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.
Almost everyone kept up their assigned exercise routines for five years, an eternity in science, returning periodically to the lab for check-ins, tests and supervised group workouts. During that time, the scientists noted that quite a few of the participants in the control had dabbled with interval-training classes at local gyms, on their own initiative and apparently for fun. The other groups did not alter their routines.
After five years, the researchers checked death registries and found that about 4.6 percent of all of the original volunteers had passed away during the study, a lower number than in the wider Norwegian population of 70-year-olds, indicating these active older people were, on the whole, living longer than others of their age.
But they also found 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