Side Bridge Research Articles

Prevalence of Musculoskeletal Disorder and Correlation with Core Endurance, Body Mass Index among Indian Classical Musical Instrument Players

Background and need of study: Commonly all classical musical instruments are played in cross leg position and without back support for prolonged periods. Core is the central part of the body, core muscles have to spare the spine from excessive load, to transfer force from the lower body to the upper body and vice versa. Strong, stable core and normal body mass index helps us to prevent musculoskeletal injuries. Therefore; the present study was conducted to find the prevalence of musculoskeletal disorder (MSD) and correlation with core endurance and body mass index (BMI) in Indian classical musical instrument players. Methodology: Observational, analytical study was conducted on 35 Indian classical musical instrument players. Male and female, age 20-60 years old, with ≥2 years of experience as a classical musical instrument player, practicing instrument for minimum 2 hours/day were included. Participation was voluntary and informed consent was taken. Nordic questionnaire was assessed for the prevalence of MSD. Weight and height assessed by BMI. Core endurance was assessed by McGill’s core endurance test. Each subject was given appropriate rest period between all tests. Outcomes were correlated using Spearman’s correlation of coefficient. Results: The common painful sites of the body were as follows: wrist/hand(91%),low back (89%),neck(71%),upperback(49%),shoulders(49%),knees(31%),elbows(29%),ankles(20%),hips(11%) among musical instrument players. Correlation was found between BMI and trunk flexor test (r=-0.696, p≤0.001), BMI and trunk extensor test (r=-0.658, p≤0.001), BMI and right side bridge test (r=-0.649,p≤0.001,)left side bridge test (r=-0.675,p≤0.001). Conclusion: A relatively high prevalence of musculoskeletal pain amongst Indian classical musical instrument players. There is moderate negative correlation between BMI and core endurance in Indian classical musical instrument players. Ergonomic advices, adapting healthy lifestyle along with overall improvement in their working efficiency, prevent MSD and thus indirectly improve their Quality of Life.

Pneumatic feed mechanism for accurate sowing of bare cotton seeds

The article considers the development of machines that improve sowing and increase the quality of technological operations when sowing cotton. The studies have been carried out for three years in the zone of sharply continental climate of the Republic of Uzbekistan on typical gray soils. The factors influencing the decrease in the efficiency of crop production for the Central Asian region are analyzed. The purpose of the use of clustered sowing of cotton with a given number of seeds in the cluster is substantiated. The results of research on the development of a pneumatic feed mechanism with optimal parameters for accurate sowing of bare cotton seeds in a clustered method for the soil and climatic conditions of Uzbekistan are presented. The physical and mechanical properties of bare cotton seeds of industrial grades C-6524 and “Sulton” were studied. An improved design of a pneumatic feed mechanism is proposed, including a sowing disc with suction cells, which are made in the form of a triangle with rounded tops and with a bridge inside. In this case, the bridge has a Y - shaped form, abuts with its ends against the sides of the triangle. At the same time, a technical result is achieved, it consists in creating the best conditions for a rational group arrangement and reliable suction of cotton seeds in the cells of the sowing disk, which improves the accuracy of their group sowing into the cluster and stable formation of maximum accuracy clusters in the furrow. The data on the economic efficiency of the use of a pneumatic planter equipped with exact feed mechanisms with substantiated parameters for sowing bare cotton seeds by the clustered method are presented.

Effects of proprioceptive training using BOSU® balance trainer on core strength and static balance in young competitive rhythmic gymnasts

