The importance of sensory-motor control in providing core stability: implications for measurement and training

Does pelvic floor and abdominal muscle function and the synergy between these muscles change in young and older women with urinary incontinence?

AIM

The aim of this study was to examine the synergistic relationship between the pelvic floor muscles (PFM) and abdominal muscles in older women with urinary incontinence (UI). Our secondary aim is to compare PFM and abdominal muscle functions and synergistic relationship according to incontinence type in younger and older women.

MATERIAL AND METHODS

This cross-sectional study was conducted with 46 older and 31 younger women. Urogenital Distress Inventory (UDI-6) and Over Active Bladder-Validated 8 (OAB-V8) were used to evaluate the severity of participants' urinary symptoms, and the Incontinence Impact Questionnaire (IIQ-7) was used to evaluate the quality of life related to the symptoms. PFM function was evaluated by superficial electromyography (EMG) and digital palpation; abdominal muscle function was evaluated by EMG.

RESULTS

The average ages of the participants in the younger and old female groups were 49.74 ± 7.25 years and 74.87 ± 5.41 years, respectively. PFM endurance (p = 0.005), number of fast repetitions (p = 0.073) and work average value of the participants in the older women group were found to be lower than those in the younger women group (p = 0.002). In the group of older women with mixed incontinence (MUI), PFM endurance (p = 0.022), PFM (p = 0.002), Transversus abdominis (TrA) (p = 0.007), rectus abdominis (RA) (p = 0.015), internal oblique (IO)(p = 0.002) and external oblique (EO) abdominal muscles (p = 0.001) work average values ​​were significantly lower. In the younger women group with urge incontinence (UUI), the PFM work average value was higher than in the older women group (p = 0.021). During PFM contraction, a moderate positive correlation was found between PFM and RA (r = 0.498, p = 0.001), IO (r = 0.405, p = 0.006) and EO (r = 0.442, p = 0.002) in the older women group.

CONCLUSION

This study showed that older women with UI demonstrated reduced PFM endurance, fewer fast PFM contractions, and lower PFM and abdominal muscle activity compared to younger women with UI. A positive association was observed between the PFM and the RA, IO, and EO muscles specifically in older women with UI. Importantly, our findings indicate that both PFM and abdominal muscle function decline with age in women, irrespective of UI status, leading to a worsening of related symptoms. Consequently, we recommend the implementation of preventive physiotherapy and rehabilitation programs beginning at a young age to preserve and optimize PFM and abdominal muscle function in women.

Effects of age/gender profiles and physical activity level on symmetry of lumbar muscle activation in pain-free older adults during various spinal movements

BACKGROUND

Back muscles simultaneously drive spinal movements and stabilize the trunk. Paraspinal muscle activity is presumed to be symmetric and gender-insensitive, and more activated with aging to protect the spine during functional tasks.

RESEARCH QUESTION

Does over-activated and asymmetric behaviors exist in the pain-free elderly population which is affected by their physical activity levels?

METHODS

Forty healthy participants (aged 64.8 ± 9.9 years, 20 males and 20 females) were recruited for this cross-sectional study. They completed the International Physical Activity Questionnaire (IPAQ) to quantify their self-reported physical activity measures including the total physical activity in MET-min/week and time spent sitting. Surface electromyographic activity of bilateral paraspinal muscles at L3 level was measured. Subjects were instructed to perform functional tasks including symmetric movements as well as right- and left-side rotation/bending. Asymmetry in muscle activation between the two sides was calculated. A multiple linear regression model was used to assess the association of muscle activations with age and gender. Pearson correlation analysis was used to verify the relationship between the asymmetry and physical activity measures.

RESULTS AND SIGNIFICANCE

The results showed a downtrend of paraspinal muscle activations with aging and the decreasing rate could differ between genders. Left-side muscle activations were generally higher than those of the right-side muscles. Muscle asymmetrical activation correlated with sitting time but not total physical activity. This study highlighted aging and gender effects on the paraspinal muscle activations as well as muscle imbalance during different movement paradigms. Future work is needed to verify the underlying mechanism for declining and asymmetrical muscle activation and its link to back disorders.

Synchronous and asynchronous remote core stability exercises in patients with axial spondyloarthritis: a randomized-controlled clinical trial

BACKGROUND

Exercise is a key component of axial spondyloarthritis (axSpA) management. As telerehabilitation has become a viable solution for delivering remote care, the effectiveness of core stability exercises via this method remains under-researched.

AIM

To compare the effects of telerehabilitation-based synchronous versus asynchronous core stability exercises on core muscle endurance, spinal mobility, disease activity, physical function, and quality of life in patients with axSpA.

METHODS

Forty-four patients with axSpA were randomly assigned to a synchronous exercise group (n = 22, 14 females) performing real-time exercises supervised by a physiotherapist, or an asynchronous group (n = 22, 10 females) following pre-recorded exercise videos. Core endurance tests, Bath Ankylosing Spondylitis Disease Activity (BASDAI), Bath Ankylosing Spondylitis Functional (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Ankylosing Spondylitis Quality of Life Scale (ASQoL), and functional mobility tests (timed-up-and-go and chair stand tests) were used to assess outcomes. Perceived change was evaluated at post-treatment using the 5-point Global Rating of Change (GRoC) scale.

RESULTS

The synchronous group demonstrated greater changes in core endurance, BASMI, BASDAI, ASQoL, BASFI, and functional mobility tests (p < 0.05) compared to asynchronous group. Asynchronous group displayed improvement only in core endurance, ASQoL, chair stand test, and some BASMI parameters (p < 0.05). Notably, 100% of participants in the synchronous group reported their condition as improved, compared to 50% in the asynchronous group shown by GRoC.

CONCLUSION

Supervised core stability exercises delivered by using a synchronous telerehabilitation program may provide better outcomes compared to unsupervised video-based exercise program.

TRIAL REGISTRATION

This study is prospectively registered at Clinicaltrials.gov (NCT06000072).

The relationship between the functional status of the extremities and "core" stabilization in women with fibromyalgia

Introduction

The aim of this study was to examine the relationship between the functional status of the extremities and "core" stabilization in women with fibromyalgia (FM).

Material and methods

Fifty-seven women with FM were included. The Widespread Pain Index (WPI), Visual Analogue Scale-Pain (VAS-Pain), Symptom Severity Scale (SSS), Fibromyalgia Impact Questionnaire (FIQ), McGill Static endurance tests (trunk flexors endurance, trunk extensors endurance, lateral bridge tests), Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH), grip strength, Lower Extremity Functional Scale (LEFS), chair-stand test, pressure pain threshold and 6-minute walk test (6MWT) were used in evaluation.

Results

The trunk flexors endurance test showed a weak correlation with 6MWT (r = 0.392), DASH (r = -0.347), LEFS (r = 0.328) and WPI (r = -0.289). The trunk extensors endurance test showed a weak correlation with grip strength-right (r = 0.285), DASH (r = -0.301) and LEFS (r = 0.321) and a moderate correlation with grip strength-left (r = 0.407), chair-stand test (r = 0.470) and 6MWT (r = 0.524). The right lateral bridge test showed a weak correlation with grip strength-right (r = 0.271), DASH (r = -0.379), LEFS (r = 0.254), WPI (r = -0.306), average of maximal values of pressure pain threshold (r = 0.316) and average of mean values of pressure pain threshold (r = 0.337); it showed a moderate correlation with grip strength-left (r = 0.418) and 6MWT (r = 0.414). The left lateral bridge test showed a weak correlation with grip strength-right (r = 0.279), chair-stand test (r = 0.276), 6MWT (r = 0.359), DASH (r = -0.294), average of maximal values of pressure pain threshold (r = 0.315) and average of mean values of pressure pain threshold (r = 0.370); it showed a moderate correlation with grip strength-left (r = 0.502) (p < 0.05).

Conslusions

Core muscle endurance is associated with upper and lower extremity functional level and pain parameters in women with FM.

Effects of core stability exercises on balance ability of children and adolescents with intellectual disabilities: A systematic review and meta-analysis

BACKGROUND

Children and adolescents with intellectual disabilities (IDs) are at risk of falls due to balance problems. One way to palliate balance deficits among this population is via core stability exercises. However, comprehensive studies that examine the effectiveness of core stability exercises in improving balance in this target population are lacking.

OBJECTIVE

This study aims to summarise and quantify the effectiveness of core stability exercises in improving the balance of this target population.

METHODS

This study followed PRISMA principles and conducted comprehensive searches in six academic databases (PubMed, Web of Science, Medline, Embase, Scopus, and the Cochrane Library) up to June 2023. The inclusion criteria were established via the PICOS framework. The risk of bias was assessed with the Cochrane risk-of-bias tool, and the certainty of the evidence was assessed via the GRADE approach. The meta-analysis was performed via RevMan 5.4, and for data that could not be pooled via meta-analysis, we used a narrative description of the results of each study.

RESULTS

Six studies of 1078 subjects were included. The findings revealed that core stability exercises improved the dynamic balance of children and adolescents with ID but had no significant effect on static (Hedges' g = 1.32, 95% CI [-0.41 to 3.06]) or static‒dynamic (Hedges' g = 1.35, 95% CI [-0.02 to 2.73]) balance compared with the control groups. The quality of evidence based on the GRADE approach was very low.

CONCLUSIONS

Core stability exercises may improve dynamic balance in children and adolescents with ID, but given the scarcity of studies included, definitive conclusions cannot yet be drawn. Although pooled analyses also highlighted improvements in static and static-dynamic balance with large effect sizes over active control groups, the results were not statistically significant and should be interpreted with caution given the wide confidence intervals. The heterogeneity among the identified studies and the limited number of eligible studies may reduce the reliability of the results, but these findings emphasise the need for additional research in this domain.

