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BACKGROUND AND OBJECTIVE: This study investigated whether equine riding affects static or dynamic mechanical contractions on the thighs and trunk muscles in inactive women. METHODS: Participants consisted of 30 women with a mean (SD) age of 21.06 (0.44) years. They were randomly allotted as follows: equine group (EQG, n= 15) and control group (CON, n= 15). Two types of muscle contraction properties in their thighs and trunk were measured through a tensiomyography (static muscle tester) and an isokinetic device (dynamic muscle tester), respectively. Using the body weights of EQG and CON as covariates, a 2-way between-groups multivariate analysis of covariance was used to investigate group differences in the mechanical quantification of the thighs and trunk. RESULTS: The effectiveness of 8 weeks of equine riding was hardly observed in a static muscle test, whereas in the dynamic muscle test, the dominant and non-dominant hip extensor/flexor, the dominant hip abductor/adductor, and trunk extensor in the EQG showed a significant increase, compared to no changes in the CON. CONCLUSIONS: This study did not find any particular differences in a static muscle test in inactive women, but showed improvements in the dynamic mechanical properties of the thighs and trunk, which are major muscle groups related to spinal alignment.

Background Leaning forward has been accepted as a foundational approach to facilitate trunk-stabilizing muscles in the abdominal and lumbopelvic regions for patients with back pain during rehabilitation. However, how trunk muscles are activated and recruited during leaning forward performed under dynamic upper-extremity motion conditions is not completely understood. Objective To determine whether activation of selected trunk muscles changes depending on shoulder movements during leaning forward exercise in healthy young adults. Methods Twenty-four healthy adults (6 men and 18 women) participated in this study. The participants performed 3 types of leaning forward exercises: leaning forward alone (leaning forward 1), leaning forward with horizontal shoulder abduction (leaning forward 2), and leaning forward with shoulder flexion (leaning forward 3). Surface electromyography (EMG) was used to record activation of the erector spinae (ES), multifidus (MF), rectus abdominis (RA), and internal oblique (IO) on the dominant side. Results There was a significant main effect of exercise type on the activation of the IO, RA, and MF muscles. Activation of the IO and MF during leaning forward 1 was significantly decreased compared to activation in leaning forward 2 and 3; the activation of IO and RA showed the greatest increase during leaning forward 3. Furthermore, the IO/RA ratio was significantly increased during leaning forward 2 and 3 in comparison to leaning forward 1; the MF/ES ratio was also significantly increased during leaning forward 3, compared with leaning forward 1. Conclusion The integration of shoulder movements during leaning forward exercises could be effective in the facilitation of EMG activity of IO and MF muscles, especially with shoulder flexion.

Background: We used two methods, direct and indirect, to study the application of vibration training. This pilot study aimed to investigate the short-term effect of direct vibration and spinal stabilization exercises on the deep trunk muscles of patients with non-specific chronic low back pain (CLBP). Methods: Sixty-two participants with non-specific CLBP were randomly placed into two groups, one with direct vibration to the trunk muscles, VSE (vibration-plus stabilization exercise) group, and one without, CSE (conventional stabilization exercise) group. The groups underwent twelve sessions of an exercise program for spinal stability. We measured the thickness and activity of the following trunk muscles using ultrasonography and surface electromyography (sEMG): transversus abdominis (TrA), external oblique (EO), internal oblique (IO), rectus abdominis (RA), lumbar multifidus (LM), and lumbar erector spinae (LES). Results: The ultrasonographic examination revealed that the ratio of muscle thickness to muscle contraction and relaxation was increased after training in the TrA and LM muscles of patients in the CSE group, and in the TrA, LM, and IO muscles in the VSE group. We also found that the LM/LES ratio in the CSE group and the IO/RA, TrA/RA, and LM/LES ratios in the VSE group were significantly increased. Using multiple regression analysis, we showed that the improvement of the symptoms was related to increased activity of the deep trunk muscles in the VSE group (pConclusion: The findings suggest that direct vibration on the trunk muscles may increase the activity of contracting deep muscles and be used in addition to the effective enhancement of stabilization exercise in patients with non-specific CLBP.Trial registration: KCT0003858. Registered 26 April 2019.

BACKGROUND: Abdominal bracing is effective in strengthening the trunk muscles; however, assessing performance can be challenging. We created a device for performing abdominal trunk muscle exercises. The effectiveness of this device has not yet been evaluated or compared OBJECTIVE: We aimed to quantify muscle activity levels during exercise using our innovative device and to compare them with muscle activation during abdominal bracing maneuvers. METHODS: This study included 10 men who performed abdominal bracing exercises and exercises using our device. We measured surface electromyogram (EMG) activities of the rectus abdominis (RA), external oblique, internal oblique (IO), and erector spinae (ES) muscles in each of the exercises. The EMG data were normalized to those recorded during maximal voluntary contraction (%EMGmax). RESULTS: During the bracing exercise, the %EMGmax of IO was significantly higher than that of RA and ES (p< 0.05), whereas during the exercises using the device, the %EMGmax of IO was significantly higher than that of ES (p< 0.05). No significant difference was observed in the %EMGmax of any muscle between bracing exercises and the exercises using the device (p= 0.13–0.95). CONCLUSIONS: The use of our innovative device results in comparable activation to that observed during abdominal bracing.

