.ir
145
July 2021. Volume 11. Number 3
Highlights
● Effect of mental imagery exercises on women's movement pattern.
● Mental exercises alone do not change the movement pattern.
● Mental exercises in conjunction with physical exercises cause lasting changes.
Plain Language Summary
The effect of mental imagery exercises on women's movement pattern was investigated. Therefore, in addition to
physical exercises, mental exercises were also used. The results of this study showed that mental exercises alone do
not change the movement pattern. But if mental exercises are used in conjunction with physical exercises, it will cause
lasting changes in women's movement pattern.
1. Introduction
he repeated movement and sustained
posture would alter muscle tissue properties [1] so that the musculoskeletal
system cannot provide the necessary
support for optimal movement with stability [2]. If the stress and strain to different body structures extend beyond tissue tolerance,
it can result in pathology [1]. Therefore, motor pattern
abnormalities can be a vital factor in musculoskeletal
disorders [3, 4]. In this regard, Janda stated that the regular muscle activation pattern during hip extension in the
prone position is respectively gluteus maximus followed
by hamstring and spinae erectors [2]. The disruption of
this natural pattern causes mechanical and compressive
stresses on the lumbar spine [2].
T
One of the most common patterns of disorder seen
clinically during the prone hip extension test is an excessive delay in applying the gluteus maximus [1]. In these
cases, hip extension is caused by the activity of hamstring muscles, which results in anterior pelvic tilt and
lumbar hyperlordosis to compensate [5, 6]. Therefore,
in the lower cross syndrome, the agonist and antagonist
balance in the lumbopelvic muscles is disturbed. In this
syndrome, erector spinae muscle stiffness is associated
with iliopsoas and rectus femoris muscle stiffness and
deep abdominal muscles weakness with gluteus maximus muscle weakness [2]. This pattern of muscle imbalance increases lumbopelvic mobility [7], and particularly in activities such as gait, the stability of the pelvis
is reduced and thus impedes the body’s mechanical efficiency [6]. That is why is used in examining movement
patterns, activity levels or sequences, and the order in
146
which muscles are activated as a criterion for examining
movement patterns [2, 3]. If the lumbopelvic muscles
function normally, they sufficiently stabilize and prevent
excessive lumbar curvature and consequently create a
normal movement pattern in the lumbopelvic area [4, 5].
Oh et al. (2007) investigated the effect of inward abdominal maneuvering on erector spinae and hip Electromyographic (EMG) activity and anterior pelvic tilt angle
during hip extension in the prone position. Their results
showed that inward abdominal maneuvering during hip
extension caused a significant decrease in the activity of
erector spinae muscle and a significant increase in the activity of the internal hamstring and gluteus maximus [6].
Also, Park et al. (2011) examined the effect of inward
abdominal maneuvering on muscle activity and pelvic
movement during knee flexion in patients with lumbar
extension rotation syndrome [7]. The results showed that
the erector spinae muscle activity of the left and right was
significantly reduced during the abdominal maneuver.
The internal and external hamstring EMG activity was
significantly increased. The pelvic tilt, knee flexion, and
pain during abdominal maneuver decreased in the prone
position during knee flexion. These studies show that by
increasing abdominal activity, pelvic tilt is reduced [7, 8].
Since the muscles reflect the function of the Central
Nervous System (CNS), any dysfunction of the CNS
and the sensory-motor system exhibit adaptive and
compensatory manifestations in the motor system [2,
4, 5]. Research findings have also shown that physical
exercise is an effective intervention to correct imbalances and muscle function. However, the use of mental
training methods that increase cerebral cortex activity
and attention [9] and thus provide better cognition has
Ghorbani M, et al. Effect of Three Methods on the PHE Pattern. PTJ. 2021; 11(3):145-156.
July 2021. Volume 11. Number 3
not been sufficiently addressed. It seems that in mental
practice, more repetition can be achieved with less time
and its results are similar to physical exercise [9-12]. In
this regard, Lebon et al. (2011) examined the increase
in muscle activation following the intervention of mental imagery exercise during anterior cruciate ligament
rehabilitation. The findings showed that imagery exercises increased muscle activation [13]. Christakou et al.