The relationship between core endurance, physical activity level and balance in office workers

Objectives. The aim of this study was to evaluate the relationship between core endurance tests and physical activity level, balance, ergonomics and pain in office workers. Methods. The study included 57 office workers who had been employed for at least 1 year. Core endurance was assessed using McGill core endurance tests. Physical activity, balance, pain and ergonomic risks were evaluated with the international physical activity questionnaire (IPAQ), timed up and go (TUG), visual analog scale (VAS) and rapid office strain assessment (ROSA), respectively. Results. A significant correlation was found between balance and static core endurance tests. However, no significant correlation was found between ergonomics and physical activity level and core endurance tests except for trunk extension and prone bridge tests. In addition, there was a significant difference in core endurance tests for patients with and without regular exercise habits. Waist circumference and hip circumference measurements were found to be significantly negatively associated with static core tests. Conclusion. Core endurance was found to be associated with exercise habits, balance, hip and waist circumference and ergonomics in office workers. Improving core endurance may be beneficial for preventing musculoskeletal risks in office workers.

The Multi-Component Structure of Core Strength

BACKGROUND/OBJECTIVES

Core strength diagnostics often focus on measuring core endurance rather than maximal core strength or core power. This study investigates whether core strength can be considered as a general ability that can be measured by a single core strength test or whether it needs to be differentiated into several components.

METHODS

Forty-two adult sports students (nfemale = 20; nmale = 22; age: 24.0 ± 2.9 years; body height: 179.0 ± 9.8 cm; body mass: 75.2 ± 12.7 kg; body fat: 18.0 ± 6.8%) participated in two randomized testing sessions in a laboratory setting. Standard measurements, such as peak rate of force development (pRFD), maximal voluntary contraction (MVC), and holding time, were taken isometrically during four exercises (ventral, dorsal, and lateral right and left).

RESULTS

A principal component analysis (PCA) extracted three principal components from twelve different core strength variables. The three identified components explained 73.3% of the total variance and were labeled as (a) maximal core strength, (b) core endurance, and (c) core power.

CONCLUSIONS

The results suggest three principal components of the core strength construct, as well as their differentiation, may be imperative. These findings should be taken into account in sport science and sports practice as they may be helpful in planning sport-specific diagnostic, performance-oriented training, and injury prevention programs.

Integrating manual therapy into conservative management of a patient with bilateral femoral head avascular necrosis: A case report with a 2-year follow up

BACKGROUND

Femoral head avascular necrosis (AVN) can contribute to substantial functional limitation. Although surgical intervention for advanced staged AVN can be useful, non-surgical interventions to improve functional independence of patients with hip AVN are not well described.

OBJECTIVE

The purpose of this case report is to describe the physical therapy intervention provided to a patient with bilateral hip AVN.

METHODS

The patient was a 56-year-old male presenting to physical therapy with bilateral femoral head AVN. Impairment-based manual therapy, therapeutic exercise, and education were provided to promote decreased pain and improved self-reported function.

RESULTS

The patient completed eight visits over the course of 10 weeks. Clinically significant improvements were noted in pain ratings and functional level as measured by the Lower Extremity Functional Scale and Harris Hip Score. Improvements were maintained at a two-year follow up period.

CONCLUSION

Early identification and physical therapy intervention can contribute to promoting functional independence for patients with bilateral hip AVN. Early intervention could potentially reduce the need for surgical intervention. Further research is necessary to describe with detail the optimal methods to accomplish these goals.

The effects of core muscle fatigue on lower limbs and trunk during single-leg drop landing: A comparison between recreational runners with and without dynamic knee valgus

BACKGROUND

A deficit in neuromuscular trunk control can impact the lower limb motion, predisposing runners to injuries. This deficit may show a greater impact on runners with dynamic knee valgus. This study aimed to compare the effect of core fatigue on kinetic, kinematic, and electromyographic parameters of the trunk and lower limbs during single-leg drop landing between runners with and without dynamic knee valgus.

METHODS

Twenty-seven recreational runners were allocated to the valgus (n = 14) and non-valgus groups (n = 13). They performed the test before and after a fatigue protocol, taking a step forward and landing on the force platform while maintaining balance. The fatigue protocol included isometric and dynamic exercises performed consecutively until voluntary exhaustion. The vertical ground reaction force, the sagittal and frontal plane angles, and the electromyographic activity were evaluated. The integral of electromyographic activity was calculated into three movement phases. ANOVA with repeated measures was used to verify the group, time, and interaction effects.

RESULTS

After fatigue, both groups showed a significant reduction in the minimum (p = 0.01) and maximum (p = 0.02) knee angles in the frontal plane (more dynamic knee valgus) and greater gluteus medius activity (p = 0.05) from the peak of knee flexion to the end of the movement. The valgus group had a greater hip excursion (p = 0.01) and vertical linear shoulder displacement (p = 0.02) than the non-valgus.

CONCLUSION

Our results suggest that core fatigue can impact the local muscle and the distal joint and that the groups presented different strategies to deal with the demand during landing.

Adjacent Vertebral Refracture Prediction Model Based on Imaging Data After Vertebroplasty for Osteoporotic Vertebral Compression Fracture

OBJECTIVES

To establish a predictive model to evaluate the risk of adjacent vertebral refracture (VRF) after percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fracture (OVCF) based on perioperative imaging data.

METHODS

This study was a retrospective cohort study which established a predictive model of VRF after PKP for OVCF. Patients who underwent PKP for OVCF in our hospital between January 2018 and December 2020 were enrolled and divided into a refracture group and normal group. Perioperative imaging data including preoperative bone mineral density (BMD), fatty infiltration (FI%) of paravertebral muscle, sagittal parameters of the spine and pelvis, and recovery rate of vertebral height were collected. The prediction model is obtained by multifactor logistic regression analysis.

RESULTS

A total of 242 patients were included, including 23 cases in the VRF group and 219 cases in the normal group. There were statistical differences in BMD, FI%, recovery rate of vertebral height, and sagittal imbalance between the 2 groups. Receiver operating characteristic curve analysis of continuous variables showed that BMD ≤-2.80, FI% ≥40%, and recovery rate of vertebral height ≥ 10% were the cutoff values. Logistic regression analysis showed that BMD ≤-2.80, FI% ≥40%, and sagittal imbalance were independent risk factors for VRF. The area under the curve according to the predicted probability was 0.85 (P < 0.05). After simplifying the model, the total point of the model was 7 points, with a cutoff value of 5 points.

CONCLUSIONS

The prediction model obtained in this study can predict refracture after PKP for OVCF early and effectively. It has an excellent predictive effect which is suitable for clinicians.

Meta-analysis of the effect of plyometric training on the athletic performance of youth basketball players

Objective

To investigate the effects of Plyometric Training (PT) on the athletic performance of youth basketball players (age 5-17.99) and to provide a theoretical basis for applying PT in basketball training practice.

Method

PubMed, Web of Science, Cochrane Library, EBSCO and other data platforms were searched, and Meta-analysis was performed using STATA 16.0 software.

Result

A total of 24 studies were included, with a sample size of 738 participants. The results showed that PT improved jumping, linear sprinting, change of direction (COD) speed, and balance in youth basketball players (p < 0.05) but did not significantly improve lower limb strength (p > 0.05). The results of subgroup analyses showed that:1) Regarding the effect of PT on different aspects of athletic performance, enhancements were found for vertical jump, 5-10 m, 20-30 m sprinting ability, velocity-oriented and force-oriented COD speed, and dynamic balance ability of youth basketball players. 2) When analyzing different participant subgroups, basketball players aged 5 to 10.99 and 11-14.99 years appeared to improve their jump, sprinting ability, and COD speed through PT training, whereas no improvements in sprinting ability and COD speed were found for players aged 15 to 17.99. Male and female youth basketball players could improve their jumping through PT, in contrast, straight-line sprinting ability and COD speed were significantly improved only by male youth basketball players, and balance ability was significantly improved only by female youth basketball players. 3) Regarding different training protocols, high-frequency PT (>2 times/week) with a low-volume (jumping ≤150 times/week) and Single-type PT (one specific movement) improved only jumping ability. In contrast, low-frequency PT (1-2 times/week) with a high-volume (jumping >150 times/week) and mixed-type PT (varied jumping drills) protocols significantly improved jumping, linear sprinting, COD speed, and balancing abilities.

Conclusion

PT can enhance the jumping, linear sprinting, COD speed, and balance of youth basketball players, but it does not affect lower limb strength. It is recommended that coaches make full use of the training-sensitive periods of young athletes by incorporating low-frequency, high-volume, and mixed-type PT into their regular training routines over the long term.

Adapted Training to Boost Upper Body Sensorimotor Control and Daily Living Functionality in Visually Impaired Baseball Players

Background and Objectives: Vision significantly contributes to postural control, balance, coordination, and body kinematics, thus deeply influencing everyday functionality. Sight-impaired subjects often show upper body anatomofunctional and kinetic chain alterations negatively impacting daily living efficiency and autonomy. The present study aimed to investigate and train, for the first time, upper body sensorimotor control in an Italian blind baseball team to boost global and segmental functionality while contemporarily prevent injuries. Materials and Methods: The whole team underwent a validated test battery using both quantitative traditional tools, such as goniometric active range of motion and muscular/functional tests, and an innovative biofeedback-based device, a Libra proprioceptive board. Consequently, a 6-week adapted training protocol was designed and leaded to improve sensorimotor control and, hence, counteract disability-related deficits and sport-specific overuse syndromes. Results: Statistically significant improvements were observed in all the investigated parameters. Noteworthy, an overall boost of global and segmental stability was detected through an orthostatic dynamic balance enhancement during the Y Balance test (p = 0.01) and trunk multiplanar control improvement on the Libra board (p = 0.01). Concurrently, the comparison of baseline vs. post-intervention outcomes revealed a consistent increase in upper body mobility (p < 0.05 for all the assessed districts), core recruitment (p = 0.01 for all the administered functional tests), and proprioceptive postural control (p = 0.01 for the Libra board validated test). Conclusions: Our findings suggest that a tailored sensorimotor training, conceived and led by an adapted physical activity kinesiologist, may effectively improve upper body functional prerequisites and global proprioceptive control, thus potentially promoting autonomy, quality of life, and physical activity/sport practice adherence in visually impaired individuals.

