SIRT1 is a regulator of autophagy: Implications for the progression and treatment of myocardial ischemia-reperfusion.

SIRT1 is a highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylase. It is involved in the regulation of various pathophysiological processes, including cell proliferation, survival, differentiation, autophagy, and oxidative stress. Therapeutic activation of SIRT1 protects the heart and cardiomyocytes from pathology-related stress, particularly myocardial ischemia/reperfusion (I/R). Autophagy is an important metabolic pathway for cell survival during energy or nutrient deficiency, hypoxia, or oxidative stress. Autophagy is a double-edged sword in myocardial I/R injury. The activation of autophagy during the ischemic phase removes excess metabolic waste and helps ensure cardiomyocyte survival, whereas excessive autophagy during reperfusion depletes the cellular components and leads to autophagic cell death. Increasing research on I/R injury has indicated that SIRT1 is involved in the process of autophagy and regulates myocardial I/R. SIRT1 regulates autophagy through various pathways, such as the deacetylation of FOXOs, ATGs, and LC3. Recent studies have confirmed that SIRT1-mediated autophagy plays different roles at different stages of myocardial I/R injury. By targeting the mechanism of SIRT1-mediated autophagy at different stages of I/R injury, new small-molecule drugs, miRNA activators, or blockers can be developed. For example, resveratrol, sevoflurane, quercetin, and melatonin in the ischemic stage, coptisine, curcumin, berberine, and some miRNAs during reperfusion, were involved in regulating the SIRT1-autophagy axis, exerting a cardioprotective effect. Here, we summarize the possible mechanisms of autophagy regulation by SIRT1 in myocardial I/R injury and the related molecular drug applications to identify strategies for treating myocardial I/R injury.

Influence and effect mechanism of filler type on the physicochemical properties, microbial numbers, and digestibility of ovalbumin emulsion gels during storage.

This study was designed to investigate the influence and effect mechanism of the filler type on the physicochemical properties, microbial numbers, and digestibility of ovalbumin emulsion gels (OEGs) during storage. Sunflower oil was emulsified with ovalbumin (20 mg mL-1) and Tween 80 (20 mg mL-1) separately to prepare ovalbumin emulsion gels (OEGs) that contained active and inactive fillers, respectively. The formed OEGs were stored at 4 °C for 0, 5, 10, 15, and 20 days. The active filler enhanced the gel hardness, water holding capacity, fat holding capacity, and surface hydrophobicity and decreased the digestibility and free sulfhydryl content during storage compared to control (unfilled) ovalbumin gel, whereas the inactive filler had the opposite effects. Protein aggregation diminished, lipid particle aggregation increased, and the amide A band shifted to a higher wavenumber for all three types of gel during storage, suggesting that the compact network structure of the OEG became rough and disordered with storage. The OEG with the active filler did not inhibit microbial growth, and the OEG with the inactive filler did not significantly promote the development of bacteria. In addition, the active filler delayed the in vitro digestion of the protein in the OEG throughout storage. Emulsion gels containing active filler facilitated the retention of the gel properties during storage, whereas emulsion gels containing inactive filler exacerbated the loss of the gel properties during storage.

Constructing a Diagnosis Model and Visualizing the Risk Relationship between Biomarkers and Overuse Injuries in Well-trained Wrestlers.

This study aimed to investigate the association between biomarkers and overuse injuries in well-trained wrestlers. Seventy-six well-trained wrestlers on a national team completed two blood sample collections, two clinical overuse injuries diagnoses, and a questionnaire survey at a 2-week interval. Multivariate logistic regression analysis and receiver operating characteristic curve were used to screen for related factors and construct the prediction probability model of overuse injuries. Using a restricted cubic spline further clarifies the relationship between biomarker levels and the risk of overuse injuries. Creatine kinase (CK), cortisol, rheumatoid factor, testosterone in men, and C-reactive protein (CRP) levels in the overuse injuries group were significantly different compared to those in the non-overuse injuries group. The diagnostic efficiency of the prediction probability model was more valuable than any single variable (area under the curve=0.96, Specificity=0.91, Sensitivity=0.89, high accuracy). A J-shaped relationship was noted between biomarkers (cortisol, CRP, and CK) and the risk of overuse injuries (cutoff point: 17.95 µg·dL-1, 4.72 mg·L-1, and 344 U·L-1; p for nonlinearity:<0.001, 0.025, and 0.043, respectively). In conclusion, a predictive model based on biomarkers (cortisol, CRP, and CK) predicted the overuse injuries risk of well-trained wrestlers. High levels of these three biomarkers were associated with a higher risk of overuse injuries, and a J-shaped relationship was observed between them.

