Search Results (133)

This article proposes single-layer neural network algorithms for solving second-order ordinary differential equations, based on the principles of functional connection. According to this principle, the hidden layer of the neural network is replaced by a functional expansion unit to improve input patterns using orthogonal Chebyshev, Legendre, and Laguerre polynomials. The polynomial neural network algorithms were implemented in the Python programming language using the PyCharm environment. The performance of the polynomial neural network algorithms was tested by solving initial-boundary value problems for the nonlinear Lane–Emden equation. The solution results are compared with the exact solution of the problems under consideration, as well as with the solution obtained using a multilayer perceptron. It is shown that polynomial neural networks can perform more efficiently than multilayer neural networks. Furthermore, a neural network based on Laguerre polynomials can, in some cases, perform more accurately and faster than neural networks based on Legendre and Chebyshev polynomials. The issues of overtraining of polynomial neural networks and scenarios for overcoming it are also considered. Full article

This study aims to report the first Latvian version of the RESTQ-76, focusing on its internal validity, reliability, structural validity, and the relationships between the factors of the questionnaire. A total of 394 athletes (225 men and 169 women), aged 18–30 years (average age = 21, SD = 1.65), participated in the study. They were recruited from various sports clubs and universities. The RESTQ-76 was translated into Latvian through a forward-backward translation process to ensure accuracy of cultural relevance. To examine the questionnaire’s structure, principal component analysis (PCA) was performed. This analysis revealed a stable four-factor model comprising 18 scales, with acceptable fit indices (RMSEA = 0.089, CFI = 0.914, TLI = 0.896, NFI = 0.889), indicating good model fit. The psychometric validity of the Latvian version is supported by the original, indicating it is appropriate for use in sports settings throughout Latvia. As research on training load and recovery continues to expand, tools like the RESTQ-76 are becoming increasingly important. They help athletes and coaches monitor recovery and stress levels, which is essential for optimizing performance and preventing overtraining in competitive sports. Full article

Iron is an essential trace element that participates in multiple physiological processes, including oxygen transport, electron transfer, DNA synthesis, and red blood cell production. Iron loss is particularly severe among athletes, so maintaining iron homeostasis is crucial for sports nutrition and health. Excess iron, iron deficiency, and ferroptosis can lead to muscle disorders and health issues, including sarcopenia, muscular atrophy, myocardial fibrosis, skeletal muscle injury, cardiovascular disease, and metabolic disorders. Maintaining iron homeostasis within physiological limits is essential for athletes to sustain high-intensity performance and accelerate recovery. Therefore, a comprehensive review of the effects of iron homeostasis and ferroptosis on muscle health is significant for identifying potential therapeutic targets and developing new disease treatment and prevention strategies. This paper systematically reviews research progress on targeted therapies for iron overload and ferroptosis in muscle diseases, clarifies the impact of iron on athletes’ physiological functions and competitive performance, and explores the potential application of iron in precision nutritional regulation. It aims to provide new insights for preventing exercise-induced muscle injury, myocardial damage, and overtraining syndrome in athletes. Full article

Background: Creatine kinase (CK) serves as a biomarker of muscle stress and damage and is often elevated in athletes after intense training. Persistent CK elevations may indicate subclinical muscle dysfunction or incomplete recovery. Methods: This prospective, randomized study included 100 male adolescent soccer players (aged 13–15 years) with elevated CK levels (>1000 U/L). Participants were allocated into two equal groups: an intervention group receiving nutritional supplementation and a control group without supplementation. Both groups abstained from training for 7 days. CK was measured at baseline, day 3, and day 7. Non-parametric tests were used to compare groups. Additionally, multiple linear regression and Lasso regression models were applied to identify predictors of CK percentage reduction over 7 days. Results: The supplementation group exhibited significantly greater CK reduction at both day 3 (median decrease: 55% vs. 28%) and day 7 (84% vs. 50.8%) compared with controls (p < 0.001 for both). Regression analyses indicated that nutritional supplementation had the highest predictive weight for CK decrease. The Lasso model achieved strong performance (R² = 0.714; MAE = 0.068), showing that approximately 71% of the variability in CK reduction could be explained by the intervention. Conclusions: Short-term nutritional supplementation with antioxidants and amino acids may significantly accelerate CK return toward athlete-appropriate CK values during rest in adolescent soccer players with elevated CK. Regression modeling confirmed supplementation as the main determinant of CK reduction, supporting the inclusion of targeted nutritional strategies in recovery protocols for youth athletes. Full article

