“This is not a weight-loss program,” Dr. Tjonna says. It is, instead, he says, “a suggestion for how people can make a kick-start for better fitness,” or maintain fitness already gained, when other obligations press on your time.
The results, Dr. Tjonna says, persuasively suggest that “getting in shape does not demand a big effort” in terms of time.
That finding, though, inevitably raises the question of whether the bar could drop even lower. Could, for instance, a mere two minutes of strenuous training effectively improve health and fitness?
Dr. Tjonna, the killjoy, doubts it. There are other groups of scientists looking at even shorter bouts of exercise, he says, “but it seems like they don’t get the same results regarding the maximal oxygen uptake” as the four-minute sessions used in his experiment. Since improved maximal oxygen uptake can reliably indicate better overall cardiovascular health, he suspects that “we need a certain length of the interval to trigger” such health and fitness benefits.
Thankfully, for those worried that a trip to the gym is an inefficient means of completing four minutes of exercise, the workout can effectively be practiced anywhere, Dr. Tjonna says. Sprint uphill for four minutes or race up multiple flights of steps. Bicycle, swim or even walk briskly, as long as you raise your heart rate sufficiently for four minutes. (Obviously, consult your doctor first if you haven’t been active in the past.)
“Everyone, we think,” Dr. Tjonna says, “has time for this kind of exercise three times a week.”