Prediction of Back Disability Using Clinical, Functional, and Biomechanical Variables in Adults with Chronic Nonspecific Low Back Pain

Background: Researchers are focusing on understanding the etiology and predisposing factors of chronic nonspecific low back pain (CNSLBP), a costly prevalent and disabling disorder. Related clinical, functional, and biomechanical variables are often studied, but in isolation. We aimed to identify key factors for managing CNSLBP by examining the relationship between back disability and related clinical, functional, and biomechanical variables and developed prediction models to estimate disability using various variables. Methods: We performed a cross-sectional correlational study on 100 recruited patients with CNSLBP. Clinical variables of pain intensity (visual analog score), back extensor endurance (Sorenson test), functional variables of the back performance scale, 6 min walk test, and the biomechanical variable C7-S1 sagittal vertical axis were analyzed to predict disability (Oswestry disability index). Results: All variables independently, as well as in multi-correlation, were significantly correlated to disability (p < 0.05). The bivariate regression models were significant between back disability and pain intensity (Y = 11.24 + 2.189x), Sorensen results (Y = 105.48 - 0.911x), the back performance scale (Y = 6.65 + 2.486x), 6 min walk test (Y = 49.20 - 0.060x), and sagittal vertical axis (Y = 0.72 + 4.23x). The multi-regression model showed significant contributions from pain (p = 0.001) and Sorensen results (p = 0.028) in predicting back disability, whereas no significant effect was found for other variables. Conclusions: A multidisciplinary approach is essential not only for the management of but also for the assessment of chronic nonspecific low back pain, including its clinical, functional, and biomechanical characteristics. However, special emphasis should be placed on clinical characteristics, including the intensity of pain and back extensor endurance.

Investigating the effects of core stability training on balance and gait in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Balance disorders are a common concern in people with multiple sclerosis (PwMS). Core stability exercises are recommended as one of the treatment principles of rehabilitation in patients with balance disorders. This systematic review and meta-analysis investigate the effects of core stabilization exercises (CSE) on balance in PwMS.

METHODS

Online databases were searched from 1980 to December 15, 2022, including PubMed/Medline, Scopus, Web of Science, CINAHL, PEDro, Embase, and ProQuest to identify randomized controlled trials (RCTs) investigating the effects of CSE on balance in PwMS. The methodological qualities of the included studies were assessed using the modified Cochrane risk bias tool for randomized trials. Random-effect meta-analyzes were performed on the Berg balance test and Biodex balance system outcomes.

RESULTS

Seven RCTs were included in this study. A total of 379 patients (EDSS<6) were enrolled in the included studies. All researchers had applied CSE within six to ten weeks with the frequency of two to three sessions/week. According to qualitative results, core stability exercise significantly changes the most balanced outcomes. The meta-analyses illustrated that allocated participants to experimental groups had statistically significantly higher Berg balance test scores (standardized mean difference: 1.1; 95 % CI: [0.1, 2.1]) and insignificant lower Biodex score (standardized mean difference: -0.59; 95 % CI: [-1.09, -0.09]) compared to the control groups.

CONCLUSION

Six to ten weeks of CSEs is an effective therapeutic strategy for balance improvement in PwMS that can help improve balance, especially in patients with moderate disability levels (EDSS3.5-6). Further randomized clinical trials are needed to compare the efficacy of CSEs and routine balance training in PwMS.

Tele-assessment of core performance and functional capacity: Reliability, validity, and feasibility in healthy individuals

INTRODUCTION

Many assessment methods are used in physiotherapy to analyze the fitness level and injury risk in athletes, and to determine the general health status and the effectiveness of the treatment applied in patients. Considering the need for telehealth use, it is essential to determine the usability of tests performed as tele-assessment. This study aimed to examine the intra-rater reliability, validity, and feasibility of the tele-assessment version of core strength and endurance and functional capacity assessments in healthy individuals.

METHODS

"Curl-up," "Modified Push-up," "Plank," and "Lateral Bridge" tests were used for core strength and endurance performance assessment, and "Timed Up and Go," "30 second Sit to Stand," and "Functional Reach Test" tests were used for functional capacity assessment in healthy individuals. Participants were evaluated first by tele-assessment, then one hour later on the same day, all assessments were repeated face-to-face procedures by the researchers thus the validity of the tele-assessment method was determined. All tests were applied as tele-assessment one week later to determine the intra-rater reliability of the tele-assessment method. The system usability scale was applied to evaluate the usability of our tele-assessment method.

RESULTS

Eighty healthy people were enrolled. Intraclass correlation coefficients ranged between 0.91 and 0.97 for core performance tests and between 0.95 and 0.97 for functional tests. All tele-assessment versions of the core performance and functional tests were highly correlated with the face-to-face versions.

DISCUSSION

Core strength-endurance and functional tests performed via tele-assessment were reliable, valid, and feasible for practically measuring the performance of healthy young adults. This study supports the tele-assessment versions of these tests.

TRIAL REGISTRATION NUMBER AND TRIAL REGISTER

Clinicaltrials.gov: NCT04899804.

Effect of core strength training on the badminton player's performance: A systematic review & meta-analysis

BACKGROUND

Core strength training (CST) has been shown to improve performance in several sports disciplines. CST is recognized as one of the crucial elements that enhance athletic performance, particularly impacting badminton skills. Despite its popularity as a strength training method among badminton players, there is a lack of comprehensive studies examining the effectiveness of CST on the performance of these athletes.

OBJECTIVE

This study aims to ascertain CST's effects on badminton players' performance.

METHOD

This study followed PRISMA principles and conducted comprehensive searches in well-known academic databases (SCOPUS, Pubmed, CNKI, Web of Science, Core Collection, and EBSCOhost) up to August 2023. The inclusive criteria were established using the PICOS framework. Following their inclusion based on PICOS criteria, the selected studies underwent literature review and meta-analysis. The methodological quality of the assessments was evaluated using Cochrane Collaboration's risk of bias tools bias risk tools and recommendations for a graded assessment, development, and evaluation.

RESULTS

The analysis included participants aged 10-19 years from 13 studies of moderate quality, totaling 208 individuals. The CST intervention s lasted between 4 to 16 weeks, with a frequency of 1 to 4 sessions per week and each session lasting 20 to 120 minutes. Sample sizes across these studies ranged from 8 to 34 participants. According to the meta-analysis, CST significantly influenced badminton performance, particularly in areas of explosive power (ES = 0.03 P = 0.04), front-court skill (ES = 2.53, P = 0.003), and back-court skill (ES = 2.33, P = 0.002).

CONCLUSION

CST enhances badminton players' fitness (strength, power, balance, and stability), in situ (front/back-court) skills, and movement position hitting. However, its effects on speed, endurance, agility, flexibility, and coordination are unclear, revealing a research gap. The precise benefits of CST, especially on flexibility and specific hitting skills (smashes, clears, drives, net shots, crosscourt, push, and lift shots), need more investigation. Additionally, research on CST's impact on female athletes is significantly lacking.

Biofeedback-Based Proprioceptive Training to Improve Functional Prerequisites of Dragon Boating in Breast Cancer Survivors

Breast cancer (BC)-related sequelae drastically impact the psychophysical functioning and quality of life of affected women. Adapted physical activity (APA) has proved to effectively counteract these impairments in a non-medicalized framework. In particular, dragon boats are able to promote body functionality, social interaction, and quality of life in BC survivors, but the literature on specific motor gestures is scarce and practice is still based more on a re-educative perspective than a performative one. In this context, the present longitudinal study investigated the benefits of an adapted biofeedback-based sensorimotor training intervention on upper body functionality in a team of dragon ladies. The 8-week intervention was conceived as integrated dry workout sessions led by an APA kinesiologist and applied a novel sensorized proprioceptive device, such as a Libra board. Post-protocol evaluation revealed a significant improvement in bilateral upper limb mobility, core endurance, and trunk stability along with a distress decrease and quality of life enhancement through validated assessment tools. Our findings suggest that integrating biofeedback-based workout sessions can effectively promote upper body functionality in BC survivors practicing dragon boating. Furthermore, our innovative approach could help spread methodological hints able to boost exercise adherence in this target population, thus counteracting cancer recurrence while promoting overall well-being.

Impact of neuromuscular training including balance, strength and plyometric exercises on static and dynamic balance in high-level male runners with mild intellectual disability

BACKGROUND

This study aims to investigate the impact of neuromuscular training (NMT) on static and dynamic postural balance (PB) among high-level male runners with intellectual disability.

METHOD

Twenty-seven runners were randomly assigned to a NMT group and a control group who maintained their conventional training. Static and dynamic PB were assessed using the centre of pressure (CoP) excursions (in bipedal and unipedal stances under open eyes (OE) and closed eyes (CE) conditions) and the star excursion balance test (SEBT), respectively, at pre-training and post-training.

RESULTS

The NMT group showed significantly (p < 0.05) decreased CoP values and increased SEBT scores at post-training compared to pre-training. The switch from OE to CE did not affect static PB in the bipedal stance, only in the NMT group.

CONCLUSIONS

The NMT was effective in improving static and dynamic PB in runners with intellectual disability. The NMT could reduce visual dependency.

Adverse effects of unilateral transfemoral amputation on para-alpine sit skiers and mitigation methods

OBJECTIVES

This study aimed to evaluate the adverse effects of unilateral transfemoral amputation on neuromuscular and kinematic parameters in alpine sit skiers, and to determine if additional restraints on the human-bucket interface could help mitigate the effects.

