Side Step Research Articles

Cutting Technique Modification: A Way to Improve Movement Quality and Develop Agility in Youth?

Abstract Thieschäfer, L, Dos’Santos, T, and Büsch, D. Cutting technique modification: a way to improve movement quality and develop agility in youth? J Strength Cond Res 38(9): 1596–1606, 2024—High-quality cutting technique is essential for agility development and safer cuttings in adolescent athletes. Certain sidestep techniques and kinematics are characteristic of high movement quality and are associated with both, faster performance and lower knee joint loading (i.e., reduced anterior cruciate ligament injury risk). The aim of this study was to determine the effects of a 6-week, side step, technique modification training intervention targeting specific kinematics on agility performance and movement quality. Twenty-two adolescent American football players were recruited for a nonrandomized, controlled, intervention study. For 6 weeks, an intervention group (IG) of 11 players participated in 25-minute cutting technique training sessions integrated into team training twice a week, whereas a control group (CG) of 11 players continued their usual training routine. Agility performance was assessed based on percentage-based change of direction deficit (CODDp) obtained during reactive agility tests at 45° and 90° angles. The Cutting Movement Assessment Score (CMAS) qualitative screening tool was used to assess 2D high-speed videos of the cuts for movement quality. The significance level was set at α = 0.01. The intervention effectively altered players' sidestep technique irrespective of cutting angle with large time × group interaction effects observed for CMAS ( = 0.82). Statistical and practical significant improvements in CMAS pre-to-post intervention were evident in the IG (−2.30 ≤ g ≤ −1.75; 313.87 ≤ BF10 ≤ 2,342.00), whereas deteriorations were found in the CG for 90° (g = 1.38; BF10 = 64.21). However, in both groups, no statistically significant differences in CODDp were observed pre-to-post intervention (0.019 ≤ p ≤ 0.586; 0.34 ≤ BF10 ≤ 3.59). The cutting technique modification training meaningfully improved movement quality, without negatively affecting agility performance, and can be used by practitioners to foster a safe technical foundation for subsequent agility development in adolescent athletes.

Relationships between flexion strength and dexterity of the toes and physical performance.

Toe function is characterised by the strength and dexterity of toe motion. However, previous studies have mostly focused on the importance of toe strength. This study aimed to investigate the relationships between flexion strength and dexterity of the toes and physical performance. Twenty healthy participants were included in this study. The flexion force of each toe was measured using a digital force gauge, and the toe dexterity was evaluated using the marble pick-up and rock-paper-scissors tests. These parameters were statistically analysed in relation to physical performance, including repeated side step and balance ability, which was evaluated using centre of pressure (COP) data during single-leg standing, tiptoe standing, and single-leg drop-jumping. A significant correlation was found between the first toe flexion force and the total trajectory length of the COP during one-leg standing and between the time required for marble pick-up and the rock-paper-scissors score and the COP during single-leg drop-jumping. The results underscore the importance of flexion strength and dexterity of the toes in human physical performance and the necessity for the evaluation and improvement of both functions.

Development of physical test norms for early age Pencak Silat

Background and Study Aim. The evaluation serves as a cornerstone in the continuous improvement of sports, significantly relying on the analysis of measurement data. The primary objective of this research is to develop tailored norms for physical tests specifically designed for early-age Pencak Silat practitioners. Material and Methods. The development of the test consisted of several key stages: design of the instrument, testing of the instrument, and finally, assembly of the instrument. The study included a total of 210 participants, with a breakdown of 111 male and 109 female martial artists. The techniques for data collection involved a variety of tests and measurements. The instruments used in this research included: sit-and-reach test for assessing flexibility, 30-meter sprint for speed evaluation, side step test for agility, sit-ups for abdominal strength, push-ups for arm and chest strength, wall sit test for leg muscle strength, and beep test for cardiovascular endurance. Data analysis was performed using a technique that grouped values into five standard categories, aided by the use of Microsoft Excel. Results. The findings of the study led to the establishment of norms for each component of the physical tests tailored to early-age Pencak Silat practitioners. These components have been classified into five distinct levels: very poor, poor, average, good, and excellent. Conclusions. The outcomes of this research facilitate the development of specific norms for each test item, incorporating weighting for every physical test component. These weightings have been meticulously adjusted in accordance with the primary energy systems utilized in the sport of Pencak Silat.

How robot-assisted gait training affects gait ability, balance and kinematic parameters after stroke: a systematic review and meta-analysis.

