Influence of shoulder angle on trunk muscle activation and perceived effort during prone-bridge exercise

BACKGROUND: The prone bridge is one of core stability exercises, which is important to maintain pelvic position as neutral. Elevated feet position is simple way to increase the external load, but have not been investigated the effect for muscle activity and pelvic position. OBJECTIVE: Present study is to investigate the effect of feet height on muscle activity and pelvic tilt angle during the prone bridge exercise. METHOD: Surface electromyographic responses of the rectus abdominis, internal oblique, erector spinae, serratus anterior, and pelvic anterior tilt angles were investigated during the prone bridge exercise with step boxes of different heights under the feet. A total of 18 healthy, physically active female volunteers completed the normal prone bridge exercise (NP), prone bridge exercise with a low step box (PL), and prone bridge exercise with a high step box (PH). RESULTS: The PL condition caused significant increases in the activity of the internal oblique muscles compared with the NP condition (P < 0.05). PL and PH, which used step boxes, showed significantly greater activation in the serratus anterior compared to the NP (P < 0.05). The pelvic anterior tilt angle during PH was significantly greater than that during PL or NP (P < 0.05). CONCLUSION: The high step box increased the pelvic anterior tilt angle with no additional abdominal muscle activity. The prone bridge exercise could be effective by adopting horizontal position between upper and lower body, compared to inclined lower body and general position.

Purpose: The purpose of the present study was to examine joint position senses and muscle activity in subjects with and without chronic low back pain and to determine the effects of different types of bridge exercises on their trunk muscle activity. Methods: Thrity -eight subjects with chronic low back pain and thrity healthy controls participated in the experiment. Joint position senses and trunk muscle activity levels were measured during the different bridge exercise methods. Results: The joint position senses of the healthy group and chronic low back pain group showed significant differences during lumbar flexion, lumbar extension, lumbar lateral flexion, and lumbar rotation. The muscle activity levels of the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) were highest in the prone bridge exercise (PBE) group, followed by the supine bridge swiss ball exercise (SBSE) group and supine bridge exercise (SBE) group in order of precedence. The muscle activity level of the erector spinae (ES) was highest in the SBSE group, followed by the SBE and PBE groups in order of precedence. Conclusion: Overall, the results suggest that chronic low back pain is associated with declines in joint position senses and that PBEs increase trunk muscle activity more than conventional bridge exercises.

BackgroundA Swiss ball is often incorporated into trunk strengthening programs for injury rehabilitation and performance conditioning. It is often assumed that the use of a Swiss ball increases trunk muscle activity. The aim of this study was to determine whether the addition of a Swiss ball to trunk bridging exercises influences trunk muscle activity.MethodsSurface electrodes recorded the myoelectric activity of trunk muscles during bridging exercises. Bridging exercises were performed on the floor as well as on a labile surface (Swiss ball).Results and DiscussionDuring the prone bridge the addition of an exercise ball resulted in increased myoelectric activity in the rectus abdominis and external oblique. The internal oblique and erector spinae were not influenced. The addition of a swiss ball during supine bridging did not influence trunk muscle activity for any muscles studied.ConclusionThe addition of a Swiss ball is capable of influencing trunk muscle activity in the rectus abdominis and external oblique musculature during prone bridge exercises. Modifying common bridging exercises can influence the amount of trunk muscle activity, suggesting that exercise routines can be designed to maximize or minimize trunk muscle exertion depending on the needs of the exercise population.

Biomechanical studies on the interrelation between trunk muscle strength and sports performance

