A new study from the Karolinska Institutet in Stockholm, Sweden, suggests that replacing time spent sitting with light-intensity physical activity may benefit health more than previously thought.

In the journal Clinical Epidemiology, the authors report how replacing just half an hour of sitting each day with housework, walking, standing, or similar low-intensity activity is linked to a 24% reduced risk of death from cardiovascular disease.

These new findings might come as a pleasant surprise, especially to those who assume that only moderate- or vigorous-intensity physical activity can make a sizable difference.

The study is particularly significant because it "objectively assessed" levels of physical activity using motion trackers rather than self-reports from participants.

"Previous studies," says study leader Dr. Maria Hagströmer, a senior lecturer in the Department of Neurobiology, Care Sciences, and Society, "asked participants about levels of physical activity, but this can lead to reporting error since it's hard to remember exactly for how long one has been sitting and moving around."

The study also confirms that replacing sedentary time with moderate- or higher-intensity physical activity has an even greater effect on reducing deaths linked to cardiovascular disease.

'Avoiding inactivity' is also important

The United States Department of Health and Human Services explain that "for substantial health benefits," adults should engage in at least 150 minutes per week of moderate-intensity aerobic exercise, preferably spread through the week in bouts of at least 10 minutes at a time. They suggest "brisk walking or tennis" as examples.

Alternatives to this are 75 minutes per week of vigorous-intensity aerobic exercise or an equivalent mixture of both moderate and vigorous. They give "jogging or swimming laps" as examples of vigorous-intensity activity.

Even more benefit comes from increasing the time spent in aerobic physical activity, as well as by doing muscle-strengthening exercises that "engage all the major muscle groups" on at least 2 days per week.

The US guidelines also state that we should aim to "avoid inactivity," noting that, "[A]dults who participate in any amount of physical activity gain some health benefits." One might therefore be forgiven for assuming that these benefits would be rather small, given the small amount of space dedicated to this advice.

The new findings may bring comfort to those whose reaction to the formal guidelines is, "I can barely find time to do the laundry and sweep the yard, never mind work out for 2.5 hours per week!"

Well, it seems that time spent doing everyday chores instead of sitting also makes a difference—and that difference is bigger than we thought.

The researchers had confirmed the dangers of prolonged sitting in an earlier study that showed that, compared with sitting for under 6.5 hours per day, sitting for more than 10 hours daily was linked to a 2.5 times greater risk of premature death.

Study used accelerometer data

For the study, the researchers analyzed data on 851 men and women who took part in Sweden's Attitude Behaviour and Change population-based study.

The physical activity data were collected using Actigraph accelerometers, and data on deaths and causes of death were gathered from Swedish registries over an average follow-up of 14.2 years.

During the follow-up, 79 of the participants died—24 from cardiovascular disease, 27 from cancer, and 28 from "other causes."

When they analyzed the activity data against the deaths and causes of death, the researchers found that light-intensity physical activity was tied to a significant 24% reduction in risk of death from cardiovascular disease and 11% reduction in risk of death from all causes.

Replacing sedentary time with just 10 minutes of either moderate- or vigorous-intensity activity each day was linked to a 38% reduced risk of death from cardiovascular disease, while 30 minutes per day was linked to a 77% reduction.

"No statistically significant reductions were found for cancer mortality," note the authors.

"This is a unique study, since we've been able to analyze a large number of people with objective measures of physical activity for up to 15 years."

Dr. Maria Hägstromer