The Ideal Interval Length

We’ve all heard of interval training, in which short bursts of high intensity activity are alternated with less strenuous stints. Now comes Gretchen Reynolds, fitness writer for the New York Times, with answers, kind of, to two important questions about interval training: how long should an intense burst last?, and exactly how intense is “intense?” The answer, says Reynolds, is it depends. Mainly, it depends on how much pain you’re willing to put on yourself. Reynolds cites the research of Martin Gibala, a professor of kinesiology at McMaster University in Canada, who put young men through all-out 30-second intervals performed at 100 percent of the men’s aerobic capacity. The good news is, the volunteers became much more fit after a few minutes a week of such strenuous interval training. The bad news? They hated it. Next, Gibala chilled things out, with 60 second intervals at 90 percent of capacity. Sure, that worked, but it required more intervals for the same benefit as the 100 percent capacity stints. Gibala’s search for the perfect interval continues. At the moment he likes a 20 second all out push with a two minute chill out period.  And Reynolds? She says she likes a Danish workout with “10-second bursts of burning, painful effort, preceded by 30 seconds of gentle exercise and 20 seconds of moderate effort.”