DESIGN

Cross-sectional, repeated measures study.

METHODS

Simulated skiing tests were conducted indoors involving 10 skiers with unilateral transfemoral amputation and 10 able-bodied participants. A Paralympic silver medalist performed slalom skiing tests on snow. These tests were conducted with and without additional strapping on the residual limb. Surface electromyography of trunk muscles and athletic performance was measured, and the asymmetry index was calculated.

RESULTS

Athletes were significantly dependent on muscle activation on the dominant side (asymmetry index = 7.8 %-28.3 %, p < 0.05). Worse athletic performance to the dominant side was found based on inclination angles of the indoor board (asymmetry index = -9.8 %, p = 0.014) and outdoor sit ski (-11.1 %, p = 0.006), and distance to the gate poles during skiing turns (18.6 %, p < 0.001). After using additional restraints, the above asymmetry index declined significantly (asymmetry index < 4.5 %, p < 0.05). Furthermore, athletic performance was significantly improved on both body sides by 11.1 %-30.7 % (p < 0.05).

CONCLUSIONS

Unilateral transfemoral amputation caused the dependence on the trunk muscles of the dominant side and the corresponding unilateral poor performance in athletes. Adjusting restraints in the human-equipment interface by additional strapping could mitigate the asymmetry issues and improve athletic performance.

Multi-Scale FC-Based Multi-Order GCN: A Novel Model for Predicting Individual Behavior From fMRI

Predicting individual behavior from brain imaging data using machine learning is a rapidly growing field in neuroscience. Functional connectivity (FC), which captures interactions between different brain regions, contains valuable information about the organization of the brain and is considered a crucial feature for modeling human behavior. Graph convolutional networks (GCN) have proven to be a powerful tool for extracting graph structure features and have shown promising results in various FC-based classification tasks, such as disease classification and prognosis prediction. Despite this success, few behavior prediction models currently exist based on GCN, and their performance is not satisfactory. To address this gap, a new model called the Multi-Scale FC-based Multi-Order GCN (MSFC-MO-GCN) was proposed in this paper. The model considers the hierarchical structure of the brain system and utilizes FCs inferred from multiple spatial scales as input to comprehensively characterize individual brain organization. To enhance the feature learning ability of GCN, a multi-order graph convolutional layer is incorporated, which uses multi-order neighbors to guide message passing and learns high-order graph information of nodal connections. Additionally, an inter-subject contrast constraint is designed to control the potential information redundancy of FCs among different spatial scales during the feature learning process. Experimental evaluation were conducted on the publicly available dataset from human connectome project. A total of 805 healthy subjects were included and 5 representative behavior metrics were used. The experimental results show that our proposed method outperforms the existing behavior prediction models in all behavior prediction tasks.

Effects of proprioception and core stability training on gait parameters of deaf adolescents: a randomized controlled trial

The current study aimed to explore the effects of proprioception versus core stability training over 8 weeks on the gait parameters of deaf adolescents. A total of 20 deaf adolescents were randomized into two groups: one group receiving proprioception training (PT, n = 10), another group receiving core stability training (CST, n = 10), and eleven typically developing adolescents assigned into the control group (CON; n = 11). Gait was recorded by two digital cameras; then, using the Kinovea software, the parameters of gait included: gait velocity, cadence, stride length, stride time, stance time, and swing time were calculated in terms of percentages of the walking cycle. After 8 weeks of PT, no significant differences were observed for all gait parameters between PT and control groups (p > 0.05). Also, after 8 weeks of CST, no significant differences were observed in gait velocity and cadence between the CST and control groups (p > 0.05). However, after 8 weeks of CST, stride length (p = 0.02) was higher in the control group; Stride time (p = 0.03), stance time (p = 0.04) and swing time (p = 0.04) were higher in the CST group. Moreover, after 8 weeks of PT, values showed significant improvements in all gait parameters (p = 0.001). Also, after 8 weeks of CST, values showed significant improvements in gait velocity and cadence (p = 0.001), but no significant differences were observed in other gait parameters (p > 0.05). The findings of this study indicated that PT improved all gait parameters, whereas CST improved gait velocity and cadence. The results of the present study also demonstrated that PT had a greater effect on gait parameters of deaf adolescents compared with CST. It seems that PT induces more training effects than CTS for enhancing gait parameters of deaf adolescents.Trial registration: Clinical trial registry number: IRCT20170312033029N2. URL: https://en.irct.ir/trial/25584 .

Back Extensor Strength as a Potential Marker of Frailty Using Propensity Score Matching and Machine Learning

This study assessed the potential of back extensor strength as an alternative marker of frailty. A total of 560 farmers were included. Computed tomography scans measured fat and muscle mass volumes at the mid-L4 vertebral level. Back extensor strength was measured in a seated posture. Multivariate linear regression was used to analyze the associations between back extensor strength and trunk muscle/fat compositions. The participants were divided into two groups based on back extensor strength. Propensity score matching, multivariate logistic regression, and Extreme Gradient Boosting (XGBoost) were employed to evaluate the relationship between Fried's frailty criteria and back extensor strength. Back extensor strength exhibited positive associations with abdominal muscle volume (r = 1.12) as well as back muscle volume (r = 0.89) (p < 0.05). Back extensor strength was linked to more frail status, such as reduced grip strength, walking speed, and frequent self-reported exhaustion. Multivariate logistic regression indicated that back extensor strength was associated with higher frail status (OR = 0.990), and XGBoost analysis identified back extensor strength as the most important predictor (gain = 0.502) for frailty. The prediction models using grip strength produced similar results (OR = 0.869, gain = 0.482). These findings suggested the potential of back extensor strength as an alternative frailty marker.

The Impact of Core Complex Training on Some Basketball-Related Aspects of Physical Strength and Shooting Performance

Exercises for the core can be categorized as promoting core-stability, core-strength, or functionality, as these are crucial aspects of most sports activities. This study aimed to examine the effects of using core complex training (CCT), complex training (CT), and core exercise (CE) on some aspects of muscle strength and shooting performance in basketball players. The 36 participants were divided into three groups of 12 each, and then the experimental approach was applied to each group. The groups were labeled as follows: the core complex training group (N = 12; age, 18.58 ± 0.67 years; height, 178.08 ± 0.79 cm; weight, 76.42 ± 1.38 kg; training age, 7.42 ± 0.51 years); the complex training group (N = 12; age, 18.50 ± 0.52 years; height, 177.92 ± 1.31 cm; weight, 76.67 ± 1.78 kg; training age, 7.33 ± 0.49 years); and the core exercise group (n = 12; age, 18.42 ± 0.52 years; height, 177.75 ± 1.29 cm; weight, 76.58 ± 1.38 kg; training age, 7.42 ± 0.67 years). For ten weeks, each of the three groups participated in three training sessions every week. This study investigates the impact of core complex training on basketball shooting ability and muscle strength. The eight-week program, consisting of weight training, plyometric exercises, and core exercises, yielded improvements in muscle strength and shooting accuracy. In tests of muscular strength and basketball shooting ability, the CCT group outperformed the CE and CT groups. The F value varied from 3.75 to 58.77, which are function values with a p < 0.05 significance level. The core complex training group exhibited superior muscle strength to that of both the complex training group and the core exercise group, in some areas. This is shown in the results of the javelin quadrathlon medicine ball test, the core muscle strength and stability test, the sit-up abdomen test, the sit-up back test, the standing long jump test, the Sargent jump test, and the shooting test (p < 0.005). Due to the effect of the core complex training program on improving performance efficiency and muscle strength, which affects the results of matches, we have recommended using the proven basic strength training program at other age stages, with the objective of including the concept, importance, and design of compound basic strength training in training programs used by basketball coaches.

Spinal Muscle Thickness and Activation during Abdominal Hollowing and Bracing in CrossFit® Athletes

Exercises that improve muscle activation are essential for maintaining spinal stability and preventing low back pain. The purpose of this study was to compare the effects of abdominal hollowing and bracing on the activation of the core muscles in CrossFit® participants using ultrasound and electromyography (EMG). Twenty-four healthy adults aged 21 to 42 years old with at least two years of CrossFit® experience performed three core stability exercises (plank, side plank, bridge) with abdominal hollowing and bracing. We measured the ultrasound relative thickness of the local core muscles (transversus abdominis, internal oblique, and lumbar multifidus), and the EMG percentage of maximal voluntary contraction (MVC) of the global core muscles (rectus abdominis, external oblique, and iliocostalis lumborum). Analysis of variance tests showed that the relative thickness of the local core muscles was greater (p = 0.016) during hollowing (range from 26.8 ± 5.33 to 88.4 ± 11.9% of rest) than bracing (range from 15.9 ± 3.54 to 61.2 ± 15.9% of rest), while the EMG of the global muscles was greater (p = 0.001) in bracing (range from 24.4 ± 7.30 to 72.5 ± 9.17% of MVC) than hollowing (range from 16.4 ± 3.70 to 56.6 ± 7.65% of MVC). These results indicate that the recruitment of spinal muscles during popular exercises is achieved with both hollowing and bracing. Nevertheless, it appears that hollowing tends to recruit more of the local muscles, whilst bracing recruits more of the global muscles. The grading of the exercises varied between muscles and varied between maneuvers, especially for the surface abdominals and lumbar muscles. CrossFit® practitioners can choose to use either hollowing or bracing to activate their core muscles more selectively or more appropriately, depending on the goal and purpose of the exercise.