Purpose: The study aimed to examine the effects of eight weeks of proprioceptive training using a BOSU® balance trainer on core strength and static balance in young rhythmic gymnasts. Methods: Twenty-three young competitive female rhythmic gymnasts, (age: 9.7 ± 1.9 yrs; weight; 26.1 ± 6.5 kg; height: 131.2 ± 10.9 cm; years of experience in RG: 3.5 ± 1.7) were assigned into an experimental group (EG, n = 12) and a control group (CG, n = 11). Both groups underwent a series of tests included the side bridge test, the stork stand balance test, and the rhythmic gymnastics balance test before and after the experimental intervention. All participants engaged in regular rhythmic gymnastics training throughout the intervention period with EG supplemented with BOSU® balance trainer proprioceptive training. The intervention programme consisted of six sets of exercises that focused on improving core strength and static balance. Training volume was kept consistent throughout the experiment, with each exercise performed for 30 s followed by a 45-s rest in 2 sets, 3 times a week. Results: Results showed that EG improved core strength significantly for right (P < 0.001) and left (P = 0.038) sides. However, there was no significant difference found in static balance (Stork Stand Balance Test and Rhythmic Gymnastics Balance Test) between EG and CG. Conclusion: The study concluded that proprioceptive training using BOSU® balance trainer implemented for 8 weeks on young competitive rhythmic gymnasts improved core strength but not in static balance

The Effects of Respiratory Muscle Functions on Trunk Muscle Endurance in Healthy Young Adults

Purpose: Respiratory muscles play a dual role in breathing and trunk stability during activities. The relationship between respiratory muscle functions and trunk stability has not yet been clarified. The aim of the study was to examine the effects of respiratory muscle functions on trunk muscle endurance in healthy young adults.
 
 Methods: McGill's trunk muscle endurance tests, which consist of trunk flexion endurance test (FE), Sorensen test (ST) and Side Bridge test (SB), were used to evaluate the participants' trunk muscle endurance. Respiratory muscle strength was evaluated by measuring intraoral maximal inspiratory and expiratory pressures using an intraoral pressure meter device. The respiratory muscle endurance test was performed with the incremental threshold load protocol using a threshold IMT device.
 
 Results: A total of 51 healthy young adults, with a mean age of 21.8 ± 3.2 years, were evaluated. The results of the linear regression models were significantly explained 46% of the variance in the SB and 38% in the FE, (for SB Adj R2=0.46, F=21.40, p< 0.001 and for FE Adj R2=0.38, F=15.65, p< 0.001). Respiratory muscle endurance contributed 30% to the endurance of the trunk flexor muscles, while respiratory muscle strength contributed only 8%. Similarly, respiratory muscle endurance contributed 38% to the endurance of the trunk lateral flexor muscles, while respiratory muscle strength contributed only 8%.
 
 Conclusion: Although respiratory muscle strength and respiratory muscle endurance were independent contributors to trunk muscle endurance, respiratory muscle endurance more affected trunk muscle endurance than respiratory muscle strength in healthy young adults.

Is assessing trunk muscle endurance in military with sub-acute and chronic low back pain clinically meaningful?

Trunk muscle endurance (TME) tests are commonly used by clinicians to assess muscle performance changes in response to rehabilitation in patients with low back pain (LBP). The aim of this study was to assess the responsiveness of three TME-tests in patients with LBP and to evaluate the relationships between changes in TME and improvement in self-reported function. Eighty-four LBP patients were evaluated at baseline and after completion of a 6-week training program. Function was assessed with the modified Oswestry Disability Index (ODI) while TME was estimated using three tests: (1) the Biering-Sørensen, (2) the side bridge endurance tests (both sides), and (3) the trunk flexor endurance test. The standardized response mean (SRM) and the minimal clinical important difference (MCID) for each TME-test, and the relationships between changes in TME and improvement in ODI were calculated. SRMs were small to large for TME-tests (range: 0.43-0.82), and large for the ODI (2.85) and no clinically useful MCID was identified for the TME-tests (area under the curve below 0.70). No significant correlations were found between changes in the TME and change in ODI scores (r < 0.15; all P > 0.05). Our results show a weak responsiveness of TME-tests in patients with LBP. There was no association between endurance performance change and self-reported functional change. TME-tests may not be a key component of rehabilitation monitoring in patients with LBP.

Effect of exercise devised to reduce arm tremor in the sighting phase of archery.

