Load Intensity Research Articles

Selective load control of lumbar muscles in robot-assisted isometric lumbar stabilization exercise

Lumbar stabilization exercises are commonly employed in the rehabilitation of patients with low back pain. However, many patients discontinue these exercises, generally calisthenics using various postures or tools, due to the difficulty of providing an appropriate exercise load intensity. This challenge results in an inability to apply the desired strength to the target lumbar muscles and sometimes leads to an excessive load on unintended areas during calisthenics. Consequently, a method that enables patients to exercise continuously and progressively recover is required, specifically one that can target the lumbar muscles with a desired load. To address this issue, we propose a rehabilitation assistive device that quantitatively controls the lumbar spine load. In isometric lumbar stabilization exercises, our method involves precise compensation for gravity. The device, equipped with a series elastic actuator, is positioned beneath the patient in a lying posture. It applies an assistive force in the direction opposite to gravity, enabling precise control of the load on the lumbar region and reducing the vertical load on the spine. To validate the effectiveness of our proposed method, we conducted experiments with 20 healthy subjects across three exercises and analyzed the electromyography signal using nonparametric statistical methods. Our objective was to determine whether the load on the target lumbar muscles could be precisely and gradually controlled. The statistical results indicate that exercises performed using the proposed device produce statistically significant load changes in the target lumbar muscles.

The Main Muscle Surface EMG Characteristics of the Rowing Athletes' in Different Roads

Objective: Through the man rowing open athletes of Hubei province for ergometry test of 3 minutes for 60% and 90% maximum load, this article aims to understand the rowing open athletes in ergometry test of main muscle group strength distribution ratio, fatigue and strength characteristics. Methods: 6 man rowing open athletes of Hubei province were chosen for ergometry test of different load test (3minutes for 60% and 90% maximum load). The characterization of surface electromyographic changes was tested in the major exertor muscles, medial head of quadriceps and tibialis anterior muscles. Results: The results showed that: Maximum load test increased from 60% to 90%; IEMG appeared significant difference (P<0.05); especially the latissimus dorsi showed very significant difference (P<0.01); MF and MPF changed little. Conclusion: 60% load intensity achieves a good training effect on the calf muscles, and 90% load intensity acts on the training of the lower limb muscles.

Wheelchair Badminton: A Narrative Review of Its Specificities

This narrative review aims to provide a comprehensive overview of the scientific literature on wheelchair badminton and its distinctive aspects, encompassing abilities and disabilities, propulsion technique, and the use of a racket. The relatively young history of wheelchair badminton is reflected in the scarcity of scientific studies within this domain, highlighting the need for further investigation. The review systematically covers existing articles on wheelchair badminton, offering a nearly exhaustive compilation of knowledge in this area. Findings suggest that athletes with abdominal capacities engage in more intense matches with a higher frequency of offensive shots compared to athletes with little or no abdominal capacities. Moreover, backward propulsion induces higher cardiorespiratory responses, overall intensity of effort, physiological stress, metabolic load, and rating of perceived exertion, particularly at high imposed rolling resistance or speeds, and makes it difficult to generate sufficient forces on the handrim, requiring adjustments in the kinematics of propulsion techniques, particularly at high rolling resistances or speeds, potentially leading to performance decrements. The use of a badminton racket further increases generated forces while decreasing the efficiency of propulsion and modifying the propulsion technique with shorter and quicker pushes, potentially impacting performance. Further research is imperative to explore additional perspectives, address existing gaps, and expand the scope of study within the wheelchair badminton domain. This narrative review serves as a foundation for future investigations, emphasizing the necessity of continued research to enhance our understanding of wheelchair badminton.