Effects of physical training programs on female tennis players' performance: a systematic review and meta-analysis

Background: Tennis is among the world's most popular and well-studied sports. Physical training has commonly been used as an intervention among athletes. However, a comprehensive review of the literature on the effects of physical training programs on female tennis players' performance is lacking. Therefore, this systematic review and meta-analysis aimed to determine the effects of physical training on performance outcomes in female tennis players. Methods: A comprehensive search was conducted on Web of Science, PubMed, SPORTDicus, Scopus, and CNKI from inception until July 2023 to select relevant articles from the accessible literature. Only controlled trials were included if they examined the effects of physical training on at least one measure of tennis-specific performance in female tennis players. The Cochrane RoB tool was employed to assess the risk of bias. The CERT scale was used to examine the quality of program information. The GRADE approach was adopted to evaluate the overall quality of the evidence. The Comprehensive Meta-Analysis software was used for the meta-analysis. Results: Nine studies were selected for the systematic review and seven for the meta-analysis, totaling 222 individuals. The study's exercise programs lasted 6-36 weeks, with training sessions ranging from 30 to 80 min, conducted one to five times per week. Muscle power (ES = 0.72; p = 0.003), muscle strength (ES = 0.65; p = 0.002), agility (ES = 0.69; p = 0.002), serve velocity (ES = 0.72; p = 0.013), and serve accuracy (ES = 1.14; p = 0.002) demonstrated significant improvement following physical training, while no notable changes in linear sprint speed (ES = 0.63; p = 0.07) were detected. Conclusion: Although research on physical training in sports is diversified, studies on training interventions among female tennis players are scarce. This review found that existing training programs yield some favorable outcomes for female tennis players. However, further research with high methodological quality is warranted on the tailoring of specific training programs for female tennis players. There should be more consistent measuring and reporting of data to facilitate meaningful data pooling for future meta-analyses.

Effectiveness of McKenzie approach and segmental spinal stabilization exercises on neck pain in individuals with cervical postural syndrome: An experimental study

BACKGROUND

This study "Effectiveness of Mckenzie approach and segmental spinal stabilization exercises on neck pain in individuals with cervical postural syndrome: an experimental study" was conducted to study and find the effectiveness of Mckenzie approach and segmental spinal stabilization exercises on reduction of pain, correction of rounded shoulder, and disability. Pain, disability, and rounded shoulders are the major limiting factors as it affects the quality of life and reduces efficiency and social participation.

MATERIALS AND METHODS

The study was conducted among 120 individuals with cervical postural syndrome, and fulfilling the inclusion and exclusion criteria was included. The outcome measures were Visual Analogue Scale (VAS), Neck Disability Index (NDI), and Vernier caliper to evaluate pain, functional disability, and rounded shoulder, respectively. Subjects were randomly divided into two groups, Group A and Group B, by using SPSS software. Interventional training was given for 6 weeks to the patients. Group A subjects were given spinal stabilization exercises. Group B subjects were given Mckenzie approach. The statistical analysis was performed using SPSS; pre-test and post-test were used to calculate the results, followed by data presentation and analysis.

RESULT

The result showed that at the end of the 6 weeks on comparison between pre- and post-intervention of Group A and Group B, both the techniques were effective, but group B was significantly effective than Group A.

CONCLUSION

It was noted that McKenzie approach and segmental spinal stabilization exercises were effective on neck pain in individuals with cervical postural syndrome, but on comparing both techniques, Mckenzie protocol is more beneficial than segmental spinal stabilization exercises. The study accepts the alternate hypothesis that there is significant effect of McKenzie approach and segmental spinal stabilization exercises on neck pain in individuals with cervical postural syndrome.

Effects of proprioception and core stability training followed by detraining on balance performance in deaf male students: a three-arm randomized controlled trial

PURPOSE

Children with hearing impairment are unable to speak and may suffer from some physical problems such as weakness in postural performance ability and development. The aim of the current study was to explore the effects of proprioception versus core stability training for an 8-week period followed by a 6-month detraining protocol on the balance performance of deaf students.

MATERIALS AND METHODS

This is a randomized controlled trial design of three groups in blinded evaluators. The study was conducted at the school gym. A total of 30 participants, of male deaf students, were randomized into three groups: (1) one group receiving proprioception training (PT, n = 10), (2), one group receiving core stability training (CST, n = 10) for 8 weeks, and (3), and control group (CON, n = 10). The Balance Error Scoring System (BESS) test and Y-balance test assess static and dynamic balance at pre- and post-training following a 6-month detraining.

RESULTS

Post 8 weeks of training intervention, PT and CST values showed significant improvements in both static (p = 0.001) and dynamic (p = 0.001) balance. Following the 6-month detraining, only the PT group maintained their improvements in both the static and dynamic balance tests (p = 0.348) and the CST group showed decreases in the balance tests (p = 0.034).

CONCLUSIONS

The results indicate that 8 weeks rehabilitation program (PT and CST) is an optimum training modality to enhance balance in deaf students and PT induces more training effects than CST for maintaining training benefits following the detraining. Clinical trial registry number: IRCT20170312033029N2; URL: https://en.irct.ir/trial/25584; Trial Id: 25584; Registration date: 2017-12-08; Study start date; 2017-12-22.

Axial muscle activation provides stabilization against perturbations while running

Incidence of traumatic brain injury is an important hazard in sports and recreation. Unexpected (blind-sided) impacts with other players, obstacles, and the ground can be particularly dangerous. We believe this is partially due to the lack of muscular activation which would have otherwise provided protective bracing. In this study participants were asked to run on the treadmill while undergoing perturbations applied at the waist which pulled participants in the fore-aft and lateral directions. To determine the effect of unexpected impacts, participants were given a directional audio-visual warning 0.5 s prior to the perturbation in half of the trials and were unwarned in the other half of the trials. Perturbations were given during the start of the stance phase and during the start of the flight phase to examine two distinct points within the locomotor cycle. Muscle activity was monitored in axial muscles before, during, and after the perturbations were given. We hypothesized that the presence of a warning would allow for voluntary axial muscle activity prior to and during perturbations that would provide bracing of the body, and decreased displacement and acceleration of the head compared to unwarned perturbations. Our results indicate that when a warning is given prior to perturbation, the body was displaced significantly less, and the linear acceleration of the head was also significantly lessened in response to some perturbations. The perturbations given in this study caused significant increases in axial muscle activity compared to activity present during control running. We found evidence that cervical and abdominal muscles increased activity in response to the warning and that typically the warned trials displayed a lower reflexive muscle activity response. Additionally, we found a stronger effect of the warnings on muscle activity within the perturbations given during flight phase than those given at stance phase. Results from this study support the hypothesis that knowledge regarding an impending perturbation is used by the neuromuscular system to activate relevant core musculature and provide bracing to the athlete.

Sustained activation in basal ganglia and cerebellum after repetitive movement in a non-task-specific dystonia

We previously observed sustained fMRI BOLD signal in the basal ganglia in focal hand dystonia patients after a repetitive finger tapping task. Since this was observed in a task-specific dystonia, for which excessive task repetition may play a role in pathogenesis, in the current study we asked if this effect would be observed in a focal dystonia (cervical dystonia [CD]) that is not considered task-specific or thought to result from overuse. We evaluated fMRI BOLD signal time courses before, during, and after the finger tapping task in CD patients. We observed patient/control differences in post-tapping BOLD signal in left putamen and left cerebellum during the non-dominant (left) hand tapping condition, reflecting abnormally sustained BOLD signal in CD. BOLD signals in left putamen and cerebellum were also abnormally elevated in CD during tapping itself and escalated as tapping was repeated. There were no cerebellar differences in the previously studied FHD cohort, either during or after tapping. We conclude that some elements of pathogenesis and/or pathophysiology associated with motor task execution/repetition may not be limited to task-specific dystonias, but there may be regional differences in these effects across dystonias, associated with different types of motor control programs.

Mediation Effect of Pain on the Relationship between Kinesiophobia and Postural Control: Comparison and Correlations in Individuals with Fibromyalgia Syndrome and Asymptomatic Individuals-A Cross-Sectional Study

Background: Individuals with fibromyalgia syndrome (FM) usually present with a fear of movement (kinesiophobia), which causes their symptoms to be maintained and exacerbated. Kinesiophobia can significantly impact postural control; ascertaining their association is crucial in evaluating and managing individuals with FM. This study aims to (1) compare postural control between individuals with FM and asymptomatic individuals, (2) estimate the relationship between kinesiophobia and postural control in individuals with FM, and (3) evaluate whether pain intensity mediates the association between kinesiophobia and postural control in individuals with FM. Methods: This study enrolled 92 individuals (mean age: 51.52 ± 7.7 years) diagnosed with FM and 106 asymptomatic individuals (mean age: 50.47 ± 6.6 years). The examiners estimated the fear of movement and the intensity of pain utilizing the Tampa scale of kinesiophobia (TSK) scores and the visual analogue scale (VAS), respectively. The postural control variables included anteroposterior (A-P) sway in mm, medio-lateral (M-L) sway in mm, and ellipse area in mm2. Results: The individuals with FM had impaired postural control compared to the asymptomatic individuals (p < 0.001). Kinesiophobia exhibited mild-to-moderate correlations with the postural control variables (nondominant side: A-P sway: r = 0.48, M-L sway: r = 0.49, ellipse area: r = 0.43. Dominant side: A-P sway: r = 0.41, M-L sway: r = 0.33, ellipse area: r = 0.44). The pain intensity significantly mediated the relationship between kinesiophobia and postural control (p < 0.001). Conclusion: Kinesiophobia showed a significant positive relationship with postural control. The individuals with FM with higher TSK scores had decreased postural control. Pain intensity mediated the relationship between kinesiophobia and postural control. These factors must be considered when evaluating and formulating treatment strategies for people with FM.

Optimizing normalization methods of the external oblique: A cross-sectional study

BACKGROUND

Adequate normalization methodology to establish maximum voluntary isometric contraction (MVIC) is needed to compare %MVIC values for core exercise completed until discontinuation. Clinicians can use %MVIC classifications to guide their preventative and rehabilitative exercise interventions.