Gait ability is often cited by stroke survivors. Robot-assisted gait training (RAGT) can help stroke patients with lower limb motor impairment regain motor coordination. PubMed, Cochrane Library, Embase were systematically searched until September 2023, to identify randomized controlled trials presenting: stroke survivors as participants; RAGT as intervention; conventional rehabilitation as a comparator; gait assessment, through scales or quantitative parameters, as outcome measures. Twenty-seven publications involving 1167 patients met the inclusion criteria. Meta-analysis showed no significant differences in speed, cadence, spatial symmetry, and changes in joint mobility angles between the RAGT group and the control group. In addition, RAGT was associated with changes in affected side step length (SMD=0.02, 95% CI: 0.01, 0.03; P<0.0001), temporal symmetry (SMD=-0.38, 95% CI: -0.6, -0.16; P=0.0006], Six-Minute Walk Test (SMD=25.14, 95% CI: 10.19, 40.09; P=0.0010] and Functional Ambulation Categories (SMD=0.32, 95% CI: 0.01, 0.63; P=0.04). According to the PEDro scale, 19 (70.4%) studies were of high quality and eight were of moderate quality (29.6%). Taken together, the review synthesis showed that RAGT might have a potential role in the recovery of walking dysfunction after stroke. However, its superiority over conventional rehabilitation requires further research. Additionally, it may provide unexpected benefits that the effects of RAGT with different types or treatment protocols were further compared.

Abstract 783: Early impact assessment of in-house EGFR testing for NSCLC in Kenya

Abstract Introduction: Quality of life and survival among non-small cell lung cancer (NSCLC) patients have improved in the last two decades owing mainly to use of tyrosine kinase inhibitors (TKIs) and other targeted therapies. Low and middle-income countries (LMICs) especially in Africa, are lagging in realizing these benefits largely due to hurdles in molecular testing. In addition, quality histology and molecular data from LMICs is deficient. The aim of this study is to assess the immediate impact of improved access to epidermal growth factor receptor (EGFR) testing in Kenya, and to establish a long term-lung cancer data base. Methods: Staring mid-June 2023, an in-house PCR-based method was adopted for EGFR testing of NSCLC in order to side step the challenges of out-of-country send outs which was until then, the only option for EGFR testing. Further, a sponsored access program was created. From prospectively accrued samples, we performed a before-and-after assessment of the number of NSCLC cases intercepted, cost and turnaround times (TAT) as measures of impact. Demographic, histopathology, and EGFR mutation profiles were analyzed in comparison to Asia, USA and European data. Whole slide histology scanned images are made to compliment the database. Results: Over the four-month period, 62 NSCLC cases were accrued, median age at diagnosis was 63 with a range of 24 - 93. The male to female ratio was 1: 1.5. Adenocarcinomas comprised 89%, squamous cell carcinoma 5% and 3% were not classifiable. Metastatic disease was reported in 14 (22%) with the brain being the commonest site. EGFR mutations were identified in 16 (25%) with exon 19 deletions and L858R mutations constituting 94% of them. Monthly requisitions for EGFR have increased 3-fold, and the average TAT has been halved to 7 days. Conclusion: Similarities between our data and global patterns are noted; median age is in the seventh decade, NSCLC is more common in women, and so are the rates of EGFR mutations, adenocarcinomas are the predominant type, and there are high rates of brain metastasis at diagnosis. EGFR mutation rates appear to be higher than USA and European data but lower than Asian data. In-house and sponsored testing has had an immediate impact in reduction of costs and TAT and increased requisitions. Assessment of access to targeted therapy, clinical outcome, survival, expansion of molecular profiling beyond EGFR, and build-up of the database including virtual histology images for exploring artificial intelligence algorithms are our next steps. Citation Format: Allan Njau, Samuel Nguku, Joseph Abuodha. Early impact assessment of in-house EGFR testing for NSCLC in Kenya [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 783.