Influence and effect mechanism of disulfide bonds linkages between protein-coated lipid droplets and the protein matrix on the physicochemical properties, microstructure, and protein structure of ovalbumin emulsion gels.

In this study, disulfide bonds between the interfacial protein film formed on the lipid particles and the protein in ovalbumin emulsion gels were blocked with 0, 1, 3, 5 and 10 mM of the N-ethylmaleimide (NEM) to explore the influence and effect mechanism of disulfide bonds between the interfacial proteins on the physicochemical properties, microstructure, and protein structure of sunflower oil-ovalbumin emulsion gels. Ovalbumin emulsion gels with NEM-treated ovalbumin emulsion (N-OE) had lower hardness, free sulfhydryl content, water holding capacity (WHC), and surface hydrophobicity, but higher spin-spin relaxation time (T2) than ovalbumin emulsion gels with NEM-treated ovalbumin substrate solution (N-OSS). In addition, N-OE and N-OSS had lower hardness, free sulfhydryl content, WHC and surface hydrophobicity, as well as a more coarse and disordered microstructure than non-NEM treated ovalbumin emulsion gel (control group). The free sulfhydryl content, hardness, WHC, and surface hydrophobicity of the ovalbumin emulsion gels all decreased as the NEM concentration rose (p < 0.05), whereas the amide A band changed to higher wave numbers. These results collectively indicated that the reduction of disulfide between the interfacial layer and the proteins inhibited the hydrophobic effect, the formation of hydrogen bonds, and prevented the formation of larger aggregates. Thus the disulfide bonds between the interfacial proteins contribute to the hardness enhancement and water stabilization of the ovalbumin gel.

Effects of six weeks of sub-plateau cold environment training on physical functioning and athletic ability in elite parallel giant slalom snowboard athletes.

Background: Hypoxic and cold environments have been shown to improve the function and performance of athletes. However, it is unclear whether the combination of subalpine conditions and cold temperatures may have a greater effect. The present study aims to investigate the effects of 6 weeks of training in a sub-plateau cold environment on the physical function and athletic ability of elite parallel giant slalom snowboard athletes. Methods: Nine elite athletes (four males and five females) participated in the study. The athletes underwent 6 weeks of high intensity ski-specific technical training (150 min/session, six times/week) and medium-intensity physical training (120 min/session, six times/week) prior to the Beijing 2021 Winter Olympic Games test competition. The physiological and biochemical parameters were collected from elbow venous blood samples after each 2-week session to assess the athletes' physical functional status. The athletes' athletic ability was evaluated by measuring their maximal oxygen uptake, Wingate 30 s anaerobic capacity, 30 m sprint run, and race performance. Measurements were taken before and after participating in the training program for six weeks. The repeated measure ANOVA was used to test the overall differences of blood physiological and biochemical indicators. For indicators with significant time main effects, post-hoc tests were conducted using the least significant difference (LSD) method. The paired-samples t-test was used to analyze changes in athletic ability indicators before and after training. Results: (1) There was a significant overall time effect for red blood cells (RBC) and white blood cells (WBC) in males; there was also a significant effect on the percentage of lymphocytes (LY%), serum testosterone (T), and testosterone to cortisol ratio (T/C) in females (p < 0.001 - 0.015, η p 2 = 0 . 81 - 0 . 99 ). In addition, a significant time effect was also found for blood urea(BU), serum creatine kinase (CK), and serum cortisol levels in both male and female athletes (p = 0.001 - 0.029, η p 2 = 0 . 52 - 0 . 95 ). (2) BU and CK levels in males and LY% in females were all significantly higher at week 6 (p = 0.001 - 0.038), while WBC in males was significantly lower (p = 0.030). T and T/C were significantly lower in females at week 2 compared to pre-training (p = 0.007, 0.008, respectively), while cortisol (C) was significantly higher in males and females at weeks 2 and 4 (p (male) = 0.015, 0.004, respectively; p (female) = 0.024, 0.030, respectively). (3) There was a noticeable increase in relative maximal oxygen uptake, Wingate 30 s relative average anaerobic power, 30 m sprint run performance, and race performance in comparison to the pre-training measurements (p < 0.001 - 0.027). Conclusions: Six weeks of sub-plateau cold environment training may improve physical functioning and promote aerobic and anaerobic capacity for parallel giant slalom snowboard athletes. Furthermore, male athletes had a greater improvement of physical functioning and athletic ability when trained in sub-plateau cold environments.

