An electromyographical comparison of torso muscle activity and ratio during modified side bridge exercises

Abstract

BACKGROUND:

Individualized exercise programs based on personal impairment could lead to successful rehabilitation. An effective way to train spine stability is to find exercises that take advantage of the synergistic relation between local and global stabilization systems.

OBJECTIVE:

This study aimed to investigate synergistic relationship between the muscles of the local and global systems during three modified side bridge exercises compared with traditional side bridge (TSB).

METHODS:

Twenty healthy participants performed TSB, both leg lift while side-lying (BLLS), torso lift on a 45 ${}^{\circ}$ bench while side-lying (TLBS), and pelvic lift on side-lying (PLS) in random order. Surface electromyography data were analyzed.

RESULTS:

The results indicate that PLS was effective as TSB on trunk muscle activity. However, BLLS and TLBS demonstrated significantly less rectus abdominal (RA) muscle activity compared to TSB ( $p<$ .001). Additionally, BLLS and TLBS had a higher internal oblique (IO)/RA muscle activity ratio than TSB ( $p<$ .001).

CONCLUSIONS:

PLS could be a suitable alternative exercise for individuals who are unable to perform TSB, as it can effectively activate trunk muscles. BLLS and TLBS may be appropriate for training the local stability system, while limiting activation of the RA.

Keywords

Modified side bridge exercise surface electromyography muscle activity and ratio

1. Introduction

Spine stability depends heavily on the trunk muscles surrounding lumbar spine [1]. A functional classification system for the trunk muscles distinguishes between local and global muscle systems [2]. The local system composes deep intrinsic muscles and controls intervertebral motion during gross whole body movements [3, 4, 5]. The global system composes superficial muscles with origin on the pelvis and insertions on the thoracic cage, controlling prime spine movements such as trunk flexion, extension, and rotation [3, 5, 6]. These muscles must be co-contracted for substantial durations of time for spine stability [7].

The side bridge exercise aims for co-activation of trunk muscles only on the side required to support the bridge position, whereas one half of the torso musculature is much less active without the high lumbar compression associated with trunk flexion or extension [7, 8, 9, 10]. Individuals with left-right muscular imbalances in a rehabilitation setting might benefit from the side bridge exercise since it activates more targeted side (the right or left side) of the trunk musculature [9]. Despite its advantages, the exercise is very challenging for some cases that may not tolerate the compressive load on the side supported during the exercise because of upper or lower extremity pain [10]. For instance, 42.5% of the participants reported upper extremity pain or fatigue as the reason for ending the side bridge test compared to the 45.8% who reported trunk side or hip fatigue or pain [11]. This leads to modified side bridge exercises which may provide an alternative for those individuals unable to perform TSB. A previous research evaluated the muscle activation of external oblique (EO), internal oblique (IO), and quadratus lumborum (QL) during the modified side bridge exercises compared to traditional side bridge (TSB) [10]. Given each exercise position of modified side bridge exercises, torso lift on a 45 ${}^{\circ}$ bench while side-lying (TLBS) was suggested for some situations unable to tolerate the compressive load on the upper-extremity while both legs lift on side-lying (BLLS) was recommended for individuals with lower-extremity issues as alternative exercises to activate the EO, IO, and QL [10].

However, not only the influence of the other torso muscle groups which could also play an essential role during the modified side bridge exercises but also a novel modified exercise: pelvic lift on side-lying (PLS), were not addressed. In addition, it is unknown that the synergistic relationship between the muscles of the local and global systems during the exercises. An effective way to train spine stability may be to find exercises that take advantage of the synergistic relationship between local and global stabilization systems [12]. Some individuals may have a poor muscle recruitment pattern between local and global stabilization systems [13]. The rehabilitation strategy should be individualized based on the rehabilitation goal to maximize the effect of therapeutic exercises. In this way, the purpose of this study was to investigate rectus abdominal (RA), EO, IO, thoracic erector spinae (TES), lumbar erector spinae (LES) muscle activity, and the patterns of muscles associated with the global and local stability systems such as IO/RA and LES/TES muscle activity ratio during three modified exercises including BLLS, TLBS and PLS compared to TSB.