Voleybolcularda Addüktör Kas Grubuna Uygulanan Kinezyolojik Bantlamanın Endurans, Güç ve Çeviklik Üzerine Akut Etkisi

Objective: This study was conducted to investigate the acute effect of kinesiology taping (KT) to the hip adductor muscle group (AMG) on endurance, strength and agility in female volleyball players (VP). Materials and Methods: Thirty female VP, with an average age of 17.53±2.55 years, who played licensed volleyball for at least two years were included in our study. KT was applied longitudinally to the athletes between the pubis and lower border of the tuberositas tibia, including the AMG using the facilitation technique (25% stretching). Evaluations were repeated before taping and 20 minutes after taping. The athletes' Adductor muscle endurance was evaluated using the Copenhagen adduction exercise, vertical jump test for lower extremity strength, and Edgren side step test for agility. Results: When the results of the study were evaluated, it was found that there was a statistically significant increase in the endurance (p&amp;lt;0.001), strength (p&amp;lt;0.001) and agility (p&amp;lt;0.001) values of the athletes after KT application. Conclusions: KT applied to the adductor area can be used by physiotherapists during competitions or training due to its positive effects on the performance of VP.

Performance enhancement of 3D‐printed carbon fiber‐reinforced nylon 6 composites

AbstractThe inherent defects of the layer‐by‐layer manufacturing process limit the mechanical performance of 3D‐printed composite parts. This paper explores a process optimization method for continuous fiber composites 3D printing to improve the mechanical performance of 3D‐printed CF/PA6 (Carbon Fiber/Nylon 6) parts. First, the effects of printing temperature, printing speed, layer thickness, and side step on the mechanical performance of 3D‐printed CF/PA6 were studied by conducting variable parameter printing experiments. All optimal printing parameters for CF/PA6 were obtained, and their impact mechanisms were analyzed. Second, the coupling effect of temperature and pressure of post‐processing reduced the internal voids of 3D‐printed CF/PA6 and improved its mechanical properties. The influence mechanism of the coupling effect of temperature and pressure was summarized, and the optimal post‐processing parameters applicable to CF/PA6 were obtained. Based on the above process optimization, the fiber volume content of the printed CF/PA6 reached 41.05%, and the bending strength and elastic modulus reached 651.54 MPa and 79.08 GPa, which were 209.05% and 179.53% higher than those before optimization. Moreover, the tensile strength and elastic modulus reached 730 MPa and 29.23GPa, which were 98.10% and 81.10% higher than those before optimization. The experimental results give a positive validation of the effectiveness and feasibility of the proposed methodology.Highlights The effects of printing temperature, printing speed, layer thickness, and side step on the mechanical properties of 3D‐printed CF/PA6 were investigated. The optimal printing parameters applicable to CF/PA6 were obtained and their influence mechanisms were analyzed. The effects of the heat press processing method on the internal voids and mechanical properties of 3D‐printed CF/PA6 were investigated, and the optimal post‐processing parameters applicable to CF/PA6 were obtained. The study resulted in optimal printing parameters and post‐processing parameters for 3D printing CF/PA6, which greatly enhanced its tensile and flexural strength and modulus.

The effect of ladder drill exercises on some physical abilities in male junior high school students

This study aimed to determine the effect of ladder drill 1 foot in each on the upper and lower extremities training carried out for 8 weeks on strength, speed, power, and agility. The type of the study was a quasi-experimental. Ladder drill exercises were carried out with an intensity of 80-90% HRmax, a frequency of 3x/week, for 8 weeks. Strength was measured using back and leg dynamometers, power was measured using the Force Plate/Accupower Test, speed with the 30-meter Running Speed Test, and agility with the Side Step Test. For statistical analysis, the researcher used the Statistical Package for Social Science (SPSS) version 21. The significance level was established at 0.05. The results of the analysis comparing pretest to posttest strength were as follows: strength pretest vs posttest (78.00±21.69 vs 122.10±22.16 seconds; p=0.000). For power, the comparison between pretest and posttest showed (42.40±11.92 vs 60.72±22.16 Joules; p=0.338). In terms of speed, the pretest vs posttest results were (5.13±0.24 vs 5.19±0.23 seconds; p=0.000), and for agility, the comparison between pretest and posttest revealed (15.00±4.35 vs 22.60±3.86 seconds; p=0.000). Executing ladder drill exercises at an intensity ranging from 80-90% of the maximum heart rate (HRmax), with a frequency of three times per week over an eight-week period, resulted in enhanced strength, speed, and agility among male junior high school students. Nevertheless, there was no notable impact observed in the power variable.

Relationship Between the Japanese Physical Fitness Test and the 3-Minute Burpee Test.

