Acute Succinate Administration Increases Oxidative Phosphorylation and Skeletal Muscle Explosive Strength via SUCNR1

Endurance training and explosive strength training, with different contraction protein and energy metabolism adaptation in skeletal muscle, are both beneficial for physical function and quality of life. Our previous study found that chronic succinate feeding enhanced the endurance exercise of mice by inducing skeletal muscle fiber-type transformation. The purpose of this study is to investigate the effect of acute succinate administration on skeletal muscle explosive strength and its potential mechanism. Succinate was injected to mature mice to explore the acute effect of succinate on skeletal muscle explosive strength. And C2C12 cells were used to verify the short-term effect of succinate on oxidative phosphorylation. Then the cells interfered with succinate receptor 1 (SUCNR1) siRNA, and the SUCNR1-GKO mouse model was used for verifying the role of SUCNR1 in succinate-induced muscle metabolism and expression and explosive strength. The results showed that acute injection of succinate remarkably improved the explosive strength in mice and also decreased the ratio of nicotinamide adenine dinucleotide (NADH) to NAD+ and increased the mitochondrial complex enzyme activity and creatine kinase (CK) activity in skeletal muscle tissue. Similarly, treatment of C2C12 cells with succinate revealed that succinate significantly enhanced oxidative phosphorylation with increased adenosine triphosphate (ATP) content, CK, and the activities of mitochondrial complex I and complex II, but with decreased lactate content, reactive oxygen species (ROS) content, and NADH/NAD+ ratio. Moreover, the succinate's effects on oxidative phosphorylation were blocked in SUCNR1-KD cells and SUCNR1-KO mice. In addition, succinate-induced explosive strength was also abolished by SUCNR1 knockout. All the results indicate that acute succinate administration increases oxidative phosphorylation and skeletal muscle explosive strength in a SUCNR1-dependent manner.

Evolution of Explosive Strength Data in Youth Volleyball Players Before and After Pandemic

Study purpose. This study aims to verify if there are significant differences and which type of correlation is between anthropometric and jumping ability variables by testing a group (elite) of Italian volleyball players (under 16), just after a month of training, applying a specific protocol. Materials and methods. In all subjects, the following anthropometric and jumping ability parameters were assessed: height, weight, body mass index, height with a stretched arm (Reach1) and height with two extended arms (Reach2). The jumping ability was measured with the Squat jump (SJ) and Run-Up (RU) test. All data on anthropometric and jumping ability parameters were presented as mean and standard deviation (Mean ± SD). Results. The results of the jumping ability parameters (Squat Jump and Run-Up) showed significant differences between treatment initial-final: Run-Up with p = 0.000 and Squat Jump with p = 0.001; and these showed a higher correlation, especially the variables linked to the ability to jump, evident differences compared to the initial period of treatment. Conclusions. In high-level youth volleyball, the anthropometric and jumping ability profile is directly linked to the evaluation and continuous monitoring of physical qualities, and jumping ability becomes an important aspect for the control of performance.

Leg Dominance and OSB12 Kick Start Performance in Young Competitive Swimmers

The purpose of this study was to examine differences in starting and kick-plate positions, pointing to an effect on kick-start performance with the dominant and non-dominant feet placed on the front edge of the OSB12 starting block. The sample included 20 female competitive swimmers whose average age was 16.1 ± 0.6 years. To assess swimmers’ lower body explosive strength and determine leg dominance, a triple hop distance test was administered. We determined the swimmers’ preferred starting position on a starting block in terms of the kick-plate setting and body position on the starting block. The results of our study demonstrate the importance of leg dominance and positioning on the OSB12 starting block. After the preferred starting position was determined, the optimal position for the kick start was selected. When the dominant leg was placed on the front edge of the starting block (p < 0.05; Cohen’s d—large effect), swimmers produced shorter block times and times to 2 and 5 m. For most of the tested swimmers, the optimal basic position on the starting block included neutral- and rear-weighted positions with the kick plate set to positions 3–4 and the right leg placed on the front edge of the OSB12 starting block.

Assessment of the influence of physical activity and screen time on somatic features and physical fitness in 6 to 7-year-old girls

