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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: 115; Prenosov: 1101
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Ključne besede: studies, kinesiology, health benefits, physical inactivity
Objavljeno v DiRROS: 28.10.2024; Ogledov: 120; Prenosov: 70
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Povzetek: Purpose: Due to its numerous positive effects on individuals and society as a whole, sport has become an important socio-economic subsystem of the national environment. To regulate, develop, and monitor the impact of sport at national, regional, and local levels, countries often develop and adopt various strategic documents, which can be found under the name of national program or strategy for sport development at the na-tional level. Due to the importance of understanding the substantial comprehensiveness of national sports strategies (NSS) and the precision of the methodological-processual approach, the purpose of the present paper is to present a methodological and sub-stantive view of the process of creating NSS and to develop a comprehensive concept (model) that appropriately places the substantive part in the phases of the process.Method: The methodology of writing conceptual research papers was used. This approach provides a bridge or link between different concepts and scientific discipli-nes. The methodological approach was the “model paper” which aims to provide a theoretical framework that predicts relationships between concepts. A model paper identifies connections between constructs and introduces new constructs.Findings: The development of the substantive model for the preparation of the NSS revealed that the comprehensive sport system at the national level can be understood within the framework of five substructures (financial, organizational, developmental, material, and program) that contribute significantly to the development and implemen-tation of activities related to sport and physical activity. They are interconnected and interdependent and are surrounded by a so-called integrity framework that protects the sport system from the deviations of modern society. The methodological process model reveals that for the implementation of the process of NSS preparation, the most appro-priate is the strategic management methodology, which enables accurate and efficient management of planning, organization, implementation, and control of the NSS. The combination of both perspectives (substantive and methodological) enables the deve-lopment of a comprehensive concept (model) of NSS preparation.Conclusions: The developed concept (model) of the NSS preparation comprehen-sively covers the issue of the NSS preparation management and is dialectical, open, flexible, and repeatable, enabling future users to manage the NSS preparation in a substantive-holistic and process-effective manner.
Ključne besede: methodological perspective, national sport strategy, preparation, substantive perspective
Objavljeno v DiRROS: 23.10.2024; Ogledov: 89; Prenosov: 48
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Povzetek: Background Hormonal doping in recreational sports is a public-health concern. The World Anti-Doping Agency (WADA) promoted the creation of the Athlete Biological Passport, aiming to monitor athlete’s biological variables over time to facilitate indirect detection of doping. Detection tests for anabolic androgenic steroids (AAS) and growth hormone (GH) are available while insulin abuse cannot be revealed. We have determined in recreational bodybuilders the metabolic effects associated with different patterns of hormone abuse. All analyses were conducted using Statistical Package for Social Sciences (SPSS) 21.0 software (SPSS Chicago, IL). Results We have assessed plasma concentrations of selected metabolic markers and fatty acid content in erythrocyte membranes of 92 male bodybuilders and in 45 healthy controls. Hormonal abuse was identified by anonymous questionnaires. 43% (%) of recruited bodybuilders regularly abused hormones, i.e., anabolic androgenic steroids (95%) often associated with GH (30%) and/or insulin (38%). HDL-cholesterol was lower in insulin and/or GH abusers. Alanine (ALT) and aspartic (AST) transaminases were greater in hormone abusing bodybuilders than in non-doping bodybuilders and controls. Insulin doping was selectively associated with increased plasma ALT-to-AST ratio. In erythrocyte membranes, elongase activity (i.e., stearic-to-palmitic ratio) was lower in insulin and/or growth hormone doping, whereas increased Δ-9 desaturase activity (i.e., palmitoleic-to-palmitic ratio) was selectively associated with insulin doping. Conclusions In conclusion, our study demonstrates that insulin and GH abuse are characterized by multiple alterations of specific metabolic markers. Although further studies are needed to test whether longitudinal monitoring of selected metabolic marker such as muscle contraction time, HDL levels, ALT-AST ratio as well as the activities of selected enzymes (e.g. Δ-9 desaturase and elongase), could contribute to the detection of insulin and GH abuse in sport.
Ključne besede: bodybuilders, doping, drug abuse, matabolism
Objavljeno v DiRROS: 03.04.2024; Ogledov: 556; Prenosov: 217
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Povzetek: Background The degree of deterioration in sarcopenia parameters may be affected by a person’s level of physical activity (PA) and sedentary behavior (SB). Our study focused on examining the PA and SB of active older adults including those with and without history of sports in youth. Methods Forty-four participants (20 men and 24 women, mean age of total sample 76.1 ± 5.2 years) were included in analysis of PA, SB habits and sarcopenia parameters, determined by skeletal muscle index, hand-grip strength, gait speed, Timed Up and Go tests (TUG). PA and SB were recorded with accelerometers. Our primary aim was to compare participants with (AH) or without a sport history in youth (NAH), in their sarcopenia parameters and PA and SB habits. Results When divided participants in two groups (AH and NAH) and adjusting for age, we have detected the differences for skeletal muscle index (p = 0.007) and hand-grip strength (p = 0.004) in favor of participants who were engaged in sports in youth. We did not find any differences in PA and SB habits between the AH and NAH groups. After adjusting for age, participants with a higher number of daily steps, longer moderate to vigorous physical activity (MVPA) bouts, a higher number of MVPA bouts in a day and higher overall MVPA engagement achieved better results in hand-grip strength and TUG. Participants with lower SB had better TUG and gait speed results. Conclusions Our findings suggest that engaging in sports activities in youth can make a difference with sarcopenia parameters. Although we found no differences in PA and SB habits between participants with AH and NAH, participants with an athlete history performed better results in sarcopenia parameters.
Ključne besede: muscles, muscle disorder, elderly, exercise, sedentarism
Objavljeno v DiRROS: 10.11.2023; Ogledov: 700; Prenosov: 1636
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