BACKGROUND The asymmetric loading of trunk muscles in sports like golf or tennis may cause side-to-side imbalances in rotational muscle strength and endurance. Such imbalances may be compounded by the presence of low back pain (LBP) and related injuries. However, trunk rotational power is a better predictor of athlete performance, and therefore its ability to reveal these asymmetries/dysbalances should be investigated. OBJECTIVE This study compares peak and mean values of power during trunk rotations on the dominant and non-dominant side in golfers, ice-hockey players, tennis players, and an age-matched control group of fit individuals. METHODS Groups of 17 golfers, 17 ice-hockey players, 21 tennis players, and 39 fit individuals performed standing trunk rotations to each side with a bar weight of 5.5, 10.5, 15.5, and 20 kg placed on the shoulders. Peak power and mean power in the acceleration phase of trunk rotations were measured using the FiTRO Torso Premium system. RESULTS Peak power and mean power in the acceleration phase of trunk rotations were significantly higher on the dominant (D) than non-dominant (ND) side at weights of 5.5 kg (14 and 14%), 10.5 kg (17 and 14%), 15.5 kg (16 and 15%), and 20 kg (16 and 16%) in ice-hockey players, at 5.5 kg (14 and 13%), 10.5 kg (17 and 14%), and 15.5 kg (15% - only peak power) in tennis players, and at 5.5 kg (17 and 18%) and 10.5 kg (19 and 17%) in golfers. However, their values did not differ significantly at these weights (< 10%) in the age-matched control group. The D/ND ratio was the highest in ice-hockey players (1.18, 1.19), followed by golfers (1.16, 1.17) and finally tennis players (1.12, 1.16). CONCLUSION Taking into account significantly higher trunk rotational power on the dominant than the non-dominant side in golfers, tennis players and ice-hockey players at lower and/or higher weights and no significant side-to-side differences in a control group of fit individuals, this parameter may be considered specific to their asymmetric loading during trunk rotations. However, whether these asymmetries/dysbalances expressed by the D/ND ratio could also identify the likelihood of LBP, needs to be proven.

BACKGROUND: High prevalence of breastfeeding (BF)-related musculoskeletal disorders (MSDs) in nursing mothers have been reported in previous studies. Studies are scarce on the biomechanical effects of the commonly utilized BF positions. OBJECTIVE: This study evaluated the electromyographic (EMG) activities of the trunk muscles in response to three BF positions commonly utilized by mothers globally. METHODS: 20 non-pregnant nulliparous females participated in this experimental study. EMG activities from erector spinae (ES) and external oblique (EO) muscles were recorded bilaterally in three BF conditions: cradle (C1); cross-cradle (C2); football (FB). Data were analyzed using descriptive statistics and inferential statistics of one-way analysis of variance with alpha level set at 0.05. RESULTS: The activity levels of right EO and ES muscles significantly increased during the C2 hold, while the left EO and ES muscles revealed significantly higher EMG levels in the C1 trial. Asymmetrical activity between the right and the left parts of the EO muscle was significantly higher during the C2 hold. CONCLUSION: These findings suggest that compared to C2 and C1 holds, FB hold may be more biomechanically efficient relative to its decreased muscular demands. The physical stresses associated with BF may be higher with the adoption of C2 and C1 holds, especially for prolonged periods.

BACKGROUND: The abdominal drawing-in exercise could help improve delayed transversus abdominis (TrA) activation during limb movement in subjects with recurrent low back pain (rLBP). However, little is known about whether the same effect is observed during lifting tasks in subjects with rLBP. OBJECTIVE: This study aimed to clarify whether a single session of abdominal drawing-in exercise could correct the altered trunk muscle activation patterns during a lifting task in subjects with rLBP. METHODS: Fifteen subjects with rLBP performed lifting tasks before and immediately after three sets of 10 repetitions of isolated TrA voluntary contractions. The time of onset and activation amplitude during the lifting tasks were measured by surface electromyography (EMG) and compared between the trials before and immediately after exercise. RESULTS: During lifting, the onset of internal abdominal oblique/TrA (IO/TrA) and multifidus activation occurred earlier, the EMG amplitude of IO/TrA increased, and the EMG amplitude of erector spinae and multifidus decreased, compared with the pre-exercise data. CONCLUSIONS: These results suggest a possibility that the abdominal drawing-in exercise might be effective in improving the muscle recruitment pattern in people with rLBP.

