Effects of different resistance training intensity on indices of oxidative stress

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.