Today’s first – morning group fitness class at Orange Theory Fitness, Capitola. I have seen these fitness centers all over, but never knew the concept behind them. Their method boils down to heart rate based interval training. Backed by the science of Excess Post-Exercise Oxygen Consumption (or EPOC), Orangetheory’s heart rate monitored training is designed to maintain a target zone that stimulates metabolism and increases energy. This is commonly known as the ‘afterburn’, work for 1 hr- keep burning for the next 36.