BACKGROUND Patients suffering from low back pain (LBP) have been reported to alter muscle contraction strategies. OBJECTIVE To compare activity and thickness of the trunk muscles (external oblique (EO), internal oblique (IO), transversus abdominis (TrA), and lumbar multifidus (LM)) during static stoop lift at different lifting loads between the subjects with and without LBP. METHODS Twenty eight subjects with LBP and twenty eight healthy subjects were recruited. The stoop lifting was performed in three conditions in 0%, 10%, and 20% of body weight. RESULTS The activity of EO (F= 9.513) and IO (F= 7.781) was significantly increased with increasing lifting loads in subjects with LBP (p< 0.05) but not significantly in subjects without LBP. The activity of the LM (F= 124.980) was significantly increased in response to lifting loads in both groups (p< 0.05). The percent change of TrA (F= 8.797) and LM (F= 48.170) muscles thickness was significantly increased with increasing lifting loads in both groups (p< 0.05). The percent change of TrA (F= 3.780) and LM (F= 16.314) muscles thickness in subjects without LBP was greater than those in subjects with LBP at all three lifting loads (p< 0.05). CONCLUSIONS The results of this study suggest that more activation of EO in subjects with LBP may contribute to increase the compressive force on the lumbar spine during stoop lift. Also, less activation of TrA and LM in subjects with LBP may contribute to decrease the lumbar stabilization during stoop lift.

Background Spinal muscles endurance is fundamental for providing adequate trunk stability. Objective The purpose of this study was to compare the side bridge static endurance ability of the right versus left side. Methods Forty right hand dominant students, aged between 18 and 25 years, were recruited from Taibah University. Every participant had to lie down on his side and bear trunk weight on the arm with shoulder abducted to 90∘ and elbow flexed to 90∘. Every participant had to lift off his trunk of the supporting surface, keeping the trunk straight in neutral position, breathing normally and holding on that position as long as tolerated. Results A paired sample t test was calculated. The mean score, in seconds, for right side bridge was 41.6 (SD = 30.08), and for left side bridge was 38.00 (SD = 26.93). No significant difference was found between right and left side bridge endurance ability [t (39) = 1.67, p> 0.05]. Pearson correlation showed high positive correlation [r (38) = 0.89, p Conclusions Among healthy participants, clinicians should expect very close endurance profile for the musculature of the two sides of trunk. Clinicians should equally train both sides of trunk muscles stabilizers in order to enhance tolerance.

BACKGROUND The selection and validation of age- and gender-specific criterion-referenced cut-points for abdominal endurance are still unclear. OBJECTIVE To stablish normative values for abdominal endurance in adolescents by age and gender using the Bench Trunk Curl-up Test (BTC). Additionally, the reliability of the BTC was analyzed. METHODS Two hundred and sixteen untrained high school students (104 males - 112 females) were grouped into five age strata. Participants performed the BTC twice with a rest period of 72 h. Descriptive statistics and percentile scores were determined for each gender/age strata. RESULTS Males showed higher BTC scores than females (males: 90.07 ± 32.65 repetitions; females: 73.43 ± 27.74 repetitions), but no significant differences between age strata nor age * gender interaction were found. Significant differences for the BTC scores between sessions were found (T1 = 72.06 ± 26.28 repetitions; T2 = 81.44 ± 31.27 repetitions). The ICC was 0.82, whereas the typical error was 17.2%. CONCLUSIONS Gender, but not age, is an important factor when abdominal endurance is compared between adolescents. Finally, the BTC is a reliable test, supporting the findings of this study. However, an extensive familiarization period to reduce the learning effect is necessary.

Made available in DSpace on 2021-06-25T11:04:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 BACKGROUND: The co-contraction of the core muscles has been reported as the key mechanism towards spinal stability. Classic Pilates exercises aimed at these muscles are known to improve the stability and strength of the trunk without damaging the deep structures of the spine. OBJECTIVE: To evaluate the co-contraction of the mobilizing (rectus abdominis; longissimus) and stabilizing (multifidus; internal oblique) trunk muscles during Pilates exercises - going up front, mountain climber, and swan. METHODS: Sixteen women, all Pilates practitioners, participated in the study. The stabilizing and mobilizing muscles of the trunk (right side) were submitted to electromyography to calculate the percentage of co-contraction during the exercises. One-way repeated measures analysis of variance (ANOVA) was used to verify the difference in %COCON between stabilizers and mobilizers among the three exercises. The post-hoc Bonferroni test (P< 0.01) was applied when necessary. The paired t-test (P< 0.01) was used to verify the difference in %COCON between stabilizers and mobilizers separately for each exercise. RESULTS: The co-contraction values of the stabilizers were higher than those of the mobilizers for all exercises. The going up front (stabilizers) and the swan (mobilizers) exercises showed the highest %COCON values. CONCLUSIONS: The Pilates method is effective for either rehabilitating pathologies or training the trunk muscles in healthy individuals and athletes. Department of Morphology Anatomy Division Piracicaba Dental School UNICAMP Department of Physical Education São Paulo State University UNESP Department of Physical Education São Paulo State University UNESP

