Explosive Force Research Articles

The big-bang started from nothing: Not the initially hot cosmic matter, but a positive vacuum pressure made the universe explode!

Mankind all over its past epochs did ask the question, how this huge and materially impressive universe could ever have started its existence. The standard dogmatic answer presently given by the majority of modern cosmologists is: By the Big-Bang! - i.e. that initial explosion of the central highly condensed world matter system! But why - it could be asked - should this system have exploded at all? Perhaps this popular BB-hypothesis of a general and global cosmic explosion creating the world is especially suggestive just in these days of wars and weapons all around. Nevertheless to declare such an initial event as the begin of the universe unexpectedly turns out to be extremely hard to explain when based on purely physical grounds. Though it is easy to envisage a granate explosion causing matter to fly apart in all directions from the center of the explosion, but as a total surprise it is extremely hard to explain which physically operating forces or pressures might be responsible to drive the initially highly compacted cosmic matter agglomeration apart of each other. If the explosion forces are imagined as due to acting thermal pressure forces of normal massive matter, then the needed pressures cannot be due to the extremely high temperatures of the condensed matter, because the thermal energy of relativistically hot matter, as relativity theory tells us, will act as an additional source of gravity, i.e. making matter even "heavier"! Hence this just impedes the initial mass agglomeration to explode and fly apart. As we shall show in the following article the explosive BB- event can only physically be explained, if the necessary pressure is not conventionally realized by the temperature of the gravitating matter, but to the contrary by the immaterial cosmic vacuum. In fact - as we shall demonstrate here - without a cosmic vacuum pressure, the so-called Big-Bang never at all could have happened. Certainly vacuum pressure up to the present days of cosmology still is a fully speculative subject, but it will become evident in the following article, that without this highly speculative, physically handable quantity a primordial Big-Bang would not have happened at all.

Learning to Play Football From Sports Domain Perspective: A Knowledge-Embedded Deep Reinforcement Learning Framework

Applying deep reinforcement learning to football games has recently received extensive attention. However, this remains challenging due to the excessively high complexity of the football environment such as high-dynamical game states, sparse rewards, and multiple roles with different capabilities. Existing works aim to address these problems without considering abundant domain knowledge of football. In this paper, a football knowledge-embedded learning framework is proposed. Specifically, the pitch control concept is innovatively introduced to design a knowledge-embedded state representation. As a result, a novel pitch control model is designed that quantitatively provides space influence values of a single player, the whole team, and the ball. Different from existing models, this model additionally considers each player's various capabilities, including flexibility, explosive force, and stamina. Furthermore, the deformable convolution network is adopted for state representation extracting, which is used to process the geometric transformation of the players' positions and spatial influence values generated by the pitch control model. Then, based on this comprehensive state representation, a PPO-based reinforcement learning scheme is adopted to generate the final policy. Finally, extensive simulations, including learning against a fixed opponent and learning from self-play, clearly show the effectiveness and adaptability of our proposed framework.

Features of using a step-platform for the development of physical abilities of girls engaged in sports aerobics at the stage of basic training

The article is devoted to studying the influence of exercises with a step-platform on the dynamics of development and improvement of physical abilities of athletes in sports aerobics. The purpose of the study is to study the effectiveness of the use of step-platform for the development of physical abilities of girls engaged in sports aerobics at the stage of basic training. To solve the problems of the study, the following methods were used: study, analysis, systematization and synthesis of literature on the topic of the study; questionnaires; pedagogical experiment; testing the level of development of physical abilities: flexibility, strength, speed strength and coordination abilities and endurance, mathematical and statistical methods. The study involved 20 girls who were involved in aerobic sports in the basic training groups of the fourth year. They were 11-12 years old by the beginning of the experiment. All subjects were divided into a control and experimental group of 10 athletes in each. For girls, the pilot group was to introduce six step-platform exercises over a 12-week period. Each of the developed complexes is aimed at the preferential development of one of the physical abilities requiring a high level of development in sports aerobics. The study proved that the systematic inclusion in training exercises of special exercises with step-platforms for three months contributed to a statistically probable increase in flexibility (at p<0.01), explosive force (at p<0.02), aerobic endurance (at p< 0.02) and strength endurance and agility (at p<0.05). In the construction of complexes should be used exercises aimed at increasing the level of both general physical preparedness and special.