(2007) used mental imagery exercises along with physiotherapy for ankle rehabilitation [14]. Although the researchers used mental intervention to help subjects, the
results showed no significant changes in pain, swelling,
and range of motion in athletes [15]. Also, Hoyek et al.
examined the effect of mental imagery on functional rehabilitation in the syndrome of impingement shoulder.
Their results showed that mental imagery exercises increased joint mobility [15].
Findings from these studies suggest that mental exercise along with physical exercise can be used to modify
muscle activity patterns [1]. Nevertheless, mental imagery exercises as an effective intervention in correcting
motor patterns and musculoskeletal disorders functionality require further studies. The present study aimed to
compare the efficacy of active, imagery, and combined
exercises on the movement configuration of hip hyperextension and power of gluteus and abdominal muscles
in women with lumbar hyperlordosis.
2. Materials and Methods
This study is quasi-experimental. To prevent alternative explanations for the observed differences, we selected all subjects from a single cohort (non-athlete women
with no history of injury and age range of 30-40 years)
[16]. The screening was first performed using an observational evaluation of the sagittal plane. The lumbar lordosis angle was measured using a flexible ruler. Women
whose lordosis angle was more than 450 [17] were included in the study after completing the motion imagery
questionnaire; those who achieved the quota [18] were
placed in the group of kinesthetic imagery and combined
exercises (active and imagery), and the rest in the active
exercise group. Also, to avoid spreading the effects of
the intervention from one group to another, it was tried
to separate the exercise groups as much as possible and
each group’s training time different from the other training group so that they would neither meet nor be aware
of each other’s work [16].
The number of samples was calculated using the G
Power software with the repeated measures analysis of
variance within and between interactions, the effect size
of 0.3 (moderate effect size), the number of groups of 3,
the measurement number of 2, at the significant level of
0.05 and statistical power of 0.85. Finally, the total number of 36 subjects (12 subjects in each group) was estimated (active exercise group: 12, kinesthetic imagery exercise group: 12, and combined exercises group: 12). The
subjects signed a written consent and entered the study.
A flexible ruler, which has been described as validity
(0.88) and reliability (0.82) tools for measure lumbar lordosis, was used to measure lumbar lordosis degree [19].
The spinal process of the T12 was used as the starting
point of the arch, and S2 as the endpoint [17]. The ruler
was then placed on the desired points, and the points
were marked on the ruler. The ruler was applied to the
paper without any changes, and the curvature formed on
the ruler was drawn by a pencil on the paper, and after removing the ruler from the paper, two distinct points were
connected to the straight line and draw a straight line on
the deepest part of the perpendicular arc and calculate the
lumbar arch size using the 4Arctg H/L2 formula [17, 19].
The strength of a gluteus maximus muscle was measured with a dynamometer. The tester would take a
prone position on the bed, then bent the knee 90 degrees,
and the leather interface is attached to the middle of the
thigh. In this case, the subject is asked to apply maximum force to the leather interface. Each subject repeats
this test twice with a one-minute interval, and the bestobtained number was considered the maximum isometric strength of the gluteus maximus muscle [17, 20-22].
Abdominal muscle strength was measured using the
double leg-lowering test (DLLT) [23]. All measurements
were completed by a team of 2 examiners. Subjects wore
shorts and removed their shoes to avoid additional external loads. The examiners explained the testing procedure
to the subjects, who then were allowed to practice the
procedure only once to demonstrate their understanding of the DLLT. When performing the test, each subject
lay supine on a wooden table with a 1-cm–thick felt pad
with the arms folded across the chest. Two trials were
performed with a 1-minute rest between trials. The test
began with an examiner helping the subject place her
legs in a vertical position with the knees extended to the
terminal range as allowed by the flexibility of the hamstrings. Each subject was instructed to keep the pelvis
posteriorly rotated, so the lumbar spine was held firm to
the table, while slowly lowering the legs to a horizontal
position. Examiner 1 monitored the position of the low
back from the subject’s right side by placing fingers between the low back (L4-5 area) and the table. Examiner
1 verbally signaled Examiner 2 when the subject’s back
Ghorbani M, et al. Effect of Three Methods on the PHE Pattern. PTJ. 2021; 11(3):145-156.