DYNAMICS OF HEAVY METAL ACCUMULATION IN TROPHIC LEVELS OF FOREST ECOSYSTEMS

The aim of the study is to examine the accumulation of heavy metals (HMs) in trophic levels (soil, wood, tree leaves and fungi of various evolutionary origin) of forest ecosystems.
 Materials and Methods. The authors examined soil, wood, leaves and fungi in forests with different anthropogenic load intensity. The collecting grounds were selected according to forest management materials. In total, 26 grounds were examined. Sampling of soil and fungi of various trophic levels was carried out on different substrates, in different forest conditions and under different levels of technogenic impact. Leaf and wood samples were taken from phytopathogen-affected and healthy trees. Chemical sample analysis was carried out using a Kvant atomic absorption spectrophotometer.
 Results. The total heavy metal content in fungi is higher than in wood, but lower than in soil. The total heavy metal content in leaves of Norway maple affected by Rhytisma acerinum is higher compared to the leaves from heathy trees. Iron predominates among the heavy metals found in the fungi under consideration; cadmium content is minimal.
 Conclusion. The largest amount of accumulated heavy metals was found in the fruiting bodies of the facultative saprotroph, and the smallest amount was in the bodies of the facultative parasite. The forest type and growing conditions affect the heavy metal content in ecosystems.

Influence of professional sports activities on bone mineral density (<i>literature review</i>)

Introduction. The positive effect of physical activity on the state of bone has been proven by many researchers. Professional sports activity is a model of the constant impact of physical activity on the human body, acting as the most powerful mechanism for activating and mobilizing the functional reserves of an athlete, which, against the background of a progressive increase in the volume, intensity and duration of exposure, shows an increase in the incidence of injuries and stress fractures, one of the leading causes of which is a decrease in bone mineral density (BMD) up to the development of osteoporosis. The risk factors for the development of the pathology of the musculoskeletal system, which have a direct impact on the formation of the BMD, in elite sports include the volume and intensity of training loads, the stereotype of the main competitive exercise, the daily balance of energy intake.The aim is to study is to analyze modern scientific publications on the impact of professional sports activities on bone mineral density.Materials and methods. The review is based on publications from the PubMed, Google Scholar, Cyberleninka, eLIBRARY databases. Preference was given to articles published in refereed sources over the past 10 years.Results. The specificity of the main competitive exercise determines the presence of asymmetry in the distribution of the BMD in athletes, in addition, the level of BMD is higher in the leading limb compared to the opposite. Increasing the qualifications, experience and age of an athlete shows a positive impact on the performance of the BMD, with the exception of certain specializations. A different effect of sports with a high osteogenic effect of shock and weight load on the state of the BMD was noted compared to the general population. Power athletes, combat and game sports athletes have higher levels BMD compared to representatives of cycling, swimming, rowing, triathlon and long-distance running, characterized by the limitation of gravitational (shock) load or a large amount of low-intensity training exposure. Lower BMD were noted in athletes in sports specializations with weight categories, aesthetic and cyclic sports, where the problem of a relative energy deficiency in sport, which negatively affects bone metabolism.Conclusions. In athletes, the volume and intensity of training loads, the stereotype of performing the main competitive exercise, the daily balance of energy intake have a direct impact on the formation of the BMD with the allocation of risk groups for the pathology of the musculoskeletal system in elite sports.

Алгоритм динамического распределения и балансировки нагрузки в распределенных облачных вычислениях

A mathematical model and algorithm of a two-level load management system for virtual clusters of a data processing center (data center) have been developed. At the first management level, virtual machines (VMs) are assigned to physical servers. At the same time, a greedy algorithm is used with restrictions on the time of searching for acceptable load distribution alternatives. The second level of management is implemented taking into account the chaotic structure of network traffic between the data center and users. Checking for the randomness of a time series of information traffic is carried out using Lyapunov exponents. The predictive model of the load intensity is implemented using the method of phase space reconstruction based on a set of values of a one-dimensional time series. When constructing a reconstructed phase space attractor, the time delay value is selected from the condition of reaching the zero value of the autocorrelation function, and the dimension of the embedding is determined by the angle of inclination of the straight line approximating the dependence of the value of the correlation integral on the radius of a given threshold point. The Tayler window is used to exclude correlated points in the numerical series. The criterion for evaluating the effectiveness of the developed algorithm is an integral indicator of the deviation of the load of each server from a given level. The proposed model can be used to build a data center load balancing system in conditions of its nonlinear nature.