Background: Optimizing training load and recovery is crucial for achieving peak performance in competitive wrestling, a sport characterized by high physical, technical, and psychological demands. Methods: This study compared the effects of two different training programs—one emphasizing high-intensity interval training (HIIT) sessions and the other based on traditional volume-oriented training—on both competitive performance and autonomic regulation measured by heart rate variability (HRV). A total of 24 elite wrestlers were divided into two equal groups, each following a different weekly training regimen over a 3-month period. HRV was recorded using a wearable 3-channel ECG Holter before training, immediately after training, and during recovery phases (up to 2 h post-exercise). HRV parameters were analyzed to assess training-induced stress and recovery status. Competitive performance was evaluated using official national championship scores and ranking positions. Results: Both training programs improved competitive performance, the HIIT-based regimen induced greater short-term suppression of parasympathetic activity (RMSSD: −32% vs. −14%; HF power: −40% vs. −18%) and increased sympathetic dominance (LF/HF: +56% vs. +22%) after training. Wrestlers in the HIIT group achieved a mean competition score of 17.92 ± 4.50 points, compared to 15.08 ± 6.26 points in the volume-oriented group. These acute autonomic shifts may provide a higher readiness for intense and explosive actions, which is advantageous in short and dynamic matches. In contrast, the volume-oriented program induced smaller acute autonomic changes but showed a slower recovery to baseline. Conclusions: These findings suggest that HRV-derived measures can serve as sensitive indicators of training load tolerance, recovery capacity, and stress susceptibility in combat sports athletes. This study highlights the value of integrating HRV monitoring into the periodization of combat training to individualize the load, prevent overtraining, and optimize performance outcomes. Full article

Background: Elite athletes are frequently subjected to high-intensity training regimens, which can result in cumulative physical stress, overtraining, and potential health risks. Monitoring autonomic responses to such load is essential for optimizing performance and preventing maladaptation. Objective: The present study aimed to assess changes in autonomic regulation immediately and two hours after training in athletes, using an integrated framework (combining time- and frequency-domain HRV indices with nonlinear and recurrence quantification analysis). It was investigated how repeated assessments over a 4-month period can reveal cumulative effects and identify athletes at risk. Special attention was paid to identifying signs of excessive fatigue, autonomic imbalance, and cardiovascular stress. Methods: Holter ECGs of 12 athletes (mean age 21 ± 2.22 years; males, athletes participating in competitions) over a 4-month period were recorded before, immediately after, and two hours after high-intensity training, with HRV calculated from 5-min segments. Metrics included HRV and recurrent quantitative analysis. Statistical comparisons were made between the pre-, post-, and recovery phases to quantify autonomic changes (repeated-measures ANOVA for comparisons across the three states, paired t-tests for direct two-state contrasts, post hoc analyses with Holm–Bonferroni corrections, and effect size estimates η²). Results: Immediately after training, significant decreases in SDNN (↓ 35%), RMSSD (↓ 40%), and pNN50 (↓ 55%), accompanied by increases in LF/HF (↑ 32%), were observed. DFA α1 and Recurrence Rate increased, indicating reduced complexity and more structured patterns of RR intervals. After two hours of recovery, partial normalization was observed; however, RMSSD (−18% vs. baseline) and HF (−21% vs. baseline) remained suppressed, suggesting incomplete recovery of parasympathetic activity. Indications of overtraining and cardiac risk were found in three athletes. Conclusion: High-intensity training in elite athletes induces pronounced acute autonomic changes and incomplete short-term recovery, potentially increasing fatigue and cardiovascular workload. Longitudinal repeated testing highlights differences between well-adapted, fatigued, and at-risk athletes. These findings highlight the need for individualized recovery strategies and ongoing monitoring to optimize adaptation and minimize the risk of overtraining and health complications. Full article

