Accepted Manuscript Abdominal muscle EMG-activity during bridge exercises on stable and unstable surfaces Dariusz Czaprowski, PT, PhD Anna Afeltowicz, PT, MSc Anna Gębicka, PT, MSc Paulina Pawłowska, PT, MSc Agnieszka Kędra, PhD Carlos Barrios, MD, PhD Michal Hadala, PT, PhD PII:
S1466-853X(13)00098-9
DOI:
10.1016/j.ptsp.2013.09.003
Reference:
YPTSP 577
To appear in:
Physical Therapy in Sports
Received Date: 10 September 2012 Revised Date:
24 July 2013
Accepted Date: 18 September 2013
Please cite this article as: Czaprowski, D., Afeltowicz, A., Gębicka, A., Pawłowska, P., Kędra, A., Barrios, C., Hadala, M., Abdominal muscle EMG-activity during bridge exercises on stable and unstable surfaces, Physical Therapy in Sports (2013), doi: 10.1016/j.ptsp.2013.09.003. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Abdominal muscle EMG-activity during bridge exercises on stable and unstable surfaces Dariusz Czaprowski, PT, PhD 1,*, Anna Afeltowicz, PT, MSc 1, Anna Gębicka, PT, MSc 1,
RI PT
Paulina Pawłowska, PT, MSc 1, Agnieszka Kędra, PhD 2, Carlos Barrios, MD, PhD 3,4, Michal Hadala, PT, PhD 3,5
Department of Physiotherapy, Józef Rusiecki University College in Olsztyn, Poland
2
Department of Posture Correction, Faculty of Physical Education and Sport in Biala
SC
1
Podlaska, Jozef Pilsudski University of Physical Education in Warsaw, Poland Physical Therapy and Exercise Center, Valencia, Spain
4
Institute for Research on Musculoskeletal Disorders, School of Medicine, Valencia Catholic,
University, Valencia, Spain 5
Fizjo-Sport, Rzeszow, Poland
TE D
*Corresponding author
M AN U
3
Dariusz Czaprowski PT, PhD Department of Physiotherapy
EP
Józef Rusiecki University College in Olsztyn, 10- 243 Olsztyn, Bydgoska 33, Poland
AC C
Tel. +48895260400; Fax. +48895260400 e-mail: [email protected]
1
ACCEPTED MANUSCRIPT
Abdominal muscle EMG-activity during bridge exercises on stable and unstable
2
surfaces
3
ABSTRACT
4
Objectives: To assess abdominal muscles (AM) activity during prone, side, and supine
5
bridge on stable and unstable surfaces (BOSU, Swiss Ball).
6
Design: Prospective comparison study.
7
Setting: Research laboratory.
8
Participants: Thirty-three healthy volunteers from a university population.
9
Main Outcome Measures: Surface electromyography of the rectus abdominis (RA),
10
the external oblique (EO) and the internal oblique with the transversus abdominis (IO-
11
TA).
12
Results: The AM exhibited the highest activity during prone bridge on a Swiss Ball
13
(RA, EO, IO-TA 44.7±19.2, 54.7±22.9, 36.8±18.6 in % of MVC, respectively). The
14
lowest activity was observed during supine bridge on a stable surface and a BOSU
15
(under 5.0). The lowest ratio analyzed on the basis of the relation of EO and IO-TA
16
activity to RA was obtained during prone bridge on the Swiss Ball (1.4±0.7 for EO,
17
0.9±0.5 for IO-TA). The highest ratio was obtained during prone bridge on stable
18
surface and supine bridges.
19
Conclusions: The highest level of activity in the abdominal muscles is achieved during
20
prone bridge on a Swiss Ball. However, this exercise provided the lowest activity of the
21
EO and IO-TA in relation to RA. It is essential to conduct further studies verifying the
22
usefulness of using Swiss Ball during core stability training.
23
Key Words: Electromyography; Swiss Ball; BOSU; Core Stability; Sport Training
AC C
EP
TE D
M AN U
SC
RI PT
1
24 25 2
ACCEPTED MANUSCRIPT
1.INTRODUCTION
26 27
Lumbar stabilization exercises are a common strategy in recreational and sport training as well as in rehabilitation (Escamila et al., 2010; Imai, Kaneoka, & Okubo,
29
2010; Marshall, Dip, & Murphy, 2005; McGill & Karpowicz, 2009). It might stem from
30
the fact that the proper activation of core stability muscles is essential for accurate
31
functioning of the lumbopelvic complex (McGill & Cholewicki, 2001). The co-
32
activation of trunk muscles is also believed to be important for obtaining a proper trunk
33
stabilization pattern in the treatment and prevention of lower back injuries (Axler &
34
McGill, 1997; O`Sullivan, Phyty, & Twomey,1997a; Rasmussen-Barr, Ang, &
35
Arvidsson, 2009).
