Efeitos de diferentes intensidades de treinamento aeróbico isocalórico sobre a função endotelial microvascular e marcadores de estresse oxidativo em ratos submetidos à dieta hiperlipídica

Abstract

In obesity, it remains unclear if high intensity aerobic training is superior to moderate intensity for improvements on endothelial function in microvasculature; mainly when exercise volume is matched by energy expenditure. Additionally, it is necessary to clarify if the high intensity training really improves microvascular endothelial function, or could exacerbate oxidative stress and impairments on endothelial function which are triggered by obesity per se. This study investigated the effects of two intensities of aerobic training, performed with isocaloric exercise bouts upon microvascular endothelial function and biomarkers of vascular oxidative stress in rats fed a high fat diet. Thus, Wistar rats (n=18 per group) were randomly assigned to standard chow diet (C) or high fat diet (H) for 12 weeks prior to be assigned into the groups: sedentary− CS and HS; moderate intensity continuous training− CM and HM; high intensity interval training− CH and HH. Over 6 weeks, CM and HM groups performed treadmill running at speeds corresponding to 65% oxygen uptake reserve (VO2RES), and CH and HH trained at 85% VO2RES interspersed with 60% VO2RES, with the duration controlled by energy expenditure. At the end of intervention, all groups had assessed: body composition, metabolic profile and cardiorespiratory capacity. Experiments of microvascular reactivity were performed in two distinct muscles. Aorta fragments were collected to perform assays of oxidative stress. Regarding the main results, HM and HH groups similarly improved endothelium dependent vasodilation in cremaster muscle (HS vs. HM: 22,9% P=0,01; HS vs. HH: 19,7% P=0,02), in adductors hindlimb (HS vs. HM: 13,4% P=0,03; HS vs. HH: 18,2% P=0,001) and also NO bioavailability (HS vs. HM: 23,9%; P=0,04; HS vs. HH: 25,1% P=0,04). Nevertheless, only high intensity training was able to improve Glutathione peroxidase activity (HS vs. HH: P=0,03; CS vs. CH: P=0,007), despite the increase of lipid peroxidation (CS vs. CH: P=0,005; HS vs. HH: P=0,04). High intensity was also able to improve endothelium dependent vasodilation in lean animals (CS vs. CH − cremaster: 26,3%; P=0,02; adutores: 19,2%; P=0,01). In conclusion, in obesity context, only high intensity aerobic training seems to be efficient to improve vascular antioxidant capacity, but total caloric expenditure of exercise sessions (volume) appeared to be more significant than intensity training to induce beneficial outcomes upon microvascular reactivity in the observed animals.