General health guidance advises people to be active, by taking part in moderate exercise such as riding a bike, running, or swimming, for at least 30 minutes, five times a week. But many people struggle to exercise for this amount of time, and have jobs and lifestyles that involve long, unavoidable periods of sitting.
Recent studies have suggested that spending long periods every day sitting down is linked to an increased risk of health problems, such as obesity and diabetes.
Researchers wanted to test a theory that these negative health effects can be avoided if people are active for short periods - say, an hour a day.
They divided 18 healthy young adults into three groups, each of which followed an exercise programme for four separate days. One group sat down for 14 hours a day. A second group sat down for 13 hours a day and exercised by cycling vigorously for one hour.
The third group exercised for six hours a day - four hours of walking at a leisurely pace and two hours of standing - and sat down for eight hours a day. Everyone had a blood test on the morning of each day, so researchers could test the participants’ blood sugar, cholesterol levels, and blood lipids, to look for signs of improved health.
People in the group who exercised vigorously for one hour a day didn’t show any improvement in the level of lipids or insulin in their blood, or how sensitive they were to the effects of insulin. Low insulin sensitivity can lead to a variety of health problems and can be an early sign of diabetes.
There was some evidence that the group who exercised for longer, but at lower intensity, had healthier levels of insulin and blood lipids.
How reliable is the research?
This study only looked at 18 people and results from such small studies can be affected by random chance. The signs of ill health the researchers tested for - levels of lipids and hormones in the blood - don’t necessarily reflect people’s actual health. The exercise programmes followed by the people in the study aren’t really representative of how people exercise in their daily lives, and we can’t be sure that there weren’t other things that influenced how ‘healthy’ people were on the days that they took part.
What does this mean for me?
This study shows that it’s better to be active as much as possible, as often as possible, to try and maintain good health. It suggests that - if you are very inactive most of the time - there aren’t any easy shortcuts to exercise.
Duvivier BMFM, Schaper NC, Bremers MA, et al. Minimal intensity physical activity (standing and walking) of longer duration improves insulin action and plasma lipids more than shorter periods of moderate to vigorous exercise (cycling) in sedentary subjects when energy expenditure is comparable. PLoS ONE. Published online 13 February 2013.
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