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July 2021. Volume 11. Number 3
began to lift from the monitoring fingers; this represented the end of the test. Examiner 2 recorded the subject’s
performance with the goniometer. The goniometer was
placed on the greater femoral trochanter; then one axis
of the goniometer was placed along the long axis of the
femur and the other along the trunk. The axis of the goniometer remained parallel to the long axis of the femur
while the test was being done. At the signal to end the test,
a stop to measure with goniometer occurred [17, 20, 21].
The EMG of transverse abdominal, hip extensors, lumbar extensors, and hip flexor muscles was measured using surface electromyography in the prone position [3].
The individual was asked to perform hip hyperextension
in the prone position. To record the electrical activity of
the muscles, we used a 16-channel electromyogram (ME
model from Flanders and dipole electrodes). In the present study, 4 channels were used for muscle examination.
Also, superficial disposable electrodes and FRG rectangular electromyographic (SKINTACT, made in Austria)
were used. Electromyographic data were collected at a
sampling rate of 1000 Hz/s. These signals were initially
pre-amplified ten times and filtered in the band-pass filter between 20 and 500 Hz. The distance between the
electrodes was 2 cm, and the electrodes were positioned
on the midline of the muscles according to SENIAM instructions, and then the electrodes were connected to the
target points: gluteus maximus muscle, 1.2 distance of
S2 to the greater trochanter; lumbar erector spine muscle, 3 cm apart of L3 lumbar; transverse abdominis muscle, 2 cm distal to the upper anterior superior iliac spine
to downward and inward and rectus femoris muscle, 1.2
distance of anterior superior iliac spine to under patella
(Appendix 1). Electromyographic parameters were recorded with a computer. A metronome controlled the
movement speed, and data analysis was performed using
the RMS algorithm (Root Mean Square) and megavine
software (Mega Electronics, Finland). The EMG of hip
hyperextension was recorded for 6 s, and then 1.5 s from
the beginning and the end of this period was eliminated.
The maximum voluntary contraction method was used
to normalize the electromyographic data, with each muscle being tested three times the maximal voluntary contraction, and the electromyographic activity of the muscles in 6 s was recorded. To process the information, 1.5
s of the first and last part of this time were deleted, and 3
s in the middle was selected. The maximum value of the
three measurements was used for analysis. Finally, the
electromyographic activity of each muscle during hyperextension of the femur was divided over the maximum
voluntary contraction of the same muscle to normalize
the numbers. Then, they were presented as a percentage
of maximal voluntary contraction [3, 4].
148
Sahrmann exercises were used for the active exercise
group [1]. Active exercises were performed three 60-75
min sessions per week for 6 weeks, including 5 min of
warm-up, the main training program for 45 to 60 min,
and cool down for 5 min (Appendix 2). The group of
kinesthetic imagery exercises performed the same Sahrmann exercise to form mentally kinesthetic imagery,
including the sense of motion, power, or effort during
imagery. The imagery exercise was performed three 6075 min sessions per week for six weeks, including 5 min
of warm-up, kinesthetic imagery program for 45 to 60
min, and cool down for 5 min. The combined exercise
group (imagery and active) was carried out by blocking
active exercises and kinesthetic imagery for this purpose, which initially performed the exercises in an active
manner after a mental manner, then the process repeated
until the end of the exercise (half the exercise as active
and half of the exercise as mentally).
The combined exercise was performed three 60-75 min
sessions per week for six weeks, including 5 min of warmup, the main exercise program for 45 to 60 min, and cool
down for 5 min. Exercises from one set with six replications in the first session began and increased to three
sets with eight replications in the last session. All exercises were designed by observing the principle of gradual
overload in the number of iterations (from one set with 6
replications, to 3 sets of 8 repetitions, 24 times repeated
in the sixth week) and the maintenance period of each
movement during the 6 weeks (of the 6 s maintenance of
contraction began to 10 s in the sixth week). The duration
of exercise in all three groups was equal (Appendix 2).