SC
M AN U
36
RI PT
28
Core stability is defined by two terms – global and local stability systems. The former refers to the larger, superficial muscles (e.g. rectus abdominis) which are the
38
prime movers for trunk and hip. The latter, local stability refers to the deep, intrinsic
39
muscles of an abdominal wall (e.g. transversus abdominis). This system is responsible
40
for the segmental stability of the lumbar spine during gross whole body movements and
41
where postural adjustments are required (Behm, Anderson, & Curnew, 2002; Hodges
42
&Richardson, 1996; McGill, 2007). Recently, attention has been paid to the fact that the
43
activity of rectus abdominis (RA) during stability exercises should be minimal
44
(Richardson, Hodges, & Hides, 2004; Richardson, Toppenberg, & Jull, 1990; Marshall
45
et al., 2005). If this is true, a training that increases the activity of RA and changes the
46
synergistic activation patterns between abdominal muscles may not be appropriate as a
47
lumbar stability exercise (Marshall et al., 2005). Although such an approach should be
48
still treated as a hypothesis, supplementing the assessment of activity of individual
49
abdominal muscles with the analysis of their synergistic activity might be interesting
AC C
EP
TE D
37
3
ACCEPTED MANUSCRIPT
50
and contribute to complementing the discussion on the selection of exercises during
51
stabilizing training. The use of unstable surfaces, such as the Swiss Ball, is becoming more popular
52
during core stabilizing exercises (Escamilla at al., 2010; Imai et al., 2010; Lehman,
54
Gilas, & Patel, 2008; Lehman, Hoda, & Oliver, 2005b; Marshall et al., 2005; Vera-
55
Garcia, Grenier, & McGill, 2000). The purported advantage of these tools is the
56
potential for increased muscular demand required to maintain postural stability (Imai et
57
al., 2010). The response of muscle activity to unstable surfaces may be variable and
58
dependent on the type of exercises or the assessed muscles (Imai et al., 2010; Lehman,
59
Gordon, & Langley, 2005a; Marshall et al., 2005). Some authors confirm that the
60
unstable surface enhances the activities of trunk muscles (Imai et al., 2010; Lehman et
61
al., 2005b; Vera-Garcia et al., 2000). Other authors claim that the type of surface,
62
whether stable or unstable, does not notably affect the activity of the trunk stabilizing
63
muscles (Lehman et al., 2008; Lehman et al., 2005a). Kavcic et al maintains that simple
64
exercises on a stable surface are able to activate spine stabilizers while simultaneously
65
minimizing lower back compression and shear forces (Kavcic, Grenier, & McGill,
66
2004).
SC
M AN U
TE D
EP
67
RI PT
53
Therefore, further research evaluating the influence of a Swiss Ball on muscle activity ought to be conducted (Marshall et al., 2005; Okubo et al., 2010). Such research
69
should also assess other training devices commonly used in sport and rehabilitation.
70
One of those is BOSU (Gamble, 2010). Apart from a range of surface types, various
71
types of exercises, such as prone, side and supine bridges, are frequently employed in
72
rehabilitation and sport programs (Gamble, 2010; Imai et al., 2010; Lehman et al.,
73
2005b). It is also important to verify their influence on abdominal muscles activity
AC C
68
4
ACCEPTED MANUSCRIPT
74
(Ekstrom, Donatelli, & Carp, 2007; Imai et al., 2010, Lehman et al., 2005; Okubo et al.,
75
2010).
76
The main purpose of the study was to determine the abdominal muscles activity in relation to the type of exercise (prone, side, and supine bridge) and the type of
78
support surface (stable, BOSU and Swiss Ball).
RI PT
77
Taking into account the fact that rehabilitation training of the ventrolateral
80
abdominals may be successfully achieved with exercises that minimize activation of the
81
rectus abdominis (O`Sullivan, Twomey , & Allison, 1998; Richardson et al., 2004;
82
Richardson et al., 1990; Marshall et al., 2005), the identification of such exercises might
83
be also interesting. Therefore, another aim of the study was the evaluation of ratio
84
which represents the activity of the external oblique and internal oblique with
85
transversus abdominis in relation to the activity of rectus abdominis (O`Sullivan et al.,
86
1998; Marshall et al. 2005).
