Are the principles of interval training the same for everyone?

Yes — but you can take interval training to many levels. If you simply want to vary your exercise routine, you can determine the length and speed of each high-intensity interval based on how you feel that day.

After warming up for a few minutes, you might increase the intensity for 30 seconds and then resume your normal pace. Finish with a cool-down. How much you pick up the pace, how often and for how long is up to you.

If you're working toward a specific fitness goal, you may want to take a more scientific approach. A personal trainer or other expert can help you time the intensity and duration of your intervals — which may include movement patterns similar to those you'll use during your sport or activity. The trainer may time the intervals based on factors such as your target heart rate and the ability of your heart and lungs to deliver oxygen to your muscles (peak oxygen intake).