Influence of Chronic Nitrate-Rich Beetroot Juice Supplementation on the Endurance Performance of Active Winter Triathletes: A Randomized Controlled Trial.

OBJECTIVE: The impact of high-nitrate beetroot juice (BRJ) supplementation has seen a recent explosion of interest in sports science. This study examined the potential influence of 7-day BRJ supplementation on the endurance performance of winter triathletes. METHODS: Eighty young active winter triathletes (44 males, age = 21.50 ± 1.15 yrs; 36 females, age = 20.66 ± 1.45 yrs) participated in this study and were provided with either BRJ (6.5 mmol NO3-/70 mL) or a placebo (PL, 0.065 mmol NO3-/70 mL) for 7 days (a dose of ×3 per day) in a randomized, double-blind design. The athletes then completed a submaximal treadmill run, intraday cycling exhaustion testing, and a 10-km cross country (XC) skiing competition on the second day. RESULTS: There was a significant decrease in the oxygen uptake, respiratory exchange ratio, and blood lactic acid level (p < 0.05) between the BRJ and PL treatment groups during V3 speed running (males: 13.3 km·h-1, females: 11.6 km·h-1). BRJ treatment also remarkably increased the time to exhaustion (TTE) during cycling exhaustion testing (males: p = 0.02, females: p = 0.04). No significant differences were observed in medium- or low-speed submaximal treadmill runs and 10-km XC skiing performance. CONCLUSIONS: One week of daily nitrate-rich BRJ supplementation improved running economy at high speed during the submaximal treadmill running test and extended the TTE of athletes during cycling exhaustion testing. However, BRJ supplementation did not improve the performance in 10-km on-snow time trials in XC skiing. Regarding nutritional strategies to improve endurance performance in exercise training and competition, these results should be carefully considered owing to the different motor skill levels and competitive abilities of participants.

Effects of a 4-week micro-hyperbaric oxygen intervention on oxidation-antioxidation system function / Efectos de la intervención con oxígeno micro-hiperbárico durante 4 semanas en la función del sistema oxidación-antioxidación / Efeitos da intervenção de oxigênio micro-hiperbárico de 4 semanas na função do sistema oxidante-antioxidante

ABSTRACT Introduction Hyperbaric oxygen intervention has an important effect on the function of the body's oxidation-antioxidant system. Objective To verify the effects of a 4-week micro-hyperbaric oxygen intervention on oxidation-antioxidation system function in skeleton athletes. Methods The experimental group underwent a 1.3 ATA HBO intervention for 4 weeks and the control group underwent natural recovery. The levels of MDA, PC, SOD, CAT, GSH-PX, T-AOC, BU, CK, T, and C of the two groups were measured at Week 0, Week 2, and Week 4. Results The MDA, PC, and CK of the Exp group were significantly lower than Con group (P < 0.05) in Week 4. The SOD, CAT, and T-AOC of the Exp group were significantly higher in Week 4 than in Week 0 (P < 0.05) and significantly higher than the Con group values (P < 0.05). Conclusions A four-week 1.3 ATA HBO intervention decreased the level of oxidative stress, increased the activity of antioxidant enzymes, and reduced the degree of exercise fatigue in skeleton athletes. Level of Evidence II; Therapeutic studies - Investigating treatment results.

RESUMEN Introducción La intervención con oxígeno hiperbárico tiene un efecto importante en la función del sistema oxidación-antioxidación del organismo. Objetivo Verificar los efectos de una intervención con oxígeno micro-hiperbárico durante 4 semanas en la función del sistema oxidación-antioxidación en atletas de skeleton. Métodos El grupo de prueba se sometió a una intervención con oxígeno micro-hiperbárico a 1,3 ATA durante 4 semanas, 4 veces a la semana, y el grupo de control se sometió a una recuperación natural. Se midieron los niveles de malondialdehído (MDA), carbonilo proteico (PC), superóxido dismutasa (SOD), catalasa (CAT), glutatión peroxidasa (GSH-PX), capacidad antioxidante total (T-AOC), urea en sangre (BU), creatina quinasa (CK), testosterona (T), y cortisol (C) en la semana 0, en la semana 2 y en la semana 4 para ambos grupos de atletas. Resultados Los valores de MDA, CP y CK del grupo de prueba fueron significativamente inferiores a los del grupo de control (p <0,05) en la semana 4. Los valores de SOD, CAT y T-AOC fueron significativamente mayores en el grupo de prueba en la semana 4 que en la semana 0 (p < 0,05) y significativamente mayores que los valores del grupo de control (p < 0,05) Conclusión: La intervención con oxígeno hiperbárico a 1,3 ATA durante 4 semanas redujo significativamente los niveles de estrés oxidativo, aumentó la actividad de las enzimas antioxidantes y redujo los niveles de fatiga relacionada con el ejercicio en los atletas de skeleton. Nivel de evidencia II; Estudios terapêuticos - Investigación de los resultados del tratamiento.

