Just 11 minutes of moderate physical activity per day may lower one's risk of premature death, according to an analysis published Tuesday in the British Journal of Sports Medicine.
The researchers analyzed data from nearly 200 studies involving a total of more than 30 million participants from around the world, who self-reported their activity levels for at least three years. The team then looked at the association between physical activity and 22 distinct health outcomes, including 14 types of cancer, making it one of the largest analyses of its kind.
The results indicated that people who were moderately active for 75 minutes per week — meaning they engaged in activities like hiking, walking briskly, cycling to work or playing actively with their children — had lower risks of overall mortality, heart disease, stroke and various cancers relative to people who were not active.
The researchers estimated that 1 in 10 premature deaths, defined by the World Health Organization as deaths between ages 30 and 70, tallied in their analysis could have been prevented if everyone had engaged in moderate physical activity for 75 minutes per week.
That's half the amount of exercise recommended by the WHO and the Centers for Disease Control and Prevention. Both say adults should get at least 150 minutes of moderate physical activity per week. Globally, 1 in 4 adults don't meet these recommendations. In the U.S., fewer than half of adults do.
The new research underscores the idea that even a little physical activity is better than none, said Leandro Garcia, an author of the analysis and a public health lecturer at Queen’s University Belfast.
"Many people think that to get moderate levels of physical activity, or to meet these recommended levels, they need to go to structured sessions of exercise or really do extra-strenuous activities, when in reality, activities that we do in our routines could also be very beneficial," he said.
Garcia added that as a general rule, moderate physical activity can be thought of as anything that elevates your heart rate while still allowing you to maintain a conversation. The types of movement that entails depend on an individual's age, health status and overall fitness level.
But Amanda Paluch, an epidemiologist and kinesiologist at the University of Massachusetts Amherst who was not involved in the new analysis, cautioned against thinking of 11 minutes as a minimum or maximum daily target.
"This is a very broad, generalized number, so putting a lot of stock in that specific number would be a little challenging," Paluch said.
Past research has generally shown that brief bouts of physical activity daily can improve people’s health.
A December study found that short bursts of intense movement lasting just one to two minutes, repeated three or four times per day, were associated with an up to 40% lower risk of death over the course of seven years. Unlike moderate physical activity, these intense exertions are the kind that leave people huffing and puffing.
According to that research, people whose days included this type of movement faced a 49% lower risk of dying from heart disease in particular, relative to people who did not engage in any vigorous activity.
Paluch's own research, published last year, found that people's overall risk of death declined as they increased their daily step count (though the effect stopped once people reached 8,000 to 10,000 steps per day).
"We are finding that lower than 10,000 steps per day, there’s still significant benefit," said Kelly Evenson, an epidemiology professor at the University of North Carolina at Chapel Hill who co-authored that study with Paluch.
Their results suggested that people with a median of around 6,000 to 11,000 daily steps had a 50% to 60% lower risk of death relative to those with a median of around 3,500 steps per day.
"We’ve seen across age that it’s never too late to start being active and that benefits accrue pretty quickly. There’s not an age in which physical activity isn’t useful," Evenson said.
All three experts interviewed agreed that the WHO and CDC recommendations are still the ideal thresholds for physical activity.
The new analysis found that if everyone studied had increased their moderate physical activity to the advised 150 minutes per week, that could have prevented nearly 16% of all premature deaths.
"Physical activity works on nearly every cell of the body," Paluch said. "It could influence things like inflammation, for example, which is associated with cancer."