Background/Objectives: This study examined the efficacy of essential amino acid (EAA) supplementation on changes in behavior and hippocampal neurotrophin, dopaminergic and serotonergic markers to a volume overload stress resembling an overtraining syndrome. Methods: Thirty-two 3-month-old male C57Bl/6J mice were randomized into four groups: Resistance training (RT), resistance training with overtraining (RTO), resistance training with overtraining and EAA (RTOEAA), or control. Mice in RTOEAA received EAA supplementation (1.5 g·kg·day⁻¹), while the other groups received a sham treatment. A 5-week resistance training protocol was employed. Training volume was increased two-fold during the final two weeks for RTO and RTOEAA to cause the OTS. EAA intervention for RTOEAA occurred during the OTS. Results: A significant decline in the maximum resistance carrying load in RTO compared to RT (p = 0.002) and RTOEAA (p = 0.029) confirmed that the animals in that group were overtrained. Significantly greater average latency times for RTO compared to RT (p = 0.009) and C (p = 0.05) indicated that the OTS caused spatial memory deficits in animals that were not supplemented. These latter changes may have been related to the significant declines in brain derived neurotrophic (BDNF) expression and elevations in dopamine 1 receptor (D1R) expressions. Increased resiliency for RTOEAA may have been related to the effect of EAA on stimulating significant increases in the expression of hippocampal tyrosine receptor kinase B (TrkB) and serotonin receptors (5-HT1A). Conclusions: EAA supplementation during a resistance model of overtraining appeared to provide increased resiliency to OTS by maintaining neurotrophin expression and enhancing serotonergic adaptation. Full article

Online Courses are one of the most popular ways to learn, but the technology used has a vital effect on the learner. In this study, we will research the prediction of students’ course engagement. International surveys show that students have a 70% interest in joining online learning, and just 30% of students are interested in traditional learning. However, keeping students engaged is one of the most difficult tasks, since low engagement contributes to lower learning outcomes and higher dropout rates. We studied more than 15 papers of existing research, and were able to achieve a 96% accuracy rate, which is a very welcome improvement on previous results. This paper examines machine learning algorithms, including Decision Trees, Random Forest, Gradient Booster, Naive Bayes, and K-Nearest Neighbors (KNN), to efficiently predict engagement during online courses. By systematically examining existing published research studies, we identify gaps and limitations of existing methods, such as problems with variant datasets, chances of overtraining, and a lack of accessibility to real-time engagement data. Full article

Background: Obesity is a multisystemic health problem causing chronic diseases like diabetes or cardiovascular diseases, but also reproductive dysfunctions like infertility in adults or altered puberty onset in children. Exercise is a recognized intervention to control or prevent energy imbalance, thus deeply contributing to metabolic health in physiological and pathological conditions. The kisspeptin system (KS), the main gatekeeper of reproduction and puberty onset in mammals, is also an upcoming “metabolic sensor”, linking energy homeostasis to reproductive ability both centrally and peripherally. Objectives: This narrative review aims at summarizing recent evidence from animal models and human studies on the role of the KS in energy homeostasis, with a focus on the upcoming role of the KS as a metabolic sensor able to modulate the functionality of the hypothalamus–pituitary–gonad axis in males as an adaptive response to exercise. Methods: PubMed and Scopus search (date: 2015–2025; keywords: kisspeptin and metabolism, male reproduction or exercise; kisspeptin and doping). Results and Conclusions: This review article illustrates the crucial role of the KS in linking energy homeostasis and male reproduction at the central and peripheral levels, and modulation of the KS by exercise in physiological and pathological conditions. Due to the large amount of data from animal models, knowledge gaps occur in the analysis of the relationship among KS, energy homeostasis, male reproduction and exercise in humans, particularly in the case of overtraining. Lastly, kisspeptin inclusion in the doping list is also discussed. Full article