RESUMO Introdução A intervenção de oxigênio hiperbárico tem um efeito importante na função do sistema oxidativo-antioxidante do corpo. Objetivo Verificar os efeitos de uma intervenção de oxigênio micro-hiperbárico de 4 semanas na função do sistema oxidante-antioxidante em atletas de skeleton. Métodos O grupo de teste foi submetido a uma intervenção de oxigênio micro-hiperbárico a 1,3 ATA de 4 semanas, 4 vezes por semana e o grupo controle passou por recuperação natural. Os níveis de malondialdeído (MDA), proteína carbonila (PC), superóxido dismutase (SOD), catalase (CAT), glutationa peroxidase (GSH-PX), capacidade antioxidante total (T-AOC), uréia sanguínea (BU), creatina quinase (CK), testosterona (T) e cortisol (C) foram medidos na semana 0, semana 2 e semana 4 para ambos os grupos de atletas. Resultados MDA, PC e CK do grupo de teste foram significativamente menores do que os valores do grupo controle (p <0,05) na semana 4. SOD, CAT e T-AOC foram significativamente maiores no grupo de teste na semana 4 do que na semana 0 (p < 0,05) e significativamente maiores do que os valores para o grupo controle (p < 0,05). Conclusão A intervenção de oxigênio micro-hiperbárico de 4 semanas a 1,3 ATA reduziu significativamente os níveis de estresse oxidativo, aumentou a atividade enzimática antioxidante e reduziu os níveis de fadiga relacionada ao exercício nos atletas de skeleton. Nível de evidência II; Estudos terapêuticos - Investigação dos resultados do tratamento.

Corrigendum: The changes of umami substances and influencing factors in preserved egg yolk: pH, endogenous protease, and proteinaceous substance.

[This corrects the article DOI: 10.3389/fnut.2022.998448.].

The changes of umami substances and influencing factors in preserved egg yolk: pH, endogenous protease, and proteinaceous substance.

The study investigated the changes of nucleotides, succinic acid, and free amino acids amounts in yolk and the causes leading to the changes after pickling to uncover the fundamental umami component of preserved egg yolk. The findings demonstrated that while the contents of 5'-adenosine monophosphate (AMP), 5'-cytidine monophosphate (CMP), 5'-guanosine monophosphate (GMP), 5'-uridine monophosphate (UMP), and succinic acid increased after slightly decreasing aspartic acid (Asp) content in preserved egg yolk increased gradually. The contents of 5'-inosine monophosphate (IMP) and other free amino acids were gradually decreased. Comparing the taste activity value (TAV), it was found that the single umami substance, succinic acid, played a key role in inducing the umami taste. In combination with the Spearman correlation analysis, it was shown that the proteinaceous substance, which is the most significant umami component in preserved egg yolk, tended to condense first and subsequently disintegrate in an alkaline environment. The orthogonal partial least squares analysis (OPLS) found that pH was also affected by the changes in proteinaceous substance. These findings offer suggestions for enhancing the pickling procedure and investigating the optimal pickling period for preserved eggs.

Targeting mitochondrial quality control of T cells: Regulating the immune response in HCC.

Most of the primary hepatocellular carcinoma (HCC) develops from Viral Hepatitis including Hepatitis B virus, Hepatitis C Virus, and Nonalcoholic Steatohepatitis. Herein, T cells play crucial roles combined with chronic inflammation and chronic viral infection. However, T cells are gradually exhausted under chronic antigenic stimulation, which leads to T cell exhaustion in the tumor microenvironment, and the exhaustion is associated with mitochondrial dysfunction in T cells. Meanwhile, mitochondria play a crucial role in altering T cells' metabolism modes to achieve desirable immunological responses, wherein mitochondria maintain quality control (MQC) and promote metabolism regulation in the microenvironment. Although immune checkpoint inhibitors have been widely used in clinical practice, there are some limitations in the therapeutic effect, thus combining immune checkpoint inhibitors with targeting mitochondrial biogenesis may enhance cellular metabolic adaptation and reverse the exhausted state. At present, several studies on mitochondrial quality control in HCC have been reported, however, there are gaps in the regulation of immune cell function by mitochondrial metabolism, particularly the modulating of T cell immune function. Hence, this review summarizes and discusses existing studies on the effects of MQC on T cell populations in liver diseases induced by HCC, it would be clued by mitochondrial quality control events.