Aim of the study is to assess the relationship between screen time, physical activity and physical fitness among girls 6–7 years-old. 21,528 girls aged 6 and 7 from Poland were assessed in terms of physical fitness. Arm strength, abdominal strength and explosive strength of the lower limbs were measured using the EUROFIT test. Basic somatic features were measured and BMI and WHtR indices were calculated. Spontaneous and organized physical activities as well screen time were assessed by the parents utilizing a questionnaire. The multiple logistic regression method was used to evaluate the influence of screen time and spontaneous physical activity on various components of physical fitness. Physically active (PA) girls (≥1h/day) and those who participated in additional physical activities (APA) during the week had significantly higher height, weight, and BMI (p<0.001), but not WHtR. They had a higher level of flexibility, explosive strength of the lower limbs and arm strength (p<0.001). With an increase in screen time, the BMI, WHtR increased significantly and explosive strength of the lower limbs, abdominal strength and arm strength were lower. Regression analysis showed that more frequent participation in extracurricular activities increased the values of BMI and WHtR in quartile 4 (Q4), and strength components: Q2–Q4 (p<0.05). Spontaneous physical activity was positively related to the values of BMI, WHtR (both: Q4; p<0.05), explosive force of lower limbs (Q3–Q4; p=0.001), and negatively related to arm strength (Q2; p=0.001). Screen time (≥2hrs/day) increased odds for higher BMI values (p<0.05). Each screen time category decreased the odds of achieving abdominal muscle strength related to the quartiles: Q2–Q4 (p<0.05), arm strength (Q4: p<0.05). ST (1 <2hrs/day) decreased arm strength (Q3; p= 0.045). Our research has shown that screen time-related sedentary behavior and physical activity affect overweight and obesity indices (especially BMI) and strength abilities. The observed associations more often affected girls with a higher level of fitness The results observed in girls aged 6-7 indicate a need for early intervention aimed at limiting time spent watching TV and computer use, as well as to encourage both spontaneous and organized physical activities.

EFFECT OF FATIGUE ON EXPLOSIVE STRENGTH AND MUSCLE ARCHITECTURE OF THE VASTUS LATERALIS

ABSTRACT Introduction: There has been little research on changes in rate of torque development (RTD) and muscle architecture. This study evaluated the effect of fatigue on RTD and muscle architecture of the vastus lateralis (VL). Methods: Seventeen volunteers (25.5 ± 6.2 years; 177.2 ± 12.9 cm; 76.4 ± 13.1 kg) underwent isokinetic knee extension assessment at 30°/s to obtain the peak torque (PT-ISK), before and after a set of intermittent maximal voluntary isometric contractions (MVIC) (15 reps – 3 s contraction, 3 s rest) used to promote muscle fatigue, monitored by the median frequency (MDF) of the electromyography from the VL, rectus femoris and vastus medialis muscles. Before and after the fatigue protocol, ultrasound images of the VL were obtained to measure muscle thickness (MT), fascicle length (FL), and fascicle angle (FA). The peak isometric torque (PT-ISM) and the RTDs in 50 ms windows were calculated for each MVIC. The RTDs were reported as absolute values and normalized by the PT-ISM. Results: Fatigue was confirmed due to significant reductions in MDF in all three muscles. After the fatigue protocol, the PT-ISK was reduced from 239.0±47.91 to 177.3±34.96 Nm, and the PT-MVIC was reduced from 269.5±45.63 to 220.49±46.94 Nm. All the RTD absolute values presented significant change after the fatigue protocol. However, the normalized RTD did not demonstrate any significant differences. No significant differences were found in the muscle architecture of the VL. Conclusions: The reduction in explosive strength occurred concomitantly with the reduction in maximum strength, as evidenced by the lack of changes in normalized TDT. Level of Evidence III.

Compatibility of Concurrent Aerobic and Strength Training for Skeletal Muscle Size and Function: An Updated Systematic Review and Meta-Analysis

Background Both athletes and recreational exercisers often perform relatively high volumes of aerobic and strength training simultaneously. However, the compatibility of these two distinct training modes remains unclear. Objective This systematic review assessed the compatibility of concurrent aerobic and strength training compared with strength training alone, in terms of adaptations in muscle function (maximal and explosive strength) and muscle mass. Subgroup analyses were conducted to examine the influence of training modality, training type, exercise order, training frequency, age, and training status. Methods A systematic literature search was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed/MEDLINE, ISI Web of Science, Embase, CINAHL, SPORTDiscus, and Scopus were systematically searched (12 August 2020, updated on 15 March 2021). Eligibility criteria were as follows. Population: healthy adults of any sex and age; Intervention: supervised concurrent aerobic and strength training for at least 4 weeks; Comparison: identical strength training prescription, with no aerobic training; Outcome: maximal strength, explosive strength, and muscle hypertrophy. Results A total of 43 studies were included. The estimated standardised mean differences (SMD) based on the random-effects model were − 0.06 (95% confidence interval [CI] − 0.20 to 0.09; p = 0.446), − 0.28 (95% CI − 0.48 to − 0.08; p = 0.007), and − 0.01 (95% CI − 0.16 to 0.18; p = 0.919) for maximal strength, explosive strength, and muscle hypertrophy, respectively. Attenuation of explosive strength was more pronounced when concurrent training was performed within the same session (p = 0.043) than when sessions were separated by at least 3 h (p > 0.05). No significant effects were found for the other moderators, i.e. type of aerobic training (cycling vs. running), frequency of concurrent training (> 5 vs. < 5 weekly sessions), training status (untrained vs. active), and mean age (< 40 vs. > 40 years). Conclusion Concurrent aerobic and strength training does not compromise muscle hypertrophy and maximal strength development. However, explosive strength gains may be attenuated, especially when aerobic and strength training are performed in the same session. These results appeared to be independent of the type of aerobic training, frequency of concurrent training, training status, and age. PROSPERO: CRD42020203777.

