Although interval training is king when it comes to the calories-out side of the exercise-diet equation, all intervals all the time isn't the way to go. Switch up your workout frequency (how often you hit the treadmill), intensity (how hard you work), and modality (whether you walk or run or cross-train on a bike), says exercise physiologist and running coach Amy Dixon.
“Perform three weekly cardio workouts, alternating between high-intensity intervals on flats and hills and endurance workouts that incorporate flat-road walking or running or hills," Dixon says, "so that you do two days of one type of cardio and one day of the other." And take advantage of all the numbers literally at your fingertips: If you always run at a 10-minute mile pace at the same incline, for example, press the up arrow on your grade and speed just enough so you notice the intensity boost but not enough to slow you down.
