The physiological benefits of sitting less and moving more: Opportunities for future research
Introduction
Being physically active is one of the important components of health. Current physical activity (PA) guidelines for Americans recommend that adults should perform an equivalent of moderate-intensity aerobic activities for at least 150 min and muscle-strengthening activities for at least 2 days, on a weekly basis.1 In addition, the guidelines recommend that adults should reduce sedentary behavior (SB). Previously, excessive SB was considered as one end of the continuum of PA, and “sedentary behavior” and “physical inactivity” were used interchangeably. While physical inactivity is defined as no moderate- to- vigorous intensity PA (MVPA) beyond basic movement from daily life activities,1 SB refers to any waking activity characterized by little energy expenditure above rest [≤1.5 metabolic equivalents (METs)].2 These activities are usually performed while in a sitting, reclining, or lying posture, such as TV viewing, computer work, and other screen time.2
Certainly SB is highly prevalent in the United States (US) and is a public health issue. Data from the National Health and Nutrition Examination Survey indicates that US adults spent 7.7 h per day on being sedentary.2 The time in SB has further increased during the coronavirus disease 2019 (COVID-19) pandemic.3 Accumulating epidemiological evidence indicates that SB or prolonged sitting is a risk factor for all-cause and cardiovascular disease (CVD) mortality.2 The risks related to SB are more pronounced in adults who are physically inactive. Such risks can be decreased by replacing sedentary time even with light-intensity PA,4 such as desk pedaling or walking around the house. In addition to the total amount of sedentary time, a prolonged bout in sedentary activities is also associated with a greater risk of mortality.5 While mounting evidence has focused on MVPA due to its substantial health benefits, little is known about the effect of SB on health. Such knowledge is important, given that the majority of the US population performs insufficient or no MVPA and is at high risk of being negatively impacted by SB.6 Interventions targeting sedentary time, such as breaking up SB by standing and moving, may be safe, feasible, and applicable to execute daily for a wide range of the population.
Therefore, this review discusses the pathophysiological effects of SB and the potential physiological benefits of reducing/breaking SB at levels below the current guidelines for PA. This review also discusses the importance of monitoring SB in the era of the COVID-19 pandemic and the clinical implications of sitting less and moving more.
Section snippets
Cardiorespiratory Fitness (CRF)
Clearly CRF is an important predictor of health outcomes and has been associated with premature mortality and chronic diseases.7 Every 1 MET increase in CRF is associated with a 19% decrease in risk of CVD mortality.8 Recent studies suggest that SB is associated with reduced CRF.9,10 More specifically, using accelerometer data, Kulinski et al. showed that each additional hour of daily sedentary time was associated with a decrease in CRF by 0.12 METs in men and by 0.24 METs in women.10 Other
Summary
Certainly, SB, such as sitting or TV viewing, may be associated with several pathophysiological changes, including decreased CRF, reduced vascular or skeletal muscle function, and increased fatigue (Fig. 1). These adverse effects of SB may impact those who do not meet the current PA recommendations, accounting for most of the US population. During the COVID-19 pandemic, the increases in SB and the related pathophysiological effects have emerged as important public health problems. This
Funding
This review was supported by the National Institute on Alcohol Abuse and Alcoholism under award number K99AA028537 (CLH). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Declaration of Competing Interest
None.
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