1. How do Serbian gymnastics coaches make decisions?Edvard Kolar, Saša Veličković, Rado Pišot, Marijo Možnik, Matej Tušak, 2025, izvirni znanstveni članek Ključne besede: Serbian gymnastics coaches, decision-making styles, structure, demographic characteristics, professional characteristics, experience
Objavljeno v DiRROS: 20.06.2025; Ogledov: 144; Prenosov: 74
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2. Twenty-one days of bed rest alter motor unit properties and neuromuscular junction transmission in young adultsFabio Sarto, Miloš Kalc, Evgeniia Motanova, Martino V. Franchi, Daniel W Stashuk, Nina Murks, Giacomo Valli, Samuele Negro, Tomaž Prašnikar, Mladen Gasparini, Giovanni Martino, Giuseppe De Vito, Aleš Holobar, Boštjan Šimunič, Rado Pišot, Marco Vincenzo Narici, 2025, izvirni znanstveni članek Povzetek: Previous studies showed that properties of higher‐threshold motor units (MUs) and neuromuscular junction (NMJ) function are preserved during short‐term disuse. This study aimed to test how a longer disuse period affects MU properties, NMJ transmission, and NMJ morphology remodeling. Nine young healthy males (age: 18‐29 years) underwent 21 days of horizontal bed rest. Pre‐ (BR0) and post‐bed rest (BR21), quadriceps maximal voluntary contraction (MVC), and size were assessed. We combined intramuscular electromyography (iEMG) and high‐density surface electromyography (HDsEMG) recordings on the vastus lateralis to assess MU properties at 25% and 50% of MVC. Muscle biopsies and blood samples were also collected. Quadriceps MVC and size decreased at BR21. We found alterations in MU properties at both contraction intensities, including reduced discharge rate, MU potential area changes, and increased complexity. NMJ transmission was found to be reduced at BR21 at 25% MVC. This functional NMJ impairment was biochemically corroborated by an increase in serum C‐terminal agrin fragment concentration, a biomarker of NMJ instability. In addition, a direct assessment of NMJ morphology revealed the presence of some denervated NMJs exclusively at BR21. In conclusion, 21‐day bed rest altered MU properties across different contraction intensities and impaired NMJ transmission with initial signs of remodeling/denervation. Disuse duration appears to be a critical factor, as previous shorter studies failed to detect some of these changes. We believe these findings are clinically relevant for disuse after trauma, surgery, or illness, and may support the development of effective countermeasures.
Ključne besede: disuse, unloading, physical inactivity, electrophysiology, electromyography
Objavljeno v DiRROS: 13.05.2025; Ogledov: 290; Prenosov: 111
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3. Mitochondrial sensitivity to submaximal [ADP] following bed rest : a novel two-phase approach associated with fibre typesLucrezia Zuccarelli, Maria De Martino, Antonio Filippi, Alice E. Knapton, Benjamin D. Thackray, Giovanni Baldassarre, Boštjan Šimunič, Rado Pišot, Giuseppe Sirago, Elena Monti, Marco Vincenzo Narici, Miriam Isola, Andrew J. Murray, Giovanna Lippe, Bruno Grassi, 2025, izvirni znanstveni članek Povzetek: Background: We recently demonstrated that following a 10-day exposure to inactivity/simulated microgravity impairments ofoxidative metabolism were located ‘upstream’ of mitochondrial function, as evaluated by maximal ADP-stimulated mitochon-drial respiration (JO 2max) determined ex vivo. The aim of this study was to evaluate mitochondrial sensitivity to submaximal[ADP] by an alternative approach aimed at identifying responses associated with fibre type composition.Methods: Isolated permeabilized vastus lateralis fibres were analysed by high-resolution respirometry in 9 young males beforeand after a 10-day horizontal bed rest. Eleven submaximal titrations of ADP (from 12.5 to 10 000 μM) were utilized to assess com-plex I + II-linked ADP sensitivity. We applied to JO 2 versus [ADP] data a traditional Michaelis–Menten kinetics equation, withthe calculation of