In archery training, side bridges are performed in a posture similar to archery shooting for training the muscles around the shoulder joint and the shoulder girdle of the pusher. The purpose of this study was to determine whether a low-tremor side-bridge exercise for 4 weeks improves bow tremor during archery movements. Participants were 20 male college students. First, we measured the tremor during side bridges performed with trunk inclinations of 25°, 40°, 55°, and 70° using an accelerometer attached to the elbow joint and identified low-tremor side bridges. The participants were then randomly divided into intervention and non-intervention groups, and the low-tremor side bridges were performed for 4 weeks. The effect of the intervention was determined by measuring the total tremor value using an accelerometer attached to the bow and changes in the median power frequency (MdPF) of the middle deltoid, upper trapezius, and lower trapezius. This intervention reduced the bow tremor and the median power frequency of the middle deltoid (p < 0.05). The findings suggested that the tremor during the archery sighting phase could be reduced by performing side bridges with a specific trunk angle for a certain period of time. This intervention was also shown to reduce the intermediate frequency of the middle deltoid. The reduced tremor can shorten the sighting phase, which can facilitate injury prevention.

만성 엉덩관절 통증 환자에게 슬라이더를 이용한 원 레그 스쿼트가 엉덩관절 근력 및 Q각에 미치는 영향

This study aimed to identify the effect of one-leg squat using a slide on hip strength, and Q angle in patients with chronic hip joint pain patients. Thirty participants subjects were recruited for this study. The experimental group applied one-leg squat using a slide and performed to intervention 3 times a week, 4 weeks, 3 sets of 10 times were performed. All participants have measured hip strengths, and Q angle in before and after the intervention. After the interventions, experimental group showed greater improvement in side bridge, hip abduction, external rotation, extension strength and Q angle than in the pre-test (p<.05). This study shows that one-leg squat using a slide improved hip strengths and Q angle in patients with chronic hip joint pain. These findings suggest that the one-leg squat using a slide has a potential for benefits on hip strengths and Q angle.

Effect of Yoga and Pilates exercises on lumbar spine physical parameters in healthy women

Purpose: In this study, it was aimed to examine the physical effects of participation in a Yoga and Pilates-based exercise program on the endurance and flexibility of the spine in order to protect the health of the lumbar region in healthy women.&#x0D; Methods: A total of 40 healthy women with a mean age of 41.62±6.91 years were included in the study. Participants were divided into two groups as Yoga and Pilates groups randomly. Both groups participated in an exercise program for 45 minutes a day, two days a week for 12 weeks. Sit and reach test was used to evaluate flexibility, and curl up, Static back endurance test and horizontal side bridge building test were used to evaluate endurance. &#x0D; Results: When both exercise groups were compared before and after treatment, statistically significant difference was found in favor of post-treatment in all measurements (p0.05). &#x0D; Conclusion: According to the results of our study, it was determined that both exercise types improved both flexibility and muscle endurance performance. However, it was seen that Yoga and Pilates exercises were not superior to each other in terms of flexibility and endurance. Both Yoga and Pilates exercise methods can be used safely to protect and improve general health and especially lumbar region health.

Effect of Fatigue on the Core Muscle Endurance in Female Athletes With and Without Non-specific Chronic Low Back Pain

Purpose: Non-specific chronic low back pain (LBP) is the most common type of chronic LBP and a common debilitating condition, especially in athletes, that can also affect performance. The core muscles are necessary to create a stable level of support for sports performance and appropriate movements of all organs, and its deficiency is related to complications, such as LBP. This research aims to investigate the effect of a fatigue protocol on core muscle endurance in athletes with and without non-specific chronic LBP. Methods: A controlled laboratory study was conducted; 42 female athletes with and without non-specific chronic LBP were selected through convenience sampling method and divided into two groups with non-specific chronic LBP and without non-specific chronic LBP. McGill’s core endurance test was used to measure core muscle endurance. The measurements were done before and after the implementation of the functional core fatigue protocol (FCFP). SPSS software, version 22 and dependent t-tests and analysis of covariance (ANCOVA) were used to evaluate mean differences obtained in the two groups. The significance level was considered 95%, and the α level was ≤0.05. Results: The analysis of covariance (ANCOVA) showed a significant difference between the two groups with and without non-specific chronic LBP after performing the functional core fatigue protocol (FCFP) in McGill’s test scores in isometric flexion exercise (P=0.001), isometric extensor exercise (P=0.001), right side bridge (P=0.001) and left side bridge (P=0.001). In the post-test measurement, the endurance of the core muscles decreased in the LBP group. Conclusion: The findings revealed that fatigue can affect the core stability and reduce the core muscles endurance of female athletes with non-specific chronic LBP. Therefore, core muscle weakness can be recognized as a risk factor for chronic LBP, and in order to prevent this damage, it is recommended to strengthen this area in rehabilitation programs.

