Investigating the impact of inter-limb asymmetry in hamstring strength on jump, sprint, and strength performance in young athletes: comparing the role of gross force.

The main purpose of this cross-sectional study was to examine the impact of the inter-limb asymmetry of hamstring strength on jump, sprint and strength performance and to compare the effects of inter-limb asymmetry of hamstring strength with gross force (GF) of the hamstring on these physical qualities in youth volleyball athletes. Eighty-one youth volleyball players (age: 16.6 ± 1.9 years; training experience: 3.0 ± 0.9 years; height: 191.4 ± 7.1 cm; body mass: 78.5 ± 12.9 kg; lean body mass: 63.5 ± 10.5 kg; body fat rate: 18.6% ± 6.1%) performed a mid-season battery of tests consisting of morphological test, depth jump (DJ), counter movement jump (CMJ), squat jump (SJ), 10 m sprint, isometric mid-thigh pull (IMTP) and hamstring strength test. All tests reported good to excellent reliability (ICC range = 0.815-0.996) and acceptable variability (CV range = 3.26-7.84%). Results show a significant negative relationship between inter-limb asymmetry of hamstring strength and all physical qualities (r = -0.271 to -0.445; p < 0.05), and a significant positive relationship between GF of hamstring and all physical qualities (r = 0.303 to 0.664; p < 0.05). Additionally, GF of hamstring was more relevant to IMTP-PF (peak force) (r = 0.664) and inter-limb asymmetry of hamstring strength was more relevant to 10 m sprint (r = -0.445). The findings from this study indicate that, for youth athletes, the GF of the hamstring is crucial for overall lower limb strength performance, and the importance of inter-limb symmetry of hamstring strength increases with the complexity of the task.

Effects of chains squat training with different chain load ratio on the explosive strength of young basketball players' lower limbs.

The purpose of this study was to explore the effects of the chain squat training (CST) with different chain load ratio (0, 10%, 20% and 30%) on the explosive power of the lower limbs of adolescent male basketball players. Forty-four youth basketball players (age 15.48 ± 0.81 years, body mass 78.86 ± 12.04 kg, height 184.95 ± 6.71 cm) were randomly allocated to one of the four groups: traditional squat training (TST), 10% chains squat training (10% CST), 20% chains squat training (20% CST), and 30% chains squat training (30% CST). Training interventions were performed 2 times per week for 6 weeks, and at the week before (Pre) and after (Post) the 6-week CST program with different chain load ratio, the no-step vertical jump, standing long jump, 15 m shuttle run, 1 R M squat and 30 m sprint test were performed. A 4 (group) × 2 (time) repeated measures analysis of variances (ANOVA) was calculated to show the scatter of each variable, and the Bonferroni's post-hoc test was used for multiple comparisons, in addition the partial eta-squared (η2) was calculated as an estimate of the ES. Significant time × group interaction was noticed for the no-step vertical jump (p < 0.001; η2 = 0.611), standing long jump (p < 0.001; η2 = 0.490) and 1 R M squat (p < 0.01; η2 = 0.333) indicating that better improvements appear in CST compared to TST. However, significant time × group interaction was noted for 15 m shuttle run (p < 0.001; η2 = 0.428), in favor of TST compared to CST. In addition, the improvements in 30 m sprint were similar between all groups. In conclusion, CST with more chain load has better training effects on lower limb explosive strength and maximum strength, based on the improvement in 1 R M squat and jumping performance. Besides, compared with TST, CST with more chain load might not help to develop better velocity adaptation at higher range of movement.

Effects of different external cooling placements prior to and during exercise on athletic performance in the heat: A systematic review and meta-analysis.

Background: Nowadays, many high-profile international sport events are often held in warm or hot environments, hence, it is inevitable for these elite athletes to be prepared for the challenges from the heat. Owing to internal cooling may cause gastrointestinal discomfort to athletes, external cooling technique seems to be a more applicable method to deal with thermal stress. Central cooling mainly refers to head, face, neck and torso cooling, can help to reduce skin temperature and relieve thermal perception. Peripheral cooling mainly refers to four limbs cooling, can help to mitigate metabolic heat from muscular contrac to effectively prevent the accumulation of body heat. Hence, we performed a meta-analysis to assess the effectiveness of different external cooling placements on athletic performance in the heat Methods: A literatures search was conducted using Web of Science, MEDLINE and SPORTDiscus until September 2022. The quality and risk of bias in the studies were independently assessed by two researchers. Results: 1,430 articles were initially identified (Web of Science = 775; MEDLINE = 358; SPORTDiscus = 271; Additional records identified through other sources = 26), 60 articles (82 experiments) met the inclusion criteria and were included in the final analysis, with overall article quality being deemed moderate. Central cooling (SMD = 0.43, 95% CI 0.27 to 0.58, p < 0.001) was most effective in improving athletic performance in the heat, followed by central and peripheral cooling (SMD = 0.38, 95% CI 0.23 to 0.54, p < 0.001), AND peripheral cooling (SMD = 0.32, 95% CI 0.07 to 0.57, p = 0.013). For the cooling-promotion effects on different sports types, the ranking order in central cooling was ETE (exercise to exhaustion), TT (time-trial), EWT (exercise within the fixed time or sets), IS (intermittent sprint); the ranking order in peripheral cooling was EWT, TT, ETE and IS; the ranking order in central and peripheral cooling was ETE, IS, EWT and TT. Conclusion: Central cooling appears to be an more effective intervention to enhance performance in hot conditions through improvements of skin temperature and thermal sensation, compared to other external cooling strategies. The enhancement effects of peripheral cooling require sufficient re-warming, otherwise it will be trivial. Although, central and peripheral cooling seems to retain advantages from central cooling, as many factors may influence the effects of peripheral cooling to offset the positive effects from central cooling, the question about whether central and peripheral cooling method is better than an isolated cooling technique is still uncertain and needs more researchs to explore it.