the apparent K m and maximal respiration (Vmax), and two ‘sequential’ hyperbolic equations, yielding two K mand Vmax values. The two-hyperbolic equations were solved and the [ADP] value corresponding to 50% of JO 2max was calculated.Isoform expression of myosin heavy chains (MyHC) 1, 2A and 2X was also determined. Control experiments were also carriedout on rat skeletal muscle samples with different percentages of MyHC isoforms.Results: The two hyperbolic equations provided an alternative fitting of data and identified two distinct phases of the JO 2 versus[ADP] response: a first phase characterized by low Vmax (Vmax1 , 28 ± 10 pmol s−1 mg−1) and apparent K m (K m1 , 62 ± 54 μM) anda second phase characterized by higher Vmax (Vmax2 , 61 ± 16 pmol s−1 mg−1) and K m (K m2 , 1784 ± 833 μM). Data were confirmedin control experiments carried out in rat muscle samples with different percentages of MyHC isoforms. Correlation and receiveroperating characteristics analyses suggest that the two phases of the response were related to the % of MyHC isoforms.Conclusions: A novel mathematical approach (two sequential hyperbolic functions) for the fitting of JO 2 versus [ADP] data ob-tained by high-resolution respirometry on permeabilized skeletal muscle fibres, obtained in humans and rats, provided an alter-native fitting of the experimental data compared to the traditional Michaelis–Menten kinetics equation. This alternative modelallowed the identification of two distinct phases in the responses, which were related to fibre type composition. A first phase, characterized by low apparent K m and Vmax values, was correlated with the percentage of less oxidative (Type 2A + 2X) MyHCisoforms. A second phase, characterized by high apparent K m and Vmax , was related to more oxidative (Type 1) MyHC isoforms.
Ključne besede: ADP, bed rest, mitochondrial sensitivity, myosin heavy chains, skeletal muscle mitochondria
Objavljeno v DiRROS: 05.05.2025; Ogledov: 273; Prenosov: 107
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4. Neuromuscular junction instability with inactivity : morphological and functional changes after 10 days of bed rest in older adultsStefano Schiaffino, Evgeniia Motanova, Fabio Sarto, Samuele Negro, Marco Pirazzini, Ornella Rossetto, Michela Rigoni, Daniel W Stashuk, Mladen Gasparini, Boštjan Šimunič, Rado Pišot, Marco Vincenzo Narici, 2025, izvirni znanstveni članek Povzetek: The neuromuscular junction (NMJ) plays a key role in modulating muscle contraction,but the impact of short-term disuse on NMJ structure and function, particularly in older humans,remains unclear. This study aimed to investigate NMJ alterations following 10 days of horizontalbed rest in 10 older males (68.5 ± 2.6 years). Before and after bed rest, vastus lateralis musclebiopsies were obtained to evaluate NMJ morphology, intramuscular EMG (iEMG) was recordedto assess NMJ function and blood samples were collected to determine circulating C-terminal agrinfragment (CAF) concentration, a biomarker of NMJ remodelling. In a sub-cohort of six participantswho had NMJs in both pre- and post-bed rest biopsies, we observed altered NMJ morphology,including reduced overlap between NMJ terminals, as well as increased endplate area and peri-meter. CAF concentration was elevated after bed rest, suggesting ongoing NMJ remodelling. iEMGanalysis showed increased motor unit potential complexity and reduced firing rate. In addition,we observed impaired NMJ transmission, inferred from increased near-fibre jiggle and segmentjitter. These findings suggest that older male individuals are susceptible to NMJ remodelling andimpaired transmission with short-term disuse, providing valuable insights into the morphologicaland functional consequences of inactivity in an ageing population. Our study highlights theimportance of developing interventions for mitigating the detrimental consequences of inactivityon neuromuscular health in older adults, which they frequently experience following injury, trauma,illness or surgery.