This study aimed to monitor internal load, well-being, and recovery status in U16 male water polo players during a congested competitive period. Fourteen athletes from an Italian club played 12 matches (seven friendly, five official) over 7 days. The internal match load was measured using the session-RPE method (s-RPE). Perceived enjoyment was measured with the Enjoyment Likert Scale (ENJ), while recovery and well-being were evaluated using the Perceived Recovery Scale (PRS) and the Hooper Index (HI), respectively. No significant main effects were found on s-RPE, PRS, and HI considering friendly and official matches. However, ENJ was significantly higher during official matches (p < 0.005). PRS values were significantly affected by daytime matches (p < 0.005), with better perceived recovery reported for morning matches. Linear mixed model analysis revealed significant associations between s-RPE and HI (p = 0.001), the fatigue item (p = 0.001), and the PRS (p = 0.004). These results suggest that as internal load increases, players experience higher fatigue and report lower recovery and well-being scores. Employing simple, non-invasive tools like the RPE, PRS, and HI can help coaches and support staff to identify early signs of overtraining or insufficient recovery, allowing for more individualized load management and injury prevention in youth water polo athletes. Full article

Background: We examined changes in hematological, biochemical, and hormonal biomarkers, along with endurance and explosive performance indices, in amateur soccer players over a 4-week preseason period. Methods: Thirteen players (age: 19.7 ± 2.0 years; body mass: 73.0 ± 6.8 kg; height: 180 ± 0.1 cm; body fat: 8.6 ± 3.5%) were monitored during a 4-week preseason program, which included 21 training days, three friendly matches, and four days of rest. Before and after this period, endurance capacity was evaluated using the Yo-Yo IR1 test, and leg power was assessed using the CMJ. Blood samples were collected for three consecutive days in week 1 and after week 4 to assess hematological and biochemical parameters. Internal load during all weeks was assessed with session RPE (sRPE). Results: There was a 25.5% increase in Yo-Yo IR1 distance (2123 ± 413 vs. 1560 ± 356 m, p = 0.002), with the estimated VO₂max and the speed associated with VO₂max (vVO₂max) improving by 8.7% (49.5 ± 3.0 to 54.2 ± 3.5 mL/kg/min, p = 0.002) and 5.3% (16.0 ± 0.7 to 16.9 ± 0.6 km/h, p = 0.002), respectively. In contrast, CMJ performance in weeks 2–4 declined by 13.4–21.0% relative to baseline, while sRPE peaked during week 3 (4011 ± 440 AU). Hematological variables were mostly stable except for small increases in MCV and MCH (1.5–1.8%, p < 0.001), while there were significant reductions in urea (12%), uric acid (6.2%), and erythropoietin (33%). Conclusions: A 4-week preseason program substantially improved aerobic capacity yet compromised leg power. Changes in biomarker profiles suggest that the training load maintained an appropriate balance between overload and recovery. These findings provide valuable guidance for coaches seeking to optimize training protocols while minimizing the risk of overtraining and preventing injuries during the competitive season. Full article