Although the importance of core muscles on human motions has been recognized, little is known about the effect of trunk muscle fatigue and activation on drop jump (DJ) performance. PURPOSE: To examine how trunk muscle fatigue and activation relate to DJ performance. METHODS: The study included 7 healthy, well-trained males (age 20.8±1.4 years, height 168.4±5.7 cm, weight 67.1±8.0 kg). Subjects held vertical trunk position against a wire with one end attached to the posterior thorax, pulling the trunk posteriorly, with the other end attached to a weight corresponding to 25% of maximal voluntary isometric contraction force. Before and after this fatiguing task, maximum voluntary isometric trunk flexor contraction force (MVIC), and double- and single-leg DJ height (DJH), contact time (CT), and DJ index (DJI; DJH/CT) were measured. Surface electromyography was recorded from the dominant side of the anterior and posterior trunk musculature during DJs. Mean differences before and after the fatiguing task were examined using paired-sample t-tests. Simple linear regression analyses tested the relation of relative changes before and after the fatiguing task in the jump performance index and trunk muscle activation during preactivation, braking, and push off phase of each DJ. RESULTS: After the fatiguing task, MVIC was significantly decreased to 68.8±11.5% (p<0.01). DJI (Pre vs. Post fatigue for double- and single-leg DJ: 1.18±0.31 vs. 0.94±0.36, 0.52±0.13 vs. 0.41±0.15) and DJH (Pre vs. Post fatigue for double- and single-leg DJ: 22.12±5.09 cm vs. 20.01±5.24 cm, 13.21±3.04 cm vs. 11.07±3.64 cm) were significantly decreased (p<0.01), and CT (0.19±0.02 s vs. 0.22±0.03 s) was significantly extended (p<0.01). Regression analyses revealed that greater ensemble trunk muscle preactivation reduction rate was associated with CT lengthening rate in double-leg DJ (R2=0.582, B=-0.257, p=0.046), and DJI reductions rate in single-leg DJ (R2=0.910, B=0.309, p=0.001) and that greater rectus abdominus (R2=0.779, B=0.138, p=0.008) and external oblique activations reduction rate during breaking phase (R2=0.703, B=0.276, p=0.018) were associated with greater DJI reduction rate. CONCLUSIONS: Trunk muscle fatigue and decreased trunk flexor muscle activation during DJ have negative effects on both double- and single-leg DJ.

Feedforward coactivation of trunk muscles during rapid shoulder movements

The nordic hamstring exercise (NHE) is a dynamic lengthening hamstring exercise that requires trunk and hip muscles activation. Thigh muscles activation, specifically hamstring/quadriceps contractions has been previously examined during NHE. Trunk and hip muscles activity have not been enough studied. The aim of this study was to analyze of hip and trunk muscles activity during NHE. Surface electromyography (EMG) and kinematic data were collected during NHE. Ten healthy men with the age range of 21–36 years performed two sets of two repetitions with downward and upward motions each of NHE. EMG activity of fifteen trunk and hip muscles and knee kinematic data were collected. Muscle activity levels were calculated through repeated measure analysis of variance in downward and upward motions, through Paired t-test between downward and upward motions and gluteus maximus to erector spine activity ratio (Gmax/ES ratio) using Pearson correlation analyses were evaluated. Semitendinosus and biceps femoris muscles activity levels were the greatest in both motions and back extensors and internal oblique muscles activity were greater than other muscles (P<0.05). The decreased Gmax/ES ratio was significantly related to peak knee extension angle in downward (r=0.687) and upward motions (r=0.753) (P<0.05). These findings indicate the importance of synergistic muscles and trunk muscles coactivation in eccentric and concentric hamstrings contractions. It could be important for early assessment of subjects with hamstring injury risk.

This study aimed to clarify the differences in the onset of trunk muscle activity with and without anticipation of the movement starting time during rapid shoulder movements. Ten healthy men in a relaxed upright position performed rapid 135° flexion, 135° abduction, and 45° extension of the shoulder on the dominant hand side with and without anticipation of the movement starting time. They moved their shoulder joints following a 3-s countdown and a light stimulus in the anticipation and non-anticipation conditions, respectively. Electromyography of the anterior and posterior quadratus lumborum, transversus abdominis, internal oblique, external oblique, rectus abdominis, lumbar multifidus, lumbar erector spinae on the non-dominant hand side, and the middle deltoid on the dominant hand side were measured. The onset of activity of each trunk muscle relative to the onset of the middle deltoid was calculated. Two-way analysis of variance (eight trunk muscles × two anticipation conditions) was used to compare the onset of electromyographic activity of the trunk muscles in each direction of the shoulder movement. There were significant interactions between the muscles and anticipation conditions during shoulder abduction and extension. The onset of activity in the anterior and posterior quadratus lumborum, transversus abdominis, and internal oblique occurred earlier with anticipation of the movement starting time than without anticipation during shoulder abduction and extension. The anticipation of movement starting time may contribute to a reliable center of mass control within the support base and improve lumbar spine stability by hastening the onset of activity of the deep trunk muscles.