Choline-Based Multi-Ingredient Supplementation Can Improve Explosive Strength during a Fatiguing Task

Various choline-based multi-ingredient supplementations (CMS) have been suggested in the current market, but the research is limited. The purpose of this study was to investigate the acute effect of a CMS on physical performance. Fourteen male college football players (20.4 ± 1.0 years) participated in a randomized double-blind crossover experiment separated by 7 days. Subjects were given a CMS or a placebo 60 min before physical performance testing measures, including maximum vertical jumps, maximum voluntary isometric contractions (MVIC), maximal voluntary concentric contractions (MVCC), and fatiguing contractions. Four MVICs and seven sets of two MVCCs at various loads (1 N·m to 60% MVIC torque) were performed with the knee extensor muscles while seated on a dynamometer before and after the fatiguing tasks. During the fatiguing tasks, 120 MVCCs (4 sets × 30 reps) were performed with a load equivalent to 20% MVIC. Twitch interpolation technique was used to assess muscle contractile properties and voluntary activation. No significant differences were seen at baseline between sessions for all testing measures including vertical jump height, strength, power, muscle contractile properties and voluntary activation. Rate of torque development and impulse was higher in supplemental session compared to control session throughout the fatiguing contractions (p = 0.018, p < 0.001, respectively). Acute CMS can improve explosive strength by delaying the onset of fatigue.

HOW DOES PARTICIPATION IN PHYSICAL ACTIVITY AFFECT PHYSICAL FITNESS ELEMENTS IN CHILDREN AGED 5-9?

This study was conducted to examine the effect of participation in physical activity on physical fitness parameters in children aged 5-9 years. A total of 83 children, 44 girls, and 39 boys, studying in a private primary school participated in the study voluntarily. The Eurofit Test Battery was used to evaluate the physical fitness levels of children. Within the scope of the Eurofit test battery; the body weight and height values of the children were measured. In the determination of motoric performances, flamingo balance, disc touch, sit-reach, standing long jump, sit-up, bent-arm hanging, and 5x10 meter sit-up tests were used. A personal information form prepared by the researchers was used to determine demographic characteristics. Whether the data is normally distributed or not was checked with kurtosis and skewness values. In the statistical analysis dimension; descriptive analysis (mean, standard deviation, median, min-max value, ratio, frequency), independent samples t test (Independent Samples t test) were used. In terms of children having an athlete license, a significant difference was found in their height, standing long jump test, sit-up test, bent-arm hanging test, 5x10 meter sit-up run test scores (p>0.05). A significant difference was found in the findings of height, body weight, standing long jump test, sit-up test, bent arm hanging test, 5x10 meter sit-up run test in terms of children's participation in traditional children's games (p>0.05). As a result, it has been determined that children's having an athlete's license increases their height, explosive strength, core strength endurance, upper extremity strength endurance, agility, and again, the students' participation in traditional children's games has positive effect on height, body weight, explosive strength, core strength endurance, upper extremity strength endurance and agility. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0891/a.php" alt="Hit counter" /></p>

Relationship Between Explosive Strength Capacity of the Knee Muscles and Deceleration Performance in Female Professional Soccer Players

The present study aimed to investigate the relationship between linear deceleration performance and explosive strength capacity of the knee muscles. Fourteen female professional soccer players completed the maximal sprint deceleration tests and knee flexor (KF) and knee extensor (KE) isokinetic concentric (240° and 60°.s−1) and eccentric contractions (30°.s−1). Linear deceleration performance was evaluated from horizontal breaking force (FH), power (PH), and impulse (IH) during a maximal linear deceleration. The peak torque (PT) of KF and KE, PT ratio between KF and KE (conventional and functional H/Q ratio), rate of torque development (RTD) for each muscle group, and RTD between KF and KE (RTD H/Q) were extracted from the isokinetic contractions. Pearson’s correlation coefficients revealed that the eccentric (30°.s−1) and concentric (60°.s−1, 240°.s−1) KE peak torque, and the concentric KF peak torque (240°.s−1) were significantly correlated with FH, PH, and IH (−0.75&lt;r&lt;−0.54). Moreover, a significant correlation was found between KE RTD during eccentric contraction and FH, PH, and IH (−0.63&lt;r&lt;−0.54). Besides, a significant correlation was observed between RTD H/Q at 60°.s−1 and PH, IH (−0.61&lt;r&lt;−0.57). No significant relationship was observed between the H/Q ratio, KF RTD and deceleration performance. These main findings indicated the importance of the ability to quickly produce high KE eccentric torque, contributing to braking force production. Meanwhile, RTD H/Q should be assessed for its essential role in knee joint dynamic stability and can be a relevant index to determine deceleration performance.