Use of means of restoration of working capacity in preparation sprinters

The purpose of the work: to analyze and systematize modern data on the use of means of rehabilitation of athletes specializing in short-distance running. Methodology: theoretical analysis and generalization of scientific and methodological literature and Internet resources.
 Scientific novelty. A comprehensive approach to the use of modern means of restoring the working capacity of sprinters is presented, the effectiveness of which depends on the period of preparation in the annual cycle, specialization, volume, intensity and direction of training loads of previous and subsequent classes, microcycles, etc.Conclusions. It was noted that among the pedagogical means of recovery, it is important to use motor switching in training programs and microcycles in the form of sports games. To manage the performance of runners, selective recovery of those components that were not primarily affected during the training session, but will be mobilized during the next training session, should be carried out. It is recommended to use the entire complex of pedagogical tools for the rational construction of the sports training process. Extra-training (physical) means of recovery in the preparatory and competitive periods of the annual training of sprinters are proposed. It is recommended that track and field athletes use complexes of physical and hygienic means of recovery of the general effect after performing significant training loads, and for medium and small loads - of local effect. Pharmacological means of recovery of athletes depending on the functional state of muscles, the size and intensity of training loads are presented. The positive effect of nutrition on the course of restorative processes is indicated.

Nutrition of elite athletes of endurance evens

The primary principle of sports nutrition for athletes’ performance is to ensure the athlete is consumption enough calories to offset energy expenditure with balance of nutrients. The nutrition is directly related to the metabolic processes during intense physical loads. Unbalanced nutrition is one of the factors limiting of athletes’ performance. The aim - scientific substantiation of the diet for elite athletes of endurance events, taking into account the energy expenditure, volume and intensity of training loads. The methods: analysis and systematization of scientific publications by research issues, analysis of actual nutrition’s, daily energy expenditure, volume and intensity of training of elite athletes of endurance events. The energy expenditure and the actual content of macronutrients and the energy value of the daily rations of elite athletes of endurance events are compared. A significant energy deficient diet, an imbalance of macronutrients, mostly carbohydrates, was revealed. Three variants of the nutritional needs and the content of macronutrients were developed, respectively, for low, medium and high intensity of energy expenditure.

Acute cardiac autonomic and hemodynamic responses to resistive breathing: Effect of loading type and intensity.

This study aimed to assess the acute impact of distinct loading breathing types and intensities on cardiac autonomic function and hemodynamic responses in healthy young adults. A randomized, crossover trial involved 28 participants who underwent inspiratory resistive breathing, expiratory resistive breathing (ERB) and combined resistive breathing, each at 30% and 60% of maximal respiratory pressures. Data on heart rate variability (HRV) and hemodynamic parameters were collected during each trial. The study revealed significant main and interaction effects for both the performed task and the intensity across all measured variables (all p < 0.001). ERB at 60% load demonstrated significantly higher HRV values in the standard deviation of normal-to-normal RR intervals, the square root of the mean squared difference of successive normal-to-normal RR intervals and high-frequency power, as well as significantly lower values in heart rate, stroke volume, stroke volume index, cardiac output, cardiac index, end-diastolic volume and end-diastolic volume index, compared to other loaded protocols (all p < 0.001). These findings highlight the acute effect of type-specific and load-dependent resistive breathing on cardiac autonomic and hemodynamic functions, where ERB at 60% intensity showed the most significant cardiovagal modulation while causing the least hemodynamic alterations.

Recovery After High-Intensity Interval Training in Professional Soccer Players: Passive-Active Combination Recovery Technique

Objective: The aim of this study is to investigate which of the passive recovery (PR), active recovery (AR) and passive-active combination recovery (PAR) techniques applied after the end of high-intensity interval training (HIIT) was more effective in professional super league soccer players. Method: 28 trained professional male soccer players (age: 24.79±2.75 years, height: 180.50±5.81 cm, weight: 74.18±5.47 kg) from the Türkiye Super League team participated in this study voluntarily. Before the study, participants were assigned to 3 groups according to heart rate (HR) and lactic acid (La) levels. Each HIIT load intensity was determined according to the Karvonen method. HIIT sessions were performed for 5 repetitions of 2 minutes (1 set = 5x2 minutes) and a 30-second rest was given between repetitions. At the end of the set, a 2-minute recovery period was applied. Three different recovery techniques, PR, AR and PAR, were applied alternately to each group at the end of the HIIT programs. Participants' HR and La values were taken at the end of HIIT and recovery techniques. Differences between the obtained data were determined by repeated measures one-way ANOVA and multiple comparison tests. P&lt;0.05 level was considered significant in all tests. Results: Although there was no significant difference in La levels between groups (p&gt;0.05), significant differences were observed between HR and loading intensities (p&lt;0.05). According to the results of multiple comparisons, the recoveries in HR and La levels were found to be significant in favor of the PAT group (p&lt;0.05). Discussion: It can be thought that football players increase the mitochondrial biogenesis, oxidative and lipid oxidation capacities of skeletal muscles due to adaptations to HIIT and similar heavy workouts. Depending on these developments in the athletes' condition, it can be said that all three recovery techniques affect the decrease of HR and La in the two-minute period. Conclusion: PR and PAR techniques were effective in reducing HR levels. AR and PAR techniques were effective in reducing La levels. Therefore, it can be said that the PAR technique is more effective in reducing both HR and La levels together.

