Assessment of the Impact of N-acetylcysteine Supplementation on Physical Performance

Study aims to verify the hypothesis: * N-acetylcysteine (NAC) supplementation improves exercise capacity in people training endurance sports and the effectiveness of this supplementation depends on the polymorphism of genes related to folate and glutathione metabolism. * NAC supplementation affects the parameters of oxidative stress among women and men training endurance disciplines

Inclusion Criteria: * Consent to participate in the study and acceptance of the established scheme for conducting the intervention * age range between 18 and 45 years old * regular training with a frequency of at least 3 times a week during the last year, Exclusion Criteria: * no consent to participate in the study and no acceptance of the established scheme of the conducted intervention * existing diseases of the blood system and neoplastic diseases * respiratory system diseases * obesity * any medical contraindications to exercise * Results obtained from exercise tests that do not meet the inclusion criteria * use of NAC during the last month * allergy to NAC * smoking * pregnancy and lactation