True Keto Boost heart rate using intervals. Research has shown time and time again that the use of intervals reap better results than continuous aerobic exercise, in fact one study has shown that 20 minutes of interval training four to five times per week for 15 weeks got nine times better results than 60 minutes of aerobic training done four to five times per week for 20 weeks. The most popular form of interval training is HIIT (high-intensity interval training) were you exercise for a set amount of time and then rest for a set amount of time circuiting through a group of exercises for a set number of rounds. But, the truth is interval training is anything where you work hard for a period of time and then rest for a period. Strength training done in a functional fitness program works the same way. You perform a group of two to three exercises back to back, take a break and repeat. That's an interval.