2.METHODS
88 89
TE D
87
M AN U
SC
79
2.1.Participants
A total of 33 healthy subjects participated in the research. There were 18 women
91
and 15 men with an age range extending from 18 to 29 years (mean 23.2±2.5; height
92
(m) ranged 1.57-1.94, mean 1.74±0.1; weight (kg) ranged 45-93, mean 68.2±13.8; BMI
93
(kgm-2) ranged 17.6-28.3, mean 22.0±2.6). The inclusion criteria for the study group
94
were the absence of low back pain over the previous 12 months and abstention from
95
physical exercise 48 hours prior to the examination. For women, the presence of
96
menstruation on the day of examination and a history of pregnancy within the last 12
97
months were considered as exclusion criteria.
AC C
EP
90
5
ACCEPTED MANUSCRIPT
99 100 101
The subjects of the study, read and signed an information and consent form approved by the local Ethics Committee. 2.2.Exercise Procedures Prior to examination, each subject was acquainted with all the exercise
RI PT
98
protocols. An instructor demonstrated how to correctly perform each task. Then, the
103
subjects completed a pre-test, receiving additional instruction about how the exercises
104
should be performed. Special attention was paid to maintaining a neutral position of the
105
spine and pelvis ensuring better activation of the stabilizing muscles (Suni, Rinne, &
106
Natri, 2006). Next, the subjects repeated the whole set of exercises (exercises assigned
107
randomly by drawing a card with a number of individual exercise) described below
108
three times. Feedback from the examiner was given during the performance of
109
exercises. There was a 1-minute rest between each exercise. There was a 4-minute break
110
between the series of exercises.
111
2.3.Description of Exercises
TE D
M AN U
SC
102
Abdominal muscles activity was recorded while holding the body in static bridge
113
positions on a 15-mm-thick stable surface (Thera-Band, Canada), on a BOSU (BOSU ®
114
Pro Balance Trainer, BOSU, Ohio, USA) and on a Swiss Ball with a diameter of 65 cm.
115
The exercises were conducted in sports footwear. Measurements started once the
116
subject took the correct position and lasted 5 seconds (Fig. 1).
117
Figure 1
118
1.Prone bridge on a stable surface (PB)
AC C
119
EP
112
The subject was asked to stay in a prone plank position (Fig. 1A). Attention was
120
paid to maintaining a neutral position in the hip joints, pelvis and lumbar spine. The feet
121
were placed to match the width of the hip and forearm and acted as support points. The
6
ACCEPTED MANUSCRIPT
122
elbows were placed under the glenohumeral joints, and the arms supported the body
123
vertically to the surface.
124
2.Prone bridge on a BOSU (PBB)
126
1B).
127
3.Prone bridge on a Swiss Ball (PBSB)
RI PT
Similar to the previous exercise, but with the forearms resting on a BOSU (Fig.
125
(Fig. 1C).
130
4.Side bridge on a stable surface (SB)
M AN U
129
SC
Similar to the previous exercise, but with the forearms resting on a Swiss Ball
128
131
The subject was asked to take a side plank position on the right forearm (Fig.
132
1D). The right elbow was under the glenohumeral joint, and the arm remained in a
133
position vertical to the surface. The left palm was resting on the hip.
134
5.Side bridge on a BOSU (SBB)
TE D
Similar to the previous exercise, but the forearm was placed on a BOSU (Fig.
135
1E).
137
The present study disregarded the assessment of muscle activity during side bridge on a
138
Swiss Ball. It resulted from difficulties in maintaining a neutral position of the spine and
139
pelvis by the subjects.
140
6.Supine bridge on a stable surface (SuB)
AC C
141
EP
136
The initial position was crook-lying, with the knees bent 90 degrees, the feet
142
supported on the heels only and the hands on the floor with palms facing down (Fig.
143
1F). The subject lifted the pelvis until the hip joints were in the neutral position.
144
7.Supine bridge on a BOSU (SuBB)
145 146
Similar to the previous exercise, but with the heels resting on a BOSU (Fig. 1G). 8.Supine bridge on a Swiss Ball (SuBSB) 7
ACCEPTED MANUSCRIPT
Similar to the previous exercise, but with the heels resting on a Swiss Ball (Fig.
147 148
1H).