Influence of specific collagen peptides and 12-week concurrent training on recovery-related biomechanical characteristics following exercise-induced muscle damage-A randomized controlled trial.

It has been shown that short-term ingestion of collagen peptides improves markers related to muscular recovery following exercise-induced muscle damage. The objective of the present study was to investigate whether and to what extent a longer-term specific collagen peptide (SCP) supplementation combined with a training intervention influences recovery markers following eccentric exercise-induced muscle damage. Fifty-five predominantly sedentary male participants were assigned to consume either 15 g SCP or placebo (PLA) and engage in a concurrent training (CT) intervention (30 min each of resistance and endurance training, 3x/week) for 12 weeks. Before (T1) and after the intervention (T2), eccentric muscle damage was induced by 150 drop jumps. Measurements of maximum voluntary contraction (MVC), rate of force development (RFD), peak RFD, countermovement jump height (CMJ), and muscle soreness (MS) were determined pre-exercise, immediately after exercise, and 24 and 48 h post-exercise. In addition, body composition, including fat mass (FM), fat-free mass (FFM), body cell mass (BCM) and extracellular mass (ECM) were determined at rest both before and after the 12-week intervention period. Three-way mixed ANOVA showed significant interaction effects in favor of the SCP group. MVC (p = 0.02, ηp2 = 0.11), RFD (p < 0.01, ηp2 = 0.18), peak RFD (p < 0.01, ηp2 = 0.15), and CMJ height (p = 0.046, ηp2 = 0.06) recovered significantly faster in the SCP group. No effects were found for muscle soreness (p = 0.66) and body composition (FM: p = 0.41, FFM: p = 0.56, BCM: p = 0.79, ECM: p = 0.58). In summary, the results show that combining specific collagen peptide supplementation (SCP) and concurrent training (CT) over a 12-week period significantly improved markers reflecting recovery, specifically in maximal, explosive, and reactive strength. It is hypothesized that prolonged intake of collagen peptides may support muscular adaptations by facilitating remodeling of the extracellular matrix. This, in turn, could enhance the generation of explosive force. ClinicalTrials.gov, identifier ID: NCT05220371.

EFFECTS OF THE FIFA 11+ WARM-UP PROGRAM ON VERTICAL JUMP AND DYNAMIC BALANCE AT U16 LEVEL IN FOOTBALL

The FIFA 11+ warm-up program was developed as an injury prevention alternative to traditional warm-up methods in football. Numerous studies have confirmed its effectiveness in reducing injuries, as well as its potential impact on performance. The objective of this study is to investigate the effects of the FIFA 11+ program on explosive force and dynamic balance, utilizing the Opto Jump equipment by Microgate. A total of 39 players were divided into two groups based on their respective teams: the intervention group (n=19) and the control group (n=20). The intervention group followed the FIFA 11+ warm-up three times a week for 12 weeks, while the control group continued with their regular warm-up routine. The results indicated no statistically significant differences between the two groups in the vertical jump test. However, in the dynamic balance test, the intervention group demonstrated significantly better results in power and reactive strength index compared to the control group. In conclusion, implementing the FIFA 11+ program for a minimum of 12 weeks, three times a week, can enhance dynamic balance and serve as a viable alternative to traditional football warm-up routines.

Management ofCombat Casualties during Aeromedical Evacuation from a Role 2 to a Role 3 Medical Facility.

