"Instead of maintaining one speed for the entire duration, we alternate between more intense and less intense but within the session," said exercise physiologist Josh O'Brien.
O'Brien demonstrated interval training on Kendra Nichifor, who is training for her second marathon. She alternates between one minute recovery periods and one minute sprints.
"I felt like a dog was chasing me! It really does get your heart rate up and it feels good," said Nichifor.
The speeds can vary, but the sprint should be fast enough that you're tired at the end and the recovery should let your heart rate come down but not all the way. Studies show that interval training builds endurance, builds muscle mass and burns more fat in less time.
The concept of interval training is not new, but new research shows the high intensity part doesn't have to be as long and you don't have to go full out 100% to see results.
"I'm seeing intervals of 30 seconds, even 10 seconds with tremendous results," said O'Brien."Workouts that last only 5 to 10 minutes can be quite effective at improving markers of cardiovascular function."
One of those cardiovascular markers is VO2 max, the maximum amount of oxygen your body can take in during exercise.
Interval training has been shown to improve your VO2 max, which means every day activities will feel easier and improve lactic acid removal which means you can work out harder.
You do need to check with your doctor before doing a workout like this, to see if you can sustain the high intensity part, especially if you have heart disease or if you're at high risk for it. You may need a stress test first.