Time duration of post-activation performance enhancement (PAPE) in elite male sprinters with different strength levels

(1) Purpose: This study aimed to explore the time duration of post-activation performance enhancement (PAPE) in elite male sprinters with different strength levels. (2) Methods: Thirteen elite male sprinters were divided into a strong group (relative strength: 1RM squat normalized by body mass of ≥ 2.5; n = 6) and a weak group (relative strength of < 2.5; n =7). All sprinters performed one static squat jump (SSJ) at baseline and 15 s, 3 min, 6 min, 9 min, and 12 min following an exercise protocol including three reps of a 90% 1RM back squat. Two force plates were used to determine the vertical jump height, the impulse output, and the power output for all SSJs. (3) Results: Significant improvements in vertical jump height and peak impulse were observed (p < 0.05) at 3, 6, and 9 min, without significant between-group differences. The peak power had a significant increase in 3 min (p < 0.01) and 6 min (p < 0.05), with also no significant difference between-group differences. Moreover, the stronger subjects induced a greater PAPE effect than the weaker counterparts at 3, 6, and 9 min after the intervention. The maximal benefit following the intervention occurred at 6 min and 3 min after the intervention in the stronger and weaker subjects, respectively. (4) Conclusions: The findings indicated that three reps of a 90% 1RM back squat augmented the subsequent explosive movement (SSJ) for 3–9 min in elite male sprinters, especially in stronger sprinters.info:eu-repo/semantics/publishedVersio

Improvement of Antioxidant Activity of Defatted Selenium-Enriched Rice Bran by Lactic Acid Bacteria Fermentation

Selenium-enriched rice bran is a major by-product in the production of selenium-enriched polished rice, which is rich in selenium, dietary fiber, and active substances such as phenolic compounds. However, the high-value utilization of selenium-enriched rice bran has not been fully explored. In this study, four strains of lactic acid bacteria (Lactobacillus acidophilus, Streptococcus thermophilus, L. plantarum, and L. delbrueckii subsp.) were used to ferment defatted selenium-enriched rice bran. The physicochemical properties, nutritional characteristics, microstructure, physicochemical properties and antioxidant activity of selenium-enriched rice bran were compared before and after fermentation. The results showed that lactic acid bacteria fermentation increased the insoluble dietary fiber/water-soluble dietary fiber ratio in selenium-enriched rice bran by 20%–45%, the contents of total phenols and total flavonoids by 5%–6% and 16%–31%, respectively, and the conversion efficiency of inorganic selenium to SeCys2 by 42%–49%. Moreover, the fermentation reduced the particle size of selenium-enriched rice bran, made the surface more loose and porous, and enhanced the hydration properties, cholesterol adsorption capacity and antioxidant activity. The decreasing order of the comprehensive scores of fermented selenium-enriched rice bran in principal component analysis (PCA) was L. plantarum > L. delbrueckii subsp. > S. thermophilus > L. acidophilus. Among these samples, the sample fermented with L. plantarum exhibited the strongest antioxidant activity in vitro, as well as the highest contents of total acid, SeCys2, total phenols and total flavonoids. This study provides a theoretical basis for the intensive development and utilization of selenium-enriched rice bran

The Effects of Inter-Limb Asymmetry on Change of Direction Performance: A Systematic Review

Objectives: This review aimed to clarify the associations between COD performance and asymmetries on horizontal jumping, vertical jumping, and strength. Methods: Three databases, including PubMed, Web of Science, and MEDLINE(EBSCOhost) were used to perform a systematic literature search. The search was up to 13 March 2022 and was limited to the literature in the English language and on the human species. Studies included reported exact measurement tools and correlation coefficients and studies in which participants aged &gt;14 years were included. Moreover, studies that were not peer-reviewed and those that did not report an asymmetry index were excluded, as were studies for which the full text was not available. The modified Downs and Black Quality Index tool was used to evaluate the quality of the studies. Results: The systematic literature identified 1151 studies, but only 12 studies were included in this review. A total of 354 participants, ranging from 15 to 23 years of age, were recruited for these studies. The methodological quality score ranged from 6 to 8, with an average of 7.25. The associations between COD performance and vertical jump height, horizontal jump distance, and lower-limb strength asymmetries were examined in 11, 5, and 2 studies, respectively. Six studies reported that vertical jump height asymmetries scores can significantly reduce COD performance, while significant associations between COD performance and horizontal jump distance asymmetries and strength asymmetries were only observed in one study each. Specifically, four studies explored the relationships between CMJ height asymmetries scores and COD performance, and all reported significant associations between them. The main limitations of this review were that it did not consider the sports in which the participants were involved. Conclusions: This study suggests that drop jump height and eccentric knee strength asymmetries can reduce COD performance. Moreover, low horizontal jump asymmetries may not influence COD performance. Further research needs to determine whether the minimal threshold of horizontal jump asymmetries would not affect COD performance