149
2.4. Data Collection and EMG Processing The isometric activity of the rectus abdominis (RA), the external oblique (EO),
151
and the combined activity of the internal oblique and transversus abdominis (IO-TA)
152
only on the right side of the body (Lehman et al., 2005a; Lehman et al., 2005b; Marshall
153
et al., 2005; Querioz, Cagliari, & Amorim, 2010) was recorded. All data signals were
154
registered and measured by means of a surface dynamic electromyography (sEMG)
155
recorder (BTS FREE EMG 300, BTS Bioengeering, Italy) at a sampling frequency of
156
1000 Hz to 16-bit analog-to-digital conversion, a common mode rejection ratio of
157
greater than 110dB at 50-60Hz and an input impedance greater than 10GΩ. The EMG
158
signals were filtered (bandwidth 10-500 Hz), rectified and subsequently quantified
159
(root-mean-squared (RMS) EMG over a 100 ms window). The device provided
160
completely wireless communication between the preamps and signal collecting unit. To
161
record the RA activity, pairs of electrodes (ARBO, Kendall, Tyco Healthcare,
162
Germany) 1 cm in diameter were placed 5 cm inferior and 3 cm lateral to the xiphoid
163
process (O`Sullivan et al. 1998). For recording the EO activity, electrodes were placed
164
just below the eighth rib’s anterior angle, superolateral to the costal margin (Beith,
165
Synnott, & Newman, 2001). To register the IO-TA activity, electrodes were placed 2
166
cm medial and caudal to the anterior superior iliac spine (Chanthapetch,
167
Kanlayanaphoporn, & Gaogasigam, 2009; Marshall et al., 2005). The muscle fibers of
168
the transversus abdominis and internal obliques are blended at this place (Marshall &
169
Murphy, 2003). The electrodes were placed on a thoroughly shaved and cleaned skin
170
with a center-to-center distance of 2 cm, parallel with the muscle fibres (Ekstrom et al.,
171
2007; Lehman et al., 2005b).
AC C
EP
TE D
M AN U
SC
RI PT
150
8
ACCEPTED MANUSCRIPT
172
2.5.EMG Normalization Procedure The muscle activity obtained during the exercises was normalized by means of
174
the MVC (Maximal Voluntary Contraction) technique, allowing for the comparison
175
among different subjects (Burden & Bartlett, 1999; Lehman & McGill, 1999; The
176
SENIAM project). For this purpose, each subject held a 3- to 5-second-long maximal
177
curl up position (for RA) and a bilateral upper-body-twist against manual resistance
178
(trunk rotation to the contralateral side for EO and trunk rotation to the ipsilateral side
179
for IO-TA), and the subject was asked to tighten muscles as much as possible (Beith et
180
al., 2001). The maximal reading was tested in either sitting or crook lying, whichever
181
achieved a greater activity for each subject. The data collected during these tasks, and
182
used for subsequent analysis as a point of reference for all other measurements was
183
from one effort only (Beith et al., 2001). The interval between individual tests amounted
184
to 2 minutes to prevent muscle fatigue (Chanthapetch et al., 2009). The first muscle to
185
assess was RA, after that EO and IO-TA as the last one.
TE D
M AN U
SC
RI PT
173
The average RA, EO and IO-TA activity obtained during each exercise
187
(arithmetic mean of the results from 3 repetitions) was then normalized and expressed
188
as a percentage of the peak activity found in the MVC test.
189
2.6.Statistical Analysis
EP
186
The data were analyzed using the SPSS 18 Statistics Package (Polish version).
191
The data distribution was assessed by the Shapiro-Wilk test. Moreover, descriptive
192
statistics were prepared for each variable (mean ±SD). The comparisons of two or more
193
variables were made using Wilks`s Lambda MANOVA omnibus test and the series of
194
Student`s t-tests with Bonferroni corrections as post hoc. Bonferroni corrections were
195
calculated for each hypothesis separately with the intention of controlling familywise
196
error rate equal 0.05. Under this premise, the correction was found equal 8x(8-1)/2=28
AC C
190
9
ACCEPTED MANUSCRIPT
for each hypothesis, and the corresponding significance level was 0.0018. Additionally,
198
two ratios of activity were calculated to indicate the relationship between the activity of
199
the EO and the RA and between the IO-TA and the RA (Marshall et al., 2005;
200
O`Sullivan et al., 1998). For comparisons of ratios the one-way ANOVA with Tukey
201
tests as post hoc and Wilcoxon tests were used. The value of α=0.05 was considered as
202
the significance level.
