Cardioprotective Effect of High Intensity Interval Training and Nitric Oxide Metabolites (NO2-, NO3-)

The aim of this study was to investigate the effects of High-Intensity Interval Training (HIIT) on nitric oxide metabolites (NO2-, NO3-) and myocardial infarct size after Ischemia/Reperfusion (I/R) injury in healthy male rats. A total of 44 Wistar rats were randomly divided into 4 groups including HIIT (n=8), HIIT + IR protocol (n=14), control (n=8), and control + IR (n=14). Each training session of HIIT consisted of 1 hour of exercise in three stages: 6-minute running at 50-60% VO2max for warm-up; 7 intervals of 7-minute running on treadmill with a slope of 50 to 20° (4 minutes with an intensity of 80-100% VO2max and 3 minutes at 50-60% VO2max); and 5-minute running at 50-60% VO2max for cool-down. The control group did not participate in any exercise program. Nitric Oxide (NO) and its metabolites were measured by using Griess reaction test. The results showed that eight weeks of exercise training exerted a significantly increasing effect on nitrite (8.55 µmol per liter, equivalent to 34.79%), nitrate (62.02 µmol per liter, equivalent to 149.48%), and NOx (66 µmol per liter, equivalent to 98.11%) in the HIIT group compared with the control group. The results showed myocardial infract size (IS) was significantly smaller (23.2%, P<0.001) in the exercise training group compared with the control group. Incremental changes in NO-NO3-, NO2- axis are one of mechanisms through which HIIT program can protect the heart from I/R injury and decrease myocardial infarction.