A split-plot experimental design was used to evaluate the influence of posture, trunk angle, and rotational velocity on peak torque output and myoelectric activity during maximal trunk extension maneuvers. To determine whether the kneeling posture alters extension torque capabilities in isometric and isokinetic exercises as compared with standing. Also, to ascertain whether recruitment of trunk muscles is modified by such a postural change. Factors such as workplace geometry may force workers to adopt awkward or unusual postures in the performance of manual tasks. An understanding of the limitations placed on strength in unconventional working postures is crucial to the proper design of jobs. Twenty-one healthy male subjects (mean age = 36 years +/- 7 SD) performed 12 trunk extension exertions in standing and kneeling postures. Isometric tests were performed at 22.5 degrees, 45 degrees, and 67.5 degrees of trunk flexion. Isokinetic tests were done at three velocities: 30 degrees/sec, 60 degrees/sec, and 90 degrees/sec. Electromyographic data were collected from eight trunk muscles to assess muscle recruitment under each condition. A priori orthogonal contrasts were specified for analysis of both torque and electromyographic data. The kneeling posture was associated with a 15% decrease in peak torque output when contrasted with standing: however, no concomitant change in trunk muscle activity was evident. Trunk hyperflexion (isometric tests) and increasing rotational velocity (isokinetic tests) were associated with reduced torque in both postures. Trunk muscle activity was primarily affected by changes in trunk angle and velocity of contraction. A reduced extensor capability exists in the kneeling posture, despite equivalent trunk muscle activity. The similar activation patterns in both postures suggest that the strength deficit does not result from alterations in trunk muscle function. Rather, it may be the consequence of a reduced capability to rotate the pelvis in the kneeling posture, due to a disruption of the biomechanical linkage of the leg structures.

Vibration training is an adjuvant to muscle-strengthening exercises. To investigate the short-term effects of direct vibration on the deep trunk muscles of patients with non-specific chronic low back pain (CLBP). Participants with non-specific CLBP were randomly placed into two groups: the vibration-plus stabilization exercise (VSE) group (n= 31) and the conventional stabilization exercise (CSE) group (n= 31). The groups underwent 12 sessions of an exercise program. The thickness and activity of the trunk muscles were measured using ultrasonography and surface electromyography. Ultrasonography revealed that the ratio of muscle thickness to contraction and relaxation was statistically increased after exercise in the bilateral transversus abdominis (TrA) and lumbar multifidus (LM) muscles in the CSE group (p= 0.031), and in the bilateral TrA, LM, and internal oblique (IO) muscles in the VSE group (p< 0.001). The LM/lumbar erector spinae (LES) ratio in the CSE group (p= 0.037), and the IO/rectus abdominis (RA), TrA/RA, and LM/LES ratios in the VSE group (p= 0.019) were statistically increased. Multiple regression analysis showed that symptom improvement was related to increased activity of the deep trunk muscles in the VSE group (p< 0.001). Direct vibration can increase the selective activity of contracting deep trunk muscles.

Neck pain is a large clinical problem where reorganized trunk and axioscapular muscle activities have been hypothesised contributing to pain persistence and pain hypersensitivity. This study investigated the effects of bilateral experimental neck pain on trunk and axioscapular muscle function and pain sensitivity. In 25 healthy volunteers, bilateral experimental neck pain was induced in the splenius capitis muscles by hypertonic saline injections. Isotonic saline was used as control. In sitting, subjects performed slow, fast and slow-resisted unilateral arm movements before, during and after injections. Electromyography (EMG) was recorded from eight shoulder and trunk muscles bilaterally. Pressure pain thresholds (PPTs) were assessed bilaterally at the neck, head and arm. Data were normalized to the before-measures. Compared with control and post measurements, experimental neck pain caused (1) decreased EMG activity of the ipsilateral upper trapezius muscles during all but slow-resisted down movements (p<0.001), and (2) increased EMG activity in the ipsilateral erector spinae muscle during slow and fast movements (p<0.02), and in the contralateral erector spinae muscle during all but fast up and slow-resisted down movements (p<0.007). The PPTs in the painful condition increased at the head and arm compared with post measurements and the control condition (p<0.001). In the post-pain condition, the neck PPT was decreased compared with the control condition (p<0.001). Acute bilateral neck pain reorganized axioscapular and trunk muscle activity together with local hyperalgesia and widespread hypoalgesia indicating that acute neck pain immediately affects trunk and axioscapular function which may affect both assessment and treatment. Bilateral clinical neck pain alters axioscapular muscle coordination but only effects of unilateral experimental neck pain has been investigated. Bilateral experimental neck pain causes task-dependent reorganized axioscapular and trunk muscle activity in addition to widespread decrease in pressure pain sensitivity.