The aim of this systematic review was to examine the effects of high-intensity interval training (HIIT) on physical performance and body composition in female basketball players. The review followed PRISMA guidelines, and the protocol was registered in the PROSPERO database (registration number: CRD420251006285). A comprehensive search was conducted across PubMed, Scopus, Web of Science, and Google Scholar. Nine studies that met the inclusion criteria were analyzed, with intervention durations ranging from 4 to 12 weeks. Despite differences in protocols, a majority of studies reported improvements in VO_2max (6/9), explosive strength (7/9), agility (5/6), and speed (5/6) and reductions in body mass and fat percentage (3/3). These findings highlight HIIT as an effective method for enhancing both aerobic and anaerobic capacities, as well as optimizing body composition. Despite variations in study protocols, HIIT consistently offers improvements in performance, irrespective of training level. The results underscore the importance of HIIT in preparing athletes, not only during the preseason but also throughout the competition period. Coaches should consider integrating HIIT into training programs, adjusting intensity and volume based on the season to optimize performance and prevent overtraining. Full article

Background/Objectives: In developed countries, an increasing number of children are participating in sports activities. However, according to current evidence, early sport specialization and overtraining are associated with an increased risk of injuries in youth athletes. Despite the prevailing practice of early sports specialization, there is a paucity of publications summarizing the influence of overtraining on injuries in youth athletes. As a result, the objective of this study was to conduct a review of publications investigating the influence of overtraining on injury prevalence in sport-active children aged between 7 and 14 years. Methods: The review included publications from January 2015 to March 2025 searched via PubMed, Science-Direct, and Scopus. Results: This review examined five publications, across which in three papers, the authors analyzed the influence of training load on the incidence of injuries during a certain period. In one study, the authors retrospectively analyzed whether there is a relationship between training frequency during skeletal growth and femoral neck deformity in adults. The other study was a case report of reactive osteochondromatous lesions of the femoral neck due to youth athlete training. In four publications, the authors reported the negative effects, and in one, no effect of training load on youth athletes. Conclusions: The current evidence suggests a potential association between high training load and elevated injury risk in young athletic populations. Nonetheless, inconsistencies across studies indicate that this relationship is likely multifactorial. Full article

The assessment of player well-being through questionnaires is vital for managing training and match demands in soccer, aiming to mitigate injury and overtraining risks. This study investigates the impact of Four-Match Congestion on the well-being of under-16 male soccer players. An observational study design was implemented, focusing on the well-being of eighteen male soccer players throughout a championship. Players were monitored daily for indicators such as muscle soreness, stress levels, mood, fatigue, sleep quality, and an overall well-being index. Data collection was conducted by research team staff without interfering with established training plans. Preliminary findings indicate significant fluctuations in well-being indicators throughout the championship, with lower well-being scores correlating with higher match intensity. Specifically, it was indicated that the athletes’ fatigue increased, while their stress levels gradually decreased (p < 0.05). Furthermore, muscle soreness, mood, and sleep quality metrics fluctuated throughout the study, with significant differences found between matches 1 and 3. These results highlight the importance of monitoring well-being to inform coaches about necessary adjustments in training loads during congested match schedules. Understanding the relationship between match demands and player well-being can lead to effective recovery strategies, enhancing performance and reducing injury risks. Future research should explore the long-term impacts of well-being monitoring and its integration into training regimens to optimize athlete management in competitive settings. Full article

Training drills are fundamental to the development of athletes across various sports disciplines, including basketball. This review examines the multifaceted factors influencing both the external and internal workload of drills during training sessions. The results of this review show that factors such as the type of drills utilized, space constraints, the number of players involved, adjustments to game rules, work-to-rest ratios, modifications to roles or tactical scenarios, the level of coach involvement, and the type of opposition all significantly impact drill workload. Research highlights that no isolated variable can fully capture the complexity or demands of an activity within a drill; instead, it is the interplay of different variables that determines the nature and focus of the drill. All the factors mentioned above should all be carefully considered to effectively tailor the physical demands and orientation of the drill. A comprehensive understanding of these factors can help coaches and athletes optimize training regimens to achieve desired performance outcomes while minimizing the risk of overtraining or injury. By synthesizing current research, this review provides valuable insights into the complex interplay of factors shaping drill workload in basketball training sessions. Full article