2. Methods

2.1 Participants

The current study was cross-sectional design and included twenty healthy men (age, 30.7 $\pm$ 3.15 years; height, 174.9 $\pm$ 5.66 cm; weight, 72.1 $\pm$ 6.43 kg; BMI, 23.81 $\pm$ 1.67 kg/m ${}^{2}$ ). Before inclusion in the study, none had previously experienced neuromuscular, cardiovascular, or orthopedic conditions, especially low back, shoulder, hip, or knee pain. The dataset in this study partially overlaps a dataset included in another study [10]. Prior to participation, all subjects were asked to sign an informed consent form approved by the Catholic University Institutional Review Board (MC17FESE0116) and conformed to the Declaration of Helsinki.

2.2 Instrumentation

Figure 1.

TSB, traditional side bridge.

Figure 2.

BLLS, both leg lift on side-lying.

Surface electromyography (sEMG) (Trigno Wireless EMG system with Trigno EMG Sensor; Delsys, Boston, MA, USA) was used to measure the activation of the RA, EO, IO, TES, and LES muscles during TSB and three modified exercises. The EMG data of each muscle were converted from analog to digital using the EMG Works Acquisition and Analysis (Delsys). Raw EMG data were filtered with a band pass Butterworth filter between 20 and 450 Hz cutoffs and the sampling rate was 1,926 Hz throughout the tests [10]. Each trial of EMG signal was high-pass filtered (20 Hz), full-wave rectified, and then low-pass filtered (6 Hz), and the root mean square value was calculated over 100-ms intervals for muscle activity [14].

Stabilizer Pressure Biofeedback (Chattanooga Group Inc, Vista, CA, USA) was used for the visual feedback from an air-filled pressure sensor. It was placed below the lean lateral torso to hold excessively increasing ranges of pelvic tilt during BLLS, TBLS, and PLS (Figs 2, 3, and 4). The feedback sensor displayed the amount of pressure change as the lateral pelvic tilt progressively flattened during BLLS, TBLS, and PLS. A pressure biofeedback unit was inflated until the pressure reached 40 mmHg, and this pressure remained between 35 and 45 mmHg during the exercises [15].

2.3 Procedures

Figure 3.

TLBS, torso lift on 45 ${}^{\circ}$ bench side-lying.

Figure 4.

PLS, pelvic lift on side-lying.

The participants were initially asked to provide their demographic information, including age, gender, height, weight, and body mass index (BMI). All participants were taught how to perform the exercises by the same instructor and performed 4 practice sets of each exercise before data collection. Once participants were familiar with four exercises, each participant completed each exercise, and the exercise sequence was randomly determined among traditional side bridge (TSB), both leg lift on side-lying (BLLS), the torso lift on 45 ${}^{\circ}$ bench side-lying (TLBS), and pelvic lift on side-lying (PLS) [15]. The participants performed a 5-second hold for each isometric exercise three times with brief rest periods (2 minutes) between each repetition, and the same procedure was performed with a 10-minute rest between each exercise to prevent a carryover effect [15, 16]. EMG data were collected for 5 seconds during the isometric phase, and calculated from the middle 3 seconds of each exercise to avoid any effects of the connecting element of the skin-electrode and possible starting or ending effects [17].

Traditional side bridge (TSB). The participant lay on the floor with their right side supported by the right hip and elbow (flexed to 90 ${}^{\circ}$ ). Once the abdominal muscles were appropriately braced to stabilize the neutral spine, the participant’s hips were extended to neutral as the hips were elevated off the mat, and support shifted from the right hip to the right knee (Fig. 1).

Both leg lift on side-lying (BLLS). While lying on the left side with legs straight and one foot on top of the other, the participant placed the pad on the left pelvis. The pressure biofeedback unit was placed beneath the trunk between the iliac crest and the distal ribs, and changes in body position such as lateral pelvic tilt were reflected in changes in pressure. Once abdominal muscles were appropriately braced to stabilize the neutral spine, both legs were slightly lifted just off the floor while ensuring minimal spine bending. The pressure biofeedback unit was set at 40 mmHg. The participant and the instructor monitored whether pressure was maintained between 35 and 45 mmHg (Fig 2).

Torso lift on 45 ${}^{\circ}$ bench side-lying (TLBS). While standing with the left side leaning on a 45 ${}^{\circ}$ bench with the feet anchored (to spare the shoulders), the participant placed the pad on the left pelvis. The pressure biofeedback unit was placed beneath the trunk. Once the abdominal muscles were appropriately braced to stabilize the neutral spine, the torso was elevated from the pad. The pressure biofeedback unit was set at 40 mmHg. The participant and the instructor monitored whether pressure was maintained between 35 and 45 mmHg (Fig. 3).