RI PT
197
3.RESULTS
204
206
3.1.Exercises and Surfaces
M AN U
205
SC
203
Table 1 summarizes the average sEMG amplitudes for each abdominal muscle during the evaluated exercises on the different surfaces. During the prone bridge, the
208
RA, EO and IO-TA reached significantly higher activity in exercises on a Swiss Ball
209
compared the exercise performed on a stable surface (P
S1466-853X(13)00098-9
DOI:
10.1016/j.ptsp.2013.09.003
Reference:
YPTSP 577
To appear in:
Physical Therapy in Sports
Received Date: 10 September 2012 Revised Date:
24 July 2013
Accepted Date: 18 September 2013
Please cite this article as: Czaprowski, D., Afeltowicz, A., Gębicka, A., Pawłowska, P., Kędra, A., Barrios, C., Hadala, M., Abdominal muscle EMG-activity during bridge exercises on stable and unstable surfaces, Physical Therapy in Sports (2013), doi: 10.1016/j.ptsp.2013.09.003. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Abdominal muscle EMG-activity during bridge exercises on stable and unstable surfaces Dariusz Czaprowski, PT, PhD 1,*, Anna Afeltowicz, PT, MSc 1, Anna Gębicka, PT, MSc 1,
RI PT
Paulina Pawłowska, PT, MSc 1, Agnieszka Kędra, PhD 2, Carlos Barrios, MD, PhD 3,4, Michal Hadala, PT, PhD 3,5
Department of Physiotherapy, Józef Rusiecki University College in Olsztyn, Poland
2
Department of Posture Correction, Faculty of Physical Education and Sport in Biala
SC
1
Podlaska, Jozef Pilsudski University of Physical Education in Warsaw, Poland Physical Therapy and Exercise Center, Valencia, Spain
4
Institute for Research on Musculoskeletal Disorders, School of Medicine, Valencia Catholic,
University, Valencia, Spain 5
Fizjo-Sport, Rzeszow, Poland
TE D
*Corresponding author
M AN U
3
Dariusz Czaprowski PT, PhD Department of Physiotherapy
EP
Józef Rusiecki University College in Olsztyn, 10- 243 Olsztyn, Bydgoska 33, Poland
AC C
Tel. +48895260400; Fax. +48895260400 e-mail: [email protected]
1
ACCEPTED MANUSCRIPT
Abdominal muscle EMG-activity during bridge exercises on stable and unstable
2
surfaces
3
ABSTRACT
4
Objectives: To assess abdominal muscles (AM) activity during prone, side, and supine
5
bridge on stable and unstable surfaces (BOSU, Swiss Ball).
6
Design: Prospective comparison study.
7
Setting: Research laboratory.
8
Participants: Thirty-three healthy volunteers from a university population.
9
Main Outcome Measures: Surface electromyography of the rectus abdominis (RA),
10
the external oblique (EO) and the internal oblique with the transversus abdominis (IO-
11
TA).
12
Results: The AM exhibited the highest activity during prone bridge on a Swiss Ball
13
(RA, EO, IO-TA 44.7±19.2, 54.7±22.9, 36.8±18.6 in % of MVC, respectively). The
14
lowest activity was observed during supine bridge on a stable surface and a BOSU
15
(under 5.0). The lowest ratio analyzed on the basis of the relation of EO and IO-TA
16
activity to RA was obtained during prone bridge on the Swiss Ball (1.4±0.7 for EO,
17
0.9±0.5 for IO-TA). The highest ratio was obtained during prone bridge on stable
18
surface and supine bridges.
19
Conclusions: The highest level of activity in the abdominal muscles is achieved during
20
prone bridge on a Swiss Ball. However, this exercise provided the lowest activity of the
21
EO and IO-TA in relation to RA. It is essential to conduct further studies verifying the
22
usefulness of using Swiss Ball during core stability training.
23
Key Words: Electromyography; Swiss Ball; BOSU; Core Stability; Sport Training
AC C
EP
TE D
M AN U
SC
RI PT
1
24 25 2
ACCEPTED MANUSCRIPT
1.INTRODUCTION
26 27
Lumbar stabilization exercises are a common strategy in recreational and sport training as well as in rehabilitation (Escamila et al., 2010; Imai, Kaneoka, & Okubo,
29
2010; Marshall, Dip, & Murphy, 2005; McGill & Karpowicz, 2009). It might stem from
30
the fact that the proper activation of core stability muscles is essential for accurate
31
functioning of the lumbopelvic complex (McGill & Cholewicki, 2001). The co-
32
activation of trunk muscles is also believed to be important for obtaining a proper trunk
33
stabilization pattern in the treatment and prevention of lower back injuries (Axler &
34
McGill, 1997; O`Sullivan, Phyty, & Twomey,1997a; Rasmussen-Barr, Ang, &
35
Arvidsson, 2009).