The role of Sirt3 in the changes of skeletal muscle mitophagy induced by hypoxic training.

We aimed to explore the role of Sirt3 in the regulation of skeletal muscle mitophagy with hypoxic training. C57BL/6J mice were randomly divided into four groups: C group (control), HT group (mice performed a hypoxic training of living in an environment with an oxygen concentration of 13.8% and treadmill exercise under normoxia for 6 weeks), T group (mice were subjected to an intraperitoneal (i.p.) injection of the Sirt3 inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP) 50 mg/kg three times per week for 6 weeks) and THT group (the hypoxic training of HT group with i.p. injection of 3-TYP in T group). The results showed that 6 weeks of hypoxic training could improve ATP synthesis in skeletal muscle. After the combined intervention of 3-TYP injection and hypoxic training, Sirt3, FOXO3a, and SOD2 protein contents were still lower than those in hypoxic training group. Hypoxic training cannot improve the negative effect of Sirt3 inhibition on muscle PINK1/Parkin signal. This study demonstrated that Sirt3 plays a key role in mediating skeletal muscle mitophagy by hypoxic training. The results of our study also provided the first evidence that mitophagy caused by hypoxic training might be transduced through the Sirt3-FOXO3a signaling pathway.

Echocardiographic myocardial work in pre-adolescent male basketball players: a comparison with cardiopulmonary exercise test-derived aerobic capacity.

Background: Pressure-strain loop (PSL) analysis provides a novel, less load-dependent non-invasive method to quantify myocardial work and demonstrates a significant correlation with the contractile reserve in adult athletes. We aim to validate PSL-derived markers in characterizing LV function in pre-adolescent basketball players by comparing results before and after the cardiopulmonary exercise test (CPX) and explore its association with CPX-derived aerobic capacity. Methods: Cardiac morphology and function in 20 pre-adolescent basketball players were assessed at 9.7 years old (9.7 ± 1.1 year) before and after cardiopulmonary exercise testing. Echocardiography was performed in all subjects, including two-dimensional speckle-tracking echocardiography (STE). Simultaneous brachial-cuff-measured blood pressure was recorded to perform PSL analysis. Results: Nineteen subjects were included in the final analysis. Exercise training in pre-adolescent males was associated with lower global work index (GWI) and global work efficiency (GWE) at rest. GWE at stress was significantly correlated with VO2max and peak O2 pulse (p = 0.0122, r = 0.56; p = 0.00122, r = 0.69, respectively). When indexed by body mass, GWI and GWE both significantly correlated with relative VO2max (p = 0.0086 and 0.0011 respectively, r = 0.58 and 0.69 respectively); GWI and GWE at baseline and stress were all significantly correlated with peak O2 pulse (GWI at baseline, p < 0.0001, r = -0.90; GWE at baseline, p < 0.0001, r = -0.89; GWI at stress, p = 0.0289, r = -0.50; GWE at stress, p < 0.0001, r = -0.83). Conclusion: PSL-analysis-derived GWI and GWE at rest indexed by body mass are associated with cardiopulmonary exercise test-derived peak oxygen consumption and oxygen pulse in pre-adolescent athletes.

Hypoxic Training Ameliorates Skeletal Muscle Microcirculation Vascular Function in a Sirt3-Dependent Manner.