Background Japan has conducted a national physical fitness survey every year since 1964, when the first Tokyo Summer Olympics were held. The survey is a test that evaluates eight physical fitness components: speed, total body endurance, instantaneous force, dexterity, muscle strength, muscular endurance, flexibility, and agility, but it requires specialized equipment and space, and it takes time to measure them all. Aims The purpose of this study was to examine the relationship between the 3-minute burpee test (3MBT), which has been reported to be associated with various physical fitness components, and a "new physical fitness test." Materials and methods The relationship between the "new physical fitness test" and the 3MBT was examined in 122 college students (male=70, female=52) with no health problems. Results The "new physical fitness test" and the 3MBT showed a moderate relationship between the 20-m shuttle run (r = 0.685, p < 0.05), side stepping (r = 0.566, p < 0.05), standing long jump (r = 0.545, p < 0.05), grip strength (r = 0.461, p < 0.05), sit and reach (r = 0.305, p < 0.05), and sit-ups (r = 0.572, p < 0.05), indicating a moderate relationship. Because this study used the Pearson product-rate correlation analysis, it is not possible to definitively assert a relationship with physical fitness factors. Conclusions However, the 3MBT is a very useful test because it requires whole-body strength, power, endurance, and aerobic capacity.

Soft Chemistry of Hard Materials: Low-Temperature Pathways to Bulk and Nanostructured Layered Metal Borides.

Conspectus"Synthesis by design" is often considered to be the primary goal of chemists who make molecules and materials. Synthetic chemists usually have in mind a target they want to make, and they want to be able to design a pathway that can get them to that target as quickly and efficiently as possible. Chemists who synthesize refractory solids, which have melting points above 1000 °C and are often chemically inert at these high temperatures, have access to only a small number of synthetic strategies due to the need to overcome solid-state diffusion, which is the rate-limiting step in such reactions. The use of extremely high temperatures to facilitate diffusion among two or more refractory solids, which precedes any chemical reaction that must occur, generally drives the system to form only the product that is the most thermodynamically stable-the global minimum on an energy landscape-for a certain combination of elements. When trying to target a different product in the same system, one generally cannot rely on thermally driven reactions. Lower-temperature reactions that side step this diffusion limitation can succeed where high temperatures fail by providing access to local minima on an energy landscape. These local minima represent metastable phases that are primed for synthesis, but only if an appropriate pathway and set of reactions can be identified. It is therefore important to develop and understand low-temperature, or "soft", chemical reactions in "hard" refractory systems. These reactions allow us to apply the retrosynthetic framework that molecular chemists rely on to systems where chemists have not previously had such control over reactions, reactivities, and metastable product formation.In this Account, we discuss the development of soft chemical reactions of hard materials in the context of a class of layered, refractory metal borides that are precursors to an emerging family of two-dimensional nanomaterials. Layered ternary metal boride phases such as MoAlB have layers of metal borides, which are chemically unreactive, interleaved with layers of aluminum, which are reactive. Some of the interlayer aluminum can be deintercalated at room temperature in dilute aqueous sodium hydroxide, transforming stable MoAlB into destabilized MoAl1-xB. Mild thermal treatment of submicrometer grains of this destabilized MoAl1-xB sample allows it to traverse the energy landscape and crystallize as Mo2AlB2, a metastable compound. Further thermal treatment transforms Mo2AlB2 into a Mo2AlB2-alumina nanolaminate and ultimately mesoporous MoB, all through continued traversing of the energy landscape using mild chemical and thermal treatments. Similar topochemical manipulations, which maintain structure but change composition, are emerging for other MAB phases and are opening the door to new types of metastable compounds and nanostructured materials in traditionally refractory systems.

Conservative Approach to Treating American Football Players With Medial Collateral Ligament Grade 2 Sprain During the Season.

The medial collateral ligament is the most commonly injured ligament in the knee. The high-speed pivoting and agility movements that are common in the sport of American Football put participants at an increased risk for a valgus force stress from contact or noncontact injuries. Positional release therapy (PRT) also considered strain/counterstrain focuses on releasing the tension in a tissue through unloading the involved body part. Two male student-athletes participating in football with a mean age of 20.5years were diagnosed by a physician with medial collateral ligament grade 2 sprain. Both patients sustained their injuries in a regular season game with a contact valgus force from an opposing player. After the initial 72hours of compression, elevation, and cryotherapy, the patients were both treated with PRT followed by progressive loading exercises. Following 4 treatment sessions of PRT over the next 6days, the patients started with quadriceps engagement exercises, single-leg squats to 60° knee flexion, side steps, triceps dips, slow controlled lunges, and toe walk. The patients progressed to full body weight squats, single-leg landing, step-up tri-extension, and sidekicks with a leg on table. Then, the patients completed function movements and sports-specific exercises. In this case series, 2 patients competing in intercollege American Football were treated with PRT and progressive loading exercises to facilitate return to unrestricted activities and improve outcome measures. Commonly, a grade 2 medial collateral ligament sprain is conservatively treated with return to sport taking 20days on average. In this type 2 case series, the clinician found success utilizing PRT early in the recovery process, which in these 2 cases lead to restoration of function, outcome measure improvement, and an expedited return to sport. The expedited return to sport occurred at an average of 18days for these patients.

