Public health officials have long encouraged walking as a way of improving general health, but many studies have focused on people in their early 60s and have sometimes ignored minority groups, such as people who aren’t white.
Between 2003 and 2006 the study looked at 4840 people who were representative of the US population over the age of 40. Pedro Saint-Maurice at the National Cancer Institute and his colleagues asked the participants to wear an accelerometer for a week, which is a fairly good gauge of usual activity.
The team found that the average daily step count of this group was 9124 steps. This figure is higher than many previous studies have found, probably because the study included younger people, those working in less sedentary jobs, and more men (who tend to be more physically active).
The researchers used the US National Death Index to determine which participants had died by the end of 2015. 4000 steps a day was used as the baseline (easily achieved by someone who drives to work and sits at their desk for the whole day.)
By comparison, the team found that taking 8000 steps was associated with a 51 per cent lower risk of dying per year, and taking 12,000 daily steps was associated with a 65 per cent lower risk of dying per year.
But there is a plateau: taking more than 12,000 steps a day didn’t seem to be associated with a further reduction of risk of yearly mortality. Up to 12,000 steps, a higher number of steps was associated with a lower risk of dying per year regardless of sex, race, level of education, health condition and whether a person smoked or drank alcohol.
The researchers also found that the intensity of the steps taken had little to no effect on the risk of yearly mortality (that is, speed doesn’t seem to matter).
“Many individuals wear wearables and monitor their step count, but there is a critical gap in knowledge between the relation of steps and health outcomes,” says I-Min Lee of Harvard University. This study corroborates and expands on previous research, she says. “It provides empirical data extending these findings to other groups of people.” (A lightly edited version of an article in New Scientist by Jason Arunn Murugesu. Journal reference: JAMA, DOI: 10.1001/jama.2020.1382)