Hypoxic training improves the microcirculation function of human skeletal muscle, but its mechanism is still unclear. Silent information regulator 2 homolog 3 (Sirt3) can improve mitochondrial function and oxidative status. We aimed to examine the role of Sirt3 in the process of hypoxic training, which affects skeletal muscle microcirculation. C57BL/6 mice were assigned to control (C), hypoxic training (HT), Sirt3 inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP), and 3-TYP + hypoxic training (3-TYP + HT) groups (n = 6/group). Sirt3 inhibition was induced by intraperitoneal injection of Sirt3 inhibitor 3-TYP. After 6 weeks of intervention, microcirculatory capillary formation and vasomotor capacity were evaluated using immunofluorescence, Western blot, biochemical tests, and transmission electron microscopy (TEM). Laser Doppler flowmetry was used to evaluate skeletal muscle microcirculation blood flow characteristics. Six weeks of hypoxic training enhanced skeletal muscle microcirculation function and increased microcirculatory vasodilation capacity and capillary formation. After the pharmacological inhibition of Sirt3, the reserve capacity of skeletal muscle microcirculation was reduced to varying degrees. After the inhibition of Sirt3, mice completed the same hypoxic training, and we failed to observe the microcirculation function adaptation like that observed in hypoxic training alone. The microcirculation vasodilation and the capillaries number did not improve. Hypoxic training improved skeletal muscle microcirculation vasodilation capacity and increased skeletal muscle microcirculation capillary density. Sirt3 is involved in the adaptation of skeletal muscle microcirculation induced by hypoxic training.

Effects of hot and humid environments on thermoregulation and aerobic endurance capacity of Laser sailors.

Objectives: The purpose was to investigate the effects of hot and humid environments on thermoregulation and aerobic endurance capacity and whether high skin temperature serves as a more important thermoregulatory factor affecting aerobic exercise capacity. Methods: A randomized cross-over design was applied to this study, in which nine Laser sailors performed the 6 km rowing test (6 km test) in both a warm (ambient temperature: 23 ± 1.4 °C; relative humidity: 60.5 ± 0.7%; wind speed: 0 km/h; WARM) and hot environment (ambient temperature: 31.8 ± 1.1 °C; relative humidity: 63.5 ± 4.9%; wind speed: 3.5 ± 0.7 km/h; HOT). Results: The time for completing 6 km test of HOT group was significantly longer than that of WARM group (P = 0.0014). Mean power of 3-4 km, 4-5 km and 5-6 km were significant lower in HOT group (P = 0.014, P = 0.02, P = 0.003). Gastrointestinal temperature and skin temperature were significantly higher in HOT group during the 6 km test (P = 0.016, P = 0.04). Heat storage at 5 min and 15 min of HOT group were significantly higher than that of WARM group (P = 0.0036; P = 0.0018). Heart rate and physiological strain index of HOT group were significantly higher than that of WARM group during the 6 km test (P = 0.01, P < 0.01). Conclusion: When skin temperature and core temperature both increased, high skin temperature may be the more important thermoregulatory factor that affected the aerobic endurance performance in hot and humid environments. The high skin temperature narrowed the core to skin temperature gradient and skin to ambient temperature gradient, which may result in greater accumulation of heat storage. The greater heat storage led to the lower muscle power output, which contributed to the reduction of the heat production.

Mechanism of Hyperbaric Oxygen Combined with Astaxanthin Mediating Keap1/Nrf2/HO-1 Pathway to Improve Exercise Fatigue in Mice.

Objective: This work aimed to explore the application and optimization of the electrophysiological monitoring system to real-time monitor the exercise-induced fatigue (EIF) animals and investigate the intervention mechanism of hyperbaric oxygen (HBO) combined with natural astaxanthin (NAX) on EIF. Methods: First, a system was constructed for acquisition, processing, and feature extraction of electrocardiograph (ECG) signal and surface electromyography (EMG) signal for EIF monitoring. The mice were randomly divided into a control group (CG), EIF group (EG), HBO treatment (HBO) group, and HBO combined with NAX treatment (HBO + NAX) group. The effect of the constructed system on classification recognition of EIF was analyzed. The levels of serum antioxidative stress indicators of mice in each group were detected, including malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), glutathione-peroxidation (GSH-Px), and total antioxidant capacity (T-AOC). In addition, the mRNA and protein levels of Keap1/Nrf2/HO-1 pathway related genes in liver tissue were detected. Results: The results showed that the normalized least mean squares algorithm effectively removed the motion artifact interference of ECG signal and can clearly display the signal peak, and high-pass filtering and power frequency filtering effectively removed the motion and baseline drift interference of surface EMG signal. The recognition sensitivity, specificity, and accuracy of the EIF recognition model based on the long- and short-term memory network were 90.0%, 93.3%, and 92.5%, respectively. Compared with the CG, the characteristics of ECG signal and surface EMG signal of the mice in the EIF group changed greatly (P < 0.05); the serum MDA level was increased obviously; the CAT, SOD, GSH, GSH-Px, and T-AOC levels were observably reduced (P < 0.05); the expressions of Keap1 and HO-1 in the liver were reduced remarkably, while the expression of Nrf2 was increased notably (P < 0.05). Compared with the EIF group, the characteristics of ECG signal and surface EMG signal of the mice in the HBO and HBO + NAX groups were obviously improved (P < 0.05); the serum MDA level was significantly reduced; the CAT, SOD, GSH, GSH-Px, and T-AOC levels were greatly increased (P < 0.05); the expressions of Keap1 and HO-1 in the liver were greatly increased, while the expression of Nrf2 was decreased sharply (P < 0.05). Conclusion: Therefore, the feature extraction and classification system of ECG signal combined with surface EMG signal could realize real-time monitoring of EIF status. HBO intervention could improve the body's ability to resist oxidative stress through the Keap1/Nrf2/HO-1 pathway and then improve the EIF state. In addition, the improvement effect of HBO + NAX was more obvious.