The dominating dimensionless numbers of an elastic-plastic thin plate under dynamic loading

The response of an elastic-plastic thin plate under dynamic loading cannot be solved theoretically since both geometrical and material nonlinearities are involved and also highly coupled. Obviously, the response will be affected by material properties, geometries, and loads, whose effects are usually studied separately. In order to avoid repeated investigations and save costs, identifying the combined dominant dimensionless number must be essential.For a plate under pressure loading, a dominating dimensionless number ξ (referred to as the loading intensity) is proposed based on energy conservation and dimensional analysis. As an input parameter, ξ whose physical meaning denotes the plastic to elastic share (energy ratio and deflection ratio), characterizes the combined effects of structure, material, and load. According to its value, responses could be classified into three cases: elastic deformation (0<ξ<1), elastic-plastic coupling deformation (1≤ξ≤100), and plastic dominating deformation (ξ>100). Furthermore, the dimensionless deflection of elastic-plastic plates could also be predicted, by combination of loading intensity ξ and relative stiffness β.In addition, for plates under other loading conditions, a series of dimensionless numbers are also given. Among them, some numbers have already been investigated by previous researchers, while others are still unconcerned. These numbers are then verified by FEM simulations, and their physical meanings are revealed. Employing these numbers, the analysis of experimental and simulation results will be in a normalized and comparable form. Particularly, it will provide scaling criteria for the dynamic scaling experiments.

The functional role of mammals in the restoration of disturbed taiga ecosystems of the Vologda Region

The article examines the participation of mammals in the restoration of disturbed ecosystems. Since in a number of regions of the North-West the intensity of anthropogenic load in the form of logging activities does not decrease, and in some cases even increases, the study of the degree of influence of each component of the ecosystem on the restoration of disturbed taiga biogeocoenoses is an urgent problem and requires comprehensive consideration. In the Vologda Oblast, logging activities are aimed at increasing the area of continuous concentrated logging, which have a serious impact on forest biogeocoenoses. Environment-forming (environment-forming or biogeocoenotic activity) animals are the work performed by organisms to implement and regulate any biogeocoenotic processes, in particular, to transform substances and energy, and maintain the equilibrium state of the system. The article considers the most pronounced types of environmental and biogeocoenotic activity of terrestrial mammals – trophic-mechanical (using the example of elk and white hare), excretory (elk, white hare, wild boar, bear, wolf and fox), hard-laying (mole) and digging-loosening (wild boar) in the territories disturbed after logging activities taiga mesoecosystems (logging). It was revealed that as a result of trophomechanical activity, phytophages do not damage the woody phytocoenosis, since the mosaic of habitat and successional processes towards deciduous plants – rowan, aspen and willow, provides phytophagous mammals with food in sufficient quantities. Excretory, excretory-recomposing and digging-loosening activities of mammals support the process of circulation of substances and the flow of energy, which contributes to self-healing, self-purification, self-regulation and increased stability of disturbed forest taiga ecosystems of Vologda Region.

The Ratio between Weekly Training and Match External Physical Loads in U17 Elite Youth Soccer Players: Implications for the Training Process.