Emergent clinical care and patient movements through the military evacuation system improves survival. Patient management differs when transporting from the point-of-injury (POI) to the first medical treatment facility (MTF) versus transporting from the Role 2 to the Role 3 MTF secondary to care rendered within the MTF, including surgery and advanced resuscitation. The objective of this study was to describe care provided to patients during theater inter-facility transports and compare with pre-hospital transports (POI to first MTF). We performed a retrospective chart review of patients with the Role 2 to the Role 3 transports in Afghanistan and Iraq from 2007 to 2016. Data collected included procedures and events at the MTF and during transport. We compared the intra-theater transport data (Role 2 to Role 3) to data from a previous study evaluating pre-hospiital transports (POI to first MTF). We reviewed the records of 869 Role 2 to Role 3 transport patients. Role 2 to Role 3 transports were longer in duration compared to POI transports (39 minutes vs. 23 minutes) and were more likely to be staffed by advanced personnel (nurses, physician assistants, and physicians) (57% vs. 3%). The sample primarily consisted of military-aged males (mean age 27 years) who suffered from explosive or blunt force injuries. Procedures performed during each phase of care reflected the capabilities of the teams and locations. Pain and cardiac events were more common in POI evacuations compared to the Role 2 to Role 3 transports, but documentation of respiratory events, hemodynamic events, neurologic events, and equipment failure was more common during the Role 2 to Role 3 transports. Survival rates were slightly higher among the Role 2 to Role 3 cohort (98% vs. 95%, difference 3% [95% confidence interval of the difference 1-5%]). Inter-facility transports (Role 2 to Role 3) are longer in duration, transport more complex patients, and are staffed by more advanced level provider types compared to transports from POI.

The effect of special exercises according to the reciprocal method in developing explosive force in long shot in football

The effect of special exercises according to the reciprocal method in developing explosive force in long shot in football

The impact of the development of explosive force on the technical preparedness of hockey players 15–16 years

This article discusses the development of the explosive power of strikers in hockey at the stage of higher sportsmanship within the framework of the developed methodology. The system of realization of its components is revealed, the rationale for the qualitative increase in the level of special technical preparedness is given, the algorithm for the implementation of the methodological component in the annual preparatory macrocycle is given.

Correlations Between Shoulder and Hip Joints in Professional Male Rugby Players and Their Impact on Body Balance

Introduction: The game of rugby is becoming more and more popular, despite the fact that it is a collision sport in which skill plays a large role. In the training process, great importance is placed on the development of general physical fitness, in particular, on strength, power and muscular endurance.Aim: The aim of this study is to analyse the co-organisation between range of motion, body balance, power and speed of the kick and throw in men practicing rugby.Material and methods: The study involved 19 players training rugby on the Extraleague team of MKS Ogniwo Sopot, with an average age of 27.325.49. The Inbody 270 body composition analyser, the EPSR1 mat measuring the distribution of foot pressure on the ground, the WiVA sensor for measuring the range of motion and the Tendo Unit for measuring the explosive force were used to carry out testing.Results: The results indicate that people with a higher level of balance perform a throw with more power and speed. It was also shown that the range of motion in the upper limb is directly proportional to the range of motion in the hip joint.Conclusions: In the sport of rugby, flexion and extension movements of both the shoulder and hip joints are performed alternately. Based on the results, it can be concluded that in rugby athletes, balance training deserves special attention, which may translate into greater speed and power of the throw during a game. At the same time, an increase in the range of motion when flexing the arm and an increase in the pressure on the forefoot were noted, and the inversely proportional relationship between the COP area of the whole body and the heel area of the left foot may indicate the transfer of body mass by the tested players to the metatarsal and forefoot.

Comparative study on the effect of steel and plastic synthetic fibers on the dynamic compression properties and microstructure of ultra-high-performance concrete (UHPC)

Ultra-high-performance concrete (UHPC) shows great potential in constructing concrete structures subjected to impact and explosive forces. In order to make UHPC structures more ductile and cost-effective, this study used four-volume fractions of plastic synthetic fiber (PSF) instead of conventional steel fibers (SF) to prepare ultra-high-performance hybrid fiber-reinforced concrete (UHP–HFRC) with a total fiber weight of 2%. The dynamic compression properties at four strain rates were also investigated using a split Hopkinson pressure bar (SHPB) test. The results show that the addition of PSF reduces the flowability and compressive strength of UHPC but contributes significantly to the flexural strength of UHPC. UHP-HFRC demonstrates higher integrity under impact loading and significant sensitivity to strain rates. As the strain rate increases, both the dynamic compressive strength and dynamic growth factor of UHP-HFRC increase, with the optimal mixing ratio of PSF and SF being 1:3.Combined with the SEM and nanoindentation test results, it can be found that the bonding ability of PSF to the substrate is stronger, and the interface zone between PSF and the substrate is 10um smaller than that between sf and the substrate. It can be concluded that it is difficult for PSF to fully replace steel fiber in referencing UHPC, while hybrid fibers should be a good choice to produce excellent UHPC composite.