OBJECTIVE

The aim of this study was to compare %MVIC of the external oblique (EO) between normalization techniques of side-lying lateral trunk flexion and Roman chair lateral trunk flexion.

METHODS

Twenty-two participants completed two MVIC techniques followed by one repetition of the prone bridge plank (PBP), torso elevated side plank (TESP), foot elevated side plank (FESP), dead bug and bird dog. The average %MVIC during the first 5-seconds, last 5-seconds and overall duration of exercise were included for analysis. ANOVA was used to compare normalized %MVIC from each of the 5 exercises between MVIC techniques. Alpha set a priori p= 0.05.

RESULTS

The side-lying table technique yielded no %MVIC values above 100%, while the Roman chair technique produced 7 values above 100%. The largest mean difference between techniques was during the last 5-seconds of the torso elevated side plank (57.87 ± 38.51%MVIC, p< 0.001).

CONCLUSION

The side-lying table technique likely provides the optimal methodology of %MVIC determination.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Application of eccentric training in various clinical populations: Protocol for a multi-centered pilot and feasibility study in people with low back pain and people with multiple sclerosis

Physical activity and exercise are effective approaches in prevention and therapy of multiple diseases. Although the specific characteristics of lengthening contractions have the potential to be beneficial in many clinical conditions, eccentric training is not commonly used in clinical populations with metabolic, orthopaedic, or neurologic conditions. The purpose of this pilot study is to investigate the feasibility, functional benefits, and systemic responses of an eccentric exercise program focused on the trunk and lower extremities in people with low back pain (LBP) and multiple sclerosis (MS). A six-week eccentric training program with three weekly sessions is performed by people with LBP and MS. The program consists of ten exercises addressing strength of the trunk and lower extremities. The study follows a four-group design (N = 12 per group) in two study centers (Israel and Germany): three groups perform the eccentric training program: A) control group (healthy, asymptomatic); B) people with LBP; C) people with MS; group D (people with MS) receives standard care physiotherapy. Baseline measurements are conducted before first training, post-measurement takes place after the last session both comprise blood sampling, self-reported questionnaires, mobility, balance, and strength testing. The feasibility of the eccentric training program will be evaluated using quantitative and qualitative measures related to the study process, compliance and adherence, safety, and overall program assessment. For preliminary assessment of potential intervention effects, surrogate parameters related to mobility, postural control, muscle strength and systemic effects are assessed. The presented study will add knowledge regarding safety, feasibility, and initial effects of eccentric training in people with orthopaedic and neurological conditions. The simple exercises, that are easily modifiable in complexity and intensity, are likely beneficial to other populations. Thus, multiple applications and implementation pathways for the herein presented training program are conceivable. Trial registration: DRKS00020483 (DRKS, German Clinical Trials Register; 24th January 2020 -retrospectively registered; https://www.drks.de/DRKS00020483).

Acute effects of maximal versus submaximal hurdle jump exercises on measures of balance, reactive strength, vertical jump performance and leg stiffness in youth volleyball players

Background: Although previous research in pediatric populations has reported performance enhancements following long-term plyometric training, the acute effects of plyometric exercises on measures of balance, vertical jump, reactive strength, and leg stiffness remain unclear. Knowledge on the acute effects of plyometric exercises (i.e., maximal versus submaximal hurdle jumps) help to better plan and program warm-up sessions before training or competition. Objectives: To determine the acute effects of maximal vs. submaximal hurdle jump exercise protocols executed during one training session on balance, vertical jump, reactive strength, and leg stiffness in young volleyball players. Materials and methods: Thirty male youth volleyball players, aged 12-13 years, performed two plyometric exercise protocols in randomized order. In a within-subject design, the protocols were conducted under maximal (MHJ; 3 sets of 6 repetitions of 30-cm hurdle jumps) and submaximal (SHJ; 3 sets of 6 repetitions of 20-cm hurdle jumps) hurdle jump conditions. Pre- and post-exercise, balance was tested in bipedal stance on stable (firm) and unstable surfaces (foam), using two variables [center of pressure surface area (CoP SA) and velocity (CoP V)]. In addition, the reactive strength index (RSI) was assessed during countermovement maximal jumping and leg stiffness during side-to-side submaximal jumping. Testing comprised maximal countermovement jumps (CMJ). Results: Significant time-by-condition interactions were found for CoP SA firm (p < .0001; d = 0.80), CoP SA foam (p < .0001; d = 0.82), CoP V firm (p < .0001; d = 0.85), and CoP V foam (p < .0001; d = 0.83). Post-hoc analyses showed significant improvements for all balance variables from pretest to posttest for MHJ but not SHJ. All power tests displayed significant time-by-group interactions for countermovement jumps (p < .05; d = 0.42), RSI (p < .0001; d = 1.58), and leg stiffness (p < .001; d = 0.78). Post-hoc analyses showed significant pre-post CMJ (p < .001, d = 1.95) and RSI (p < .001, d = 5.12) improvements for MHJ but not SHJ. SHJ showed larger pre-post improvements compared with MHJ for leg stiffness (p < .001; d = 3.09). Conclusion: While the MHJ protocol is more effective to induce acute performance improvements in balance, reactive strength index, and vertical jump performance, SHJ has a greater effect on leg stiffness. Due to the importance of postural control and muscle strength/power for overall competitive performance in volleyball, these results suggest that young volleyball players should implement dynamic plyometric protocols involving maximal and submaximal hurdle jump exercises during warm-up to improve subsequent balance performance and muscle strength/power.

Trunk Biomechanics in Individuals with Knee Disorders: A Systematic Review with Evidence Gap Map and Meta-analysis

BACKGROUND

The trunk is the foundation for transfer and dissipation of forces throughout the lower extremity kinetic chain. Individuals with knee disorders may employ trunk biomechanical adaptations to accommodate forces at the knee or compensate for muscle weakness. This systematic review aimed to synthesize the literature comparing trunk biomechanics between individuals with knee disorders and injury-free controls.

METHODS

Five databases were searched from inception to January 2022. Observational studies comparing trunk kinematics or kinetics during weight-bearing tasks (e.g., stair negotiation, walking, running, landings) between individuals with knee disorders and controls were included. Meta-analyses for each knee disorder were performed. Outcome-level certainty was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE), and evidence gap maps were created.

RESULTS

A total of 81 studies investigating trunk biomechanics across six different knee disorders were included (i.e., knee osteoarthritis [OA], total knee arthroplasty [TKA], patellofemoral pain [PFP], patellar tendinopathy [PT], anterior cruciate ligament deficiency [ACLD], and anterior cruciate ligament reconstruction [ACLR]). Individuals with knee OA presented greater trunk flexion during squatting (SMD 0.88, 95% CI 0.58-1.18) and stepping tasks (SMD 0.56, 95% CI 0.13-.99); ipsilateral and contralateral trunk lean during walking (SMD 1.36; 95% CI 0.60-2.11) and sit-to-stand (SMD 1.49; 95% CI 0.90-2.08), respectively. Greater trunk flexion during landing tasks in individuals with PFP (SMD 0.56; 95% CI 0.01-1.12) or ACLR (SMD 0.48; 95% CI 0.21-.75) and greater ipsilateral trunk lean during single-leg squat in individuals with PFP (SMD 1.01; 95% CI 0.33-1.70) were also identified. No alterations in trunk kinematics of individuals with TKA were identified. Evidence gap maps outlined the lack of investigations for individuals with PT or ACLD, as well as for trunk kinetics across knee disorders.

CONCLUSION

Individuals with knee OA, PFP, or ACLR present with altered trunk kinematics in the sagittal and frontal planes. The findings of this review support the assessment of trunk biomechanics in these individuals in order to identify possible targets for rehabilitation and avoidance strategies.

TRIAL REGISTRATION

PROSPERO registration number: CRD42019129257.

Muscle Quality and Functional and Conventional Ratios of Trunk Strength in Young Healthy Subjects: A Pilot Study

BACKGROUND

The trunk strength conventional ratio (CR) has been evaluated. However, the functional ratio and the ratio of strength to body weight (BW) or muscle mass (MM) have been poorly explored. Relative strength is a measure of muscle quality.

OBJECTIVES

To analyze the trunk strength ratio normalized by BW and MM and compare the trunk's conventional and functional ratios collected in isokinetic and isometric conditions.

METHODS

Twenty-seven healthy males (21.48 ± 2.08 years, 70.22 ± 7.65 kg) were evaluated for trunk isometric and isokinetic strength using a functional electromechanical dynamometer.

RESULTS

The extensor's strength was greater than the flexors, with a CR of 0.41 ± 0.10 to 0.44 ± 0.10. Muscle quality was higher in eccentric contraction and high velocity for flexors and extensors. The functional flexor ratio (FFR) ranged between 0.41 ± 0.09 and 0.92 ± 0.27. The functional extensor ratio (FER) ranged between 2.53 ± 0.65 and 4.92 ± 1.26. The FFR and FER showed significant differences between velocities when considering the peak strength (p = 0.001) and mean strength (p = 0.001).

CONCLUSIONS

Trunk extensors were stronger than the flexors; thus, the CR was less than one. Muscle quality was higher at a high velocity. Unlike CR, FFR and FER behaved differently at distinct velocities. This finding highlights the need to explore the behavior of the functional ratio in different populations.

Amplitude of Electromyographic Activity of Trunk and Lower Extremity Muscles during Oscillatory Forces of Flexi-Bar on Stable and Unstable Surfaces in People with Nonspecific Low Back Pain

BACKGROUND

Recently, the oscillatory bar has been proposed as a new and effective rehabilitation tool in people with nonspecific low back pain (NSLBP), although its effects on muscular control in this population have not been well documented, especially in lower extremity muscles and different support surface conditions.

OBJECTIVE

This study aimed to evaluate and compare the effects of flexi-bar use on stable and unstable surfaces on electromyographic activity of trunk and lower extremity muscles in healthy persons and those with NSLBP.

