Background: Oxidative stress is a chemical stress where the balance between prooxidants and antioxidants is disturbed in favor of the former. The main reason for its appearance is harmful radicals, the production of which increases during physical activity. During exercise, they are formed during repeated contractions of skeletal muscles due to increased oxygen consumption, which provokes an increased leakage of electrons from the respiratory chain complexes in the mitochondria. The generation of reactive oxygen species is associated with oxidative damage in several tissues: increased protein and glutathione oxidation, lipid peroxidation, accelerated fatigue, muscle damage, inflammation and reduced performance in athletes. Athletes have begun using antioxidant supplements to reduce fatigue and improve athletic performance, but research on their effectiveness has so far shown inconsistent results.
Aim: The aim of the master's thesis is to systematically review the literature on the subject of oxidative stress in individuals who are regularly physically active and to evaluate the impact of nutritional supplements with antioxidants on inflammatory markers, recovery and performance of athletes. For evaluation, we monitored various biological markers in the blood: MDA, TNF-α, IL-6, CRP, CK, GSH, LDL, SOD, GPx, CAT and TAC.
Methods: After compiling an appropriate search profile, we searched the literature in the PubMed and Web of Science databases, following the principles of the Recommended Reporting Items for Systematic Reviews and Meta-Analyses.
Results: From a total of 1263 hits, we included 28 studies that met the inclusion criteria. We read them and collected the basic data with a short summary in a spreadsheet. We assessed the quality of the selected research and analysed it according to the country of implementation, the year of publication and the number of participants. Then we carried out a substantive comparison, where we divided the research into subgroups according to the similarity of the supplements. Research has shown inconsistent results, but for the most part we find that antioxidant supplementation is not protective against muscle damage, and we have found very little evidence of improved physical performance. Most studies have reported a positive effect of antioxidants on reducing levels of oxidative stress and inflammation and increasing levels of antioxidants in plasma and cells. A decrease in MDA, TNF-α, IL-6 and CRP and higher values of TAC, SOD and GPx compared to placebo are often observed with supplements.
Conclusion: Based on our systematic review of the literature, we can conclude that the mentioned topic is complex and is still at the center of discussions. For more reliable findings, we would need a narrower and more specific examination of each supplement for a specific form of movement with a larger number of subjects
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