A new study at Harvard University concludes that for older women, walking as few as 4,500 steps a day reduced mortality compared with those who took only 2,700 steps a day.

Any movement, whether or not it counts as exercise, may help to extend people’s lives. People who are active have lower incidences of heart disease, obesity, and Type 2 diabetes and usually live longer than people who are sedentary. However, confusion remains about how much exercise we need and how intense it should be. Past research suggests meeting or even exceeding a 10,000-step-a-day goal. Mobile applications and fitness trackers have 10,000-step-a-day exercise goals built into them. The Canadian Physical Activity Guideline for adults 18-64 years is 150 minutes of moderate-to-vigorous aerobic physical activity per week, in bouts of 10 minutes or more.

In an interview with New York Times, I-Min Lee, a professor of medicine at Harvard University, who led the study, said: “People may not intuitively grasp what 150 minutes a week of exercise means in practical terms. Step counts are simpler, more concrete and convenient measure of physical activity. We can understand the concept of a step and how to add them up.”

Dr. Lee and her team looked at data from the Women’s Health Study, which has been tracking the health and habits of older women for decades. In that study, thousands of older women worn sophisticated activity monitor for a week. The monitors tracked the steps each woman took per minute throughout the day (but without showing any readouts of the totals, so the women would not know or respond to the counts).

Dr. Lee and her team gathered the step-count and health data from almost 17,000 of the participants, most of them in their 70s, and none of whom reported poor health. They also checked death records for the subsequent four to five years and than compared step counts and mortality. The team found that the women who had moved the least, taking only about 2,700 steps a day, were the most likely to have died during the follow-up period. Women who moved more often had considerably less risk of premature death, up to 7,500 steps a day. The threshold for reducing the risk of premature death was about 4,500 steps a day. Thos who reached 4,500 steps were 40 per cent less likely to have died during the follow-up period.

In terms of intensity, majority of the women strolled, rather than rushed; only a few walked intensively and for exercise. In this study, only the number of steps per day was associated with mortality, not the speed with which the women accumulated them.

This study looked at older women and mortality – further research is required to see if the findings apply to men or younger people. Dr. Lee concluded: “Even so, the findings suggest that step counts can be a useful way to measure exercise and that taking more steps is better than taking fewer.”