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The relevance of reactive oxygen species (ROS) production relies on the dual role shown by these molecules in aerobes. ROS are known to modulate several physiological phenomena, such as immune response and cell growth and differentiation; on the other hand, uncontrolled ROS production may cause important tissue and cell damage, such as deoxyribonucleic acid oxidation, lipid peroxidation, and protein carbonylation. The manganese superoxide dismutase (MnSOD) antioxidant enzyme affords the major defense against ROS within the mitochondria, which is considered the main ROS production locus in aerobes. Structural and/or functional single nucleotide polymorphisms (SNP) within the MnSOD encoding gene may be relevant for ROS detoxification. Specifically, the MnSOD Ala16Val SNP has been shown to alter the enzyme localization and mitochondrial transportation, affecting the redox status balance. Oxidative stress may contribute to the development of type 2 diabetes, cardiovascular diseases, various inflammatory conditions, or cancer. The Ala16Val MnSOD SNP has been associated with these and other chronic diseases; however, inconsistent findings between studies have made difficult drawing definitive conclusions. Environmental factors, such as dietary antioxidant intake and exercise have been shown to affect ROS metabolism through antioxidant enzyme regulation and may contribute to explain inconsistencies in the literature. Nevertheless, whether environmental factors may be associated to the Ala16Val genotypes in human diseases still needs to be clarified. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to determine if the critical swimming velocity (CSV), defined as the theoretical maximal swimming velocity that could be maintained for a long period of time without exhaustion, corresponds to the exercise intensity at onset blood lactate accumulation (OBLA), and if it could be utilized as a practical index for assessing endurance performance in elite physically disabled swimmers. Eight elite physically disabled swimmers swam four different distances (50, 100, 200 and 400 m) at maximal effort. The swimming time was taken during each trial. The CSV was expressed as the slope of a regression line between the covered swimming distance and the corresponding times of all possible combinations of 2 or 4 time trials. Results indicate that all the CSVs calculated were similar independently of the distances utilized for their calculation. Afterwards, a CSV confirmation test consisting of 3 x 10-min trials at 95, 100, 105% of the CSV was carried out. The lactate concentration at the end of each trial was 3.32, 4.03 and 5.73 mmol x l(-1), respectively. Lactate concentration at 100% CSV approached the value of 4 mmol x l(-1), which is considered the exercise intensity at OBLA. We conclude that the CSV corresponds with the OBLA intensity and could be a valuable index to plan a training schedule for physically disabled swimmers. [ABSTRACT FROM AUTHOR]