Dose-response relationship between training load and anaerobic performance in female short-track speed skaters: A prospective cohort study.

This study aimed to assess the dose-response relationship (DRR) between measures of training load (TL) and anaerobic performance in female short-track speed skaters. TL data from 22 female short-track speed skaters (mean ± SD; calendar age 20.7 ± 2.01 years, training length 4.18 ± 1.23 years, height 164.20 ± 5.53 cm, weight 52.00 ± 5.58 kg) was collected over a six week period. Participants completed two anaerobic capacity assessments (cycling parameters: total work, maximal anaerobic power [MAnP], power duration indices, maximal blood lactate, fatigue indices, and peak power output [PPO]) pre- and post-training, which included three tests (short-term, intermediate-term, and 120 s maximal anaerobic test). The mean weekly TL measures calculated were total distance, red zone (time spent > 85% of peak heart rate), Edwards training impulse (eTRIMP), Stagno training impulse (gTRIMP), Lucia training impulse, and session ratings of perceived exertion. The gTRIMP identified a curvilinear relationship and explained 79% and 63% of the variance in changes of MAnPi and PPO (R2 = 0.79, 95%CI = 0.64 to 1.00, turn point 621AU; R2 = 0.63, 95%CI = 0.27 to 1.00, turn point 633AU, respectively). Likewise, The eTRIMP identified a curvilinear relationship and explained 62% and 54% of the variance in changes of MAnPi and PPO (R2 = 0.62, 95%CI = 0.11 to 1.00, turn point 485AU; R2 = 0.54, 95%CI = 0.07 to 1.00, turn point 515AU, respectively). All other variables exhibited a DRR below moderate. This study investigated a TL strategy to improve the speed endurance of female short-track speed skaters and suggested the superiority of gTRIMP and eTRIMP methods of internal TL.

Effects of 4-Week Tangeretin Supplementation on Cortisol Stress Response Induced by High-Intensity Resistance Exercise: A Randomized Controlled Trial.

Objective: This study aimed to investigate the effects of 4-week tangeretin supplementation on the cortisol stress response induced by high-intensity resistance exercise. Methods: A randomized controlled trial of twenty-four soccer players was conducted during the winter training season. The experimental group (EG) took the oral supplement with tangeretin (200 mg/day) and the control group (CG) took placebo for 4 weeks. Before and after the 4-week intervention, all players performed a high intensity bout of resistance exercise to stimulate their cortisol stress responses. Serum cortisol, adreno-corticotropic hormone (ACTH) and superoxide dismutase (SOD) were obtained by collecting blood samples before (PRE), immediately after (P0), and 10 (P10), 20 (P20) and 30 minutes (P30) after the exercise. Results: The serum cortisol level (PRE, p = 0.017; P10, p = 0.010; P20, p = 0.014; P30, p = 0.007) and ACTH (P10, p = 0.037; P30, p = 0.049) of experimental group significantly decreased after the 4-week intervention. Compared with control group, EG displayed a significantly lower level of the serum cortisol (PRE, p = 0.036; P10, p = 0.031) and ACTH (P30, p = 0.044). Additionally, EG presented significantly higher superoxide dismutase activity level compared with CG at P30 (p = 0.044). The white blood cell of EG decreased significantly (PRE, p = 0.037; P30, p = 0.046) and was significantly lower than CG at P20 (p = 0.01) and P30 (p = 0.003). Conclusion: Four-week tangeretin supplementation can reduce serum cortisol and ACTH, which may ameliorate the cortisol stress response in soccer players during high-intensity resistance exercise training. It can also enhance antioxidant capacity, accelerate the elimination of inflammation throughout the body, and shorten recovery time after high-intensity exercise.