Objective We developed an innovative exercise device for the abdominal trunk muscles (ATMs) that has a built-in system to measure muscle strength. We aimed to examine the reliability of the strength measurement as well as the effect of strengthening using the device. Methods Twenty healthy adults participated in a reliability study of the muscle strength measurement. The first and second measurement were done in one day with an hour rest interval by raters 1 and 2, and the third by rater 1 following a one-week interval. We calculated the intraclass correlation coefficient (ICC). Another seven healthy men participated in a training program using the device, consisting of strengthening twice a week for 5 weeks. ATM strength was measured before and after the training period, and a positron emission tomography (PET) scan series was performed, consisting of examinations during rest before training (control condition) and during exercise after training (training condition). Results The intra-rater (ICC = 0.95) and inter-rater (ICC = 0.99) reliability of the strength measurement were excellent. ATM strength was significantly higher after training than before. 18F-fluorodeoxyglucose accumulation within the diaphragm, abdominal rectus, abdominal external and internal oblique, transverse abdominal, and levator ani muscles was significantly higher in the training condition than in the control. Conclusions Our innovative device showed excellent reliability to quantify ATM strength. Strengthening using the device increased strength and activated the abdominals, diaphragm, and pelvic floor muscles.

BACKGROUND Various forms of trunk exercise have been used for increasing abdominal strength. The plank exercise and bilateral leg raise exercise are one of these trunk exercises. However, there are few studies that compared the effects of these exercise variations. OBJECTIVE The present study aimed to investigate how effectively the trunk muscles during plank and bilateral leg raise exercises are activated. METHOD Surface electromyography responses of the rectus abdominis, internal oblique, and erector spinae muscles were investigated during the plank and bilateral leg raise exercise with different hip position. A total of 18 healthy, physically active female volunteers completed the normal plank exercise, plank exercise with placing the lower leg in a horizontal condition, bilateral leg raise exercise, and bilateral leg raise with lower leg as horizontal condition. RESULTS The horizontal condition caused significant increases in activity of the internal oblique muscles compared with the general condition (p< 0.05). The bilateral leg raise exercise showed significantly greater activation in the rectus abdominis compared to the plank exercise (p< 0.05). CONCLUSION The present study showed that the horizontal condition had the advantage of activating the internal oblique muscles, and the leg raise exercise is effective in strengthening global muscle such as the rectus abdominis.

BACKGROUND: Trunk muscle exercises are widely performed, and many studies have been performed to examine their effects on low back pains. However, the effect of trunk muscles activations during walking with pelvic floor muscle contraction (PFMC) and abdominal hollowing (AH) has not been clarified. OBJECT: To investigate whether walking with PFMC and AH is more effective for promoting local trunk muscle activation than walking without PFMC and AH. METHODS: Twenty healthy men (28.9 ± 3.14 years, 177.2 ± 4.25 cm, 72.1 ± 6.39 kg, body mass index 22.78 ± 2.38 kg/m 2 ) were participated in this study. Surface electrodes were attached over the multifidus (MF), lumbar erector spinae (LES), thoracic erector spinae (TES), transverse abdominus-internal oblique abdominals (TrA-IO), external oblique abdominals (EO), and rectus abdominus (RA). The amplitudes of electromyographic signals were measured during a normal walking with and without PFMC and AH. RESULT: PFMC and AH while walking was found to result in significant bilateral increases in the normalized maximum voluntary contraction (MVC) of MFs and TrA-IOs ( p< 0.05). Ratios of local muscle activity to global muscle activities were increased while performing PFMC and AH during normal walking. Bilateral TrA-IO/EO activity ratios were significantly increased by PFMC and AH ( p< 0.05). CONCLUSION: Performance of the PFMC and AH during walking resulted in significantly more recruitment of local trunk muscles. This study suggests that PFMC and AH during normal daily walking improves activation of muscles responsible for spinal dynamic stabilization and might be useful if integrated into low back disability and pain physical rehabilitation efforts.

Objective To investigate the efficacy of a 4-week community aquatic physiotherapy program with Ai Chi or the Bad Ragaz Ring Method (BRRM) on pain and disability in adults with chronic low back pain (CLBP). Methods Adults with CLBP (n= 44; mean ± SD age, 52.6 ± 5.5 y; 37 women) were assigned to either an Ai Chi (n= 23) or BRRM (n= 21) program (4 weeks, twice weekly). Results Both the Ai Chi (-1.4; 95% CI -2.6 to -0.2; p= .025) and BRRM (-2.0, 95% CI -3.1 to -0.8; p= 0.003) groups demonstrated significant pre- to post-treatment decreases in Roland-Morris Disability Questionnaire scores and improvements in prone bridge duration (Ai Chi: 11.7 s; 95% CI 1.6 to 21.8; p= 0.025; BRRM: 19.0 s; 95% CI 6.1 to 31.8; p= 0.006). The Ai Chi group revealed a significant improvement in single-leg stand test duration (2.9 s; 95% CI 0.1 to 5.7; p= 0.045) and the BRRM group reported significant decrease in pain intensity (-11.6; 95% CI -19.1 to -4.2; p= 0.004). Conclusions A 4-week aquatic physiotherapy program with Ai Chi or BRRM resulted in significant pre- to post-treatment improvements in disability and global core muscle endurance. Ai Chi appeared to have an additional benefit of improving single-leg standing balance and BRRM an additional benefit of reducing pain.