High or low volume beetroot juice supplementation might positively affect physical capacity and isokinetic muscle function in power athletes

BACKGROUND: Beetroot juice is an ergogenic aid containing high levels of nitrate and is known to have many physiological benefits. OBJECTIVE: This study aimed to examine the effects of beetroot juice supplementation on the physical capacity and isokinetic muscle function of power athletes. METHODS: Thirteen power athletes were orally administered three different volumes of beetroot juice: placebo (70 ml), low-volume beetroot juice (70 ml), and high-volume beetroot juice (140 ml). The Harvard step test, 20 m sprint, side-step, reaction time, Wingate test, blood lactate analysis, and isokinetic knee and trunk tests were performed to confirm their physical capacity and isokinetic muscle function. Significant differences between the drink groups were determined using repeated-measures ANOVA. RESULTS: There were no significant differences in the Harvard step, side step, whole-body reaction time, anaerobic power, blood lactate concentration, and isokinetic muscular strength in the knee and trunk for all groups. However, the 20 m sprint and isokinetic muscular endurance of the knee extensor were significantly higher with beetroot juice intake. CONCLUSIONS: Our findings suggest that &gt; 70 ml of beetroot juice supplement before performance may be useful as an ergogenic supplement to improve performance-related physical fitness, including speed and muscular endurance, in power athletes.

Management policies impact fishers’ income beyond tolerable limits: The case of the Chilean TURFs in Central Chile

Fish trade worldwide seeks sustainable fishery production which right-based-fisheries should provide. However, fisheries managed in TURF system (Territorial Use Rights for Fisheries), as occurs for loco (Concholepas concholepas) and kelp fisheries in central Chile, can turn out to be highly fluctuating. This can pose a challenge to fisher’s livelihood depending on the income variability this type of management produces. This work analyzes temporal variations of loco and kelp abundances and landings at increasing spatial scales, investigating which would be a TURF size that could dampen the influence of natural variations on fishers’ income enough for it to be tolerable. We analyzed loco and kelp abundance and landings data from hard bottom TURFs in Atacama (n = 22) and Coquimbo (n = 61) regions of Central Chile, which represent 81.4% of the total TURFs in these regions. Income variations less than 39% were considered tolerable, according to a study conducted by the National Consumer Service, where 61% of a person’s salary is necessary to cover essential needs in Chilean family. Loco and kelp landings variations exceeded that criterion at all analyzed spatial scales, suggesting that they cannot rely solely on those fisheries within a TURF. Even increasing the size of TURF including the coast of an entire region, does not dampen variability to a tolerable value. This explains the reason for former fisher migrations within these fisheries, something present regulations prevent, generating a complex situation which is necessary to revise in order not to maintain an incentive to side step regulations.

Effects of Band-Resisted Abduction on Muscle Activity between the Barbell Hip Thrust and Barbell Glute Bridge

The importance of hip extensor and abductor muscles for sport performance and injury reduction is well-documented. To target these muscle groups, the barbell hip thrust and barbell glute bridge are used to load the posterior kinetic chain while band-resisted abduction exercises, like band-resisted side stepping, target the lateral kinetic chain. However, combining band-resisted hip abduction with barbell hip-extension dominant exercises has not yet been investigated. In this study, ten male subjects underwent a two-part research protocol with surface electromyography (sEMG) measured during a 5-repetition maximum (5-RM) load performance to determine differences in peak and mean muscular activity between band-resisted barbell hip thrust (BBHT) and barbell hip thrust (BHT), and between band-resisted barbell glute bridge (BBGB) and barbell glute bridge (BGB). The results indicated three significant differences between the pairs, with both banded conditions eliciting greater sEMG activity in the Upper Gluteus Maximus compared to non-banded conditions. However, BGB unexpectedly elicited greater sEMG activity in the Gluteus Medius compared to BBGB. The differences in muscle activity could potentially be explained by reciprocal inhibition and synergistic dominance. Further research is needed to make definitive statements on the superiority of band-resisted barbell exercises over non-banded barbell exercises and transferability to sport performance.

