by Brianna Crandall — August 8, 2016 — A new study of over 1 million people finds that doing at least one hour of physical activity per day, such as brisk walking or cycling for pleasure, may eliminate the increased risk of death associated with sitting for 8 hours a day, as experienced by most office workers as well as others.
Physical inactivity is linked to an increased risk of heart disease, diabetes and some cancers and is associated with more than 5 million deaths per year and, as the first global economic analysis of physical inactivity shows, costs the world economy over U.S. $67.5 billion per year in health-care costs and lost productivity.
The findings come from a new four-paper series published a week ago in The Lancet and launched in London ahead of the Summer Olympic Games. The authors of the Lancet Series: Physical Activity 2016: Progress and Challenges warn there has been too little progress in tackling the global pandemic of physical inactivity since the 2012 Olympics, with a quarter of adults worldwide still failing to meet current recommendations on physical activity.
Physical activity can help offset risks of prolonged sitting
In the first article of the series, researchers analyzed data from over 1 million people from 16 studies. The research team wanted to see how many hours of daily physical activity would be required to eliminate the association between prolonged sitting time and increased risk of death. Examples of physical activity were brisk walking at 5.6 km/h or cycling for pleasure at 16 km/h.
People who sat for 8 hours a day but were physically active had a much lower risk of death compared to people who sat for fewer hours a day, but were not physically active. This suggests that physical activity is particularly important, no matter how many hours a day are spent sitting. In fact, the increased risk of death associated with sitting for 8 hours a day was eliminated for people who did a minimum of 1 hour physical activity per day. The greatest risk of death was for people who sat for long periods of time and were inactive.
WHO guidelines recommend that adults should do at least 150 mins of physical activity per week, which is much lower than the 60-75 mins per day identified in this analysis. The study also warns of the progress that remains to be made in increasing levels of physical activity since only about 25% of people in the analysis did an hour or more physical activity per day.
Lead author Professor Ulf Ekelund, the Norwegian School of Sports Sciences, Norway, and the University of Cambridge, U.K., commented:
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.
The study also researched the related effects of prolonged television watching. The authors warn that the study mainly included data from people aged over 45 years old from the USA, Western Europe and Australia, so may not apply to other populations.
Economic burden vs. disease burden
The series also includes what is said to be the first study to estimate the global economic burden of physical inactivity. The study found that high-income countries bear a much larger proportion of the economic burden associated with physical inactivity, whereas low-income and middle-income countries have a larger proportion of the disease burden.
Smarter approaches
Another paper in the series concluded that increasing levels of physical activity will require collaboration between schools, urban planning, transport, sports and recreation and the environmental sectors, and greater efforts should be made to actively monitor physical activity as a risk factor in clinical practice.
The authors point to several successful examples such as the Bus Rapid Transit (BRT) System introduced in Curitiba (Brazil), Bogota (Colombia) and Cambridge (U.K.) that puts stops further apart than traditional bus stops to encourage walking; or the Coordinated Approach to Child Health (CATCH) in the USA that promotes a healthy school environment including physical activity, food, nutrition and sun protection.
The thoughtful design and operation of buildings can also help improve the health of occupants and visitors, as promoted by the American Institute of Architects (AIA) Design and Health initiative and the WELL Building Standard.