All obtained information is presented in average and
standard deviation. The obtained data were analyzed using a repeated measure ANOVA test. Before this test, M
Box and Mauchly tests were used for the prediction of
the assumptions. After the fitting of the data, we investigated the normal distribution of errors. Since the M
Box test was insignificant for any research variables,
the homogenous condition of the variance matrix was
observed correctly. Also, no significant lack of variables
in Leven’s test indicates the equality of between-group
variance, observance, and variance of error-dependent
variables in all groups. Finally, the Mauchly test showed
that the test was not significant for any variable, so the
assumption of the equality of variance in the subjects
was observed. The assumption results of the normal distribution of errors were P≥0.05, indicating the normal
distribution of the error. The significance level was considered 0.05 for all calculations. We also performed a
Bonferroni post hoc test to compare a couple of groups.
All statistical calculations were performed in SPSS v. 24.
Ghorbani M, et al. Effect of Three Methods on the PHE Pattern. PTJ. 2021; 11(3):145-156.
July 2021. Volume 11. Number 3
3. Results
Table 1 presents the general characteristics of the subjects by the group. Considering the stage effect in Table 2,
there is a significant difference between exercise groups
in the pre-test and post-test on the variables of lumbar
lordosis degree, electromyographic activity of gluteus
maximus, lumbar erector spinae, transverse abdominis,
and rectus femoris muscles, and strength of gluteus and
abdominal. In other words, there was a significant difference between the pre-test and post-test scores of these
groups. Also, the interaction of group-time and group on
the variables of lumbar lordosis degree and strength of abdominal muscles showed a significant difference between
the exercise groups. A Bonferroni post hoc test was also
used to compare the groups in the pre-test and post-test
stages between the exercise groups (Tables 3, 4 and 5).
4. Discussion
This study investigated the effect of kinesthetic imagery, active, and combined exercises on the electromyographic pattern of hip hyperextension and the power of
gluteus maximus and abdominal muscles in women with
lumbar hyperlordosis. In lower cross syndrome, the pattern of movement changes due to stiffness and shortness
of flexor hip muscles, erector spinae muscles, and weakness of abdominal muscles and gluteus muscles. These
muscle imbalances have detrimental effects on the static
and dynamic state of the body, especially when walking.
This syndrome causes anterior pelvic tilt and increased
lumbar lordosis, and slight flexion of the hip joints [1-3].
It alters the transfer of forces in the lumbar and pelvic
areas [1], so correcting lumbar hyperlordosis functional
abnormalities is necessary.
One of the study’s objectives was to investigate the effect of mental imagery exercises on the EMG activity of
the muscles of the transverse abdominis, gluteus maximus, and rectus femoris. The results showed that imag-
ery exercise increased gluteus maximus activity and reduced rectus femoris muscle activity. In mental imagery,
movement is activated by the brain structures that are involved in cognitive control and motor planning; in other
words, all cognitive stages of motion control including
projection, planning, and readiness of motion are similar
to real moves [11, 12]. In the executive phase the movement is controlled, but the same neural pathway that is
activated in active activity results in increased activity
of motor units [12], and the activity of the gluteus maximus is increased. Conversely, the activity of the opposite
muscle, the rectus femoris, is reduced. Also, increasing
the EMG activity following imagery exercises may be
related to the activation of the central nervous system.
Based on equivalence and functional equality between
mental imagery and motor activity and also, because
mental imagery reorganizes the cortex of the same physical exercise that is followed by an increase in the cortex
output signals, the muscle tends to increase the level of
higher surface activation [11, 12]. Also, Levan et al. investigated the increase in the activation of muscles following mental imagery during the rehabilitation of the
anterior cruciate ligament. Their findings showed that
mental imagery increased the muscle tone but decreased
the pain [13]. Mental imagery exercises did not affect the
transverse abdominis muscle probably because it is deep
and needs more intense and longer training to change its
activity. Also, because the exercises did not affect the activity rate of the transverse abdominis muscle, so it could
not reduce the activity rate of the lumbar erector spinae.
