Effects of progressive resistance exercise intensity on oxidative stress in resistance exercise trained and untrained men

Acute resistance exercise-induced oxidative stress responses are conflicting and the relation between oxidative stress and some exercise components, e.g. ?intensity? ? ?volume?, is not clear. Therefore the purposes of this study were (a) to determine time-dependent effects of progressive intensity of resistance exercise (RE) on blood lactate level, oxidative stress and antioxidant defense system markers, (b) to determine time-dependent effects of progressive intensity of RE on blood lactate level, oxidative stress and antioxidant defense system markers in RE trained (RET group) and untrained (UT group) men, (c) to determine relationship between oxidative stress, antioxidant defense system markers and VO2 max, one repetition maximum (1RM) and relative strength, (d) to search possible threshold intensity required to evoke oxidative stress.Resistance exercise trained (RET group: n=8, age: 25,50 ± 4,72 years, RE experience: 5,31 ± 3,40 years, 1RM: 137,4 ± 19,9 kg) and untrained (UT group: n=8, age: 29,00 ±5,87 years, 1RM: 110,5 ± 17,67 kg) volunteers participated to this study. To elicit blood oxidative stress all subjects performed the leg extension RE test at 5 different but progressive intensities: 1) 1x17 reps at 50% of 1RM; 2) 1x14 reps at 60% of 1RM; 3) 1x12 reps at 70% of 1RM; 4) 2x5 reps at 80% of 1RM; 5) 3x3 reps at 90% of 1RM, with 5 min rest between intensities and 90 sec rest between sets. The RE intensities were standardized for total volume. Blood samples were drawn before (PRE), immediately post each intensities (T50%, T60%, T70%, T80% and T90%) and after (30 min post =T30min, 60 min post = T60min and 24 h post = T24h) the RE in order to analyze blood lactate, lipid hydroperoxide (LHP), advanced oxidation protein products (AOPP), protein carbonyl (PCO), 8-hydroxy-2?-deoxyguanosine (8-OHdG), total glutatyon (tGSH) and superoxide dismutase (SOD).LHP significantly increased during the test and then significantly decreased in recovery period in both groups, the T24h LHP level was lower than PRE LHP level. During the test AOPP level decreased and later increased. In recovery period the T30min AOPP level was significantly lower than PRE and T24h AOPP level. PCO and SOD significantly increased in both groups however 8-OHdG and GSH were not affected by the RE intensity. The results indicated that there were no significant training status (group) x RE intensity (time) interaction for examined variables. In addition, a significant correlation was found between VO2max and PRE LHP and PRE PCO concentration and between VO2max and T24h GSH concentration. A significant correlation was also seen between all GSH measures (except PRE) and 1RM and relative strength.Most of the studies used only one or two oxidative stress biomarker that makes it difficult to explain effects of RE on oxidative stress precisely. On the other hand different RE intensities may affect biomarkers in contrast. Results suggest that for standardized exercise volume RE-intensity increased oxidative stress responses both in RE trained and untrained young men.