Research on the external physical load on elite youth soccer players during the weekly training microcycle in competitive periods and official matches is limited. The aims of this study were twofold: a) investigate possible differences in external physical load (PL) across player positions in U17 elite youth soccer players during official matches; b) determine the weekly training to match physical load ratio (WTMLr) across player positions. The sample included 20 outfield players from an elite soccer academy (mean age 15.94 ± 0.25 years) playing in four positions: central defender (CD), full-back (FB), central midfielder (CM) and Striker (S). Data were collected during the spring in-season period for 17 official matches played in a 4-3-3 game format. Indicators of external physical load monitored were: total distance (TD); total distance in high-speed running (HSR; > 16.1 km.h-1); total distance in sprint running (SPR; > 21.6 km.h-1); and relative physical load intensity (%HSR). The WTMLr was calculated for TD, HSR, SPR and %HSR as the ratio of the average weekly sum of training PL to the average sum of PL in an official match for a given players' position. Collectively, the training intensity during a one-week microcycle (%HSR in WTMLr) achieved only 76 % of match demands. CD performed significantly lower in all measured indicators of external PL during the official match than all other positions (p < 0.05; g > 0.80) except for TD in S. S achieved significantly higher SPR during official matches compared to CD (p < 0.05; g > 0.80), CM, and FB (g > 0.80). In contrast, CD reported higher WTMLr (medium-large effect size) in HSR and SPR indicators than all other positions. CM performed significantly higher %HSR in WTMLr than S and FB (p < 0.05; g > 0.80). Results revealed insufficient training intensity relative to match demands and, at the same time, weekly training PL did not meet match demands (especially in HSR and SPR) for players across the different positions. Therefore, practitioners should select appropriate training methods (drills and games) to ensure sufficient training intensity (HSR and SR metrics) and consider using the WTMLr, which can be used to help optimise and individualise training PL for different player positions.

Field Testing and Numerical Simulation of the Dynamic Response of Loess Hill Site under High-Speed Train Load

In this study, the loess hill site of an elevated bridge section in Tongwei-Qin’an of the Baolan high-speed railroad was selected as the research object, and the vibration acceleration of the loess hill site under the elevated bridge was tested in the field under the train operating load. The results show that under the same intensity of train load, the time range of vibration acceleration observed by field test and numerical simulation decays linearly with increasing distance from the source, while the amplification effect appears in the loess hill site at a greater distance, and the vibration duration also appears to increase. The vibration acceleration waveforms at each observation point observed by field tests and numerical simulations are similar, and the peak vertical acceleration at each observation point obtained from numerical simulations is overall greater than the peak acceleration at each point obtained from field tests, with aSimulated− max/aObservated− max values ranging from 1.04 to 1.63. The Fourier spectrum frequencies recorded by numerical simulation and field test are mainly concentrated in the range of 1∼40 Hz, but the difference between the main frequencies recorded by the two is large. The main frequency of the energy spectrum recorded by the numerical simulation is around 15 Hz, which is the same as the main frequency of the energy spectrum vibration of the input vibration wave, and the main frequency of the energy spectrum vibration recorded by the field test is around 25 Hz.

Investigation of loading intensity effect (LIE) on the failure mechanism of shield tunnel subjected to fire

The overload damage seriously threatens the service life of the tunnel structure, and the elevated temperatures under the extreme load of fire pose a more serious threat to the structure. In this study, a thermal–mechanical methodology is proposed to analyze the combined effects of loading intensity and fire on tunnel structures. The methodology is also validated by experimental studies. Impacts of loading intensity effect (LIE) on temperature distribution, deformation development and inner force distribution are discussed respectively. Results indicate that LIE aggravates heat flow invasion, making uneven temperature distribution of the segmental ring. On the other hand, LIE has a direct influence on the development of mid-span deformation of lining segments, and induces the failure of lining segments due to excessive deformation at the initial stage of heating. higher loading intensity induces a higher initial axial stress level of the tunnel structure. It is also found that the failure of the segmental ring can be attributed to the development of plastic hinges originated from the coupled thermo-mechanical effect. The findings not only reveal the combined effects of overload damage and fire on tunnel structures, but also provide valuable insights on fire prevention in case of tunnel fire.

