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Physical inactivity remains the greatest public health problem of the 21st century: evidence, improved methods and solutions using the ‘7 investments that work’ as a framework
  1. Stewart G Trost1,
  2. Steven N Blair2,
  3. Karim M Khan3
  1. 1 School of Human Movement Studies, University of Queensland, St Lucia, Queensland, Australia
  2. 2 Arnold School of Public Health, University of South Carolina, South Carolina, South Carolina, USA
  3. 3 Department of Family Practice, The University of British Columbia, Vancouver, British Columbia, Canada
  1. Correspondence to Dr Karim M Khan, Aspetar: Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar; karim.khan{at}

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In 2009, BJSM's first editorial argued that ‘Physical inactivity is the greatest public health problem of the 21st century’.1 The data supporting that claim have not yet been challenged. Now, 5 years after BJSM published its first dedicated ‘Physical Activity is Medicine’ theme issue ( we are pleased to highlight 23 new contributions from six countries. This issue contains an analysis of the cost of physical inactivity from the US Centre for Diseases Control.2 We also report the cost-effectiveness of one particular physical activity intervention for adults.3

Proven ‘investments that work’ to limit the disease of physical inactivity

The essential framing document for this BJSM issue is ‘the 7 investments for Physical Activity’ from the International Society for Physical Activity and Health (ISPAH).4 The articles in this issue elaborate on these 7 evidence-based investments. We recommend anyone advocating for the public health benefits of physical activity to consider framing their argument in the multisector, multisystem approach concisely captured in the ‘7 investments that work’ document. There is no ‘magic bullet’ to alleviate physical inactivity so do not try to suggest one. There are seven proven, relatively easy to implement steps. Many jurisdictions are already implementing elements of the ‘7 investments’; the document was approved by the WHO5 and cited by the International Olympic Committee in its Lausanne Consensus.6

The built environment and transit

The built environment (and access to transit) is a major determinant of physical activity/inactivity. Prolonged sitting in cars is one outcome of a poorly designed community and Professors Owen,7 as well as Ekblom-Bak,8 Ferreira9 quantify the serious risks—including death—associated with sedentary behaviour in various settings as well as in various populations. Professor Biddle,10 shares a very comprehensive review of interventions to alleviate the problem. Taken together, these articles on ‘sitting disease’ add weight to the argument for ‘health breaks’ from prolonged sitting and the argument for ‘healthy cities’ where walking and transit are the easy choices.


Schools can provide an ideal physical activity environment to promote activity in children and also help them learn how to maintain activity. Mai Chinapaw11 reports on children's physical activity level within a randomised controlled trial (RCT). In almost 5000 children with valid accelerometry data, Professor Josephine Booth12 showed a longitudinal association between moderate to vigorous physical activity and academic achievement at ages 11, 13 and 16. This article from the Avon Longitudinal Study of Parents and Children (ALSPAC) generated a great deal of press interest when released on ‘online first’.

Community-based approaches in promoting physical activity

The increasing attention to routine physical activity in adulthood comes from BE ACTIVE in the UK.3 Older people also benefit remarkably as shown from the national UK data by Hamer13 and in Western Australia by Almeida.14

Sports for promoting physical activity

Sport is one part, but is probably not a large part of lifetime physical activity levels. However, some individuals do maintain participation in sports throughout adulthood. Zhao15 showed that meeting the US Physical Activity Guidelines (engaging in ≥150 min/week of the equivalent moderate-intensity physical activity) was associated with a 36% reduction in mortality. This finding was based on around 10 000 people with 5 years follow-up from the large representative US National Health and Nutrition Examination Survey database. This article underscores that moderate levels of physical activity (150 min/week) are associated with dramatic, significant, health benefits. No medication comes anywhere near such an effect. Readers will also be aware of sports tremendous power in health education. This is currently being best championed by FIFA as outlined in this review6 and elsewhere in BJSM and other sports medicine journals.

Healthcare—promoting physical activity

An overarching contribution in ‘Exercise is Medicine’16 comes from Sweden via the Swedish Exercise on Prescription contribution and the ‘FYSS’ book ( This was highlighted in 2011 ( and in the 2013 Swedish theme issue of BJSM ( For non-believers, Anokye17 asks the question ‘Is Brief Intervention in Primary Care’ a cost-effective way of promoting physical activity? Shuval18 also provides a questionnaire instrument to rapidly assess sedentary behaviour in the primary care setting. Also widely useful for primary care practice, Dr Jayakody's (UK) systematic review19 of exercise for anxiety disorders sits well alongside Professor Pfaff's20 RCT of exercise to relieve depression in middle-aged and older adults.

Advocating—nationally and in the medical curriculum

The broad advocacy role for Exercise is Medicine, performed so eloquently by Dr Robert Sallis in the 2009 series,21 this time comes from Scotland22 and South Carolina.23 Scotland's Dr Andrew Murray has partnered with the storied surgeon Minister for Health—Sir Henry ‘Harry’ Burns—to launch and extend physical activity levels across the nation. If you are in a position to influence medical education, look to the new medical school in South Carolina which provides an ‘Exercise is Medicine’ a role model for universities all across the USA and beyond. A university with vision and courage.

What about measuring physical activity?

We are delighted to publish Harvard Professor I-Min Lee's keynote address24 from the 3rd International Conference on Ambulatory Monitoring of Physical Activity and Movement (ICAMPAM). Professor Lee focuses particularly on the issues and challenges when scaling up the use of accelerometers into large-scale population studies. Trost25 critically review when, and in what context, objective measurement devices perform at the level needed.

Looking forward, the best clinically relevant articles from the 3rd ICAMPAM will be published in July 2014's issue of BJSM. That issue will launch the 2015 ICAMPAM (possibly in Ireland, but it's still a secret!). Of course you will also hear about this, and other conferences on BJSM's Twitter (@BJSM_BMJ) and Facebook accounts.

In summary, the editors are pleased that so many of the world's leaders on physical activity as a public health issue contributed to this Exercise is Medicine theme issue. We hope that readers will find the articles of interest, and will help them promote and advance the cause of physical activity in societies around the world. We look forward to seeing some of you in Rio de Janeiro at the 5th International Congress of Physical Activity and Public Health (April 8–11) ( And keep BJSM in mind for your articles in this field—we are starting early on the 2015 issue of Exercise is Medicine!


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  • Competing interests None.

  • Provenance and peer review Commissioned; internally peer reviewed.

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