Objectives To compare the thickness of lateral abdominal muscles and Cross Sectional Area (CSA) of lumbar Multifidus Spinae (LM) muscles of competitive off-road cyclists with and without Low Back Pain (LBP). We also aimed to compare the maximum isometric back strength and endurance, as well as flexibility of lower back in cyclists with LBP and in the controls. Methods The thickness of Transversus Abdominis (TrA), Internal Oblique (IO) and External Oblique (EO) along with the CSA of LM muscles of 14 professional competitive off-road cyclists with LBP and 24 controls were measured by ultrasound (US) in hook-lying position on the examination table, and mounted on the bicycle. In addition, the back strength and endurance of the subjects and the flexibility of the participants were measured. Results Data showed a significantly lower thickness of Transversus Abdominis (TrA) and CSA of LM muscles in cyclists with LBP comparing to controls in all positions. No significant result regarding the flexibility of the subjects in case group comparing with the controls was found (p= 0.674). In addition, it was found that there is no significant difference in isometric back strength of the subjects between the groups (p= 0.105). However, we found that subjects with LBP have a lower endurance in back dynamometry with 50% of their maximum isometric back strength (p= 0.016). Conclusion In this study, useful information regarding possible factors associated with low back pain in off- road cyclists was found (lower thickness of TrA and LM muscles and decreased back endurance).

In the present study, we aimed to examine the changes in the thickness of the transversus abdominis (TrA) and internal oblique (Io) muscles using ultrasonography in adults who performed bridge exercises with the abdominal drawing-in maneuver and a sling and received micro vibrations. In total, 32 subjects were divided into a therapy (n= 16) and control (n= 16) groups. The therapy group completed nine sets, with four repetitions, of bridge exercises with the sling and received vibrations. The control group completed nine sets, with four repetitions, of bridge exercises with the sling and did not receive vibrations. The thicknesses of the TrA and Io muscles were measured in both groups using ultrasonography before and after therapy. According to the pressure applied to the biofeedback unit, both groups showed significant changes in the thicknesses of the TrA and Io muscles after therapy (P0.05). The change in the thickness of the TrA muscle after therapy was significantly different between the 2 groups when the pressures applied at 38, 42, and 46 mmHg (P0.05). Moreover, the change in the thickness of the Io muscle did not significantly different between the 2 groups at any of the pressures applied (P0.05). These findings indicate that approximately 15 minutes of vibrations during bridge exercises on unstable surfaces with a sling facilitates the activation of the deep trunk muscles and further enhances the activation of the TrA.

Background Measuring isometric strength is necessary in many areas of health and sport. However, trunk muscles have some particular characteristics that make them difficult to evaluate with simple, inexpensive instruments. Objective To evaluate the reliability and validity of an instrument constructed with a hand-held dynamometer and a metallic structure (HHD+S) for measuring maximum isometric voluntary trunk muscle strength. Methods Maximum isometric voluntary trunk muscle strength (extension, flexion and lateral flexion) was measured in 20 healthy individuals using the custom-made instrument (HHD+S) and the gold standard Back-Check (BC). Results The results showed that the two instruments had high and similar intra-subject reliability. The validity of the HHD+S was demonstrated by the high Pearson coefficient correlation between the two instruments (r ⩾ 0.78). Conclusions Given the good trial reliability and the close correlation between the two instruments, we believe that the use of a hand-held dynamometer together with the custom-made metallic structure (HHD+S) allows an evaluation of the maximum isometric voluntary trunk muscle strength to be made, that is very similar in quality, accuracy and reliability to the BC.

Background Mechanomyography (MMG) has been used to investigate mechanical characteristics of muscle contraction in clinical and experimental settings. Objective The aim of this study was to determine the test-retest reliability of mechanomyographic amplitude (MMGRMS) measurements as a tool for measuring the maximal voluntary isometric contractions (MVICs) of trunk muscles in healthy participants. Methods There were ten young adults participating in this study. Accelerometers were used to detect surface MMG signals from three trials of 5-s MVICs of the rectus abdominis, external obliques, erector spinae, and multifidus in the vertical, transverse, and longitudinal directions. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimum detectable change were calculated. Results Good to excellent test-retest reliability of mechanomyographic amplitude (MMGRMS) measurements was achieved for all MVICs of trunk muscles in healthy participants, as indicated by ICCs ranging from 0.99 to 0.64 for MMGRMS of the trunk muscles during MVIC. Conclusions This study demonstrates that MMG is a reliable measurement to detect the activation amplitudes of trunk muscles during MVIC.

