Sedentary behaviour is when someone is awake, in a sitting, lying or reclining posture, in a state of low energy expenditure, typically expending less than 1.5 metabolic equivalent of tasks (METs) (1, 2). METs allow comparisons to be made between the energy expended during different states (3). METs are calculated as a ratio of the rate of energy expended during an activity compared to the rate of energy expended at rest (3). For example, 1.0 METs is the rate of energy expenditure while sitting at rest (3). A 2.0 METs activity, such as ironing, expends twice the energy used by the body when sitting at rest (3). Physical activity is any movement of the body produced by skeletal muscles that requires energy expenditure (4). Physical activity can therefore be viewed as a spectrum, ranging from sedentary behaviour to light, moderate and vigorous physical activity (Fig 1.). Physical inactivity is a separate entity, instead defined as when an individual has insufficient levels of physical activity, i.e. less than current physical activity recommendations (2, 5).
The effect of sedentary behaviour on health has been an area of interest among researchers since the pioneering work of the epidemiologist, Jeremy Morris, in the 1940s and 1950s. Morris and colleagues demonstrated that sedentary bus drivers had higher rates of mortality due to coronary heart disease than bus conductors, their more active colleagues (6, 7). Since then, there has been an ever-increasing weight of evidence to demonstrate the negative health effects of sedentary behaviour (8). It is now acknowledged that sedentary behaviour is associated with multiple adverse health outcomes, including mental health issues, obesity, type 2 diabetes, multiple forms of cardiovascular disease and dementia, as well as breast, colorectal, endometrial and ovarian cancer (8-12). As a result of these adverse health outcomes, sedentary behaviour is associated with increased all-cause mortality, even when allowing for confounding variables (12-15). These findings demonstrate a dose-response relationship, whereby increasing sedentary time corresponds with increasing mortality rate (12-15). Sedentary behaviour has significant economic costs. Sedentary behaviour was estimated to cost the UK National Health Service (NHS) £0.7 billion in 2016-2017 (16). A total of 69,276 deaths could potentially have been avoided in the UK if sedentary behaviour was eliminated (16). In light of these findings, 2019 UK physical activity guidelines state that through all stages of life, individuals should minimise their sedentary behaviour, and break up periods of sedentary behaviour where possible (5).
Previous studies have examined levels of sedentary behaviour among other professions (17, 18), however General Practice is a different working environment, with different challenges and opportunities from other professions, even within the field of healthcare. Primary care has been described as “the cornerstone” of the NHS, providing over 300 million patient consultations per year (19, 20). This enables General Practitioners (GPs) to play an important role in both primary and secondary prevention, by providing evidence-based lifestyle guidance to patients. GPs can reinforce important public health messages among their patients, making them more specific, individualised and personally relevant. Numerous studies have demonstrated that GPs who are more physically active are more likely to recommend physical activity to their patients (21-30). Patients are also more likely to make healthy lifestyle changes recommended by their doctor if they believe their doctor follows the health advice themselves (31-34). It could therefore be argued that reducing sedentary behaviour and increasing physical activity among GPs could lead to health benefits for both GPs themselves, at an individual level, and their patients, at a population level. Within the context of day-to-day General Practice, this would primarily involve interrupting or replacing prolonged periods of sitting with physical activity. One example is the use of active workstations, such as standing desks, combined with short breaks for physical activity, such as “exercise snacks”. Sitting while using a computer or telephone is a form of sedentary behaviour (≤1.5 METs), whereas standing while using a computer or telephone is a form of light physical activity (1.8 METs) (35). Reducing sedentary behaviour among GPs, by replacing sedentary behaviour with physical activity, could therefore play a vital role, as part of a multifaceted approach alongside public health initiatives and changes to the built environment, in ensuring a culture shift away from an increasingly sedentary society, towards an increasingly physically active society.
The aim of this systematic review is to identify the current levels of sedentary behaviour among GPs. The review examines and synthesises how sedentary behaviour has been measured in the primary care literature.