Acceleration of metal plates by hybridization of electrical and chemical energy for potential application in high-velocity impact welding

Vaporizing foil actuator welding is employed to connect dissimilar metals by utilizing the energy of an electrical explosion as the driving force for flyer plate acceleration. Herein, the electrical and chemical energies of explosives were combined to increase flyer plate velocity. A metal foil or wire mesh was used as an actuator, and a small amount of explosives was placed on the foil. Uniform acceleration of the flyer plate on the actuator was recorded using a high-speed video camera. The electrical energy applied to the actuator was measured synchronously by filming. The explosion of chemical explosives was successfully initiated owing to the electrical explosion of the actuator. In all experiments, the combination of the electrical explosion and chemical reaction improved the acceleration of the samples, facilitating higher velocities. The impact of the actuator type (mesh or foil) and the electric discharge parameters on the performance was studied. While foil actuators were more efficient in experiments on electric explosions alone, mesh actuators were superior when the chemical explosive was added. Explosions of the mesh actuator could initiate low density pentaerythritol tetranitrate (PETN) (the space-filling rate of PETN was approximately 30%). An explosive force of 0.3 g of PETN was converted into a driving force, imparting the flying plate with a velocity greater than 210 m/s. Electrical energy consumption for PETN initiation may be assumed to have an insignificant impact on flyer plate acceleration. In future, the proposed method may be used to connect heavier and thicker materials without expensive high-performance capacitors.

The universe generated by the explosion of the primordial cosmic vacuum!

Over all its epochs mankind always has put the fundamental question: When and why at all did the universe start its existence? Most cosmologists univocally do answer this question with the standard dogmatic answer: By the Big-Bang! - namely by the initial explosion of an extremely concentrated world matter system! This standard paradigm of a general and global explosion creating this world obviously appears to be highly suggestive, though such an explosive event unexpectedly turns out to be extremely hard to understand on purely physical grounds. This is because it is extremely hard to explain which pressures might be responsible to drive the initially highly compacted cosmic matter apart. The somewhat naive idea that the required explosion forces in view of the extremely high temperatures and the extreme highly compacted primordial cosmic matter, are due to extreme initial pressure forces does not solve the problem, because relativistically hot matter will be just an additional source of gravity, hence just contrary to the expectations impedes matter to fly apart. It can, however, be shown that the expected explosive BB- event can only physically occur, if the required pressure is not established by the temperature of gravitating matter, but by the cosmic vacuum. In fact we show that without this cosmic vacuuum pressure, the so-called Big-Bang never could have happened, even though vacuum pressure up to the present days of cosmology, still may be a rather speculative subject. In the following article we shall demonstrate that with a revised understanding of this highly speculative quantity one can explain the present universe as an explosion of the primordial cosmic vacuum followed by a succesive materialisation of this vacuum into cosmic matter at the ongoing cosmic expansion.

Neuromuscular Plantar Flexor Performance of Sprinters versus Physically Active Individuals.

Comparison of the neuromuscular performance of different athlete types may give insight into the in-vivo variability of these measures and their underpinning mechanisms. The study aims to compare the neuromuscular function of the plantar flexors of sprinters and physically active individuals to assess any differences in explosive force performance. Neuromuscular performance of a group of sprinters (highly trained/national level, n = 12; elite/international level, n = 2) and physically active individuals (n = 14) were assessed during involuntary, explosive, and maximum voluntary isometric plantar flexions, across different muscle-tendon unit (MTU) lengths (10° plantarflexion (PF), 0° (anatomical zero/neutral, AZ), and 10° dorsiflexion (DF)). Plantarflexion rate of torque development (RTD) was measured in three 50-ms time windows from their onset. The synchronous activation of the plantar flexor agonist muscles was calculated as the time difference between 1) the first and last muscle onset and 2) the onsets of the two gastrocnemii muscles. Muscle size and MTU stiffness were assessed using sonograms of the medial gastrocnemius and myotendinous junction. Sprinters exhibited greater involuntary RTD across time points (0-50, 50-100 ms) and MTU lengths. Additionally, sprinters demonstrated greater early phase voluntary RTD (0-50, 50-100 ms) across MTU lengths. Sprinters also demonstrated greater late-phase RTD (100-150 ms), and relative maximal voluntary torque at the DF angle only. The sprinters demonstrated a more synchronous activation of the gastrocnemii muscles. There were no observable differences in muscle size and MTU stiffness between groups. These findings suggest sprint-specific training could be a contributing factor toward improved explosive performance of the plantar flexors, particularly in the early phase of muscular contraction, evidenced by the greater explosive torque producing capabilities of sprinters.