Ključne besede: ageing, C-terminal agrin, fragment disuse, electromyography, motor unit, NMJ unloading
Objavljeno v DiRROS: 19.03.2025; Ogledov: 381; Prenosov: 260
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6. Addressing the paradox of rest with innovative technologiesRado Pišot, Uroš Marušič, Luka Šlosar, 2025, drugi znanstveni članki Povzetek: The paradox of rest lies in its dual nature: essential for recovery yet potentially harmful when prolonged. Prolonged physical inactivity (PI) significantly contributes to non-communicable diseases (NCDs). Studies show nearly a third of adults worldwide were insufficiently active in 2022, with the economic costs of PI projected to reach INT$520 billion by 2030. Bedrest models have illuminated the rapid onset of insulin resistance, general functional decline and muscle atrophy associated with PI, particularly in hospitalised older adults. Innovative technologies, such as extended reality (XR), offer promising solutions for mitigating the effects of PI and can enhance non-physical rehabilitation techniques such as motor imagery and action observation. These technologies provide immersive, personalised therapeutic experiences that engage multiple senses, transforming passive recovery into an active process and addressing both the physical and cognitive consequences of inactivity. Results of bedrest study showed significant preservation of muscle mass, improved strength and enhanced insulin sensitivity in the intervention group compared to controls. These findings highlight the potential of XRbased strategies in addressing structural and functional declines during inactivity. As part of the Interreg VI-A Italia-Slovenija project X-BRAIN.net, advanced XR-equipped active rooms were developed to aid post-stroke rehabilitation in acute care settings. XR technologies, particularly VR, have shown promise in providing dynamic and adaptable therapeutic environments that facilitate early and targeted interventions. Future advancements focus on integrating XR with brain-computer interfaces (BCIs) and synchronised visual-haptic neurofeedback, enhancing sensorimotor cortical activation and improving rehabilitation outcomes. Comprehensive multimodal approaches, including nutritional, physical and non-physical interventions, are emerging as effective strategies to personalise and optimise patient recovery.
Ključne besede: physical inactivity, functional and cognitive decline, rehabilitation, extended reality, multimodal interventions
Objavljeno v DiRROS: 05.03.2025; Ogledov: 262; Prenosov: 142
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7. Frequency of physical activity-related injuries among adolescents : an umbrella reviewKerrtu Toivo, Peter Bakalár, Mari Leppänen, Jari Parkkari, Ensar Abazović, Boštjan Šimunič, Kaja Teraž, Marta Malinowska-Cieślik, Jaroslava Kopčáková, Aurel Zelko, Agnieszka Michalska, Dagmar Sigmundova, Rado Pišot, Armin Paravlić, 2025, pregledni znanstveni članek Povzetek: Objectives: The aim of this umbrella review was to investigate the frequency of physical activity-related injuries (PARI) among adolescents. Our secondary objective was to describe the available reviews of injuries in three settings: organized sports, leisure time physical activity (PA), and school physical education (PE). Methods: We conducted an overview of reviews consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines on the frequency of physical activity related injuries in adolescents. Results: We identified 19 systematic reviews with at least moderate quality to include in the review. We were not able to pool data from reviews and conduct meta-analysis due to heterogeneity of injury definitions, exposure times, and sample demographics. All reviews included studies of injuries sustained in organized sports, and injury incidence was higher during matches than training. No systematic reviews were found focusing on leisure time or school-based PA injuries. Conclusion: High-quality research is essential to understand the frequency of various types of physical activity related injuries among adolescents in organized sports, PE, and leisure time activities to develop more effective prevention strategies.
