Purpose. To determine the effect of sprint exercise and a detraining period , on lipid peroxidation (malondialdehyde) and response of antioxidant system (FRAP, plasma uric acid, bilirubin and total protein). Methods. Male wistar rats (3 months old) were used. The rats were randomly divided into two groups: 1) experimental group (n=20), 2) control group (n=15, without any program training). Experimental rats participated in a high intensity training program consisting of treadmill running 3 days a week for 12 weeks. Each session included four to eight 40s sprints at a pace of 50-60 m/min (5-15º incline), with a 120s recovery interval between each sprint. Five trained rats experienced the detraining so that effects of detraining studies, from 8th to 12th weeks. Blood samples were collected at 24h after the first session, end of 8th week and end of 12th week. Concentration of malondialdehyde (MDA) was measured spectrometrically using thiobarbitoric acid (TBA) reagent. Ferric reducing ability of plasma (FRAP) assay was performed using TPTZ reagent as described by Benzie and Strain (1996). Plasma uric acid, bilirubin and total protein were determined using commercial kits on an autoanalyzer (Technican). Results and Discussion. Data analyzing by using two-way analysis of variance (and also by t-test to compare differences in groups) showed: There were significant difference between two groups about MDA (P=0.022), FRAP (P=0.005) and Bilirubin (P=0.002), at least one of evaluation periods, While, total protein and uric acid unchanged. In experimental group, indeed, there was significant difference through various assessment about MDA (P=0.001), FRAP (P=0.001), Bilirubin (P=0.008) and uric acid (P=0.012).In summary, results of this protocol of sprint exercise training are consistent with previous work that demonstrates an increase in lipid peroxidation in response to high intensity exercise (3, 4). Indeed, the present study indicates that long-term, high intensity training c