Flattop Modulation Technique for a Low-Device Count Single-Stage AC-DC DAB Converter to Improve Its Overall Efficiency

This article proposes a flattop modulation technique for a single-stage, single-phase bidirectional ac-dc dual-active-bridge (DAB) converter for achieving a flattopped DAB inductor current. The flattopped DAB inductor current has a low root mean square (rms) value, and it improves the soft-switching performance of the converter. The novelty of the proposed technique is that it guarantees flattopped DAB inductor current throughout the ac line cycle and has direct control over the ac current. In this technique, sinusoidal pulse width modulation (PWM) is performed at the ac side bridge for direct ac current control. Sinusoidal phase shift modulation is performed at the dc side to generate a bridge output voltage with a pulsewidth identical to the ac side bridge. The high-frequency (HF) transformer turns ratio is appropriately selected to match the voltages at the DAB inductor’s ends. Thereby, flattop DAB inductor current is achieved throughout the line cycle. The proposed modulation technique ensures a regulated dc bus at the ac side and provides a ripple-free ac current by interleaving. The operation of the converter under the flattop modulation technique is analyzed in detail, and parameter design guideline is provided. Experimental results from a 2-kW converter prototype support the theoretical claims.

Lumbar Kinematics Assessment of Patients with Chronic Low Back Pain in Three Bridge Tests Using Miniaturized Sensors.

Lumbar muscle atrophy, diminished strength, stamina, and increased fatigability have been associated with chronic nonspecific low back pain (LBP). When evaluating patients with LBP, trunk or core stability, provided by the performance and coordination of trunk muscles, appears to be essential. Several clinical tests have been developed to identify deficiencies in trunk performance, demonstrating high levels of validity and reproducibility. The most frequently prescribed tests for assessing the core body muscles are the prone plank bridge test (PBT), the side bridge test (SBT), and the supine bridge test (SUBT). However, quantitative assessments of the kinematics of the lumbar spine during their execution have not yet been conducted. The purpose of our study was to provide objective biomechanical data for the assessment of LBP patients. The lumbar spine ranges of motion of 22 healthy subjects (Group A) and 25 patients diagnosed with chronic LBP (Group B) were measured using two inertial measurement units during the execution of the PBT, SUBT, and SBT. Statistically significant differences between the two groups were found in all three tests' kinematic patterns. This quantitative assessment of lumbar spine motion transforms the three bridge tests into an objective biomechanical diagnostic tool for LPBs that may be used to assess the efficacy of applied rehabilitation programs.

Relationship between Cross-Sectional Area and Function of Core Muscles: An MRI Study

Background Particular attention has been paid to the core muscles because they serve as a muscular corset that works as a unit to stabilize the body and spine. Training programs for improving core stability often target improving core strength and endurance. Increased muscle size is also an expected effect of training programs. However, the relationship between core muscle cross-sectional area (CSA) and strength, stability, and clinical core test scores has not been identified. Purpose To investigate the relationship between core muscle CSA and muscle functions (strength, endurance, and stability). Study design A cross-sectional study Methods Fifty healthy participants (24 men, 26 women) participated in this study. The CSA of core muscle was measured using MRI. Maximal isometric trunk flexor strength, endurance, the score of double leg loading test were used to measure core muscle function. The relationship between core muscle CSA and muscle function was examined by Pearson’s correlation coefficient and Spearman rho correlation coefficient. Results Maximal isometric trunk flexor strength and side bridge strength were positively correlated with core muscle CSA. The isometric endurance test scores also showed a positive correlation with core muscle CSA except for the score of trunk flexor endurance test. Conclusions Only core strength showed moderate to excellent correlation with core muscle CSA. These findings indicate that core training to achieve muscle hypertrophy could lead to improved core strength but not core endurance.

Effects of Core Stability Training on Functional Movement Patterns in Tennis Players.