Explosive force acquisition of sprinter lower limb in training based on WSN

Explosive force acquisition of sprinter lower limb in training based on WSN

Post-activation performance enhancement of flywheel training on lower limb explosive power performance.

The study aimed to investigate the post-activation performance enhancement (PAPE) of flywheel training (FT) on lower limb explosive power performance. Using a randomized crossover design, 20 trained men (age = 21.5 ± 1.4years; training experience 5.5 ± 1.2years) completed seven main conditions after three familiarization sessions. The first three conditions tested the PAPE of the FT on the counter movement jump (CMJ) under three different inertial loads (0.041kg·m2 as L; 0.057kg·m2 as ML; and 0.122kg·m2 as P), whereas the following four conditions tested the PAPE of FT on the 30m sprint, which consisted of three inertial loads (L, ML, and P) and a control condition. Participants were required to perform the CMJ or 30m sprint at baseline (Tb) and immediately (T0), 4min (T4), 8min (T8), 12min (T12), and 16min (T16) after exercise, respectively. The results of the CMJ conditions showed that PAPE peaked at T4 (p < 0.01) and almost subsided at T12 (p > 0.05) in ML and P conditions. Meanwhile, PAPE appeared earlier in the P condition, and the effect was more significant (P:ES = 1.09; ML:ES = 0.79). 30m sprint results showed significant improvement only in the ML condition. The PAPE peaked at T4 (p < 0.05, ES = -0.47) and almost subsided at T8 (p > 0.05). It was mainly due to the significant enhancement of the 10-30m segmental timing performance at T4 (p < 0.05, ES = -0.49). This study indicates that the size of the inertial load could influence the magnitude of the PAPE produced by the explosive force of the lower limb. The PAPE of the vertical explosive force increased with increasing inertial load, but the PAPE of the horizontal explosive force did not appear at the maximum inertial load. The most effective elicitation of the PAPE was at 4-8min after the FT.

Analysis of the rate of force development reveals high neuromuscular fatigability in elderly patients with chronic kidney disease.

