HIIT—High-Intensity Interval Training—sounds deceptively simple, therefore easy: Exercise for just four minutes at a time with as much speed, energy, and intensity as possible. In truth, it can be brutal as hell.
Yet according to a large, long-term study conducted by the Norwegian University of Science and Technology and reported in The BMJ, exercise of any kind, including HIIT, can seriously reduce the possibility of premature death.
The New York Times reports that the Norwegian study was unusually comprehensive and first launched a decade ago.
Drawing data from 1,500 relatively healthy volunteers in their 70s who agreed to exercise regularly for five years, the researchers found plenty of evidence supporting the many past studies asking the same questions about fitness and longevity.
Here's more from the Times:
The scientists tested everyone’s current aerobic fitness as well as their subjective feelings about the quality of their lives and then randomly assigned them to one of three groups. The first, as a control, agreed to follow standard activity guidelines and walk or otherwise remain in motion for half an hour most days. (The scientists did not feel they could ethically ask their control group to be sedentary for five years.)
Another group began exercising moderately for longer sessions of 50 minutes twice a week. And the third group started a program of twice-weekly high-intensity interval training, or H.I.I.T., during which they cycled or jogged at a strenuous pace for four minutes, followed by four minutes of rest, with that sequence repeated four times.
While nearly 5 percent of the elderly volunteers passed away during the study, scientists found, according to the NYT, "interesting, if slight, distinctions between the groups. The men and women in the high-intensity-intervals group were about 2 percent less likely to have died than those in the control group, and 3 percent less likely to die than anyone in the longer, moderate-exercise group."
Those in the "moderate" group were more likely to have died during the study (though no one died mid-workout).
The Times reports head researcher Dr. Dorthe Stensvold concluded that while exercise is not a cure-all, "intense training — which was part of the routines of both the interval and control groups — provided slightly better protection against premature death than moderate workouts alone."
It is worth noting that Norwegians are already unusually healthy in general, so it is likely many in the study were in great shape anyway.
Like many past studies along these lines there's a caveat here: Don't wait till you are 70 to start adding intense intervals into your routine. If you haven't done it before seek out some training or even video instruction and plan for it.
Then go forth and HIIT it.