Pelvic lift on side-lying (PLS). While lying on the right side with the hip and knee (flexed to 30 ${}^{\circ}$ and 90 ${}^{\circ}$ , respectively), the participant placed the pad on the right pelvis. The pressure biofeedback unit was placed beneath the trunk. Once the abdominal muscles were appropriately braced to stabilize the neutral spine, the pelvis was lifted just off the floor with the right greater trochanter off by extending both hip and support shifted from the right hip to the right knee $.$ The pressure biofeedback unit was set at 40 mmHg. The participant and the instructor monitored whether pressure was maintained between 35 and 45 mmHg (Fig. 4).

EMG data collection. In this study, motor control symmetry was assumed between the left and right sides of the body based on a previous work [18]. The muscle activities of RA, EO, IO, TES, and LES of the right side were recorded using sEMG, [10, 15]. Prior to the attachment of the electrodes, the hair at the placement sites was shaved and the skin was cleaned by rubbing with alcohol [17]. Electrodes were placed as follows: for the RA, approximately 3 cm lateral to the umbilicus [18, 19]; for the EO, approximately 15 cm lateral to the umbilicus and at the transverse level of the umbilicus [18, 19]; for the IO, approximately halfway between the anterior superior iliac spine of the pelvis and the midline, just superior to the inguinal ligament [18, 19]; for the TES, approximately 5 cm lateral to the T9 (actually longissimus and iliocostalis at T9) [17, 20]; for the LES, approximately 3cm lateral to the L3 spinous process (actually longissimus and iliocostalis at L3) [21].

Each maximal voluntary contraction (MVC) for RA, EO, IO, TES, and LES was measured to normalize the EMG data. During measurement of MVC of the RA, EO, and IO muscles, each participant adopted a sit-up posture with the torso at approximately 45 ${}^{\circ}$ in the horizontal position, with knees and hips flexed at 90 ${}^{\circ}$ , manually braced by a research assistant [17, 19]. The MVC of the RA was measured during attempting the upper trunk flexed in the sagittal plane while the researcher applied maximal downward resistance [17, 19]. The MVC of the EO was measured during leftward trunk rotation as the researcher applied maximal resistance from the participant’s left side onto the right shoulder [17, 19]. The MVC of the IO was measured during a rightward trunk rotation as the researcher applied maximal resistance from the participant’s right side onto the left shoulder [17, 19]. The MVC of the TES and the LES were measured while a participant was strapped in a prone position, with the torso horizontally cantilevered over the end of the bench (Biering-Sorensen position) [16, 17]. For the TES, the participant attempted to extend the upper trunk in the sagittal plane and retract the shoulders (squeezing the scapulae together) while manual resistance was applied to the shoulders by the researcher [16]. For the LES, the MVC was measured while a participant attempted to extend the lower trunk and the hips against manual resistance when in a prone position, with the torso on the bench and the legs horizontally cantilevered over the end of the bench [16, 17]. Prior to the test, each participant was allowed to become familiar with the MVC maneuvers [16, 17, 19]. After a period of adaptation, each participant performed 3 MVC’s of each muscle for 5 seconds for normalization, and the mean value from three trials with a 3-minute rest interval was used for data analysis [16, 17, 19]. The EMG amplitudes collected during each exercise were expressed as a percentage of the average MVC (%MVC) [17]. The difference in the ratio of local muscle activity to global muscle activity (separately for abdominal and back muscles) was evaluated [12, 13]. The paired ratios between the RA and IO (the IO/RA) were calculated for the abdominal muscles (the IO/RA) [13], and the paired ratios between the TES and LES (the TES/LES) were also calculated for the back muscles [12].

2.4 Statistical analysis

Data analysis was performed using the Statistical Package for the Social Sciences (SPSS), version 24 (SPSS Inc., Chicago, IL, USA). The normality of the data was tested using the Kolmogorov-Smirnov test ( $p>$ 0.05). One-way repeated analysis of variance was conducted with four different exercises (TSB, BLLS, TLBS, and PLS), as factors to examine differences in muscle activity of RA, EO, IO, TES and LES, and muscle activity ratio (IO/RA and LES/TES). The level of statistical significance was set at $p<$ 0.05. If a significant difference was found, post hoc pairwise Bonferroni-corrected comparison was performed ( $\alpha$ : 0.05/6 $=$ 0.008). Additionally, Cohen’s d and partial eta-squared ( $\eta^{2}$ ), an effect-size measure, were calculated. The mean difference between conditions and 95% Wald confidence interval (CI) were also calculated. The sample size was calculated by G*Power 3.1.9.7 (Effect size $f$ : 0.30, $\alpha$ : 0.05, Power 0.80) for a repeated-measures analysis of variance (RMANOVA) on the basis of previous reports [10, 22]. The power analysis indicated that at least 20 participants were required to achieve a power of 0.80 at $p<$ 0.05.