The other objective of the present study was to investigate the effect of active corrective exercises on the
EMG activity of transverse abdominis, gluteus maximus, erector spinae, and rectus femoris muscles. And the
achieved results are consistent with the results of Oh et
al. (2007) and Park et al. (2011) and showed that corrective exercises increased the EMG activity of gluteus
maximus and reduced the activity of the EMG of erector
Table 1. General characteristics of the study subjects
Mean±SD
Groups
P
Age (y)
Active exercise
34.06±3.15
Imagery exercise
34.27±4.17
Combined exercise
35.08±4.06
P
Height (cm)
P
65.73±16.06
160.60±14.21
0.93
159.54±10.62
Weight (kg)
0.87
161.32±13.08
63.52±15.93
0.81
22.81±64.34
One-way ANOVA test was used to investigate intergroup differences in age, height, and weight.
P≥0.05 indicates no significant difference between groups.
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July 2021. Volume 11. Number 3
Table 2. Repeated measures analysis of variance for comparison of pre-test and post-test on the variables
Variables
Lordosis degree
Activity of the
gluteus maximus
Activity of the
erector spinae
Activity of the
transverse abdominis
Activity of the
rectos femoris
Strength of the
gluteus maximus
Strength of the abdominal muscles
Source
Sum of Squares
df
Mean Square
P
Partial Eta Squared
Time
606.391
1
606.391
0.001
0.883
Groups×Time
114.384
2
57.192
0.001
0.586
Error
80.725
29
2.784
-
-
Groups
103.084
2
51.542
0.013
0.260
Error
293.525
29
10.122
-
-
Time
218.116
1
218.116
0.001
0.414
Groups×time
5.314
2
2.657
0.781
0.17
Error
309.039
29
10.657
-
-
Groups
14.331
2
7.166
0.925
0.005
Error
2668.887
29
92.031
-
-
Time
1001.710
1
1001.710
0.001
0.395
Groups×Time
30.372
2
15.186
0.753
0.019
Error
1535.078
29
52.934
-
-
Groups
43.184
2
21.592
0.827
0.013
Error
3276.082
29
112.968
-
-
Time
86.578
1
86.578
0.021
0.171
Groups×Time
12.630
2
6.315
0.651
0.029
Error
420.910
29
14.514
-
-
Groups
66.454
2
33.27
0.877
0.009
Error
7302.291
29
251.803
-
-
Time
615.471
1
615.471
0.001
0.584
Groups×Time
108.082
2
54.041
0.041
0.198
Error
438.706
29
15.128
-
-
Groups
106.205
2
53.102
0.774
0.018
Error
5957.654
29
205.436
-
-
Time
197.659
1
197.659
0.001
0.531
Groups×Time
26.629
2
13.315
0.127
0.133
Error
174.308
29
6.011
-
-
Groups
55.229
2
27.615
0.628
0.032
Error
1696.708
29
58.507
-
-
Time
1467.108
1
1467.108
0.001
0.729
Groups×Time
342.526
2
171.263
0.001
0.386
Error
544.583
29
18.779
-
-
Groups
415.159
2
207.580
0.204
0.104
Error
3585.950
29
123.653
-
-
P≥0.05 indicates no significant difference; P≤0.05 indicates a significant difference.
