They began by recruiting 20 overweight, adult men and women who were, at the start, inactive but healthy enough to walk. They outfitted the volunteers with activity trackers and asked them to continue their normal lives for two weeks, while the researchers established their baseline step counts, which turned out to average about 5,000 steps a day.
Then the researchers had the volunteers download a phone app that sent them individualized step-count goals every day. The goals ranged, at random, from the same number of steps someone took at baseline up to 2.6 times as many. So, one day, participants might be aiming for their normal 5,000 steps and, the next day, 13,000.
The experiment continued for 80 days, after which researchers compared people’s daily goals, achievements and resulting, overall activity levels. And they found that people clearly walked more on days when they were asked to walk more; whenever goals exceeded people’s baseline step counts, they were more active, even if the goals were quite ambitious.
But few people achieved the highest step-count goals, often falling far short and, in general, walking little more than — or even less — than on days when the goals were more moderate.