Musings of a Cardiologist

High-intensity interval training, or HIIT, is the go-to workout for gym warriors, and a growing number of apps are promising to burn more fat in less time.

HIIT alternates periods of high-intensity sprints with periods of rest, and the technique has risen to prominence recently as more athletes discover its benefits. It helps burn more calories and fat in a shorter amount of time, boosts aerobic capacity and helps users bust through weight-loss, speed and endurance plateaus.

Used in conjunction with more moderate intensity aerobic workouts (and with a doctor’s blessing), it’s a valuable addition to the repertoire of any advanced exerciser. Most HIIT workouts are generally shorter than typical workouts, often lasting 15-20 minutes — but what a grueling 15-20 minutes they are.

The number and length of high-intensity sessions and rest periods vary, depending on taste, activity and ability: some athletes like three-minute sprints with 1-minute rest periods, for example, and proponents of the so-called Tabata intervals — named after the Japanese researcher who studied its effects — like 20 seconds of extremely high-intensity work with 10 seconds of rest. Whatever your interval, many apps can help you keep track of intervals, cueing you to changes — keeping your attention off the clock and instead on getting through to the next level.