The Effectiveness of Aerobic Gymnastics Program in Lowering Blood Pressure in Elderly People with Hypertension: A Case Study in Cibungur Village

This study aims to investigate the effect of aerobic exercise program on lowering blood pressure in elderly people with hypertension in Cibungur Village. The study population consisted of 40 elderly people with certain inclusion criteria who lived in Cibungur Village and had the physical ability to perform gymnastic movements. The sampling technique uses purposive sampling method. Systolic and diastolic blood pressure data were measured before and after the implementation of the hypertensive gymnastics program. The research design used was pre-experimental with one group pre-test and post-test design. Aerobic gymnastics programs involve movements such as High Footsteps, Boxing and Kicking Stances, Side Steps, Sliding Kicks, Skipping Ropes, and Body Stretching and Warm-Up. Gymnastics programs are run in regular sessions supervised by experienced instructors. Blood pressure measurement is done using a sphygmomanometer and stethoscope.&#x0D; The results showed that aerobic exercise programs produced positive changes in the blood pressure of elderly people with hypertension. There was a decrease in systolic and diastolic blood pressure after participating in the gymnastics program. Data analysis showed a significant impact of gymnastics programs in lowering blood pressure in hypertensive elderly populations.&#x0D; This research has important implications for efforts to prevent and manage hypertension in the elderly. Aerobic exercise programs can be an effective alternative and can be implemented easily to help lower blood pressure in the elderly population with hypertension. Follow-up studies with larger sample sizes and control groups can provide deeper insights into the benefits and effectiveness of gymnastics programs in the management of hypertension in the elderly.

Tes dan Pengukuran Kondisi Fisik Pada Atlet PORPROV 2022

The purpose of this research is community service to carry out tests and measurements of the physical condition of Porprov athletes in 2022. The research method used is in the form of community service through test surveys and physical condition measurements. There are several stages of the activity carried out, namely the explanation of the chairman of the implementation of the activity to the athletes, an explanation of the procedure for carrying out the sit and reach test, vertical jump, sprint run, push up, sit up, squat jump, back up, side step test and beep test, collection test result data, evaluation. The results of the community service research conducted by the Tri Dharma College between the Physical Education, Health and Recreation Study Programs from Suryakancana University and the Cianjur Indonesian National Sports Committee on 378 athletes from 38 sports branches found that the physical conditions possessed by the athletes varied from low to low, moderate to good. It is hoped that this activity will continue to be carried out and synergized from year to year, so that it can become a training for athletes to achieve achievements in the future

Stepping strategies of young adults undergoing sudden external perturbation from different directions

Stepping strategies following external perturbations from different directions is investigated in this work. We analysed the effect of the perturbation angle as well as the level of awareness of individuals and characterised steps out of the sagittal plane between Loaded Side Steps (LSS), Unloaded Medial Steps (UMS) and Unloaded Crossover Steps (UCS). A novel experimental paradigm involving perturbations in different directions was performed on a group of 21 young adults (10 females, 11 males, 20–38 years). Participants underwent 30 randomised perturbations along 5 different angles with different levels of awareness of the upcoming perturbations (with and without wearing a sensory impairment device) for a total of 1260 recorded trials. Results showed that logistic models based on the minimal values of the Margin of Stability (MoS) or on the minimal values of the Time to boundary (Ttb) performed the best in the sagittal plane. However, their accuracy stayed above 79% regardless of the perturbation angle or level of awareness. Regarding the effect of the experimental condition, evidences of different balance recovery behaviours due to the variation of perturbation angles were exposed, but no significant effect of the level of awareness was observed. Finally, we proposed the Distance to Foot boundary (DtFb) as a relevant quantity to characterise the stepping strategies in response to perturbations out of the sagittal plane.