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July 2021. Volume 11. Number 3
Table 3. Intergroup effects in the pre-test and post-test stages
Variables
Lordosis degree
Activity of the gluteus
maximus
Activity of the erector
spinae
Activity of the transverse
abdominis
Activity of the rectos
femoris
Strength of the gluteus
maximus
Strength of the abdominal
muscles
Stages
Beta
Standard Error
t
P
Pre-test
-0.200
0.966
-0.207
0.837
Post-test
5.350
1.197
4.468
0.001
Pre-test
-0.722
3.534
-0.204
0.840
Post-test
-1.084
2.518
-0.430
0.670
Pre-test
-1.787
2.647
-0.675
0.505
Post-test
0.809
4.838
0.167
0.868
Pre-test
1.905
5.008
0.380
0.706
Post-test
1.618
4.873
0.332
0.742
Pre-test
-4.434
3.900
-1.137
0.265
Post-test
-0.774
5.023
-0.154
0.879
Pre-test
2.383
2.549
0.935
0.357
Post-test
5.551
2.309
0.346
0.732
Pre-test
3.717
4.017
0.925
0.363
Post-test
-6.617
3.158
-2.095
0.045
P≥0.05 indicates no significant difference; P≤0.05 indicates a significant difference.
Table 4. Bonferroni post hoc test results for phase effect on the study variables
Variables
Stages
Lordosis
Activity of the gluteus
maximus
Activity of erector
spinae the
Activity of the transverse abdominis
Activity of rectos
femoris the
Strength of the gluteus
maximus
Strength of the abdominal muscles
Active
Imagery
P
Pre-test: 48.30±2.21
Stages
P
Pre-test: 48.40±2.31
0.21
Post-test: 46.10±4.06
Pre-test: 80.38±8.01
0.03
Pre-test: 84.20±4.22
0.02
Post-test: 77.54±11.25
Pre-test: 79.87±7.63
Pre-test: 77.96±10.94
0.6
Post-test: 79.26±12.91
Pre-test: 75.11±9.02
Pre-test: 79.54±7.09
0.001
Post-test: 68.94±12.38
Pre-test: 23.80±5.88
Pre-test: 21.41±5.96
0.03
Post-test: 24.70±4.76
Pre-test: 118.30±11.73
0.01
Post-test: 73.10±10.88
Pre-test: 19.90±6.00
0.07
Post-test: 25.50±5.58
0.02
Post-test: 81.01±10.13
Pre-test: 78.28±11.14
0.02
Post-test: 72.33±12.04
0.001
Post-test: 74.52±10.95
Pre-test: 78.24±15.21
0.16
Post-test: 82.63±11.18
0.01
Post-test: 83.86±6.85
Pre-test: 84.17±8.55
0.10
Post-test: 75.33±11.75
0.001
Post-test: 40.75±2.34
Post-test: 83.34±6.15
Pre-test: 82.41±5.30
0.01
Post-test: 25.50±5.71
Pre-test: 109.00±8.43
0.11
P
Pre-test: 48.50±2.23
Pre-test: 78.82
0.04
Post-test: 82.78±4.01
Stages
0.001
Post-test: 40.20±2.39
Pre-test: 79.66±6.3
Post-test: 121.30±9.14
Combined
Pre-test: 114.58±7.82
0.001
Post-test: 121.50±6.25
0.001
Post-test: 127.91±6.55
P≥0.05 indicates no significant difference; P≤0.05 indicates a significant difference.
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Table 5. Bonferroni post hoc test results for group effect on pre-test and post-test on lumbar lordosis degree variables
Variables
Lumbar lordosis
Pre-test
Lumbar lordosis
Post-test
Groups
P
Imagery – Active
0.837
Imagery – Combined
0.918
Active – Combined
0.872
Imagery – Active
0.022
Imagery – Combined
0.037
Active – Combined
1.00
P≥0.05 indicates no significant difference; P≤0.05 indicates a significant difference.
spinae and rectus femoris muscles [7, 8]. For this reason,
it is used in corrective exercises (Sahrmann exercises)
to enhance the gluteus maximus muscle and abdominal
muscles, which reduces the erector spinae activity. Also,
the exercises used to increase gluteus maximus strength
lead to a reduction in the rectus femoris strength [2].
However, there was no significant effect on the activity
of the transverse abdominis muscle. Probably because
the transverse abdominis muscle is deep and needs more
intense and more prolonged training to change its activity rate. Therefore, according to the research objectives,
the effect of combined exercise on the EMG activity of
the transverse abdominis, gluteus maximus, erector spinae, and rectus femoris muscles was investigated.