Influence of training load intensity on young soccer players' sleep patterns

Influence of training load intensity on young soccer players' sleep patterns

Impact of catalyst carrier with TPMS structures on hydrogen production by methanol reforming

As the core part of a microreactor, the reaction carrier provides reaction site and energy supply for hydrogen production. Among various types of reaction carriers, porous reaction carriers with complex flow path structures can effectively improve hydrogen production performance, and thus are widely applied in fuel cells. To optimize the structure of catalyst carriers and improve the efficiency of hydrogen production of methanol reforming, we designed four TPMS porous carrier structures, namely structures D, G, P and IWP, and analyzed the effect of carrier structure and parameters on hydrogen production reaction in theory. After that, we manufactured TPMS carriers with varied structures and parameters using 3D printing, and designed and carried out loading tests, flow velocity simulation experiments and pressure drop calculation to study the influence of the structure morphology on load intensity, heat and mass transfer and other performance indexes with catalyst load. Finally, we carried out hydrogen production experiments in microreactors with different TPMS structures, from which we obtained an pattern influence of hydrogen production conversion rate and hydrogen velocity etc. At different velocities and temperatures. The experimental results indicate that structure type and parameters of TPMS node and porosity have a great effect on the performance of hydrogen production. Specifically, structure D performs the best and structure P performs the worst in hydrogen production. When the velocity is 1.7 ml/h and the temperature is 250 °C, the maximum difference of the hydrogen conversion rate between D and P structure can reach to 22 %, and that of the hydrogen velocity can reach to 0.02 mol/h.

Proteomic and Metabolomic Analyses of the Blood Samples of Highly Trained Athletes

High exercise loading causes intricate and ambiguous proteomic and metabolic changes. This study aims to describe the dataset on protein and metabolite contents in plasma samples collected from highly trained athletes across different sports disciplines. The proteomic and metabolomic analyses of the plasma samples of highly trained athletes engaged in sports disciplines of different intensities were carried out using HPLC-MS/MS. The results are reported as two datasets (proteomic data in a derived mgf-file and metabolomic data in processed format), each containing the findings obtained by analyzing 93 mass spectra. Variations in the protein and metabolite contents of the biological samples are observed, depending on the intensity of training load for different sports disciplines. Mass spectrometric proteomic and metabolomic studies can be used for classifying different athlete phenotypes according to the intensity of sports discipline and for the assessment of the efficiency of the recovery period.

Dynamics of stress-index and spectral indicators of cardiointervalogram of elite skiers-racers in the preparatory, competition and transition periods depending on the volume and intensity of training loads

Acutality: Heart rate variability, allows you to assess the state of the autonomic nervous system, which is useful for studying the condition of athletes, including endurance athletes, for example, ski racers. The stress index indicator is often used to assess the impact of stress on a person. It is shown that the stress index is closely correlated with the intensity of metabolism and with the indicators of energy consumption of the body.Objective. To provide information on the values of the stress index for athletes depending on a number of factors, including their sports specialization, and for ski racers on the volume and intensity of the training load during the preparatory, competitive, transitional periods of the ski season.Materials and methods. The literature analysis in the Pubmed database for the last 10 years in English and Russian languages has been carried out.Conclusion. A review of the literature on the magnitude of the stress index showed that athletes who train for endurance, this indicator is low, especially among ski racers, if it is compared with the magnitude of the index in representatives of other sports, as well as with healthy people who do not play sports. There is no information about the value of the stress index in athletes in foreign literature, but there is such information in the domestic literature, which allowed us to present this review, which also includes the results of our research.

Stepwise Identification Method of Thermal Load for Box Structure Based on Deep Learning.

Accurate and rapid thermal load identification based on limited measurement points is crucial for spacecraft on-orbit monitoring. This study proposes a stepwise identification method based on deep learning for identifying structural thermal loads that efficiently map the local responses and overall thermal load of a box structure. To determine the location and magnitude of the thermal load accurately, the proposed method segments a structure into several subregions and applies a cascade of deep learning models to gradually reduce the solution domain. The generalization ability of the model is significantly enhanced by the inclusion of boundary conditions in the deep learning models. In this study, a large simulated dataset was generated by varying the load application position and intensity for each sample. The input variables encompass a small set of structural displacements, while the outputs include parameters related to the thermal load, such as the position and magnitude of the load. Ablation experiments are conducted to validate the effectiveness of this approach. The results show that this method reduces the identification error of the thermal load parameters by more than 45% compared with a single deep learning network. The proposed method holds promise for optimizing the design and analysis of spacecraft structures, contributing to improved performance and reliability in future space missions.