Chronic kidney disease (CKD) induces muscle wasting and a reduction in the maximum voluntary force (MVF). Little is known about the neuromuscular fatigability in CKD patients, defined as the reduction of muscle force capacities during exercise. Neuromuscular fatigability is a crucial physical parameter of the daily living. The quantification of explosive force has been shown to be a sensitive means to assess neuromuscular fatigability. Thus, our study used explosive force estimates to assess neuromuscular fatigability in elderly CKD patients. Inclusion criteria for CKD patients were age≥60years old and glomerular filtration rate (GFR)<45mL/min/1.73m2 not on dialysis, and those for controls were GFR>60mL/min/1.73m2 , age and diabetes matched. The fatigability protocol focused on a handgrip task coupled with surface electromyography (sEMG). Scalars were extracted from the rate of force development (RFD): absolute and normalized time periods (50, 75, 100, 150 and 200ms, RFD50 , RFD75 , RFD100 , RFD150 and RFD200 , respectively), peak RFD (RFDpeak in absolute; NRFDpeak normalized), time-to-peak RFD (t-RFDpeak ) and the relative force at RFDpeak (MVF-RFDpeak ). A statistical parametric mapping approach was performed on the force, impulse and RFD-time curves. The integrated sEMG with time at 0-30, 0-50, 0-100 and 0-200ms time intervals relative to onset of sEMG activity was extracted and groups were compared separately for each sex. The cohort of 159 individuals had a median age of 69 (9IQR ) years and body mass index was 27.6 (6.2IQR ) kg/m2 . Propensity-score-matched groups balanced CKD patients and controls by gender with 66 males and 34 females. In scalar analysis, CKD patients manifested a higher decrement than controls in the early phase of contraction, regarding the NRFDpeak (P=0.009; η2 p =0.034) and RFD75 and RFD100 (for both P<0.001; η2 p =0.068 and 0.064). The one-dimensional analysis confirmed that CKD males manifest higher and delayed neuromuscular fatigability, especially before 100ms from onset of contraction. sEMG was lower in CKD patients than controls in the 0-100ms (at rest: P=0.049, Cohen's d=0.458) and 0-200ms (at rest: P=0.016, Cohen's d=0.496; during exercise: P=0.006, Cohen's d=0.421) time windows. Controls showed greater decrease of sEMG than CKD patients in the 0-30ms (P=0.020, Cohen's d=0.533) and 0-50ms (P=0.010, Cohen's d=0.640) time windows. As opposite to females, males showed almost the same differences between groups. Our study is the first to show that CKD patients have higher fatigability than controls, which may be associated with an impaired motor-unit recruitment, highlighting a neural drive disturbance with CKD. Further studies are needed to confirm these findings.

Influence of 12 weeks of basketball training on college students' heart function.

This study aims to investigate the influence of 12 weeks of basketball training on college students' heart function. The subjects were 30 college male basketball players. Carry out 8-week interval training, monitor the training load and interval time of athletes, and strictly control the heart rate during the interval. Before and after training, we used safe and effective experimental instruments - without any damage to the athletes - to detect the relevant indicators of the athletes' physiological functions; hence we compared and analyzed the various indicators before and after training. The time domain indexes Root Mean Square of Successive Differences (RMSSD), Statistically Determined Spatial Drift (SDSD), percentage of NN50 in the total number of NN intervals (PNN50), and Standard Deviation of all NN intervals for all 5-min segment (SDNN) after training were significantly higher than those before training, and the differences were statistically significant (p<0.05). Average (Avag) and Statistically Determined Allocation Weights (SDAW) after training were significantly higher than those before training, the difference was statistically significant (p<0.05); Asymmetry (Asym) and Tension index (TI) were significantly lower than those before training, the difference was statistically significant (p<0.05), Application Information Index (ApInf) had no significant difference (p>0.05). There was no significant difference in shooting hit rate (p>0.05). The speed of the 8-character dribble in the whole field after training was significantly lower than that before training, and the differences were statistically significant (p<0.05). There was no significant difference in average jump height, maximum jump height, average time in the air, and best jump time in the air after training (p>0.05). For the test of athletes' explosive power, five vertical jumps in situ were selected for testing, and the jump height and time in the air of each vertical jump were counted to calculate the maximum and average values of five vertical jumps. The results showed that there was no significant change in the explosive force of the athletes' lower limbs after training. The reason may be that strength training needs to follow the principles of heavy load, specialization, exercise sequence and reasonable interval. The intermittent training method used during training is not specialized in strength training, and the reasonable interval of strength training was not considered in the training process. Intermittent training can increase the tension of the cardiac vagus nerve of college basketball players, increase the cardiac reserve function and the load that the heart can bear, so that the cardiac function can be improved well. It can improve the cardiopulmonary function and aerobic work ability of college basketball players. It can improve the adjustment ability of the heart, lungs, liver, and other organs of college basketball players. It also can increase the load intensity that the central nerve can bear and improve the function of the central nerve and autonomic nerve. The anti-fatigue ability of athletes can be improved. It can improve the speed quality of college basketball players.

