The purpose of the present study was to compare oxidative modification of DNA in the 24 hours following hypertrophy- and strength-intensity resistance exercise (RE) protocols. A week after one repetition maximum (1RM) test, 10 resistance-trained men performed strength-intensity RE (4 sets of 5 exercises to failure at 90% of the 1RM, with 3 min rest) and hypertrophy-intensity RE (4 sets of 5 exercises to failure at 75% of the 1RM, with 90 second rest) in a randomized and crossover design. Urine samples were collected before (Pre), after (Post), 3h after (3h Post) and 24 h after RE (24h Post) for analyzing oxidative DNA damage as measured by urinary 8-hydroxy-2- deoxyguanosine (8-OHdG). The findings indicated that urinary 8-OHdG significantly increased at 3h Post and 24 h Post in both hypertrophy (75% of the 1RM)- and strength (90% of the 1RM)-intensity resistance exercise protocols (p<0.05). However, there were not significant differences in oxidative DNA damage between to RE protocols (p>0.05). In conclusion, a single session of hypertrophy- and strength-intensity resistance exercise lead to increase oxidative DNA damage and that these effects seems to be independent of the RE intensity.