SC
M AN U
36
RI PT
28
Core stability is defined by two terms – global and local stability systems. The former refers to the larger, superficial muscles (e.g. rectus abdominis) which are the
38
prime movers for trunk and hip. The latter, local stability refers to the deep, intrinsic
39
muscles of an abdominal wall (e.g. transversus abdominis). This system is responsible
40
for the segmental stability of the lumbar spine during gross whole body movements and
41
where postural adjustments are required (Behm, Anderson, & Curnew, 2002; Hodges
42
&Richardson, 1996; McGill, 2007). Recently, attention has been paid to the fact that the
43
activity of rectus abdominis (RA) during stability exercises should be minimal
44
(Richardson, Hodges, & Hides, 2004; Richardson, Toppenberg, & Jull, 1990; Marshall
45
et al., 2005). If this is true, a training that increases the activity of RA and changes the
46
synergistic activation patterns between abdominal muscles may not be appropriate as a
47
lumbar stability exercise (Marshall et al., 2005). Although such an approach should be
48
still treated as a hypothesis, supplementing the assessment of activity of individual
49
abdominal muscles with the analysis of their synergistic activity might be interesting
AC C
EP
TE D
37
3
ACCEPTED MANUSCRIPT
50
and contribute to complementing the discussion on the selection of exercises during
51
stabilizing training. The use of unstable surfaces, such as the Swiss Ball, is becoming more popular
52
during core stabilizing exercises (Escamilla at al., 2010; Imai et al., 2010; Lehman,
54
Gilas, & Patel, 2008; Lehman, Hoda, & Oliver, 2005b; Marshall et al., 2005; Vera-
55
Garcia, Grenier, & McGill, 2000). The purported advantage of these tools is the
56
potential for increased muscular demand required to maintain postural stability (Imai et
57
al., 2010). The response of muscle activity to unstable surfaces may be variable and
58
dependent on the type of exercises or the assessed muscles (Imai et al., 2010; Lehman,
59
Gordon, & Langley, 2005a; Marshall et al., 2005). Some authors confirm that the
60
unstable surface enhances the activities of trunk muscles (Imai et al., 2010; Lehman et
61
al., 2005b; Vera-Garcia et al., 2000). Other authors claim that the type of surface,
62
whether stable or unstable, does not notably affect the activity of the trunk stabilizing
63
muscles (Lehman et al., 2008; Lehman et al., 2005a). Kavcic et al maintains that simple
64
exercises on a stable surface are able to activate spine stabilizers while simultaneously
65
minimizing lower back compression and shear forces (Kavcic, Grenier, & McGill,
66
2004).
SC
M AN U
TE D
EP
67
RI PT
53
Therefore, further research evaluating the influence of a Swiss Ball on muscle activity ought to be conducted (Marshall et al., 2005; Okubo et al., 2010). Such research
69
should also assess other training devices commonly used in sport and rehabilitation.
70
One of those is BOSU (Gamble, 2010). Apart from a range of surface types, various
71
types of exercises, such as prone, side and supine bridges, are frequently employed in
72
rehabilitation and sport programs (Gamble, 2010; Imai et al., 2010; Lehman et al.,
73
2005b). It is also important to verify their influence on abdominal muscles activity
AC C
68
4
ACCEPTED MANUSCRIPT
74
(Ekstrom, Donatelli, & Carp, 2007; Imai et al., 2010, Lehman et al., 2005; Okubo et al.,
75
2010).
76
The main purpose of the study was to determine the abdominal muscles activity in relation to the type of exercise (prone, side, and supine bridge) and the type of
78
support surface (stable, BOSU and Swiss Ball).
RI PT
77
Taking into account the fact that rehabilitation training of the ventrolateral
80
abdominals may be successfully achieved with exercises that minimize activation of the
81
rectus abdominis (O`Sullivan, Twomey , & Allison, 1998; Richardson et al., 2004;
82
Richardson et al., 1990; Marshall et al., 2005), the identification of such exercises might
83
be also interesting. Therefore, another aim of the study was the evaluation of ratio
84
which represents the activity of the external oblique and internal oblique with
85
transversus abdominis in relation to the activity of rectus abdominis (O`Sullivan et al.,
86
1998; Marshall et al. 2005).