3. Results

Table 1
Muscle activation (%MVC) between exercise conditions

Muscles	TSB	BLLS	TLBS	PLS	$F$	$P$	$\eta 2$
	Exercises
RA (Mean $\pm$ SD)	24.49 $\pm$ 13.83	9.47 $\pm$ 5.83 ${}^{*}$	11.52 $\pm$ 7.34 ${}^{*}$	16.40 $\pm$ 9.37	9.730	$<$ 0.001	0.300
EO (Mean $\pm$ SD)	48.91 $\pm$ 15.40	53.31 $\pm$ 17.46	54.48 $\pm$ 16.40	52.44 $\pm$ 15.74	.436	0.728	0.017
IO (Mean $\pm$ SD)	56.27 $\pm$ 16.03	59.42 $\pm$ 23.86	64.23 $\pm$ 20.74	62.16 $\pm$ 17.11	.624	0.602	0.024
TES (Mean $\pm$ SD)	23.69 $\pm$ 8.56	17.62 $\pm$ 6.81	21.25 $\pm$ 11.85	26.56 $\pm$ 10.95	3.024	0.350	0.109
LES (Mean $\pm$ SD)	52.79 $\pm$ 9.26	49.51 $\pm$ 16.20	52.06 $\pm$ 13.90	59.73 $\pm$ 16.80	1.853	0.145	0.068
IO/RA ratio (Mean $\pm$ SD)	3.15 $\pm$ 2.08	10.39 $\pm$ 9.40 ${}^{*}$	7.54 $\pm$ 4.62 ${}^{*}$	4.76 $\pm$ 2.52	6.758	$<$ 0.001	0.214
LES/TES ratio (Mean $\pm$ SD)	2.52 $\pm$ 0.93	3.14 $\pm$ 1.31	2.80 $\pm$ 0.95	2.59 $\pm$ 1.19	1.286	0.258	0.050

Abbreviations: MVC, maximal voluntary contraction; SD, standard deviation; TSB, traditional side bridge; BLLS, both leg lift on side-lying; TLBS, torso lift on 45 ${}^{\circ}$ bench side-lying; PLS, pelvic lift on side-lying; RA, rectus abdominal; EO, external oblique; IO, internal oblique; TES, thoracic erector spinae; LES, lumbar erector spinae. ${}^{*}$ Significant difference with TSB (post-hoc analyses).

One way RMANOVA indicated a significant difference in RA muscle activity ( $F_{3,76}=$ 9.730, $p=$ 0.000, $\eta p2=$ 0.300) among the four different exercises (Table 1). TSB showed significantly greater RA muscle activity than BLLS ( $p<$ 0.001; ES $=$ 1.415; mean difference $=$ 15.020; 95% CI: 4.927, 25.111) and significantly greater than TLBS ( $p<$ 0.001; ES $=$ 1.172; mean difference $=$ 12.977; 95% CI: 2.885, 23.069). There was no significant difference in EO ( $F_{3,76}=$ 0.436, $p=$ 0.728, $\eta p2=$ 0.017), IO ( $F_{3,76}=$ 0.624, $p=$ 0.602, $\eta p2=$ 0.024), TES ( $F_{3,76}=$ 3.024, $p=$ 0.035, $\eta p2=$ 0.109), and LES muscle activity ( $F_{3,76}=$ 1.853, $p=$ 0.145, $\eta p2=$ 0.068) among TSB, BLLS and TLBS. There was no significant difference in RA, EO, IO, TES, and LES muscle activity between TSB and PLS (Table 1).

