Just one hour of daily exercise is required to counteract the health risks associated with long periods of sitting, according to a new study published in The Lancet.
The researchers, from a collaboration of universities including Cambridge, aimed to find out whether or not it is possible to reduce or eliminate the increased risk of early death associated with prolonged periods of sitting.
They analysed 16 studies, including data from over a million men and women. They grouped subjects into four quartiles depending on their level of physical activity, ranging from less than 5 minutes per day in the bottom group to over 60 minutes in the top. They define moderate exercise as the equivalent of walking at 3.5 miles per hour or cycling at 10 miles per hour, for example.
It was found that between 60 and 75 minutes of moderate intensity exercise per day is sufficient to eliminate the increased risk of early death associated with sitting for over eight hours a day. But three quarters of people in the study failed to reach this target.
People who are physically inactive (regardless of time spent sitting) were found to be between 28 and 59 per cent more likely to die early, compared with those in the most active quartile. This increased risk is similar to that faced by an obese person, or a smoker.
Professor Ulf Ekelund, the study’s lead author, said: ‘There has been a lot of concern about the health risks associated with today’s more sedentary lifestyles. Our message is a positive one: it is possible to reduce – or even eliminate – these risks if we are active enough, even without having to take up sports or go to the gym’
‘For many people who commute to work and have office-based jobs, there is no way to escape sitting for prolonged periods of time. For these people in particular, we cannot stress enough the importance of getting exercise, whether it’s getting out for a walk at lunchtime, going for a run in the morning or cycling to work. An hour of physical activity per day is the ideal, but if this is unmanageable, then at least doing some exercise each day can help reduce the risk.’
This study seems impressive, with a robust meta-analysis of 16 prospective cohort studies (although 2 were unpublished studies). The statistical methodology is rigorous and in total the data relating to more than 1 million individuals were analysed. The results are applicable to individuals aged 45 years and over, particularly those who spend 8 hours (or more) daily sitting (at a desk, for example) .
The authors found that 1 hour (or more) per day of moderate level physical activity (for example, walking at 3.5 miles per hour) seems to effectively eliminate the increased risk of premature death conferred by a sedentary daily lifestyle associated with 8 or more hours of sitting time.
These findings suggest that in order to eliminate this additional risk of premature death, a greater level of physical activity is required than that which is recommended by current physical activity guidelines, which suggest that adults do at least 150 minutes of moderate intensity exercise per week. However, the study findings relate to aggregated data and as such, are not directly applicable to each individual. Nonetheless, the findings are compelling given the robustness of the methodology.
Research score: 4/5