I found a free article by Martin Gibala,Ph.D., a major researcher into high-intensity interval training (HIIT). He prefers to abbreviate it as HIT.
I don’t like to exercise, so I’ve been incorporating HIIT into my workouts for over a year. It’s helped me maintain my level of fitness to that required of U.S. Army soldiers, without being a exercise fanatic.
So what’s HIIT? Gibala’s definition:
High-intensity interval training is characterized by repeated sessions of relatively brief, intermittent exercise, often performed with an “all out” effort or at an intensity close to that which elicits peak oxygen uptake (i.e., ≥90% of VO2peak).
HIIT involves short sessions of very intense exercise two or three times per week, for as little as 15 minutes. That’s total time, not 15 minutes per session! Yet you see a significant fitness improvement. Be aware: the brief exercise bouts should be exhausting.
The Gibala article has all the scientific journal references you’d want, plus a suggested HIIT program for an absolute beginner.
One final quote from Dr. Gibala:
It is unlikely that high-intensity interval training produces all of the benefits normally associated with traditional endurance training. The best approach to fitness is a varied strategy that incorporates strength, endurance and speed sessions as well as flexibility exercises and proper nutrition. But for people who are pressed for time, high-intensity intervals are an extremely efficient way to train. Even if you have the time, adding an interval session to your current program will likely provide new and different adaptations. The bottom line is that — provided you are able and willing (physically and mentally) to put up with the discomfort of high-intensity interval training — you can likely get away with a lower training volume and less total exercise time.
PS: Why won’t Gibala give some credit to Izumi Tabata who did a pioneering study on HIIT in 1996?
PPS: Gibala narrated this stationary bike HIIT video.
h/t Tony Boutagy