Effects of restrictive clothing on lumbar range of motion and trunk muscle activity in young adult worker manual material handling

Purpose The purpose of this study is to compare muscle activations of neck, trunk and leg in cerebral palsy of spastic diplegia with genu recurvatum and knee flexion contracture, when using anterior and posterior walkers.Methods We selected 21 cerebral palsy and received the written consent to participate in this study. The inclusion criteria for participation required patients to have spastic diplegic CP; to be between 3~6 years of age, to have a GMFCS III grade, to have no botulinum toxin injection and orthopedics surgery within before six months starting the study. Measurements of muscle activities (sternocleidomastoid, splenius capitis, rectus abdominis, erector spinea, gluteus maximus, rectus femoris, medial hamstring and calf muscles) were evaluated anterior and posterior walker ambulations. Statistical evaluation of these data were accomplished by utilizing the paired t-test and independent t-test by SPSS 20.0 program. Significance level was set at p<.05.Results The following results were obtained. There was significant difference on muscle activation of neck, trunk and legs(soleus except) in anterior and posterior walkers. There was no significant difference in muscle activation of neck but significant difference in muscle activation of trunk, legs between genu recurvatum and knee flexion contracture(rectus abdominis, medial hamstring when using anterior walker, rectus abdominis, erector spinea, gluteus maximus, medial hamstring when using posterior walker).Conclusion The conclusion of this study is the different knee joint forms would have different effect on muscle activation of trunk and legs while cerebral palsy of spastic diplegic ambulated with anterior walker and

1186 - The Effects of Sling Device on Trunk Muscles Activities During Prone Bridge Exercise

Dynamic balance is a measure of core stability. Deficits in the dynamic balance have been related to injuries in the athletic populations. The Star Excursion Balance Test (SEBT) is suggested to measure and improve dynamic balance when used as a rehabilitative tool. To determine the electromyographic activity of the hip and the trunk muscles during the SEBT. Descriptive. University campus. Twenty-two healthy adults (11 males and 11 females; 23.3 [3.8]y, 170.3 [7.6]cm, 67.8 [10.3]kg, and 15.1% [5.0%] body fat). Surface electromyographic data were collected on 22 healthy adults of the erector spinae, external oblique, and rectus abdominis bilaterally, and gluteus medius and gluteus maximus muscle of the stance leg. A 2-way repeated measures analysis of variance was used to determine the interaction between the percentage maximal voluntary isometric contraction (%MVIC) and the reach directions. The %MVIC for each muscle was compared across the 8 reach directions using the Sidak post hoc test with α at .05. %MVIC. Significant differences were observed for all the 8 muscles. Highest electromyographic activity was found for the tested muscles in the following reach directions-ipsilateral external oblique (44.5% [38.4%]): anterolateral; contralateral external oblique (52.3% [40.8%]): medial; ipsilateral rectus abdominis (8% [6.6%]): anterior; contralateral rectus abdominis (8% [5.3%]): anteromedial; ipsilateral erector spinae (46.4% [20.2%]): posterolateral; contralateral erector spinae (33.5% [11.3%]): posteromedial; gluteus maximus (27.4% [11.7%]): posterior; and gluteus medius (54.6% [26.1%]): medial direction. Trunk and hip muscle activation was direction dependent during the SEBT. This information can be used during rehabilitation of the hip and the trunk muscles.