The aim of this study was to assess the effects of a six-week core stability training program on the fundamental movement pattern assessed using the Functional Movement Screen Test in tennis players. The study group consisted of 160 subjects (74 women, 86 men) with a mean age of 20.26 ± 1.55. The Functional Movement Screen Test (FMS™), as well as the core stability tests including the lateral trunk muscles endurance test (the side bridge test), the abdominal muscles endurance test and the trunk extensors muscle endurance test—were used to evaluate the effects of core stability training. Statistical analysis revealed significant differences in the FMS test scores before and after introducing a core stability exercise program. Initially, the average total score of the FMS test in female tennis players was 14.58 ± 2.91, and after core stability training it was 17.20 ± 1.68 (p < 0.001). In the male group, the total FMS test score was 14.44 ± 2.76 before and 16.91 ± 1.36 after (p < 0.001) in the final assessment. Additionally, statistically significant differences were observed in the core stability test scores before and after introducing a stabilisation training program. The results of the study showed that specific core strengthening exercises could improve the FMS test scores in adult tennis players. This may also have an influence on reducing injury risk in this group, although further studies would be required to test this.

Lipid and metabolic alteration involvement in physiotherapy for chronic nonspecific low back pain

BackgroundChronic nonspecific low back pain (cNLBP) is a common health problem worldwide, affecting 65–80% of the population and greatly affecting people’s quality of life and productivity. It also causes huge economic losses. Manual therapy (MT) and therapeutic exercise (TE) are effective treatment options for cNLBP physiotherapy-based treatment. However, the underlying mechanisms that promote cNLBP amelioration by MT or TE are incompletely understood.MethodsSeventeen recruited subjects were randomly divided into an MT group and a TE group. Subjects in the MT group performed muscular relaxation, myofascial release, and mobilization for 20 min during each treatment session. The treatment lasted for a total of six sessions, once every two days. Subjects in the TE group completed motor control and core stability exercises for 30 min during each treatment session. The motor control exercise included stretching of the trunk and extremity muscles through trunk and hip rotation and flexion training. Stabilization exercises consisted of the (1) bridge exercise, (2) single-leg-lift bridge exercise, (3) side bridge exercise, (4) two-point bird-dog position with an elevated contralateral leg and arm, (5) bear crawl exercise, and (6) dead bug exercise. The treatment lasted for a total of six sessions, with one session every two days. Serum samples were collected from subjects before and after physiotherapy-based treatment for lipidomic and metabolomic measurements.ResultsThrough lipidomic analysis, we found that the phosphatidylcholine/phosphatidylethanolamine (PC/PE) ratio decreased and the sphingomyelin/ceramide (SM/Cer) ratio increased in cNLBP patients after MT or TE treatment. In addition, eight metabolites enriched in pyrimidine and purine differed significantly in cNLBP patients who received MT treatment. A total of nine metabolites enriched in pyrimidine, tyrosine, and galactose pathways differed significantly in cNLBP patients after TE treatment during metabolomics analysis.ConclusionOur study was the first to elucidate the alterations in the lipidomics and metabolomics of cNLBP physiotherapy-based treatment and can expand our knowledge of cNLBP physiotherapy-based treatment.

Effects of a 6 week core strengthening training on measures of physical and athletic performance in adolescent male sub-elite handball players.

The objective was to investigate the effects of a 6-week core strengthening training within the regular handball training sessions compared to regular handball training only. Male sub-elite handball players were randomly assigned to an intervention (INT: n = 13; age: 16.9 ± 0.6 years) or a control (CON: n = 13; age: 17.2 ± 0.8 years) group. The INT group performed the "big 3" core exercises cross curls-up, side bridge (both sides), and the quadrupedal stance ("birddog exercise") triweekly for 20-30 min while the CON group conducted regular handball training only. Pre- and post-training assessments included measures of muscular endurance (Closed Kinetic Chain Upper Extremity Stability Test [CKCUEST] and the Bourban test), shoulder mobility/stability (Upper Quarter Y Balance [YBT-UQ] test), and throwing velocity. The ANCOVA revealed significant differences between means in favour of the INT group for the dorsal chain (p < 0.001, = 0.46) and the lateral chain (left side: p = 0.015, = 0.22; right side: p = 0.039, = 0.17) of the Bourban test, the composite score (p = 0.024, = 0.20) of the throwing arm reach and the inferolateral reach direction (p = 0.038, = 0.17), and the composite score (p = 0.027, = 0.19) of the non-throwing arm reach of the YBT-UQ. However, performance in the CKCUEST and throwing velocity did not show any group-specific changes. Therefore, 6 weeks of core strengthening training were effective in improving some components of physical but no handball-specific athletic (i.e., throwing velocity) performance in adolescent male sub-elite handball players. Practitioners may still opt for this training regimen when stimulus variability is sought or when a low load/low movement approach (e.g., during rehabilitation) is favoured.