In terms of the ratio of local muscle activity to global muscle activity, there were significant differences in IO/RA muscle activity ratio ( $F_{3,76}=$ 6.758, $p=$ 0.000, $\eta p2=$ 0.214) among the four different exercises. BLLS showed significantly greater IO/RA muscle activity ratio ( $p<$ 0.001; ES $=$ 1.064; mean difference $=$ 7.244; 95% CI: 1.466, 13.022) than TSB, and TLBS also significantly greater than TSB ( $p=$ 0.004; ES $=$ 1.223; mean difference $=$ 4.401; 95% CI: 1.378, 10.179). There was no significant difference in LES/TES muscle activity ratio ( $F_{3,76}=$ 1.286, $p=$ 0.258, $\eta p2=$ 0.050) among the four different exercises (Table 1).

4. Discussion

Figure 5.

Comparison of the rectus abdominal (RA), external oblique (EO), internal oblique (IO), thoracic erector spinae (TES), lumbar erector spinae (LES), IO/RA, and LES/TES muscle activity (%MVC) for each of the exercises. Bars indicate the standard error. MVC, maximal voluntary contraction; TSB, traditional side bridge; BLLS, both leg lift on side-lying; TLBS, torso lift on 45 ${}^{\circ}$ bench side-lying; PLS, pelvic lift on side-lying. ${}^{*}$ Significant difference with TSB (post-hoc analyses).

This study aimed to assess RA, EO, IO, TES, and LES muscle activity, and IO/RA and LES/TES muscle activity ratio in BLLS, TLBS, and PLS to validate the effects of the three modified side bridge exercises compared to TSB. This study is one of the first to investigate muscle activity and activation patterns in order to establish a modified side bridge exercise framework. The current study found that PLS can be effective as TSB in activating RA, EO, IO, TES, and LES. These findings support that PLS may be a sufficient technique to provide a training effect to activate RA, EO, IO, TES, and LES as TSB, while reducing the compressive load on the upper-extremity and the lower-extremity. It could lead to personalized interventions to improve co-activation of trunk muscles only on the targeted side (the right or left side) to correct muscular imbalances for individuals in situations unable to perform TSB. The asymmetric trunk loading in the frontal plane causes specific biomechanics with trunk hyperextension motions and/or trunk lateral bend and rotation in a variety of sports performances [23] or daily activities [24], resulting in the imbalanced activity of torso muscles between the right and the left part [25]. For example, the asymmetric loading of trunk muscles in sports like golf or tennis may cause side-to-side imbalances in rotational muscle strength and endurance [25, 26]. Such imbalances may be compounded by low back pain and related injuries [23, 25]. In addition, carrying a shoulder bag with the weight on the right side of the body could contribute to an increase in muscle activity in the contralateral part (left) and a decrease of muscle activity in the ipsilateral part (right) of the trunk by causing them to move in an asymmetrical pattern [24]. Consequently, this habitual daily activity can be a potential cause of musculoskeletal disorder due to the lack of trunk muscle synchrony or subclinical level muscular imbalance in the trunk [24]. Given the electromyographic evidence, PLS may have merit in training the targeted side of imbalanced trunk muscles by activating RA, EO, IO, TES, and LES muscle for individuals who cannot perform TSB.

The activity of RA was greater during TSB compared to BLLS and TLBS, while the IO/RA activity ratio was greater during BLLS and TLBS than during TSB (Fig. 5). This result may be attributed to the exercise position of TSB, which was quite different from those of BLLS or TLBS. Since the hips were extended (or posterior roll of the pelvis) in a squat-like manner from flexed hip to 90 ${}^{\circ}$ during performing TSB, the increased activation of the RA could be related to the counteracting flexed hip (the anterior roll of the pelvis) required to overcome external toque of the body on the supporting leg [13, 27]. As the hip is flexed at 90 ${}^{\circ}$ at the starting position in TSB, the center of mass of the thigh is anterior to the hips, creating a greater gravitational moment arm of the legs [28]. Once the hips were extended in a squat-like manner, the weight force of the trunk on the supporting leg could cause an external torque of flexed hip (or the anterior roll of the pelvis) about the pelvis that challenges the stability of the body [29]. RA could contribute more to the extended hip (or posterior roll of the pelvis) to overcome the greater hip flexor torque [30], while oblique muscles cannot produce a hip flexion or extension torque [13]. In contrast, BLLS and TLBS were performed in both legs straight position with a neutral hip. Another possible reason for this finding may be related to that TSB and PLS were close-kinetic chain exercises, while BLLS and TLBS were open-kinetic chain exercises. In an early study [31], closed-kinetic exercises could elicit greater EMG amplitude due to challenging balance and stability than open-kinetic exercises. Indeed, the evidence offered supports that the RA’s relative activity increased compared to other torso muscles during spine stabilization exercises on the unstable surface [13, 32], consistent with the present results. TSB was performed with a smaller base of support than BLLS and TLBS, which ultimately could contribute to increased RA activity.