BACKGROUND AND OBJECTIVE: Sitting posture may often place large burden on trunk muscles, while trunk muscle activities in the sitting posture have not been well clarified. In this study, a difference in trunk muscle activity between two kinds of sitting postures was evaluated, focusing on low back pain induced by posture holding. MATERIAL AND METHODS: An experiment was conducted on the subjects sitting on a stable-seat and on an unstable-seat, with the pelvis inclined forward, backward, rightward, and leftward. RESULTS: With the pelvis inclined forward, rightward and leftward, muscle activities were significantly increased in a stable-seat sitting posture. In contrast, no significant increase in muscle activity was observed with the pelvis inclined in every direction in an unstable-seat sitting posture. CONCLUSIONS: With the pelvis inclined in the stable-seat sitting posture, muscle activities were imbalanced, while with the pelvis inclined in the unstable-seat sitting posture, muscle activities were not imbalanced. Thus, it is suggested that with the pelvis inclined to the maximum extent in the stable-seat sitting posture, low back pain may be induced by imbalanced muscle activities.

BACKGROUND AND OBJECTIVES: Osteitis pubis refers to a painful, inflammatory condition involving the pubic bones, pubic symphysis, and adjacent structures. So, the aims of the study were to evaluate the strength of trunk muscles of soccer players suffering from osteitis pubis, and to compare the agonist/antagonist ratio of trunk muscles in osteitis pubis athletes with that of healthy athletes. MATERIALS AND METHODS: Twenty-five soccer male athletes with osteitis pubis, and 25 healthy soccer athletes. Peak torque/body weight (PT/BW) was recorded from trunk muscles during isokinetic concentric and eccentric contraction modes at a speed of 120 ◦ /s for healthy and osteitis pubis soccer players. RESULTS: There was a significant decrease in concentric contraction of back muscles in osteitis pubis group (p = 0.01). A significant decrease in eccentric contraction of abdominal muscles was also recorded in osteitis pubis group (p = 0.008). Concentric abdominal/back muscles ratio was significantly higher in osteitis pubis group (p = 0.016), with no significant difference in eccentric abdominal/back muscles ratio between both groups ( p> 0.05). CONCLUSION: Osteitis pubis group displayed concentric weakness of back muscle and eccentric weakness of abdominal muscles that lead to disturbance of the normal concentric abdominal/back ratio.

BACKGROUND AND OBJECTIVES: Intrinsic variability is present in all actions, including repetitive tasks. The aim of this study was to evaluate the variability of anticipatory postural adjustments (APAs) of trunk muscles in participants with low back pain (LBP). MATERIAL AND METHOD: The study included 21 participants with recurrent non-specific LBP (15 men, 6 women) and 21 healthy volunteers. Standard deviation of electromyographic activity of the external oblique (EO), transverse abdominis/internal oblique (TrA/IO), and erector spinae (ES) muscles onset relative to deltoid muscle onset was recorded in 75 rapid arm flexions, and the correlation with the participants’ avoidance belief (the FABQ score) and disability (the Roland-Morris Questionnaire score) was statistically analyzed. RESULTS: participants with LBP exhibited less variability in timing of APAs of the TrA/IO muscle compared with the control group (P = 0.047). The timing of APAs of the TrA/IO muscle was significantly correlated with the FABQ score (P = 0.006). There was no significant correlation between this variable and disability (P = 0.09). Decrease in variability of the timing of APA of the EO (P = 0.45) and ES (P = 0.6) muscles was not significant. CONCLUSION: The variability of the postural responses of participants with LBP decreased. Restoring variability in postural control responses might be a goal in rehabilitating these patients.

Background and purpose Slumped sitting is known to increase disc pressure and aggravate chronic low back pain. In addition, it has been recognized that co-contraction of the deep spine-stabilizing muscles enhances lumbar segmental stability and the sacro-iliac joint. The purpose of this study was to compare the electromyographic (EMG) activity of the trunk muscles and the muscle thickness of the transverse abdominis (TrA) during slumped sitting with the same parameters during co-contraction and investigate how co-contraction influences spinal curvature. Subjects and methods Nine healthy male volunteers participated in the study. EMG signals were recorded during both sitting postures. In order to measure the muscle thickness of the TrA, ultrasound images were captured. While the subjects performed both sitting postures, spinal curvature was measured using a hand-held device. Results Significantly more activity of the trunk muscles, with the exception of the rectus abdominis muscle, and significantly greater muscle thickness of the TrA were observed during co-contraction of the trunk muscles than during slumped sitting. Co-contraction also resulted in significantly increased lumbar lordosis and a greater sacral angle when compared to slumped sitting. Conclusion In this study, it was demonstrated that the instructions given to the subjects on co-contraction of the trunk muscles during sitting increased muscle activity with the exception of the rectus abdominis muscle, muscle thickness of the TrA, and lumbar lordosis.

