April 11, 2018

Lack of Exercise 'Killing As Many As Smoking'

First published 19.07.2012; Edited and republished 11.04.2018
'A lack of exercise is now causing as many deaths as smoking across the world, a study suggests.' This Lancet report was published in 2012, but remains valid today in 2018 as it was years ago. So, MedicalNotes.com has republished this report to remind us all how important exercising our bodies is.

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 it.

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.

Global challenge

It is recommended that adults do 150 minutes of moderate exercise, such as brisk walking, cycling or gardening, each week.

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.

Although 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. 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. 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."

The study

The study was carried out by a collaboration of international academic researchers on behalf of the Lancet Physical Activity Series Working Group. The report stated that the research received no direct funding.

The study was published in the peer-reviewed medical journal The Lancet, and is part of its wider series on physical activity.

This was an ecological study that aimed to estimate the effect of physical inactivity on health at a national and international level.

This type of study is useful to establish national and global patterns of physical activity and its influence on disease.

The researchers stated that strong evidence shows physical inactivity increases the risk of many major adverse health conditions including:
  • death (from any cause)
  • coronary heart disease
  • high blood pressure
  • stroke
  • metabolic syndrome (including obesity and abnormal blood cholesterol levels)
  • type 2 diabetes
  • breast and colon cancer
  • depression
Because a large proportion of the world’s population is inactive, this link is a major public health issue. The researchers aimed to quantify the effect of physical inactivity on these major conditions by estimating how much a disease could be prevented if inactive people were to become more active and to estimate the gain in life expectancy this could produce.

Researchers defined physical inactivity as activity that failed to meet current World Health Organization (WHO) recommendations. The recommendations are split into different age groups:
  • 5-17 years
  • 18 to 64 years
  • 65 years and above
For adults, these include the recommendation to do at least 150 minutes (2.5 hours) of moderate-intensity aerobic physical activity throughout the week, or at least 75 minutes of vigorous intensity activity, or a combination of the two. Physical activity included:
  • leisure time physical activity
  • walking or cycling
  • work
  • household chores
  • playing games and sports


This ecological study estimated the global impact of physical inactivity and models the theoretical lives saved if physical inactivity levels were to be reduced across the globe.

This study serves to highlight the large and wide-ranging impact of physical inactivity on global disease levels and death. However, the following study limitations should be considered:
  • Physical activity was based on self-reported physical activity levels, which can be misleading. The authors of the research say that this tends to underestimate differences between active and inactive people and so would underestimate the impact of physical inactivity globally. The researchers therefore concluded that their estimates ‘are likely to be very conservative’. Using a more objective measure of physical activity would address this issue above but may not be a practical way of obtaining such information.
  • The same population attributable fraction (PAF) was used for all countries to estimate the impact of physical inactivity on disease and death. This PAF was largely based on North American and European data. This means it will have assumed that the impact of physical inactivity on death and disease was similar in all countries. It is unclear whether this assumption would be accurate across the globe in countries such as those with low incomes (developing countries).
  • The researchers examined only major non-communicable diseases and deaths from any cause affected by physical activity. They did not assess other diseases affected by physical activity in this study and so the actual impact may be larger.
  • Not all physically inactive people are inactive voluntarily, some may be physically incapable. The impact on life expectancy and deaths avoided due to the elimination of physical inactivity all together is not realistic. However, this is useful to stimulate debate.
  • As it is an ecological study, it does not tell us much about variation among individuals within these countries, only national and global trends.
While smoking (an active harm) and inactivity (a passive harm) may kill similar number of people, smoking rates are lower than the number of inactive people, making smoking a more risky activity to the individual.

1). BBC News: Inactivity 'killing as many as smoking' - BBC Health. Accessed 19.07.12. Available here: http://www.bbc.co.uk/news/uk-wales-politics-18876880
2). NHS Choices: Lack of exercise as 'deadly' as smoking. Accessed 10.04.18. Available here: https://www.nhs.uk/news/lifestyle-and-exercise/lack-of-exercise-as-deadly-as-smoking/

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