2.METHODS
88 89
TE D
87
M AN U
SC
79
2.1.Participants
A total of 33 healthy subjects participated in the research. There were 18 women
91
and 15 men with an age range extending from 18 to 29 years (mean 23.2±2.5; height
92
(m) ranged 1.57-1.94, mean 1.74±0.1; weight (kg) ranged 45-93, mean 68.2±13.8; BMI
93
(kgm-2) ranged 17.6-28.3, mean 22.0±2.6). The inclusion criteria for the study group
94
were the absence of low back pain over the previous 12 months and abstention from
95
physical exercise 48 hours prior to the examination. For women, the presence of
96
menstruation on the day of examination and a history of pregnancy within the last 12
97
months were considered as exclusion criteria.
AC C
EP
90
5
ACCEPTED MANUSCRIPT
99 100 101
The subjects of the study, read and signed an information and consent form approved by the local Ethics Committee. 2.2.Exercise Procedures Prior to examination, each subject was acquainted with all the exercise
RI PT
98
protocols. An instructor demonstrated how to correctly perform each task. Then, the
103
subjects completed a pre-test, receiving additional instruction about how the exercises
104
should be performed. Special attention was paid to maintaining a neutral position of the
105
spine and pelvis ensuring better activation of the stabilizing muscles (Suni, Rinne, &
106
Natri, 2006). Next, the subjects repeated the whole set of exercises (exercises assigned
107
randomly by drawing a card with a number of individual exercise) described below
108
three times. Feedback from the examiner was given during the performance of
109
exercises. There was a 1-minute rest between each exercise. There was a 4-minute break
110
between the series of exercises.
111
2.3.Description of Exercises
TE D
M AN U
SC
102
Abdominal muscles activity was recorded while holding the body in static bridge
113
positions on a 15-mm-thick stable surface (Thera-Band, Canada), on a BOSU (BOSU ®
114
Pro Balance Trainer, BOSU, Ohio, USA) and on a Swiss Ball with a diameter of 65 cm.
115
The exercises were conducted in sports footwear. Measurements started once the
116
subject took the correct position and lasted 5 seconds (Fig. 1).
117
Figure 1
118
1.Prone bridge on a stable surface (PB)
AC C
119
EP
112
The subject was asked to stay in a prone plank position (Fig. 1A). Attention was
120
paid to maintaining a neutral position in the hip joints, pelvis and lumbar spine. The feet
121
were placed to match the width of the hip and forearm and acted as support points. The
6
ACCEPTED MANUSCRIPT
122
elbows were placed under the glenohumeral joints, and the arms supported the body
123
vertically to the surface.
124
2.Prone bridge on a BOSU (PBB)
126
1B).
127
3.Prone bridge on a Swiss Ball (PBSB)
RI PT
Similar to the previous exercise, but with the forearms resting on a BOSU (Fig.
125
(Fig. 1C).
130
4.Side bridge on a stable surface (SB)
M AN U
129
SC
Similar to the previous exercise, but with the forearms resting on a Swiss Ball
128
131
The subject was asked to take a side plank position on the right forearm (Fig.
132
1D). The right elbow was under the glenohumeral joint, and the arm remained in a
133
position vertical to the surface. The left palm was resting on the hip.
134
5.Side bridge on a BOSU (SBB)
TE D
Similar to the previous exercise, but the forearm was placed on a BOSU (Fig.
135
1E).
137
The present study disregarded the assessment of muscle activity during side bridge on a
138
Swiss Ball. It resulted from difficulties in maintaining a neutral position of the spine and
139
pelvis by the subjects.
140
6.Supine bridge on a stable surface (SuB)
AC C
141
EP
136
The initial position was crook-lying, with the knees bent 90 degrees, the feet
142
supported on the heels only and the hands on the floor with palms facing down (Fig.
143
1F). The subject lifted the pelvis until the hip joints were in the neutral position.
144
7.Supine bridge on a BOSU (SuBB)
145 146
Similar to the previous exercise, but with the heels resting on a BOSU (Fig. 1G). 8.Supine bridge on a Swiss Ball (SuBSB) 7
ACCEPTED MANUSCRIPT
Similar to the previous exercise, but with the heels resting on a Swiss Ball (Fig.
147 148
1H).
