If melting mega calories is your goal, you're better off varying your heart rate throughout your workout, which will boost your average intensity overall, says Dixie Douville, a master instructor for Mad Dogg Athletics. Still, she cautions, really pushing yourself every time you hit the gym increases injury risk and can diminish rewards in the long run. Instead, aim for intervals once or twice a week and a steady-paced routine (between 65 and 80 percent of your maximum heart rate) the other three or four days.

Answered by FitnessEditor