MATERIAL AND METHODS

18 healthy men and 18 men with NSLBP participated in this cross-sectional study. The root mean square value of electromyographic activity was calculated in the trunk and lower extremity muscles during 4 different task conditions: quiet standing (QS) or flexi-bar use on a rigid or foam support surface. A repeated measures test was used for statistical analysis.

RESULTS

The results showed that the amplitude activity of almost all muscles was significantly greater during flexi-bar use than in the QS condition (P<0.05). The rectus femoris, tibialis anterior, and gastrocnemius demands were significantly greater on the foam than the rigid surface (P<0.05).

CONCLUSION

This study showed that oscillatory forces caused by flexi-bar use can increase muscle activation in multiple segments (hip and ankle in addition to trunk muscles) that are crucial for postural stability. Furthermore, the foam surface appeared to target the rectus femoris in addition to the ankle muscles. Using a flexi-bar may be helpful in NSLBP rehabilitation, and exercising on a foam surface may enhance additive hip muscle activity in people with NSLBP.

Functional Performance, Leg Muscle Strength, and Core Muscle Endurance in Multiple Sclerosis Patients With Mild Disability: A Cross-Sectional Study

This study aimed to investigate the relationship of sit-to-stand and walking performance with leg muscle strength and core muscle endurance in people with multiple sclerosis (PwMS) with mild disabilities. In this study, 49 PwMS (Expanded Disability Status Scale score = 1.59 ± 0.79) and 26 healthy controls were enrolled. The functional performances, including sit-to-stand and walking performances, were evaluated with the five-repetition sit-to-stand test, timed up and go test, and 6-min walking test. The PwMS finished significantly slower five-repetition sit-to-stand, timed up and go, and 6-min walking test than the healthy controls. In addition, the significant contributors were the weakest trunk lateral flexor endurance for five-repetition sit-to-stand; the Expanded Disability Status Scale score, and the weakest hip adductor muscle for timed up and go; the weakest hip extensor muscles strength for 6-min walking test. The functional performances in PwMS, even with mild disabilities, were lower compared with healthy controls. Decreases in both leg muscle strength and core muscle endurance are associated with lower functional performance in PwMS.

Effects of Eight-Week Circuit Training with Core Exercises on Performance in Adult Male Soccer Players

Core exercises have been widely promoted in the last 25 years. However, the scientific debate about its efficacy for improving individual and team sports performance is still open. Thus, the present study aims to investigate the effects of circuit training with a core exercise program on physical performance in competitive amateur soccer players. The training was conducted during the off-season period, two times per week for 8 weeks. Pre- and post-evaluations were conducted using the following tests: Y-Balance Test (YB), standing long jump (SLJ), medicine ball chest press (MBC), curl-up (CU), and Illinois Agility Test (IAT). A total of 19 adults were divided into an experimental group (EG, n = 11, age 22 years, weight 71.2 ± 4.8 kg, height 174 ± 5.8 cm) and a control group (CG, n = 8, age 22 years, weight 73.2 ± 4.1 Kg, height 176 ± 6.3 cm). The EG showed significant improvements in lower and upper body strength, core endurance and balance, whereas the CG did not report significant changes in the pre- and post-test comparison. Despite study limitations, our positive results show that circuit training with core exercises appears to be a good strategy for performance improvement in adult soccer players.

Differences in trunk and lower extremity muscle activity during squatting exercise with and without hammer swing

Perturbation exercises enhance lower limb and trunk muscles, and adding swing perturbation while loading during exercise might improve muscle activation or strength. This study aimed to check variations in trunk and lower limb muscle activity during conventional isometric squats, and whether it will change with or without swing using the Hammerobics-synchronized squat method. Twelve healthy men participated in this study. Activities for the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, rectus femoris, biceps femoris long head, semitendinosus, gluteus maximus, multifidus, and internal oblique muscles were measured using surface electromyography during a Hammerobics-synchronized squat and conventional isometric squat. Muscle activities were statistically compared between squat methods. Hammerobics-synchronized squats significantly activated the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, semitendinosus, and multifidus muscles, in both phases, compared with the conventional isometric squats. The Hammerobics-synchronized squat exercise can be considered for trunk and foot stability exercise.

Does 8 Weeks of Integrated Functional Core and Plyometric Training Improve Postural Control Performance in Young Rhythmic Gymnasts?

It has been suggested that core stability and plyometric training (CPT) can enhance athletes' postural control. Nevertheless, the effects of an integrated core and plyometric training program on rhythmic gymnastics (RG) performance are unclear. This study aimed to evaluate the effects of an integrated functional CPT program on young rhythmics gymnasts' postural performance. A sample of 44 young female rhythmic gymnasts from a competitive team (age = 10.5 ± 1.8 years) participated in the study. The subjects were randomly divided into a control group and an experimental group. Pre- and posttest design was used. Postural control was assessed using single-leg stance tests and RG-specific balances over a force platform and evaluated by expert RG judges. The experimental group (n = 23) completed an 8-week functional CPT program based on RG technical requirements. Meanwhile, the control group (n = 21) received their usual training sessions. A mixed model of analysis of variance was applied to evaluate the effects of an intrasubject factor and an intersubject factor on each of the dependent variables. After 8 weeks, the experimental group obtained significant better results in some variables of the right support leg with eyes open and left support leg with eyes open single-leg support (p < .01), improvements were also found in some specific RG balances: Arabesque measured on the force platform (p < .01) and the side leg with help balance scored by the judges (p < .01). In conclusion, an integrated functional CPT program improved postural control in young rhythmic gymnasts. Coaches should consider using this CPT to improve RG performance.

Effects of Surface-Type Plyometric Training on Physical Fitness in Schoolchildren of Both Sexes: A Randomized Controlled Intervention

Plyometric training (PT) has been found to be effective for children’s fitness. However, no study has examined the effects of sex on physical fitness adaptations from surface-type PT in children. This study compared the effects of short-term surface-type PT (firm vs. sand) on the physical fitness of schoolchildren of both sexes. Sixty girls (age = 10.00 ± 1.15 years) and sixty boys (age = 10.02 ± 1.12 years) participated in a short-term (4 weeks), randomized and parallel PT design with pre-to-post measurements. Children were divided into two experimental groups (firm group: PT performed on a clay surface, 20 boys and 20 girls; sand group: PT performed on a dry surface of 20 cm deep sand, 20 boys and 20 girls) and a control group (CG, 20 boys and 20 girls). Squat jump, standing long jump, 20 m sprint, 5-10-5 shuttle, dynamic balance, and maximal aerobic velocity were measured at baseline and after intervention. Both experimental groups showed greater pre-post changes in all assessed variables than the CG (p < 0.0001). No significant differences in pre-post changes were observed relative to surface type or sex (p > 0.05). These findings suggest that a twice-weekly PT program induced physical fitness improvements, which may have transfer to health status during childhood. Additionally, surface type and sex did not affect the training-induced changes in physical fitness.

Variability of the Center of Mass in Trained Triathletes in Running After Cycling: A Preliminary Study Conducted in a Real-Life Setting

While the sport of short-distance (Sprint) triathlon provides an opportunity to research the effect of the center of mass (CoM) when cycling and running, much remains to be done. The literature has failed to consistently or adequately report how changes to hand position influence subsequent running as inferred by the magnitude of CoM acceleration. The demands of cycle training in a drops and aerodynamic position followed by running remain unquantified in Sprint Distance triathlon. Thus, far data collected indicate that the cycle to run transition (T2) is important for overall race success. While many age-groupers participate in Sprint Distance triathlon, the lack of T2 based research make comparisons between cycle hand position and ensuing running difficult. The motion of the human body when cycling and running in triathlon can be described by the motion of its CoM in a local coordinate system. Unobtrusive wearable sensors have proven to be an informative resource to monitor the magnitude of CoM accelerations in running. However, the extent to which they are used in cycling is unclear. Therefore, the aim of the present study was to analyse the temporal magnitudes of CoM acceleration when cycling position and cadence is changed and to analyse these effects on running after cycling. Ten recreational triathletes completed two 20 km cycling trials at varied cadence in a drops position (parts of the handlebars that curve outward, CycleDrops) and an aerodynamic position (arms bent, forearms parallel to the ground, CycleAero) immediately followed by a 5 km run at self-selected pace. Torso kinematics by way of CoM acceleration magnitude were captured in a typical training setting using a triaxial accelerometer. CoM acceleration was quantified in m/s2 and variability was measured by the coefficient of variation (CV) and root mean square (RMS). Results from CycleAero indicated that acceleration of the CoM in longitudinal (CV = 1%) and mediolateral directions (CV = 3%) was significantly reduced (p &lt; 0.001) compared to CycleDrops. As for rate of perceived exertion (RPE), a significant difference was observed with triathletes reporting higher values in CycleAero alongside a greater CoM acceleration magnitude in the anteroposterior direction. The CoM varied significantly from RunAero with less longitudinal (CV = 0.2, p &lt; 0.001) and mediolateral acceleration observed (CV = 7.5%, p &lt; 0.001) compared to RunDrops. Although greater longitudinal acceleration was observed in the initial 1 km epoch of RunAero, triathletes then seemingly adjusted their CoM trajectory to record lower magnitudes until completion of the 5 km run, completing the run quicker compared to RunDrops (22.56 min1 ± 0.2, 23.34 min1 ± 0.5, p &lt; 0.001, CV = 1.3%). Coaches may look to use triaxial accelerometers to monitor performance in both cycling and running after cycling.

