Changes in blood antioxidant status in American football players and soccer players over a training macrocycle

Background: The effectiveness of sport training programs should be assessed regularly against biochemical indices. This study assesses changes in the antioxidant status indices in American football players (AF) and soccer players (SP) over a training macrocycle. Methods: The study was carried out with Poland's American Football League players (AF, n = 11, age 24.0 +/- 3.7 years) and first-league soccer players (SP, n = 11, age 26.5 +/- 3.8 years). Resting venous blood samples were collected from the players at the beginning of the three periods (preparatory, competition, and transition) making up the training macrocycle to determine the activity levels of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione reductase (GR), creatine kinase (CK), and lactate dehydrogenase (LDH), as well as the concentrations of non-enzymatic antioxidants (uric acid-UA and glutathione-GSH) and the levels of malondialdehyde (MDA). Results: The period effect on SOD (p < 0.001), CAT (p < 0.05), GPx (p < 0.05), GSH (p < 0.0001) and UA (p < 0.0001), and the group x period interaction effect on SOD, CAT and GPx (p < 0.05), GSH (p < 0.001), and UA (p < 0.01) proved to be significant. Also significant were the group effect on MDA (p < 0.001) and LDH (p < 0.0001) and the period effect on MDA (p < 0.01) and LDH (p < 0.001). The activity of SOD and CAT and the concentration of GSH were higher in both AF (12%, 2%, and 15%, respectively) and SP (33%, 10%, and 42%) at the start of the competition period than in the preparatory period, but the concentration of MDA and the activity of CK and LDH was lower (0.8%, 29%, 5% (AF) and 2%, 11%, 5% (SP). The highest activity of GPx and LDH and the greatest concentrations of UA and MDA occurred in the early transition period. Conclusion: The study revealed an association between American footballers' and soccer players' training loads in the preparatory period and moderate improvements in their blood antioxidant status at the beginning of the competition period. (c) 2021 The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).