When it comes to cardio, high-intensity interval training gives you the biggest bang for your buck: a short sprint-based workout improves your health as much as a longer, low-intensity slog. But should you pick the workout with the 20-second bursts or the one that has you sprinting for three minutes? Here's how to choose.
Picture: the North Carolina National Guard
If you want the shortest workout that still gives results, try a 10-minute session that includes three 20-second bursts of all-out effort. Researchers found that this routine, done just three times a week, was enough to improve cardio endurance, muscle growth, and (in men but not women) blood sugar. The only catch: those 20-second bursts have to be really, really intense.
If you want the most effective interval workout, look for one where the bursts of effort are 3-5 minutes long. That's the conclusion from a meta-analysis published in PLOS One that judged workouts based on how much they increased VO2max, a measure of cardio endurance. Be warned: it's hard to keep up the needed intensity for 3-5 minutes.
If you want the easiest effective workout (remembering that high intensity intervals are never exactly easy), the sweet spot is one minute hard followed by one minute of recovery. That's because, without a researcher (or coach) calibrating our bike and egging us on, most of us have trouble working hard enough to get the most out of those other protocols. We won't push ourselves quite hard enough on the 20-second bursts, and will likely peter out before the end of a 3-minute interval. According to Dr. Martin Gibala, a prominent researcher in this field, one-minute intervals are the best option for the average Joe or Jane hitting the gym.
Want to Try High-Intensity Interval Training? Consider These Four Things [The Globe and Mail]