Long noncoding RNA distal-less homeobox 2 antisense 1 restrains inflammatory response and apoptosis of periodontal ligament cells by binding with microRNA-330-3p to regulate Ro60, Y RNA binding protein.

OBJECTIVE: This study aims to investigate the role of long noncoding RNA distal-less homeobox 2 antisense 1 (DLX2-AS1) in lipopolysaccharide-induced inflammatory response and apoptosis of periodontal ligament cells (PDLCs). DESIGN: Lipopolysaccharide was used to induce inflammation response of PDLCs. The expression of DLX2-AS1, microRNA-330-3p and Ro60, Y RNA binding protein (RO60) in lipopolysaccharide-treated PDLCs was detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Enzyme linked immunosorbent assay (ELISA) was performed to evaluate the concentration of inflammatory cytokines in PDLCs after DLX2-AS1 overexpression or RO60 downregulation. The apoptosis of PDLCs after lipopolysaccharide treatment or indicated transfection was analyzed by flow cytometry analysis. The level of apoptosis-related proteins, Bax and Bcl-2, were examined by western blotting. The binding capacity between microRNA-330-3p and DLX2-AS1 (or RO60) was verified by luciferase reporter assays. RESULTS: DLX2-AS1 was downregulated in PDLCs after lipopolysaccharide treatment. DLX2-AS1 overexpression decreased the production of inflammatory cytokines and inhibited cell apoptosis. microRNA-330-3p bound with DLX2-AS1 and displayed high expression in lipopolysaccharide-induced PDLCs. In addition, the downregulation of RO60, a target gene of microRNA-330-3p, reversed the suppressive influence of DLX2-AS1 overexpression on the inflammatory response and apoptosis of PDLCs. CONCLUSIONS: DLX2-AS1 restrains inflammatory response and apoptosis of PDLCs via the microRNA-330-3p/RO60 axis.

Rational Design of LLZO/Polymer Solid Electrolytes for Solid-State Batteries.

Hybrid composite electrolytes incorporate polymer matrixes and garnet filler attract the focus of concern for all-solid-state batteries, which possess high ionic conductivity, superior electrochemical stability, and wide electrochemical window of ceramic electrolyte advantages, and exhibit excellent flexibility and tensile shear strength from polymer electrolyte benefits. Hence, the unique structure design of solid-state electrolytes resolves the existing defects that the use of either single garnet or polymer electrolytes implemented into battery devices. This review summarizes Li7 La3 Zr2 O12 (LLZO)/polymer solid composite electrolytes (SCEs), comprising LLZO/polymer SCEs with various structures and different ratios of LLZO fillers, LLZO/polymer with different kinds of polymers matrix and hybrid lithium-salt, and Li+ transport pathways within the LLZO/polymers SCEs interface. The purpose here is to propose the viewpoints and challenges of LLZO/polymer SCEs to promote the development of next-generation solid electrolytes.

Computational Auxiliary for the Progress of Sodium-Ion Solid-State Electrolytes.

All-solid-state sodium batteries (ASSBs) have attracted ever-increasing attention due to their enhanced safety, high energy density, and the abundance of raw materials. One of the remaining key issues for the practical ASSB is the lack of good superionic and electrochemical stable solid-state electrolytes (SEs). Design and manufacturing specific functional materials used as high-performance SEs require an in-depth understanding of the transport mechanisms and electrochemical properties of fast sodium-ion conductors on an atomic level. On account of the continuous progress and development of computing and programming techniques, the advanced computational tools provide a powerful and convenient approach to exploit particular functional materials to achieve that aim. Herein, this review primarily focuses on the advanced computational methods and ion migration mechanisms of SEs. Second, we overview the recent progress on state-of-the-art solid sodium-ion conductors, including Na-ß-alumina, sulfide-type, NASICON-type, and antiperovskite-type sodium-ion SEs. Finally, we outline the current challenges and future opportunities. Particularly, this review highlights the contributions of the computational studies and their complementarity with experiments in accelerating the study progress of high-performance sodium-ion SEs for ASSBs.