The results showed that the combined exercises on increasing the activity of the gluteus maximus and transverse abdominal muscles. There was a significant effect
on the decrease of the activity of the rectus femoris and
erector spinae muscles because the imaging exercises
can alter the rate of muscle activity [15, 22], followed up
with the active exercise to stabilize the nerve and muscle
coordination [15]. Mental practice also increases the activity of the cerebral cortex and increases attention, thus
providing better cognitive power. The most important
neuromuscular compatibility code, which is cognition,
is caused by mental exercise without fatigue, and with
active exercises the cognition created is stable [22, 23].
The present study also investigated the effect of imagery exercises on the strength of the gluteus and abdominal muscles. Results showed that imagery exercises
had no significant effect on the strength of gluteus and
abdominal muscles, which was not consistent with the
study of Yao et al. Although imagery exercises affected
muscle activity rate, it did not affect muscle strength because it was repeated three sessions per week. While in
the study of Yao et al., five sessions per week of exercise
were found to affect muscle strength [23].
152
The other objective of our study was to investigate the
effect of active exercises on the strength of abdominal
muscles. The results showed that active exercises significantly increased the strength of abdominal muscles,
which was consistent with the study results of Levine et
al. (1997) [24] and Ferreira et al. (2004) [25]. Because
by increasing the activity of the abdominal muscles and
changing the time of their activation, which plays an essential role in the function of the lumbopelvic structure,
we can eliminate the muscle imbalances [24, 25]. The results also showed that combined exercises had a significant effect on increasing the strength of abdominal muscles. As in the study of Lebon et al. who examined the
benefits of mental imagery training on muscle strength,
the findings showed that the strength of the leg press
was significantly higher in the MVC (maximum voluntary contraction) mental imagery group than the control
group [12, 26], because mental training alters the central
command of the muscular nervous system. Studies have
shown that the brain is activated to produce stronger
signals through repeated mental efforts to activate the
muscle. As a result, a stronger command in the central
nervous system may use inactive motor units, resulting
in more force generation [9, 12, 26]. Furthermore, when
mental imagery exercises are combined with active exercises, proper neuromuscular coordination is created and
as a result, abdominal strength is increased. The present study also aimed to investigate the effect of active
exercises on the strength of gluteus maximus muscles.
The results showed that active exercises significantly
increased the strength of gluteus maximus muscles. The
study results were consistent with Alvim et al. and Arab
et al. study results [27, 28].
As mentioned in these studies, the gluteus maximus
muscle plays an essential role in controlling the pelvis
and prevents pelvic tilt and subsequent increase in the
lumbar hyperlordosis. Therefore, with active exercises,
we could induce positive changes in reducing the lumbar
Ghorbani M, et al. Effect of Three Methods on the PHE Pattern. PTJ. 2021; 11(3):145-156.
July 2021. Volume 11. Number 3
hyperlordosis by changing the rate of activity and activity
pattern of the gluteus maximus. The results showed that
combined exercises had a significant effect on increasing
the strength of gluteus maximus muscles. The study results were consistent with the study of Kumar et al., who
examined imagery exercises on the strength muscle and
the gait performance in people with stroke [29]. In this
study, strength and performance were improved in the
two groups of control (active exercises) and experiments
(active and imagery exercises), and there was a significant difference between the two groups [29]. Therefore,
studies show that imagery exercises due to physiological and psychological effects can be used as a complementary therapy in rehabilitation and movement pattern
modification [29, 30].
Overall, both active and combined exercise methods
effectively change the activity of the muscles of the
lumbopelvic area. Also, the function of the selected
muscles has changed, and more coordination has been
established between the selected muscles. As a result,
the movement pattern has changed, and more stability
has been provided in this area. Based on the results, it
reduced the degree of lumbar lordosis in women with
lumbar hyperlordosis [1-5].
Authors' contributions
All authors equally contributed in preparing this article.