Eight weeks of core stability training improves landing kinetics for freestyle skiing aerials athletes.

This study aimed to analyze the effect of 8weeks of core stability training on core stability performance in aerials. Participants were randomly assigned to a control group (CG; n = 4male + 5female; age 15.89 ± 1.54years; height 163.11 ± 6.19cm; weight 55.33 ± 5.07Kg) and a training group (TG; n = 4male+5female; age 16.11 ± 2.47years; height 161.56 ± 5.25cm; weight 57.56 ± 8.11Kg). Body shape, the performance of core stability, and landing kinetics were measured after 8weeks of core stability training. Independent sample t-tests were used to compare baseline values between groups. A two-way repeated-measures analysis of variance (ANOVA) (time × group) was used. The TG improved body shape, and waist circumference (t = -2.333, p = 0.020). Performance of core stability, squat (t = -4.082, p = 0.004), trunk flexion isometric test (t = -4.150, p = 0.003), trunk lateral bending isometric test (t = -2.668, p = 0.008), trunk rotation isometric test (t = -2.666, p = 0.008), side bridge (t = -2.666, p = 0.008), back hyperextension (t = -4.116, p = 0.003), single foot triple jump (t = -4.184, p = 0.003), and single-leg balance with eyes closed (t = 4.167, p = 0.003). Performance in landing kinetics, End/Phase (t = -4.015, p = 0.004), sagittal axes (t = -4.598, p = 0.002), frontal axis (t = 3.116, p = 0.014), peak power hip changing range (t = 2.666, p = 0.017), peak power knee changing range (t = 2.256, p = 0.049). Core stability training leads to improvements in body shape, the performance of core stability, and landing kinetics. Therefore, these improvements can improve the sporting performance in aerials competitions.

Disability Associated with Shoulder Pain during Life Span of Competitive Swimmers; A Cross-sectional study

Background: The occurrence of shoulder pain among competitive swimmers is bizarre, but no strategy exists to diminish shoulder injuries in swimmers. Objective: To assess the disability associated with shoulder pain across the lifespan of competitive swimmers. Methods: A cross-sectional study including 58 swimmers who were selected based on inclusion criteria for this study from different swimming centers in Lahore, Pakistan. The questionnaire consisted of a total of 28 questions, 24 questions on Penn shoulder score and 4 questions on disability of arm, shoulder and hand questionnaire score and a diagnostic side bridge test was assessed 2 times by each participant to check endurance. Manual muscle testing was performed bilaterally on the serratus anterior, middle trapezius and lower trapezius muscles. Means and standard deviations were calculated for quantitative variables while frequency and percentages were used for qualitative variables. Chi-square was estimated to find the association between disability and shoulder pain. Results: There were 21 (36.2%) males and 37 (63.2%) females participated in the study. This showed that hand dominance affects the ability of competitive swimmers. For the side bridge average time, left and right hand, the p-value was &lt;0.001 which was statistically significant. Conclusion: This study concludes that disabilities are associated with shoulder pain across the lifespan of competitive swimmers. Pain and discomfort in the shoulder is the main risk factor among competitive swimmers that can ultimately lead to the disability of the extremity. As only a few participants were fully satisfied with the current level of their shoulder functioning.