The human neck is part of the musculoskeletal core: cervical muscles help stabilize the pelvis during running and jumping

During locomotion, cervical muscles must be active to stabilize the head as the body accelerates and decelerates. We hypothesized that cervical muscles are also part of the linked chain of axial muscles that provide core stabilization against torques applied to the hip joint by the extrinsic muscles of the legs. To test whether specific cervical muscles play a role in postural stabilization of the head and/or core stabilization of the pelvic girdle, we used surface electromyography to measure changes in muscle activity in response to force manipulations during constant speed running and maximum effort counter-movement jumps. We found that doubling the mass of the head during both running and maximum effort jumping had little or no effect on (1) acceleration of the body and (2) cervical muscle activity. Application of horizontal forward and rearward directed forces at the pelvis during running tripled mean fore and aft accelerations, thereby increasing both the pitching moments on the head and flexion and extension torques applied to the hip. These manipulations primarily resulted in increases in cervical muscle activity that is appropriate for core stabilization of the pelvis. Additionally, when subjects jumped maximally with an applied downward directed force that reduced acceleration and therefore need for cervical muscles to stabilize the head, cervical muscle activity did not decrease. These results suggest that during locomotion, rather than acting to stabilize the head against the effects of inertia, the superficial muscles of the neck monitored in this study help to stabilize the pelvis against torques imposed by the extrinsic muscles of the legs at the hip joint. We suggest that a division of labor may exist between deep cervical muscles that presumably provide postural stabilization of the head versus superficial cervical muscles that provide core stabilization against torques applied to the pelvic and pectoral girdles by the extrinsic appendicular muscles.

Perturbation-based trunk stabilization training in elite rowers: A pilot study

Introduction

Low back pain is a major health issue in elite rowers. High training volume, frequent flexion movements of the lower spine and rotational movement in sweep rowing contribute to increased spinal strain and neuropathological patterns. Perturbation-based trunk stabilization training (PTT) may be effective to treat neuromuscular deficits and low back pain.

Methods

All boat classes (8+, 4+/-, 2-) of the male German national sweep rowing team participated in this non-randomized parallel group study. We included 26 athletes (PTT: n = 12, control group: n = 14) in our analysis. Physical and Sports therapists conducted 16 individualized PTT sessions á 30–40 minutes in 10 weeks, while the control group kept the usual routines. We collected data before and after intervention on back pain intensity and disability, maximum isometric trunk extension and flexion, jump height and postural sway of single-leg stance.

Results

We found less disability (5.3 points, 95% CI [0.4, 10.1], g = 0.42) for PTT compared to control. Pain intensity decreased similar in both groups (-14.4 and -15.4 points), yielding an inconclusive between-group effect (95% CI [-16.3, 14.3]). Postural sway, strength and jump height tend to have no between- and within-group effects.

Conclusion

Perturbation-based trunk stabilization training is possibly effective to improve the physical function of the lower back in elite rowers.

What are gender differences in lower limb muscle activity during jump-landing tasks? A systematic review and meta-analysis

Background

Gender differences in muscle activity during landing have been proposed as a possible contributing factor to the greater incidence of anterior cruciate ligament injuries in women. Conflicting results among a few studies in this regard makes it impossible to reach correct conclusions.

Objectives

The aim of this study was systematic review and the meta-analysis of previous studies which have compared the electromyographic activity of lower limb muscles in gluteus muscles (maximus and medius), quadriceps (rectus femoris, vastus medialis and lateralis), hamstrings (biceps femoris and semimembranosus), and gastrocnemius in men and women in jump–landing task.

Methods

A systematic search of the PubMed, SCOPUS, Science Direct databases was performed for eligible articles in October 2020. Cross-sectional studies that compared the muscle activity of male and female athletes without a history of previous injury in the jump–landing task were included. Unisex and non-athlete's studies were extracted from the included studies. The data were synthesized using a fixed and random effects model.

Results

Eight studies involving 145 participants were included. All participants were people who participated in regular exercises. The meta-analysis of timing and muscle activity was performed in the feedforward (pre contact) and feedback (post contact) stages. There were no significant differences in the muscle activity of biceps femoris (MD = −12.01; 95% CI − 51.49 to 27.47; p = 0.55; I² = 87%), vastus medialis (MD = −53.46; 95% CI − 129.73 to 22.81; p = 0.17; I² = 91%), semimembranosus (MD = 1.81; 95% CI − 6.44 to 10.07; p = 0.67; I² = 0%), gluteus medius (MD = −3.14; 95% CI − 14.24 to 7.96; p = 0.58; I² = 48%), and rectus femoris (MD = −5.83; 95% CI − 14.57 to 2.92; p = 0.19; I² = 87%) in the pre contact phase between two sexes. There was a significant difference between men and women in the activity of vastus lateralis muscle in the post contact phase (MD = −34.90; 95% CI − 48.23 to − 21.57). No significant difference was observed between the men and women in the timing of semimembranosus (MD = 23.53; 95% CI − 14.49 to 61.54; p = 0.23; I² = 56%) and biceps femoris muscle activity (MD = −46.84; 95% CI − 97.50 to 3.83; p = 0.07; I² = 82%).

Conclusion

The results showed that in all lower limb muscles except vastus lateralis there were no significant differences between muscle activity and muscle contraction timing in both sexes before and after foot contact. Therefore, it can be concluded that the reason for the greater susceptibility of ACL injuries in women than men is maybe related to other factors such as biomechanical and hormonal. Additional good quality research in this regard is required to strengthen these conclusions.

Effect of Six-Week Resistance and Sensorimotor Training on Trunk Strength and Stability in Elite Adolescent Athletes: A Randomized Controlled Pilot Trial

Intervention in the form of core-specific stability exercises is evident to improve trunk stability. The purpose was to assess the effect of an additional 6 weeks sensorimotor or resistance training on maximum isokinetic trunk strength and response to sudden dynamic trunk loading (STL) in highly trained adolescent athletes. The study was conducted as a single-blind, 3-armed randomized controlled trial. Twenty-four adolescent athletes (14f/10 m, 16 ± 1 yrs.;178 ± 10 cm; 67 ± 11 kg; training sessions/week 15 ± 5; training h/week 22 ± 8) were randomized into resistance training (RT; n = 7), sensorimotor training (SMT; n = 10), and control group (CG; n = 7). Athletes were instructed to perform standardized, center-based training for 6 weeks, two times per week, with a duration of 1 h each session. SMT consisted of four different core-specific sensorimotor exercises using instable surfaces. RT consisted of four trunk strength exercises using strength training machines, as well as an isokinetic dynamometer. All participants in the CG received an unspecific heart frequency controlled, ergometer-based endurance training (50 min at max. heart frequency of 130HF). For each athlete, each training session was documented in an individual training diary (e.g., level of SMT exercise; 1RM for strength exercise, pain). At baseline (M1) and after 6 weeks of intervention (M2), participants’ maximum strength in trunk rotation (ROM:63°) and flexion/extension (ROM:55°) was tested on an isokinetic dynamometer (concentric/eccentric 30°/s). STL was assessed in eccentric (30°/s) mode with additional dynamometer-induced perturbation as a marker of core stability. Peak torque [Nm] was calculated as the main outcome. The primary outcome measurements (trunk rotation/extension peak torque: con, ecc, STL) were statistically analyzed by means of the two-factor repeated measures analysis of variance (α = 0.05). Out of 12 possible sessions, athletes participated between 8 and 9 sessions (SMT: 9 ± 3; RT: 8 ± 3; CG: 8 ± 4). Regarding main outcomes of trunk performance, experimental groups showed no significant pre–post difference for maximum trunk strength testing as well as for perturbation compensation (p &gt; 0.05). It is concluded, that future interventions should exceed 6 weeks duration with at least 2 sessions per week to induce enhanced trunk strength or compensatory response to sudden, high-intensity trunk loading in already highly trained adolescent athletes, regardless of training regime.

The Effect of Eight-Week Functional Core Training on Core Stability in Young Rhythmic Gymnasts: A Randomized Clinical Trial

It is suggested that core stability (CS) might improve rhythmic gymnasts’ performance. Nevertheless, the effect of core stability training (CST) in CS performance is not clear. Purpose: Evaluating the effect of an eight-week functional CST on young rhythmics gymnasts’ CS performance. Method: A sample of 45 young female rhythmic gymnasts from a competitive team (age = 10.5 ± 1.8 years, height = 144.1 ± 10.6 cm, weight 38.2 ± 8.9 kg, peak height velocity (PHV) = 12.2 ± 0.6 years) participated in the study. The participants were randomly allocated into the control group (CG) and experimental group (EG) and completed pre-tests and post-tests of specific CS tests using a pressure biofeedback unit (PBU). The CS was assessed by the bent knee fall out (BKFO), the active straight leg raise (ASLR) tests and the pelvic tilt test, all performed on the right and left sides. The EG (n = 23) performed an eight-week functional CST program based on rhythmic gymnastics (RG) technical requirements added to the traditional RG training sessions. Meanwhile, the CG (n = 22) received the traditional RG training sessions. Results: Mixed model analysis showed non-significant interaction effects; however, the ANOVA omnibus test showed a time effect (p < 0.05) in right BKFO (F1,42 = 4.60; p = 0.038) and both pelvic tilt tests (right F1,42 = 22.01, p < 0.001; left F1,42 = 19.13, p < 0.001). There were non-significant interaction effects. The fixed effects estimated parameters for right BKFO showed that both groups had less pressure variation after intervention compared with pre-intervention (β = −1.85 mmHg, 95%CI = [−3.54 to −0.16], t42 = −2.14, p = 0.038). Furthermore, the left pelvic tilt (β = 37.0 s, 95%CI = [20.4 to 53.6], t42 = 4.37, p < 0.001) improved 8.9 s more than the right pelvic tilt (β = 28.1 s, 95%CI = [16.3 to 39.8], t42 = 4.69, p < 0.001) considering both groups together. Conclusions: Adding a functional CST to regular training showed a trend in improving the performance of CS-related variables, which could help improve RG-specific performance. Coaches working with rhythmic gymnasts should consider adding a functional CST to regular training to improve CS performance leading to increased specific RG performance.