Conflict of interest
The authors declared no conflict of interest.
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Therefore, it is recommended that in addition to physical
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Appendix 1.
Muscles
Electrode Position
Gluteus maximus muscle
1.2-cm distance of S2 to greater trochanter
Lumbar erector spinae muscle
3 cm apart of L3 Lumbar
Transverse abdominis muscle
2 cm distal to the upper anterior superior iliac spine to downward and inward
Rectus femoris muscle
1.2-cm distance of anterior superior iliac spine to under patella
Appendix 2.
Protocol of corrective exercises for the subjects in the active group
Training period: six weeks
Number of practice sessions per week: three
Duration of each training session: 60-75 minutes
Warm-up exercises include walking and stretching movement for five minutes
The main program of exercises was performed for 45 to 60 minutes
Cool down program for five minutes
Corrective Exercises for Lumbar Lordosis
Exercise number
How to perform the exercises
1
Hip and knee extensions: The person lies in a supine position and extends the hip and knee by sliding the heel: it helps to increase
the activation of the abdominal muscles to maintain the position of the pelvis.
2
Knee flexion in the prone position: The person lies on the prone position and bends the knee, and to prevent anterior pelvic tilt, she
contracts the abdominal muscles, which helps to reduce the activity of the rectus femoris and tensor fascia latae muscles.
3
Posterior rocking: The person lies in a quadrate limbs position and then tries to fill the lower back with a contraction of the
abdomen, and the spine is in one direction. This exercise increases the activation of the abdominal muscles and decreases the
activity of the lumbar extensor muscles.
4
Pulsing up in the prone position: The person lies on the prone position and then bends the knee and pulses upwards; this movement
helps to increase the activation of the gluteal muscles.
5
Hip abduction: Hip abduction in a side position improves pelvic control through the lateral abdominal muscles. When the muscles
of the tensor fascia latae, anterior gluteus medius, and gluteus minimus are short, improving the performance of the posterior
gluteus medius muscle is essential to counteract the activity of these hip flexor muscles.
6
Femoral extension and shoulder flexion in a quadrate limbs position: The person is placed on a quadrate limb and then tries to
do the opposite femoral extension and flexion of the shoulder. This movement helps to improve abdominal activity and improves
pelvic control, and increases balance.
7
Sitting posture: Correction of sitting posture defects is the most important treatment criterion.
8
Standing exercise: Standing and leaning against the wall of the lumbar vertebrae, bend the knees and hips, and contract the
abdominal muscles. This exercise is the best exercise to improve the control of the abdominal muscles while avoiding the activity
of the hip flexor muscles.
Set and number of repetitions of exercises
Week
Set
Repetition
1
1
6
2
1
8
3
2
6
4
2
7
5
2
8
6
3
8
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Protocol of corrective exercises for the subjects in the kinesthetic imagery group
Training period: six weeks
Number of practice sessions per week: three
Duration of each training session: 60-75 minutes
Warm-up exercises include walking and stretching movement for five minutes
The main program of exercises was performed for 45 to 60 minutes
Cool down program for five minutes
It includes corrective exercises in which the person was asked to imagine the exercise in mind and then hold mentally the contraction for 15 seconds and do mentally each exercise 6-8 repetitions like active corrective exercises.
Table of set and number of repetitions of exercises
Week
Set
Repetition
1
1
6
2
1
8
3
2
6
4
2
7
5
2
8
6
3
8
Protocol of corrective exercises for the subjects in the combined group
Training period: six weeks
Number of practice sessions per week: three
Duration of each training session: 60-75 minutes
Warm-up exercises include walking and stretching movement for five minutes
The main program of exercises was performed for 45 to 60 minutes
Cool down program for five minutes
Combined group exercises include active exercises and kinesthetic imagery that were performed in a blocked form and included active and imagery until the end of the exercise, respectively.
Table of set and number of repetitions of exercises
156
Week
Set
Repetition
1
1
6
2
1
8
3
2
6
4
2
7
5
2
8
6
3
8
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