Low-Load Blood Flow Restriction Squat as Conditioning Activity Within a Contrast Training Sequence in High-Level Preadolescent Trampoline Gymnasts.

To investigate the effects of implementing low-load blood flow restriction exercises (LL-BFRE) instead of high-load exercises (HL-RE) in a contrast training program on strength and power performance of high-level young gymnasts. Fifteen high-level pre-pubescent trampoline gymnasts (national level, Tanner Stage II, intermediate experience in strength training) were divided into two groups to complete the same structure of a ten-week contrast strength training program differing only in the configuration of the first resistance exercise of the contrast sequence. The LL-BFRE group (n = 7, four girls, 13.9 ± 0.4 y) performed the first resistance exercise of the contrast with LL-BFRE (20%-30% 1RM, perceived pressure of 7 on a scale from 0 to 10). The HL-RE group (n = 8, four girls, 13.8 ± 0.5 y) trained the first resistance exercise of the contrast sequence with moderate-to-high load (60%-85% 1RM). Before and after the training period, isometric mid-thigh pull (IMTP), squat jump (SJ), counter movement jump (CMJ), and drop-jump (DJ) were performed to evaluate the effect of the intervention on strength and power capacities as primary outcomes. Changes in participants' anthropometric measures, muscle mass, left and right thigh girth, IMTP relative to bodyweight (IMTP-R), eccentric utilization ratio (EUR), and reactive strength index (RSI) were assessed as secondary outcomes. There was no significant interaction (p > 0.05) between group x time in any power and strength outcome, although SJ and EUR showed a trend to significant interaction (p = 0.06 and p = 0.065, respectively). There was an overall effect of time (p < 0.05) in all power and strength variables (CMJ, SJ, EUR, DJ, RSI, IMTP, and IMTP-R). There was a significant interaction in muscle mass (MM) [ß = 0.57 kg, 95% CI = (0.15; 0.98), t13 = 2.67, p = 0.019], revealing that participants in LL-BFRE increased their muscle mass (6.6 ± 3.1%) compared to HL-RE (3.6 ± 2.0%). Anthropometric variables did not present any group or interaction effect. However, there was a time effect (p < 0.05). Implementing LL-BFRE in place of HL-RE as a conditioning activity in a contrast training sequence might be equally effective in improving lower-body strength and power in preadolescent trampoline gymnasts.

[Exercise regulates lipid metabolism via lipophagy and its molecular mechanisms].

Lipophagy is a kind of selective autophagy, which can selectively identify and degrade lipid droplets and plays an important role in regulating cellular lipid metabolism and maintaining intracellular lipid homeostasis. Exercise can induce lipophagy and it is also an effective means of reducing body fat. In this review, we summarized the relationship between exercise and lipophagy in the liver, pancreas, adipose tissue, and the possible molecular mechanisms to provide a new clue for the prevention and treatment of fatty liver, obesity and other related metabolic diseases by exercise.

Role of TRPV1 in High Temperature-Induced Mitochondrial Biogenesis in Skeletal Muscle: A Mini Review.

Transient receptor potential vanilloid 1 (TRPV1) is a protein that is susceptible to cell environment temperature. High temperatures of 40-45°C can activate the TRPV1 channel. TRPV1 is highly expressed in skeletal muscle and located on the sarcoplasmic reticulum (SR). Therefore, TRPV1 activated by high-temperature stress releases Ca2+ from the SR to the cytoplasm. Cellular Ca2+ accumulation is a key event that enhances TRPV1 activity by directly binding to the N-terminus and C-terminus. Moreover, Ca2+ is the key messenger involved in regulating mitochondrial biogenesis in skeletal muscle. Long-term activation of TRPV1 may promote mitochondrial biogenesis in skeletal muscle through the Ca2+-CaMKII-p38 MAPK-PGC-1α signaling axis. The discovery of the TRPV1 channel highlights the potential mechanism for high-temperature stress improving muscle mitochondrial biogenesis. The appropriate hot stimulus in thermal environments might be beneficial to the muscular mitochondrial adaptation for aerobic capacity. However, the investigation of TRPV1 on mitochondrial biogenesis is at an early stage. Further investigations need to examine the role of TRPV1 in response to mitochondrial biogenesis in skeletal muscle induced by different thermal environments.