Moss-derived mesoporous carbon as bi-functional electrode materials for lithium-sulfur batteries and supercapacitors

In this work, we reported a moss-derived biomass porous carbon (MPC) as a bi-functional electrode material for both the lithium-sulfur battery and the supercapacitor. The MPC was prepared from a high-temperature calcination procedure using the moss as the carbonaceous precursor. Using NaOH, the MPC was activated to give a mesoporous structure with a high specific surface area (1057.1 m2 g−1) and large pore volume (0.72 cm3 g−1). When it was used as the cathode material in lithium-sulfur batteries, the MPC material realized a sulfur loading and exhibited a remarkably improved electrochemical performance, i.e., a high discharge capacity of 1070 mAh g−1 at 0.1 C. This activated MPC also worked well as a capacitive electrode in supercapacitors, demonstrating a high specific capacitance of 332 F g−1 (scan rate of 1.0 A g−1) and a high capacity retention \u3e 97% in a long-term cycle of 1000 charge/discharges. This work demonstrated a facile method for the utilization of activated waste biomass material for future clean energy applications

Relationships between Functional Movement Quality and Sprint and Jump Performance in Female Youth Soccer Athletes of Team China

This study aimed to determine the optimal functional movement screen (FMS) cut score for assessing the risk of sport injury, and to investigate the correlations between functional movement quality and sprint and jump performance. Twenty-four (N = 24) athletes performed all tests in one day at 10–30 min intervals, and the FMS test was performed first, without a warm-up session. After a standard warm-up, athletes then completed the Y-balance Test (YBT), sprint, counter-movement jump (CMJ), and standing long jump (SLJ), in turn. For each test, the best of three attempts was recorded for further analysis. A receiver operating characteristic (ROC) curve and area-under-the-curve (AUC) were used to determine the optimal FMS cut score for assessing the risk of sport injuries, and Spearman’s rank correlation analysis was used to quantify associations between functional movement scores and athletic performance. The average FMS score was 16.2 and the optimal FMS cut score for assessing the risk of sport injuries was 14.5. There were moderate relationships between total FMS score and 10–20 m sprint time (r = −0.46, p p p p p p p p > 0.05). Taken together, the results indicate that a FMS score of 14 is not a gold standard for assessing the risk of injury in all populations; we recommend that the FMS cut score of 14.5 should be the optimal score for assessing risk of injury in young female elite soccer players. Moreover, the FMS and YBT were introduced to assess the quality of functional movements, and they cannot be used to assess sprint and jump performance. Practitioners can use components of the FMS that have similar characteristics to specific sports to assess athletic performance

Effects of school-based neuromuscular training on fundamental movement skills and physical fitness in children: a systematic review

Objectives The primary purpose of this review was to clarify the effects of school-based integrated neuromuscular training (INT) on fundamental movement skills and physical fitness in children. The secondary purpose was to examine whether school-based INT intervention is superior to physical education (PE) intervention in enhancing motor skills and fitness. Methods A systematic literature search was performed in four electronic databases: PubMed, Web of Science, MEDLINE (EBSCOhost), and Cochrane Central Register of Controlled Trials. The last search was performed on December 21, 2021, and was limited to the English language, human species, and peer reviewed journals. Randomized controlled trials and cluster randomized controlled trials that examine the effects of school-based INT on motor skills and/or fitness in healthy children who were aged up to 14 years old were included. Moreover, studies included in this study should compare school-based INT-induced adaptions with those generated by PE interventions. Studies that involve athletic children and additional exercise training were excluded. The Physiotherapy Evidence Database (PEDro) scale was used to assess the quality of the study. Results Of 1,026 studies identified, seven original trials that meet the inclusion criteria were included in this review. Based on the PEDro scale, the PEDro score of seven studies was between six and eight points with a mean score of 5.29. Among the seven studies included in this study, four studies assessed physical fitness including muscular fitness (n = 4), speed (n = 3), endurance (n = 2), and flexibility (n = 2). Three studies examined the effects of INT on postural control and three studies explored its effects on motor skills. Concerning movement competence, significant and greater improvements in postural control and fundamental motor skills were observed following school-based INT interventions compared to PE intervention in two and three studies, respectively. Regarding physical fitness, neuromuscular training significantly increased muscular fitness, speed, endurance, flexibility in three, two, one, and one studies, respectively. However, only greater improvements in muscle fitness were observed in school-based INT group compared to PE group. The main limitations of this review were the lack of descriptions of training intensity and volume and the low methodological quality of the included studies. Conclusion This review provides evidence that school-based neuromuscular training programs are superior to PE lessons in improving postural control, fundamental motor skills and muscular strength. Therefore, INT could be incorporated into traditional physical education classes in school. Trial registration number: CRD42022297349