The Relationship Between the Force Production in the Isometric Squat and Bench Press Exercises and the Lower and Upper Body Anaerobic Power Parameters

The primary aim of this study was to investigate relationships between the muscular force in the isometric bench press and squat movements and the Wingate anaerobic test (WanT) results for the upper and lower body. Secondary purpose was to investigate possible correlations between the WanT and the explosive isometric force. Eighteen healthy male volunteer athletes (age: 23.37 ± 1.65, height: 178.37 ± 5.67, body mass; 76.69 ± 3.73) with at least 2 years of strength training participated in the study. During the two test sessions, one-repetition maximum (1-RM), isometric squat and isometric bench press tests and anaerobic power tests with Wingate anaerobic power and arm ergometer were performed. Results of the study showed a high degree of correlation between isometric squat (Squatiso) and lower body Peak Power and Average Power (r (14) = 0.766, p &amp;lt; 0.001 and r (14) = 0.690, p &amp;lt; 0.003 respectively). However, there was no significant relationship between Squatiso and Fatigue Index (FI) (p &amp;gt; 0.05). In isometric bench press, there was also a high level of correlation between upper body peak power and average power (r (14) = 0.620, p &amp;lt; 0.01 and r (14) = 0.749, p &amp;lt; 0.001 respectively). These data can be used to classify the power capabilities of the athletes and determining the training loads to be used in achieving the training goals. In addition, periodic measurements of the maximum power and strength performances of the athletes with field tests and laboratory test batteries according to the characteristics of the sports branch can also provide significant contributions to the coaches and researchers.

Design and motion analysis of a frog-like jumping robot based on a soft body detonation drive

Inspired by the instantaneous power of the hindlimbs of frogs and the dexterous posture adjustment of their forelimbs, a frog-like jumping robot based on a soft body detonation drive was designed. By combining the flexibility of silicone material and the detonation characteristics of mixed hydrogen–oxygen gas, a soft body detonation driver was constructed to cause the robot to jump from the hindlimbs to achieve a high energy instantaneous explosive force. Moreover, a spring-based forelimb mechanism is designed. This mechanism not only adjusts the robot with different starting jump posture angles but also maintains a smooth landing by providing cushioning. The kinematics and efficiency models of jumping are also established by the D-H parameter method and geometric method, and they are verified and analysed. Finally, combined with the control system, an experimental prototype (weight 495 g) with a height of 135 mm, a trunk length of 120 mm, front and hindlimbs of 195 mm, and a width of 90 mm is developed. The experiment proved that the robot can not only achieve 6 consecutive jumps, a single jump height of 0.6 m and a spanning distance of 1.2 m but also easily cross rectangular obstacles.

The Addition of Sprint Interval Training to Field Lacrosse Training Increases Rate of Torque Development and Contractile Impulse in Female High School Field Lacrosse Players.

Field lacrosse requires sudden directional changes and rapid acceleration/deceleration. The capacity to perform these skills is dependent on explosive muscle force production. Limited research exists on the potential of sprint interval training (SIT) to impact explosive muscle force production in field lacrosse players. The purpose of this study is to examine SIT, concurrent to field-lacrosse-specific training, on the rate of torque development (RTD), contractile impulse, and muscle function in female high school field lacrosse players (n = 12; 16 ± 1 yrs.). SIT was performed three times per week, concurrent to field-lacrosse-specific training, for 12 weeks. Right lower-limb muscle performance was assessed pre-, mid-, and post-SIT training via isometric and isokinetic concentric knee extensor contractions. Outcomes included RTD (Nm·s-1), contractile impulse (Nm·s), and peak torque (Nm). RTD for the first 50 ms of contraction improved by 42% by midseason and remained elevated at postseason (p = 0.004, effect size (ES) = -577.3 to 66.5). Contractile impulse demonstrated a training effect across 0-50 ms (42%, p = 0.004, ES = -1.4 to 0.4), 0-100 ms (33%, p = 0.018, ES = 3.1 to 0.9), and 0-200 ms (22%, p = 0.031, ES = -7.8 to 1.6). Isometric (0 rad·s-1) and concentric (3.1 rad·s-1) strength increased by 20% (p = 0.002, ES = -60.8 to -20.8) and 9% (p = 0.038, ES = -18.2 to 0.0) from SIT and field-lacrosse-specific training, respectively (p < 0.05). SIT, concurrent to field-lacrosse-specific training, enhanced lower-limb skeletal muscle performance, which may enable greater sport-specific gains.