Dose–response effect of incremental lateral-wedge hardness on the lower limb Biomechanics during typical badminton footwork

ABSTRACT Badminton footwork has been characterised with jump-landing, cross step, side side and lunges, which requires movement agility to facilitate on-court performance. A novel badminton shoe design with systematic increase of lateral wedge hardness (Asker C value of 55, 60, 65, and 70) was developed and investigated in this study, aiming to analyse the dose–response effect of incremental wedge hardness on typical badminton footwork. Stance time and joint stiffness were employed to investigate the footwork performance, and the factorial Statistical non-Parametric Mapping and Principal Component Analysis (PCA) were used to quantify the biomechanical responses over the stance. As reported, shorter contact times (decreased by 8.9%–13.5%) and increased joint stiffness (in side step) of foot-ankle complex were found, suggesting improved footwork stability and agility from increased hardness. Time-varying differences were noted during the initial landing and driving-off phase of cross and side steps and drive-off returning of lunges, suggesting facilitated footwork performance. The reconstructed modes of variations from PCA further deciphered the biomechanical response to the wedge dosage, especially during drive-off, to understand the improved footwork agility and stability.

Gluteal Muscle Forces during Hip-Focused Injury Prevention and Rehabilitation Exercises.

This study aimed to compare and rank gluteal muscle forces in eight hip-focused exercises performed with and without external resistance and describe the underlying fiber lengths, velocities, and muscle activations. Motion capture, ground reaction forces, and electromyography (EMG) were used as input to an EMG-informed neuromusculoskeletal model to estimate gluteus maximus, medius, and minimus muscle forces. Participants were 14 female footballers (18-32 yr old) with at least 3 months of lower limb strength training experience. Each participant performed eight hip-focused exercises (single-leg squat, split squat, single-leg Romanian deadlift [RDL], single-leg hip thrust, banded side step, hip hike, side plank, and side-lying leg raise) with and without 12 repetition maximum (RM) resistance. For each muscle, exercises were ranked by peak muscle force, and k-means clustering separated exercises into four tiers. The tier 1 exercises for gluteus maximus were loaded split squat (95% confidence interval [CI] = 495-688 N), loaded single-leg RDL (95% CI = 500-655 N), and loaded single-leg hip thrust (95% CI = 505-640 N). The tier 1 exercises for gluteus medius were body weight side plank (95% CI = 338-483 N), loaded single-leg squat (95% CI = 278-422 N), and loaded single-leg RDL (95% CI = 283-405 N). The tier 1 exercises for gluteus minimus were loaded single-leg RDL (95% CI = 267-389 N) and body weight side plank (95% CI = 272-382 N). Peak gluteal muscle forces increased by 28-150 N when exercises were performed with 12RM external resistance compared with body weight only. Peak muscle force coincided with maximum fiber length for most exercises. Gluteal muscle forces were exercise specific, and peak muscle forces increased by varying amounts when adding a 12RM external resistance. These findings may inform exercise selection by facilitating the targeting of individual gluteal muscles and optimization of mechanical loads to match performance, injury prevention, or rehabilitation training goals.

Intra-Positional and Inter-Positional Differences in Agility Tests among Youth Female Volleyball Players

In their structure, indoor sports require quick changes of movement direction. Players should possess a high level of ability to change the direction and speed of movement in response to a stimulus, which is one of the major prerequisites for a high level of performance. During a volleyball match, players are involved in different defensive and offensive activities in which agility plays an important role. The aim of this study was to determine the differences between less successful and more successful youth female volleyball players, as well as their inter-positional and intra-positional differences in agility. The study was conducted on a sample of 204 youth female volleyball players whose mean chronological age was 14.11±0.84 years. The players were divided into 5 subgroups according to their playing position (setters, opposite players, passer-hitters, middle blockers, and libero players). The variable sample used to assess agility consisted of 3 tests: Side steps, 9-3-6-3-9 test, and Step-hop test. Methods of data analysis included the determination of metric characteristics for all three agility tests. The analysis of covariance revealed a significant impact of biological age indicators on all agility tests. Furthermore, discriminant analysis of differences showed that more successful volleyball players achieved better results in all three agility tests. High reliability of the test was determined by Cronbach’s Alpha coefficient (0.87-0.96). The results of this study showed a positive effect of agility tests in differentiating less successful and more successful players regardless of their position. More successful players achieved better results than less successful players in all tests. Greater biological maturity and training experience represent great competitive advantage in this age group. The obtained inter-positional and intra-positional differences and the influence of the biological age indicator on inter-positional and intra-positional differences in agility tests imply that higher biological maturity and training experience are great competitive advantages in this age group. The primary goal of training in younger age groups should not be the current success in the competition, but rather the preparation for achieving the best possible results in senior competition.