TLBS or BLLS would be appropriate approaches to facilitating the dynamic stabilizing role of the local abdominal stability system because local over global stability is crucial for motor control and rehabilitation training. The prior study emphasized the minimal activation of the RA compared to other trunk muscles for spine stabilization exercises [12, 13, 22]. They highlighted that motor control is essential to coordinate muscle recruitment between local and global muscles to maintain spine stability during functional activities [33]. Another interesting point is that there was no significant difference in the ratio of LES/TES among the four exercises. This result is consistent with other work demonstrating that all back muscles contribute similarly to controlling spine positions and movements during different exercises [33]. Therefore, therapists may choose the modified side bridge exercises that put appropriate demands on targeted muscles but remain within their patients’ capacity. For example, especially in case of chronic low back pain, the patients were associated with significantly higher RA or TES activation than healthy control subjects during several loaded and unloaded movements [12, 34]. TLBS or BLLS may be considered when the goal of rehabilitation is to target for coordinate contraction of these muscles in some patients with unilateral low back symptoms. Therapists may select BLLS or TLBS depending on a patient’s upper or lower extremity conditions.

This study has several limitations. First, the results of this study must be validated with more research involving a larger sample size despite their statistical significance and sufficient power. Second, this study did not measure the deeper torso muscles such as transverse abdominis and multifidus. However, several studies reported the possibility and validity of IO/RA and LES/TES to estimate the synergistic relation between local and global system [12, 13]. Thus, IO/RA and LES/TES measurements would likely be reliable, despite the need to measure deeper torso muscles during modified side bridge exercises to verify activation patterns of the local and global stability systems. Lastly, this study was conducted for healthy adult over a short period of time. Therefore, these results should be generalized with caution until further prospective studies are performed on the long-term effects of modified side bridge exercises, including adverse events in particular clinical population.

5. Conclusion

Individualized exercise programs based on personal impairment could maximize the effect of rehabilitation. Despite the wide variety of exercises that are prescribed for spine stability, it is required to construct the program properly considering individual physical conditions and rehabilitation goals when a therapist selects appropriate exercises. This study focused on addressing torso muscle activation and activation ratio of the modified side bridge exercises for the population group unable to perform TSB. The data suggest that PLS may be an effective rehabilitation technique to activate RA, EO, IO, TES, and LES, while reducing the compressive load on the side supported. BLLS or TLBS may be exercises that lead to coordinate activation of trunk muscle for training the local stability system to activate ideal muscular patterns by preferentially activating the IO, while limiting activation of the RA. As a result of these findings and given the importance of effective rehabilitation techniques, additional studies are warranted to clarify which individuals may benefit from the modified intervention such as BLLS, TLBS, or PLS.

Funding

The authors received no financial support for the research.

Statement of informed consent

Informed consent was obtained prior to performing the procedure, including permission for publication of all photographs and images included herein.

Authors contributions

Chi-Whan Choi reviewed the literature, analyzed and interpreted the preliminary data, and provided the first draft of the manuscript in addition to the revision. Jung-Wan Koo conducted the overall design, statistical analysis, and interpretation of findings. Yeon-Gyu Jeong provided support to the development of the discussion and clinical implications of findings.

Ethical approval

This study was conducted in accordance with the Declaration of Helsinki. The collection and evaluation of all protected patient health information was performed in a Health Insurance Portability and Accountability Act (HIPAA)-compliant manner.

Footnotes

Acknowledgments

The authors would like to acknowledge the contribution of all the participants who participated in this study.

This work was presented as a poster at the 2022 North American Congress on Biomechanics (NACOB).

Conflict of interest

The authors have no conflicts of interest to report.

References

Borghuis

Hof

Lemmink

KAP

. The Importance of Sensory-Motor Control in Providing Core Stability: Implications for Measurement and Training. Sport Med. 2008; 38: 893-916. PMID: 18937521. doi: 10.2165/00007256-200838110-00002.

Bergmark

. Stability of the lumbar spine: A study in mechanical engineering. Acta Orthop. 1989; 60: 1-54. PMID: 2658468. doi: 10.3109/17453678909154177.

