Inactivity ‘killing as many as smoking’
A lack of exercise is now causing as many deaths as smoking across the world, a study suggests.
The report, published in the Lancet to coincide with the build-up to the Olympics, estimates that about a third of adults are not doing enough physical activity, causing 5.3m deaths a year.
That equates to about one in 10 deaths from diseases such as heart disease, diabetes and breast and colon cancer.
Researchers said the problem was now so bad it should be treated as a pandemic.
And they said tackling it required a new way of thinking, suggesting the public needed to be warned about the dangers of inactivity rather than just reminded of the benefits of being active.
The team of 33 researchers drawn from centres across the world also said governments needed to look at ways to make physical activity more convenient, affordable and safer.
It is recommended that adults do 150 minutes of moderate exercise, such as brisk walking, cycling or gardening, each week.
Physical inactivity is recognized as an important risk factor for multiple causes of death and chronic morbidity and disability.
Physical activity was chosen rather than physical fitness as the measure of exposure because it is through increases in the behaviour (physical activity) that health benefits accrue and improvements in cardiorespiratory fitness can be achieved. Moreover, there were insufficient data available worldwide to consider fitness as the exposure.
Exposure was assessed as a trichotomous variable to avoid limiting the assessment of total burden to only that associated with the highest risk, namely the most inactive (a dichotomous approach). However due to a lack of data on physical inactivity, use of a more detailed (continuous) exposure variable was not possible nor was the use of a fourth category of ‘high activity’. Therefore, our estimates of burden are likely to underestimate the total attributable burden to inactivity because of limitations with measures of exposure. Level 1 exposure (inactive) was defined as “doing no or very little physical activity at work, at home, for transport or in discretionary time”. Level 2 exposure (insufficiently active) was defined as “doing some physical activity but less than 150 minutes of moderateintensity physical activity or 60 minutes of vigorous-intensity physical activity a week accumulated across work, home, transport or discretionary domains”.
We found a wide range of survey instruments and methodologies have been used for collecting, analysing and reporting data on physical activity. Most data were available for discretionary-time activity, some data were found on occupational activity and little and no national data were available for transport- and domestic-related activity, respectively. A comprehensive literature search and contact with key agencies and known researchers uncovered over 50 data sets on physical inactivity in adult populations covering 43 countries across 13 subregions.
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Physical inactivity
Fiona C. Bull, Timothy P. Armstrong, Tracy Dixon,
Sandra Ham, Andrea Neiman and Michael Pratt
The Lancet study found people in higher income countries were the least active with those in the UK among the worst, as nearly two-thirds of adults were judged not to be doing enough.
The researchers admitted comparisons between countries were difficult because the way activity was estimated may have differed from place to place.
Nonetheless, they said they remained confident that their overall conclusion was valid.
Pedro Hallal, one of the lead researchers, said: “With the upcoming 2012 Olympic Games, sport and physical activity will attract tremendous worldwide attention.
The independent causal relationship between physical inactivity and ischaemic heart disease, ischaemic stroke, type II diabetes, colon cancer and breast cancer is well established; we provided new estimates of the magnitude of risk associated with inactivity. A comprehensive search of literature from 1980 onwards identi?ed well over 100 studies assessing the relationship between physical inactivity and the set of health outcomes that met our criteria. Also, several quantitative and qualitative reviews of the association between physical inactivity and ischaemic heart disease and stoke were found but there were no quantitative meta-analyses for breast cancer, colon cancer and type II diabetes. Most of the epidemiological studies meeting our inclusion criteria measured discretionary-time activity, some studies assessed occupational activity but only a few studies incorporated transport-related activity. No study included domestic-related physical activity. Given these data and differences between previous work and our de?nition of exposure, we completed a series of new meta-analyses for each health outcome. To address concerns regarding measurement error associated with physical activity, an adjustment factor was incorporated into the meta-analyses. All risk estimates were attenuated for ages 70 and over. There is emerging consensus on the protective effects of activity in regards to preventing falls, osteoarthritis and osteoporosis and impaired mental health but these disease end-points did not meet our inclusion criteria.
Physical inactivity
Fiona C. Bull, Timothy P. Armstrong, Tracy Dixon,
Sandra Ham, Andrea Neiman and Michael Pratt
“Although the world will be watching elite athletes from many countries compete in sporting events… most spectators will be quite inactive.
“The global challenge is clear - make physical activity a public health priority throughout the world to improve health and reduce the burden of disease.”
Prof Lindsey Davies, president of the UK Faculty of Public Health, agreed.
“We need to do all we can to make it easy for people to look after their health and get active as part of their daily lives,” she said.
“Our environment has a significant part to play. For example, people who feel unsafe in their local park will be less likely to use it.”
But others questioned equating smoking with inactivity.
While smoking and inactivity kill a similar number of people, smoking rates are much lower than the number of inactive people, making smoking more risky to the individual.
Dr Claire Knight, of Cancer Research UK, said: “When it comes to preventing cancer, stopping smoking is by far the most important thing you can do.”
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By Nick Triggle
Health correspondent, BBC News