Study on Synergistic Corrosion Inhibition Effect between Calcium Lignosulfonate (CLS) and Inorganic Inhibitors on Q235 Carbon Steel in Alkaline Environment with Cl−

The synergistic corrosion inhibition effect between calcium lignosulfonate (CLS) and three kinds of inorganic inhibitors (Na2MoO4, Na2SnO3, and NaWO4) with various molar ratios on Q235 carbon steel in alkaline solution (pH 11.5) with 0.02 mol/L NaCl was investigated by cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, linear polarization, scanning electron microscopy, and X-ray photoelectron spectroscopy. Molybdate and stannate in hybrid inhibitor could promote the passivation of steel and form a complex film, which could suppress the corrosion effectively. Moreover, the insoluble metal oxides in the complex film formed by three kinds of inorganic inhibitor could help the adsorption of CLS onto the steel surface. The CLS molecules could adsorb onto the steel surface and metal oxides to form an adsorption film to protect the steel from corrosion. A three-layer protection film formed by a hybrid inhibitor, including passivation film, deposition film, and adsorption film, would effectively inhibit the corrosion reactions on the steel surface. The CLS compound with molybdate with the ratio of 2:3 shows the best inhibition effect on both general corrosion and localized corrosion

Active vibration isolation performance of the bistable nonlinear electromagnetic actuator with the elastic boundary

This paper thoroughly investigates the broadband active vibration isolation of a bistable nonlinear electromagnetic actuator with an elastic boundary (simply named EB-bistable actuator). A new feedback control law is proposed to control the actuator's input current, to significantly attenuate the broadband vibration transmissibility from the base excitation to the actuator mover (supporting the payload). The control law comprises the polynomial function of the mover's absolute velocity. The mathematical models of the EB-bistable actuator and its application for vibration isolation are derived and experimentally validated. Then, based on the verified model, the paper comprehensively investigates the EB-bistable actuator with the proposed control law, which validates the broadband active vibration isolation performance for different system parameters. The input-to-state stability (ISS) of the control law for any non-negative control weights is proved, and thus it is a model-free control method. Results of one investigated case show that the maximum vibration transmissibility can be attenuated by over 90%. The lower bound of the effective vibration isolation bandwidth (where the vibration transmissibility is smaller than 0 dB) is reduced by 19.69%, i.e. the bandwidth is significantly broadened. Moreover, the study proves the effectiveness of the active vibration isolation for the structural variation and initial condition change. Finally, the paper thoroughly discusses the influence of the control law parameters on the active vibration isolation performance. The parametric studies develop useful guidelines for the active vibration isolation of the EB-bistable actuator

Influence of a Precursor Film with a Copper Gradient on the Properties of a Copper Indium Gallium Selenide Solar Cell

A precursor film with a Cu gradient was prepared in order to improve the quality of the absorber film produced by sputtering CIGS targets when using glass substrates. Two ceramic quaternary targets with different copper content were used for alternatively sputtering to get a bi-layer precursor film with a Cu gradient; meanwhile, the crystallization property and cell performance were studied. This was done in order to study the activities of the Cu element in the precursor layer before and after selenization. The film states of the temperature-rise period and high temperature selenization period were investigated. The appropriate structure of the precursor film was the Cu-rich layer underneath the Cu-poor layer. The Cu&ndash;Se phase, which is important for the crystalline property, can be produced in the Cu-rich layer under the heating period. The Cu-poor layer on the top reacts with the Cu-Se compound in the annealing process at a high temperature, and the big grain size of the absorber layer can be obtained due to Cu diffusion promoted by the gradient in the precursor film, as well as better conversion efficiency. This result shows that constructing the precursor film with a Cu gradient by sputtering different quaternary CIGS targets is a very promising fabrication method to obtain high-performance solar-cell devices with a good crystallization property under an annealing temperature of 550 &deg;C and is suitable for further industrialized application