Anders

Brose

Hofmann

, et al. Evaluation of the EMG-force relationship of trunk muscles during whole body tilt. J Biomech. 2008; 41: 333-339. PMID: 17959185. doi: 10.1016/j.jbiomech.2007.09.008.

Magnani

Lehnen

Rodrigues

, et al. Local dynamic stability and gait variability during attentional tasks in young adults. Gait Posture. 2017; 55: 105-108. PMID: 28437756. doi: 10.1016/j.gaitpost.2017.04.019.

Khosrokiani

Letafatkar

Sheikhi

, et al. Hip and Core Muscle Activation During High-Load Core Stabilization Exercises. Sports Health. 2021; 14: 415-423. PMID: 34060953. doi: 10.1177/19417381211015225.

Atrsaei

Dadashi

Hansen

, et al. Postural transitions detection and characterization in healthy and patient populations using a single waist sensor. J Neuroeng Rehabil. 2020; 17: 1-14. PMID: 32493496. doi: 10.1186/s12984-020-00692-4.

McGill

Karpowicz

. Exercises for Spine Stabilization: Motion/Motor Patterns, Stability Progressions, and Clinical Technique. Arch Phys Med Rehabil. 2009; 90: 118-126. PMID: 19154838. doi: 10.1016/j.apmr.2008.06.026.

Kavcic

Grenier

McGill

. Quantifying tissue loads and spine stability while performing commonly prescribed low back stabilization exercises. Spine. 2004; 29: 2319-2329. PMID: 15480148. doi: 10.1097/01.brs.0000142222.62203.67.

McGill

. Low Back Disorders. 3rd ed. IL: Champaign, IL: Human Kinetics; 2015.

10.

Choi

Koo

Jeong

. Comparison of trunk muscle activity during modified side-bridge exercises and traditional side bridge exercise. J Sport Rehabil. 2020; 29: 963-969. PMID: 31816597. doi: 10.1123/jsr.2019-0052.

11.

Juan-recio

Prat-luri

Galindo

, et al. Is the Side Bridge Test Valid and Reliable for Assessing Trunk Lateral Flexor Endurance in Recreational Female Athletes? Biology (Basel). 2022; 11: 1043. PMID: 36101422. doi: 10.3390/biology11071043.

12.

Van Dieën

Cholewicki

Radebold

. Trunk muscle recruitment patterns in patients with low back pain enhance the stability of the lumbar spine. Spine (Phila Pa 1976). 2003; 28: 834-841. PMID: 12698129.

13.

Marshall

Murphy

. Core stability exercises on and off a Swiss ball. Arch Phys Med Rehabil. 2005; 86: 242-249. PMID: 15706550. doi: 10.1016/j.apmr.2004.05.004.

14.

Gallina

Garland

Wakeling

. Identification of regional activation by factorization of high-density surface EMG signals: A comparison of Principal Component Analysis and Non-negative Matrix factorization. J Electromyogr Kinesiol. 2018; 41: 116-123. PMID: 29879693. doi: 10.1016/j.jelekin.2018.05.002.

15.

McBeth

Earl-Boehm

Cobb

, et al. Hip muscle activity during 3 side-lying hip-strengthening exercises in distance runners. Journal of Athletic Training. 2012; 47: 15-23. PMID: 22488226. doi: 10.4085/1062-6050-47.1.15.

16.

Ekstrom

Osborn

Hauer

. Surface electromyographic analysis of the low back muscles during rehabilitation exercises. J Orthop Sports Phys Ther. 2008; 38: 736-745. PMID: 19195137. doi: 10.2519/jospt.2008.2865.

17.

Vera-Garcia

Moreside

McGill

. MVC techniques to normalize trunk muscle EMG in healthy women. J Electromyogr Kinesiol. 2010; 20: 10-16. PMID: 19394867. doi: 10.1016/j.jelekin.2009.03.010.

18.

McGill

Andersen

Cannon

. Muscle activity and spine load during anterior chain whole body linkage exercises: the body saw, hanging leg raise and walkout from a push-up. Journal of Sports Sciences. 2015; 33: 419-426. PMID: 25111163. doi: 10.1080/02640414.2014.946437.

19.

Ito

Nonaka

Ogaya

, et al. Surface electromyography activity of the rectus abdominis, internal oblique, and external oblique muscles during forced expiration in healthy adults. Journal of Electromyography and Kinesiology. 2016; 28: 76-81. PMID: 27077819. doi: 10.1016/j.jelekin.2016.03.007.

