The purposes of this study were (a) to determine whether acute resistance exercise training (RET) induces oxidative stress, (b) to determine whether chronic RET decreases oxidative stress level at rest condition in previously untrained men, and (c) also to investigate how the RET intensity influences the training-induced oxidative stress response. Sixteen young men who did not have RET experience in the past were randomly divided in 2 groups. Hypertrophy-intensity group (n = 9) performed 3 sets of 12 repetitions at an intensity corresponding to 70% of 1 repetition maximum (1RM), whereas strength-intensity group (n = 7) performed 3 sets of 6 repetitions at an intensity corresponding to 85% of 1RM. Resistance exercise training involved 6 exercises, and it was performed 3 times a week on nonconsecutive days for 6 weeks. Blood samples were obtained just before (pre-RET) and immediately after RET (post-RET) on the first day of the first week, on the last day of the fourth and sixth weeks. The results indicated that malondialdehyde (MDA) significantly decreased (p < 0.05) in both groups immediately after RET; however, there was no significant acute alteration in glutathione (GSH) level in both groups (p > 0.05). After 6 weeks of training, pre-RET values of MDA significantly decreased and pre-RET values of GSH significantly increased in both hypertrophy- and strength-intensity groups (p < 0.05). These alterations occurred independently of training intensity. This study indicated that hypertrophy- and strength-intensity whole-body RET performed regularly for 6 weeks, decreased MDA concentration and increased GSH level in healthy young men. Results suggest that chronic RET has protective effects against oxidative stress similar to aerobic exercises and that these effects seem to be independent of the training intensity.

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The relationship between oxidative stress and some exercise components of resistance exercise (e.g. intensity, exercise volume) has not been clearly defined. Additionally, the oxidative stress markers may respond differently in various conditions. This study aims to determine the effects of progressive intensity of resistance exercise (RE) on oxidative stress and antioxidants in trained and untrained men, and also to investigate the possible threshold intensity required to evoke oxidative stress. RE trained (N=8) and untrained (N=8) men performed the leg extension RE at progressive intensities standardized for total volume: 1x17 reps at 50% of one-repetition maximum (1RM); 1x14 reps at 60% of 1RM; 1x12 reps at 70% of 1RM; 2x5 reps at 80% of 1RM; and 3x3 reps at 90% of 1RM. Blood samples were drawn before (PRE) and immediately after each intensity, and after 30 minutes, 60 minutes and 24 hours following the RE. Lipid-hydroperoxide (LHP) significantly increased during the test and then decreased during the recovery in both groups (p<0.05); the POST-24 h LHP level was lower than PRE-LHP. Protein carbonyl (PCO) and superoxide dismutase (SOD) significantly increased (p<0.05); however, 8-hydroxy-2’-deoxyguanosine (8-OHdG) and glutathione (GSH) were not affected by the RE (p > 0.05). The results indicated that there was no significant training status x intensity interaction for examined variables (p > 0.05). Standardized volume of RE increased oxidative stress responses. Our study suggests that lower intensity (50%) is enough to increase LHP, whereas higher intensity (more than 80%) is required to evoke protein oxidation.