The purpose of the present study was to examine the effects of resistance exercise (RE) to failure with different intensities on lipid peroxidation response. A week after one repetition maximum (1RM) test, 10 resistance-trained men performed high-intensity RE (4 sets of 5 exercises to failure at 90% of the 1RM, with 3 min rest) and moderate-intensity RE (4 sets of 5 exercises to failure at 75% of the 1RM, with 90 second rest) in a randomized and cross-over design. Urine samples were collected before (Pre), after (Post), 3h after (3h Post) and 24 h after RE (24h Post) for analyzing lipid peroxidation as measured by 8-isoprostane (8-iso PGF2α). The findings indicated that urinary 8-iso PGF2α significantly increased at Post and 3h Post RE with 75% of 1RM compared to Pre RE (p<0.05). Also, urinary 8-iso PGF2α significantly increased at Post RE with 90% of 1RM compared to Pre RE (p<0.05). In addition, urinary 8-iso PGF2α concentrations significantly increased at Post and 3h Post RE with 75% of 1RM compared to RE with 90% of 1RM (p<0.05). Total exercise volume (kg) and volume in each exercise (kg) were significantly higher in RE with 75% 1RM protocol compared to RE with 90% 1RM protocol (p<0.05). These data suggest that lipid peroxidation is higher in moderate-intensity RE performed to failure compared with high-intensity RE performed to failure.