20.

McGill

. Electromyographic activity of the abdominal and low back musculature during the generation of isometric and dynamic axial trunk torque: Implications for lumbar mechanics. Journal of Orthopaedic Research. 1991; 9: 91-103. PMID: 1824571. doi: 10.1002/jor.1100090112.

21.

McGill

Juker

Kropf

. Quantitative intramuscular myoelectric activity of quadratus lumborum during a wide variety of tasks. Clin Biomech. 1996; 11: 170-172. PMID: 11415616. doi: 10.1016/0268-0033(95)00056-9.

22.

Nakai

Kawada

Miyazaki

, et al. Trunk muscle activity during trunk stabilizing exercise with isometric hip rotation using electromyography and ultrasound. J Electromyogr Kinesiol. 2019; 49: 102357. PMID: 31557703. doi: 10.1016/j.jelekin.2019.102357.

23.

Renkawitz

Linhardt

Grifka

. Electric efficiency of the erector spinae in high performance amateur tennis players. J Sports Med Phys Fitness. 2008; 48: 409-416. PMID: 1897 4731.

24.

Motmans

RREE

Tomlow

Vissers

. Trunk muscle activity in different modes of carrying schoolbags. Ergonomics. 2006; 49: 127-138. PMID: 16484141. doi: 10.1080/00140130500435066.

25.

Zemkova

Poor

Jele

. Between-side differences in trunk rotational power in athletes trained in asymmetric sports. J Back Musculoskelet Rehabil. 2019; 32: 529-537. PMID: 30584114. doi: 10.3233/BMR-181131.

26.

Kawama

Ike

Soma

, et al. Side-To-Side Difference in Electromyographic Activity of Abdominal Muscles during Asymmetric Exercises. J Sport Sci Med. 2022; 21: 493-503. PMID: 36523892. doi: 10.52082/jssm.2022.493.

27.

Marshall

Murphy

. Changes in muscle activity and perceived exertion during exercises performed on a swiss ball. Appl Physiol Nutr Metab. 2006; 31: 376-383. PMID: 1690 0226. doi: 10.1139/h06-006.

28.

Berry

Lee

Foley

, et al. Resisted side stepping: The effect of posture on hip abductor muscle activation. J Orthop Sports Phys Ther. 2015; 45: 675-682. PMID: 26161629. doi: 10.2519/jospt.2015.5888.

29.

Willcox

Burden

. The influence of varying hip angle and pelvis position on muscle recruitment patterns of the hip abductor muscles during the clam exercise. J Orthop Sports Phys Ther. 2013; 43: 325-331. PMID: 23485733. doi: 10.2519/jospt.2013.4004.

30.

McGill

. The mechanics of torso flexion: situps and standing dynamic flexion manoeuvres. Clin Biomech. 1995; 10: 184-192. PMID: 11415551. doi: 10.1016/0268-0033(95)91396-v.

31.

Mendonca

Vila-Chã

Teodósio

, et al. Contralateral training effects of low-intensity blood-flow restricted and high-intensity unilateral resistance training. Eur J Appl Physiol. 2021; 121: 2305-2321. PMID: 33982187. doi: 10.1007/s00421-021-04708-2.

32.

Dolenec

Svetina

Strojnik

. Electromyographic Comparison of an Abdominal Rise on a Ball with a Traditional Crunch. Sensors. 2022; 5: 1979. PMID: 35271 124. doi: 10.3390/s22051979.

33.

Stevens

Bouche

Mahieu

, et al. Trunk muscle activity in healthy subjects during bridging stabilization exercises. BMC Musculoskelet Disord. 2006; 7: 1-8. PMID: 16987410. doi: 10.1186/1471-2474-7-75.

34.

De Ridder

Danneels

Vleeming

, et al. Trunk extension exercises: How is trunk extensor muscle recruitment related to the exercise dosage? J Electromyogr Kinesiol. 2015; 25: 681-688. PMID: 26003038. doi: 10.1016/j.jelekin.2015.01.001.

An electromyographical comparison of torso muscle activity and ratio during modified side bridge exercises

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Methods

2.1 Participants

2.2 Instrumentation

3. Results

Table 1 Muscle activation (%MVC) between exercise conditions

Funding

Statement of informed consent

Authors contributions

Ethical approval

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Muscle activation (%MVC) between exercise conditions