A new definition of physical activity

In my book, I offer a new definition of physical activity. Definitions are important because they set the scene for everything that follows. I propose that:

physical activity involves people moving, acting and performing within culturally specific spaces and contexts, and influenced by a unique array of interests, emotions, ideas, instructions and relationships.

A new definition is needed to move the concept of physical activity beyond it’s previous entrenchment in biomedical and epidemiological discourse. Previous definitions are too narrow and therefore insufficient to account for the complex nature of physical activity. There is an opportunity to open up the discourse of physical activity to be more inclusive of the wide variety of academic disciplines that study it, the increasing number of governmental departments that address it, and most importantly the enormous range and depth of human experiences which are attached to it.

Some historical context

Perhaps the most well-known and most cited definition of physical activity comes from Caspersen, Powell and Christenson (1985), who describe it as “any bodily movement produced by skeletal muscles that results in energy expenditure” (p. 126). It is important to note that this definition is authoritative within academia. Caspersen’s et al. 1985 article has been cited 8138 times according to Google Scholar (at the time of writing), an indication of its popularity. Other slight variations on this definition are also popular. This definition informs many health policies around the world (Australian Government, 2011; WHO, 2018). In 2018, the World Health Organisation’s (WHO) Global Strategy on Physical Activity deployed a slight variation of this definition – instead of activity resulting in energy expenditure, the WHO claimed that “any bodily movement produced by skeletal muscles that requires energy expenditure” (p. 14). In any case, I argue the sentiment remains the same.

The definition by Caspersen and colleagues is confined to, and thereby constrained by, epidemiology discourse. Indeed, the first sentence of their 1985 article declares that “The epidemiological study of any concept or event requires that the item under investigation be defined and measured” (p. 126). And so, in describing the “elements” of physical activity, the focus is on “bodily movement, skeletal muscles, energy expenditure, kilo-calories” and a positive correlation with “physical fitness” (p. 127). And so the definition is heavily laden with a particular type of science. The aim here is not to allege Caspersen’s definition and description of physical activity is insufficient for epidemiology. However, there are various reasons why the definition falls short of articulating what physical activity (really) is.

Towards a new definition …

First, I argue that physical activity is not the sole domain of epidemiology. The British Medical Journal describes epidemiology as “the study of how often diseases occur in different groups of people and why” (BMJ, 2019). By framing physical activity solely in relation to disease-potential and disease management, much is marginalised and ignored.

Caspersen’s et al definition is dis-integrated and exclusionary. It is dis-integrated because it prioritises some aspects – the anatomical (bodily movement, skeletal muscles), physiological (energy expenditure) – to the exclusion of others.

The cerebral, psychological and emotional aspects of physical activity are not accounted for. The elements of physical activity by Caspersen et al omit any reference to personal motives, emotions or thought. Struggle, pain, joy, achievement to name a few are inherent components of physical activity (either as motivations, outcomes or both), and so need to be accommodated. To illuminate this point, consider how Brian Pronger’s (2002) could not reconcile the embodied emotion and amazement of his active childhood with the technological knowledge of his university studies in physical education:

“I wrote about ‘the powerful source,’ the wonder and infinity that I discovered in swimming. And I said that when I started to study physical education, that dimension was completely absent from everything we were taught. The technological education I was receiving rendered the wonder second. And as I survey the array of scientific, government and commercial texts on physical fitness, I hear only silence in this regard. The technology of physical [fitness] seems deaf to this dimension of life. So the question of secondness here is: what kind of life is produced in such deafness? But another question also arises: what latent possibilities does that silence hold?” (p. 15)

While policy texts on physical activity do increasingly mention ideas about mental wellbeing, they still tend to stop well short of ‘wonder’.  A more holistic definition of physical activity will move beyond “bodily movement” to appreciate lived experiences which inform physical activity.

Second, any definition of physical activity should not ignore the political and social aspects of activity that are shape the provision and structure of physical activity, from state resources for outdoor public space, to the culturally dominant expectations about what sorts of physical activity are encouraged. The political aspect of physical activity can be extended further to consider the efforts that are made to control, persuade and judge the physical activities that people partake in. There is space for depth, richness and inclusivity by redefining physical activity to account for its complexities, nuances and politics. As Silk, Andrew and Thorpe (2017) mention in their discussion of physical cultural studies, human movement can and should be considered from a variety of levels, including “the socio-cultural, discursive, processual, institutional, collective, communal, corporeal, affective and subjective” (p. 1). And so by including this depth in a new definition, there is room to expand both conversations about physical activity and policies which promote it.

So to repeat, this proposed new definition of physical activity involves people moving, acting and performing within culturally specific spaces and contexts, and influenced by a unique array of interests, emotions, ideas, instructions and relationships.

This definition involves three aspects not captured in earlier definitions:

  • An emphasis on people who move, as distinct from dis-integrated references to muscles and energy systems.
  • The inclusion of social and cultural contexts allows for the consideration of the people’s opportunities and constraints.
  • Emphasizing unique interests, emotions, ideas, instructions and relationships will allow people to account for the plethora of intrinsic and extrinsic factors which inform physical activity.

I welcome improvements on this definition! I also hope this is not the end of discussion about what physical activity is.



Australian Government Department of Health (2011). Definitions. Retrieved from https://www.health.gov.au/internet/publications/publishing.nsf/Content/phd-physical-rec-older-disc~Definitions

British Medical Journal (2019). Chapter 1. What is epidemiology? https://www.bmj.com/about-bmj/resources-readers/publications/epidemiology-uninitiated/1-what-epidemiology

Caspersen CJ, Powell KE, Christenson GM. Physical activity, exercise, and physical fitness: definitions and distinctions for health-related research. Public Health Rep. 1985; 100:126–131

Pronger B. (2002). Body Fascism. Salvation in the Technology of Physical Fitness. Toronto: University of Toronto Press.

Silk, M., Andrews, D. and Thorpe, H. (eds), (2017). Routledge handbook of physical cultural studies. London: Routledge.

World Health Organisation (2018). More Active People for a Healthier World, Global Action Plan on Physical Activity 2018-2030. WHO.


2 thoughts on “A new definition of physical activity

  1. Borja del Pozo Cruz

    Hey Joe, this is really awesome reflections.
    I am totally a fan of these.
    Thanks for doing this great job.
    Dr. Borja del Pozo Cruz, Senior Research Fellow.
    Motivation and Behavior Program.
    Australian Catholic University


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