149
2.4. Data Collection and EMG Processing The isometric activity of the rectus abdominis (RA), the external oblique (EO),
151
and the combined activity of the internal oblique and transversus abdominis (IO-TA)
152
only on the right side of the body (Lehman et al., 2005a; Lehman et al., 2005b; Marshall
153
et al., 2005; Querioz, Cagliari, & Amorim, 2010) was recorded. All data signals were
154
registered and measured by means of a surface dynamic electromyography (sEMG)
155
recorder (BTS FREE EMG 300, BTS Bioengeering, Italy) at a sampling frequency of
156
1000 Hz to 16-bit analog-to-digital conversion, a common mode rejection ratio of
157
greater than 110dB at 50-60Hz and an input impedance greater than 10GΩ. The EMG
158
signals were filtered (bandwidth 10-500 Hz), rectified and subsequently quantified
159
(root-mean-squared (RMS) EMG over a 100 ms window). The device provided
160
completely wireless communication between the preamps and signal collecting unit. To
161
record the RA activity, pairs of electrodes (ARBO, Kendall, Tyco Healthcare,
162
Germany) 1 cm in diameter were placed 5 cm inferior and 3 cm lateral to the xiphoid
163
process (O`Sullivan et al. 1998). For recording the EO activity, electrodes were placed
164
just below the eighth rib’s anterior angle, superolateral to the costal margin (Beith,
165
Synnott, & Newman, 2001). To register the IO-TA activity, electrodes were placed 2
166
cm medial and caudal to the anterior superior iliac spine (Chanthapetch,
167
Kanlayanaphoporn, & Gaogasigam, 2009; Marshall et al., 2005). The muscle fibers of
168
the transversus abdominis and internal obliques are blended at this place (Marshall &
169
Murphy, 2003). The electrodes were placed on a thoroughly shaved and cleaned skin
170
with a center-to-center distance of 2 cm, parallel with the muscle fibres (Ekstrom et al.,
171
2007; Lehman et al., 2005b).
AC C
EP
TE D
M AN U
SC
RI PT
150
8
ACCEPTED MANUSCRIPT
172
2.5.EMG Normalization Procedure The muscle activity obtained during the exercises was normalized by means of
174
the MVC (Maximal Voluntary Contraction) technique, allowing for the comparison
175
among different subjects (Burden & Bartlett, 1999; Lehman & McGill, 1999; The
176
SENIAM project). For this purpose, each subject held a 3- to 5-second-long maximal
177
curl up position (for RA) and a bilateral upper-body-twist against manual resistance
178
(trunk rotation to the contralateral side for EO and trunk rotation to the ipsilateral side
179
for IO-TA), and the subject was asked to tighten muscles as much as possible (Beith et
180
al., 2001). The maximal reading was tested in either sitting or crook lying, whichever
181
achieved a greater activity for each subject. The data collected during these tasks, and
182
used for subsequent analysis as a point of reference for all other measurements was
183
from one effort only (Beith et al., 2001). The interval between individual tests amounted
184
to 2 minutes to prevent muscle fatigue (Chanthapetch et al., 2009). The first muscle to
185
assess was RA, after that EO and IO-TA as the last one.
TE D
M AN U
SC
RI PT
173
The average RA, EO and IO-TA activity obtained during each exercise
187
(arithmetic mean of the results from 3 repetitions) was then normalized and expressed
188
as a percentage of the peak activity found in the MVC test.
189
2.6.Statistical Analysis
EP
186
The data were analyzed using the SPSS 18 Statistics Package (Polish version).
191
The data distribution was assessed by the Shapiro-Wilk test. Moreover, descriptive
192
statistics were prepared for each variable (mean ±SD). The comparisons of two or more
193
variables were made using Wilks`s Lambda MANOVA omnibus test and the series of
194
Student`s t-tests with Bonferroni corrections as post hoc. Bonferroni corrections were
195
calculated for each hypothesis separately with the intention of controlling familywise
196
error rate equal 0.05. Under this premise, the correction was found equal 8x(8-1)/2=28
AC C
190
9
ACCEPTED MANUSCRIPT
for each hypothesis, and the corresponding significance level was 0.0018. Additionally,
198
two ratios of activity were calculated to indicate the relationship between the activity of
199
the EO and the RA and between the IO-TA and the RA (Marshall et al., 2005;
200
O`Sullivan et al., 1998). For comparisons of ratios the one-way ANOVA with Tukey
201
tests as post hoc and Wilcoxon tests were used. The value of α=0.05 was considered as
202
the significance level.
RI PT
197
3.RESULTS
204
206
3.1.Exercises and Surfaces
M AN U
205
SC
203
Table 1 summarizes the average sEMG amplitudes for each abdominal muscle during the evaluated exercises on the different surfaces. During the prone bridge, the
208
RA, EO and IO-TA reached significantly higher activity in exercises on a Swiss Ball
209
compared the exercise performed on a stable surface (P