Energetic, bio-oil, biochar, and ash performances of co-pyrolysis-gasification of textile dyeing sludge and Chinese medicine residues in response to K2CO3, atmosphere type, blend ratio, and temperature

Hazardous waste stream needs to be managed so as not to exceed stock- and rate-limited properties of its recipient ecosystems. The co-pyrolysis of Chinese medicine residue (CMR) and textile dyeing sludge (TDS) and its bio-oil, biochar, and ash quality and quantity were characterized as a function of the immersion of K2CO3, atmosphere type, blend ratio, and temperature. Compared to the mono-pyrolysis of TDS, its co-pyrolysis performance with CMR (the comprehensive performance index (CPI)) significantly improved by 33.9% in the N2 atmosphere and 33.2% in the CO2 atmosphere. The impregnation catalyzed the co-pyrolysis at 370°C, reduced its activation energy by 77.3 kJ/mol in the N2 atmosphere and 134.6 kJ/mol in the CO2 atmosphere, and enriched the degree of coke gasification by 44.25% in the CO2 atmosphere. The impregnation increased the decomposition rate of the co-pyrolysis by weakening the bond energy of fatty side chains and bridge bonds, its catalytic and secondary products, and its bio-oil yield by 66.19%. Its bio-oils mainly contained olefins, aromatic structural substances, and alcohols. The immersion of K2CO3 improved the aromaticity of the co-pyrolytic biochars and reduced the contact between K and Si which made it convenient for Mg to react with SiO2 to form magnesium-silicate. The co-pyrolytic biochar surfaces mainly included -OH, -CH2, C=C, and Si-O-Si. The main phases in the co-pyrolytic ash included Ca5(PO4)3(OH), Al2O3, and magnesium-silicate.

Side-To-Side Difference in Electromyographic Activity of Abdominal Muscles during Asymmetric Exercises.

A side-to-side difference in the muscle size of the rectus abdominis has been suggested to increase the strain injury risk. Attenuating the difference in size of the rectus abdominis may decrease the injury risk. To explore ways to highly activate one side of the rectus abdominis, we aimed to clarify the activity levels of both sides of the muscle during asymmetric abdominal exercises. Fifteen male sprinters performed the following five asymmetric exercises for the right and left sides: (i) sit-up twist, (ii) oblique leg raise, (iii) side bridge, (iv) side bridge roll out with the elbow, and (v) side bridge roll out with the foot. Side bridge roll out with the elbow and that with the foot were performed using a wheeled platform. During the exercises, electromyographic signals were recorded bilaterally from the upper, central, and lower portions of the rectus abdominis. We calculated the root mean square of electromyograms during the concentric and eccentric phases of the exercises and normalized to that during maximal voluntary contractions. In all portions of the rectus abdominis, the root mean squares of electromyograms were significantly higher in the moving side than in the non-moving side during the concentric and eccentric phases of the side bridge, the side bridge roll out with the elbow and that with the foot (all p < 0.01), but not in sit-up twist or oblique leg raise. The root mean squares of electromyograms of all portions of the rectus abdominis in the moving side were significantly higher in the side bridge roll out with the elbow and that with the foot than in the side bridge during both phases (all p < 0.01). The results suggest that the application of the wheeled platform to side bridge is useful to highly activate one side of the rectus abdominis.

Synchronization Strategy Based on Resonant Current Detection for Bidirectional Wireless Charging System

Bidirectional wireless power transfer (BWPT) greatly improves the reliability of power supply. However, wireless communication between the primary and pickup controllers is usually required to transmit load information, which has time delay and is easily interfered by electromagnetic fields. Existing solutions to avoid the use of communication can be divided into three categories: additional DC/DC circuit, primary side bridge control and secondary side bridge control. Compared with the other two methods, the secondary side bridge control has low loss and good robustness. But it usually requires Phase-Locked Loop (PLL) to eliminate the frequency error between primary and secondary side bridges, which increases the complexity. In this paper, a constant current control strategy without communication is proposed. It is based on the secondary side bridge control and the switching sequence of the secondary side bridge is periodically synchronized according to the phase of the resonant current. It works robustly without the need for additional hardware such as PLL or Multiplier. The harmonic sensitivity analysis, parameter optimization design and stability analysis are carried out to improve the control efficiency. Experimental results based on a 1kW prototype with dual LCC resonant network are presented to verify the effectiveness of the proposed control strategy.