The aim of the work was to determine the activity of trunk muscles in the sagittal plane in relation to body posture type in women treated for breast cancer. Fifty women having undergone treatment for breast cancer, with an average age of 61, participated in the study. All patients were studied by application of the photogrammetric method in order to determine posture; on the basis of the compensation ratio (mu), the examined group was divided into three posture sub-groups: kyphotic (K), lordotic (L) and balanced (R). At Biodex Multi Joint 3 examination system for isokinetic tests, the functional evaluation of trunk flexor muscles and extensor muscles was performed. Women having undergone mastectomy who participate regularly in rehabilitation are characterized by diverse posture types: kyphotic, lordotic and balanced. Women with lordotic posture achieved the highest force-speed parameter values in the trunk muscles irrespective of the muscle group examined, while the lowest values were observed in women exhibiting kyphotic posture. The function of trunk muscles in women following mastectomy depends on body posture type.

Objective: The effect of a newly developed training device on trunk muscle co-ordination patterns was investigated. Design: A cross sectional survey of 30 healthy volunteers was executed. The task was to maintain position and motion of a flexible pole that was set into oscillation. Oscillations were applied at three frequencies (3, 3.5, 4.5 Hz), in horizontal and vertical directions. SEMG signals of five trunk muscles were measured. Co-ordination was assessed by calculating mean relative amplitudes and mean, as well as, grand averaged muscle ratios during oscillation cycle for front over back (F/B), internal over external oblique (OI/OE), and multifidus over erector spinae (MF/ES) muscles. Results: Vertical oscillation evoked increased mean MF relative amplitudes and mean F/B and MF/ES muscle ratios in comparison with horizontal oscillation. Grand averaged F/B ratio was phase shifted about 180 ◦ of relative cycle between both oscillation directions. With increasing oscillation frequency mean F/B ratio increased, but OI/OE ratio decreased. Amplitude range of grand averaged muscle ratios during oscillation cycle was augmented with increasing frequency. Conclusions: The gathered normative data can serve as an initial data basis for further investigations on low back pain patients. Relative to oscillation direction and frequency, demands on trunk muscles vary from primarily stabilizing towards mobilizing activities.

Despite the popularity of core stabilization, there is limited evidence as to the relationship between performance on tests of isometric trunk muscle endurance and physical activity levels in adults.To investigate the relationship between isometric trunk muscle endurance and physical activity related energy expenditure in healthy young adults.A total of 51 participants (24 female) participated in the study. Median age and body mass index were; 22 years (Min-max: 18-26 years) and 21.8 kg/m2 (Min-Max: 18.59-28.98 kg/m2), respectively. Participants completed the International Physical Activity Questionnaire. Isometric trunk muscle endurance was assessed with holding times of isometric trunk flexor, extensor, and lateral side bridge tests. Collected data were summarized based on median and interquartile ranges. The Spearman's correlation test was used to ascertain the relationship between isometric trunk muscle endurance and physical activity related energy expenditure.There were no gender differences in holding times of the trunk flexor and trunk extensor endurance tests (p0.05). Males showed higher endurance scores for side bridge test than females (p0.001). No difference was found in physical activity related energy expenditure between males and females. No correlation was observed between isometric trunk muscle endurance and physical activity related energy expenditure for either females or males (p0.05).According to our findings, trunk muscle endurance is not related to physical activity related energy expenditure in healthy young adults.

OBJECTIVE: This study aimed to determine the effect of walking speed on the electromyographic (EMG) activity of the rectus abdominis (RA) and erector spinae (ES) muscles during treadmill high-heeled walking at different shoe heel heights. METHODS: Twenty-five young healthy women volunteered to participate in this study. The subjects performed treadmill walking at speeds of 3 km/h and 6 km/h for 30 seconds under 3 high-heeled conditions: barefoot, 3-cm heels, and 7-cm heels. Surface electromyography (EMG) data were collected from standard sites on the RA and ES muscles during treadmill walking. RESULTS: For all heel heights, the EMG activity of the RA and ES muscles was significantly higher at the 6 km/h speed than at the 3 km/h speed ( p< 0.05). Furthermore, EMG activity increased significantly with increasing shoe heel height, regardless of the walking speed ( p< 0.05). CONCLUSION: These findings indicate that walking speed and shoe heel height may contribute to the increased activity of the trunk muscle during high-heeled walking. This study provides information for future studies performed with the aim of predicting possible changes in trunk muscle activity during high-heeled walking.

Decades of debate have yet to yield a universal solution to the treatment of low back pain, a problem that afflicts 80% of adults in the United States at some point of their lives [1,2]. Exercise, in general, has become widely recognized as playing a large role in the rehabilitation of back pain sufferers. Yet, there is no consensus on which types of exercises to utilize. Most exercise techniques address the muscles with the specific purpose of impacting the skeleton or the spinal cord and nerve roots, rather than the muscles themselves. This reinforces the notion that muscles are not the direct source of pain, but rather only reflect pathology elsewhere. We reintroduce a rational exercise regimen first developed by Hans Kraus, M.D. in 1949. This regimen was shaped over a period of several years, through usage by thousands of back pain sufferers. It directly addresses specific trunk muscle deficiencies and tension, which are postulated by the authors to be the major factors producing low back pain. The exercise protocol has shown to be highly effective and inexpensive to administer on a wide-scale basis. Recent clinical experiences utilizing the Kraus techniques are discussed.