Ključne besede: physical activity-related injuries, sports injuries, adolescence, frequency, prevalence, incidence
Objavljeno v DiRROS: 22.01.2025; Ogledov: 390; Prenosov: 204
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8. Conceptual framework of coaches’ decision-making in conventional sportsEdvard Kolar, Roberto Biloslavo, Rado Pišot, Saša Veličković, Matej Tušak, 2024, izvirni znanstveni članek Povzetek: Introduction: A coach’s managerial and pedagogical tasks in the sports training process constitute the substantive core of their work, while decision-making serves as the fundamental method underpinning these tasks. Some decisions made by coaches result from deliberate, analytical thinking, which involves extensive information gathering, analysis, and discussion. Others, however, are made quickly and spontaneously, triggered by unforeseen situations during training or competition that demand immediate action. Consequently, the purpose of this study is to develop a conceptual framework for understanding coaches’ decision-making behavior in conventional sports. This framework aims to establish appropriate relationships between the various decisions coaches make during the training process and theoretical concepts related to decisionmaking, both in general and within the coaching context. Methods: To design the research, we used the methodology of a conceptual paper and a “model paper” approach, which seeks to build a theoretical framework that predicts relationships between distinct research concepts and scientific disciplines, aiming to integrate them into a cohesive model of coaches’ decision-making behavior. Results: The proposed conceptual framework encompasses a comprehensive range of situations that may arise during the sports training process and potential ways to address them. This framework identifies different types of decisions and characteristics associated with coaches’ decision-making behavior. It incorporates various sport-specific and general theories of decision-making and cognitive functioning to offer a deeper understanding of how coaches process and execute decisions in diverse contexts. Discussion: The developed conceptual framework outlines three primary types of decisions—strategic, tactical, and operational—each playing a distinct role in the broader sports training process. These decisions are based on different cognitive processes, which manifest in varied decision-making behaviors and are reinforced by specific leadership styles. The practical value of this framework lies in its potential application for selecting appropriate experts to address the diverse decision-making scenarios encountered in sports training. This ensures the alignment of decision-making styles with the requirements of specific training situations, thereby enhancing the effectiveness and outcomes of the coaching process.
Ključne besede: sport training, coaches, decision-making behavior, types of decisions, conceptual framework
Objavljeno v DiRROS: 09.01.2025; Ogledov: 557; Prenosov: 496
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9. Initial glutathione depletion during short-term bed rest : pinpointing synthesis and degradation checkpoints in the γ-glutamyl cycleFilippo Giorgio Di Girolamo, Filippo Mearelli, Mariella Sturma, Nicola Fiotti, Kaja Teraž, Alja Ivetac, Alessio Nunnari, Pierandrea Vinci, Boštjan Šimunič, Rado Pišot, Gianni Biolo, 2024, izvirni znanstveni članek Povzetek: Hypokinesia triggers oxidative stress and accelerates the turnover of the glutathione system via the γ-glutamyl cycle. Our study aimed to identify the regulatory checkpoints controlling intracellular glutathione levels. We measured the intermediate substrates of the γ-glutamyl cycle in erythrocytes from 19 healthy young male volunteers before and during a 10-day experimental bed rest. Additionally, we tracked changes in glutathione levels and specific metabolite ratios up to 21 days of bed rest. Using gas chromatography-mass spectrometry and the internal standard technique, we observed a 9 ± 9% decrease in glutathione levels during the first 5 days of bed rest, followed by an 11 ± 9% increase from the 5th to the 10th day, nearly returning to baseline ambulatory levels. The cysteinyl-glycine-to-glutathione ratio, reflecting γ-glutamyl cyclotransferase activity (a key enzyme in glutathione breakdown), rose by 14 ± 22% in the first 5 days and then fell by 10 ± 14% over the subsequent 5 days, again approaching baseline levels. Additionally, the γ-glutamyl cysteine-to-cysteine ratio, indicative of γ-glutamyl cysteine synthetase activity (crucial for glutathione synthesis), increased by 12 ± 30% on day 5 and by 29 ± 41% on day 10 of bed rest. The results observed on day 21 of bed rest confirm those seen on day 10. By calculating the ratio of product concentration to precursor concentration, we assessed the efficiency of these key enzymes in glutathione turnover. These results were corroborated by directly measuring glutathione synthesis and degradation rates in vivo using stable isotope techniques. Our findings reveal significant changes in glutathione kinetics during the initial days of bed rest and identify potential therapeutic targets for maintaining glutathione levels.
Ključne besede: antioxidant, muscle unloading, glutathion turnover, γ-glutamyl cycle, gamma-glutamyl cycle
Objavljeno v DiRROS: 21.11.2024; Ogledov: 444; Prenosov: 1316
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