BACKGROUND AND OBJECTIVES: Incidence of Low Back Pain (LBP) in athletes is as high as 30%. Patients with LBP show altered postural and neuromuscular responses to various functional tasks. The objective of the study was to compare long latency reflex response (occurring between 40 to ∼ 100 ms duration) in athletes with chronic LBP with asymptomatic athletes. METHODS: Surface electromyography (EMG) of superficial trunk muscles – Rectus Abdominis (RA) and Erector Spinae (ES) were studied in athletes with chronic LBP (n = 24) and asymptomatic athletes (n = 25). Perturbations were introduced in standing both expectedly and unexpectedly. The latency of onset and the Root Mean Square (RMS) amplitudes within the reaction duration were compared between the two groups. RESULTS: The latency of onset was delayed in Unexpected perturbations but no change was observed in Expected tasks. The mean RMS amplitudes were significantly lower in both tasks for RA and in the Expected task for ES ( p< 0.05). CONCLUSION: Chronic LBP athletes exhibit a delay in onset latency to Unexpected perturbations and reduced long latency response amplitudes to perturbation tasks compared to asymptomatic athletes. These changes could predispose athletes to recurrent low back pain and further injury.

Objective: Hand-held flexible poles which are brought into oscillation to cause alternating forces on trunk, are advocated as training devices that are supposed to solicit increased levels of stabilizing trunk muscle activity. The aim of this study was to verify this claim by comparing electromyographic (EMG) activity of trunk muscles during exercises performed with a flexible pole and a rigid pole. Methods: Twelve healthy females performed three different exercises with flexible and rigid poles. EMG activity of iliocostalis lumborum (IL), multifidus (MU), rectus abdominis (RA), external oblique (EO) and internal oblique (IO), and was continuously measured. The EMG signals were analyzed in time domain by calculation of the Root Mean Square (RMS) amplitudes over 250 ms windows. The mean RMS-values over time were normalized by the maximum RMS obtained for each muscle. Results: The IO showed a 72% greater EMG activity during the exercises performed with the flexible pole than with the rigid pole (p=0.035). In exercises performed in standing, the IO was significantly more active than when sitting (p=0.006). Conclusion: As intended, the cyclic forces induced by the oscillating pole did increase trunk muscle activation. However, the effect was limited and significant for the IO muscle only. © 2011 - IOS Press and the authors.

Background: Trunk muscle fatigue has high relevance in human performance. Most authors agree that the use of the median frequency is preferred as a fatigue indicator. Most work has to date, been done on dynamic fatigue measurements, using the similarity index (SI). Objective: Repeated trunk flexion-extensions were measured using the B200 Isostation. Muscle activity was recorded by surface electromyography (EMG) in order to evaluate fatigue of trunk flexor and extensor muscles. Twenty male university studen ts participated in this pilot study, including 6 apparently he althy subjects with a history of low back pain (LBP), and 14 healthy matched controls. All participants were instructed to perf orm repeated trunk flexion-extension against 50% of their ba ck extensors maximal volutary contractions (MVCs) resistance until they could no longer perform the task. The SI was calculated from quantitative analysis of EMG data recording during dynamic trunk flexion extension task. Median frequency was also meas ured before and after fatiguing contractions. Results: The results of this study revealed a significant decrease in the SI and median frequency measurements following fatigue in both groups (p < 0.05). Conclusion: The results of this study indicated that in both groups changes in SI measurements following fatigue are in agreement with the changes in median frequency measurements.

Objectives: Low back pain after load-carrying is the most important disorder in musculoskeletal system and a cause of dysfunction and economic problems. Holding materials can disturb spinal stability; nevertheless, there are few researches about the pattern of trunk muscle recruitment in patients with chronic low back pain (CLBP) during load holding. Methods: Ten female patients with CLBP and ten matched healthy subjects participated in this study. Normalized electromyog- raphy activation of trunk muscles during holding loads was analyzed. Results: The low back pain group demonstrated significantly higher activation levels of the External oblique abdominis muscle during loading 12 kg in flexed trunk position and lower activation levels of the Internal oblique abdominis muscle during loading 6 and 12 kg in neutral trunk position than the control group. With the highest external load and trunk flexion, the electrical activity of back muscles increased significantly in both groups. With increasing load, the activation of Rectus abdominis muscle in patients with CLBP and the activation of Rectus abdominis and Internal oblique muscles were increased significantly in healthy subjects. Conclusion: Higher activation of global and lower activation of local abdominal muscles in patients with CLBP may represent that pain changes neuromuscular control systems. The increased activity of extensor muscles during trunk flexion is probably needed for stability and controlling of flexion.