The Effects of Breaking up Prolonged Sitting Time

A Review of Experimental Studies

Fabiana Braga Benatti; Mathias Ried-Larsen

Disclosures

Med Sci Sports Exerc. 2015;47(10):2053-2061. 

In This Article

Abstract and Introduction

Abstract

Introduction: Prolonged time spent in sedentary behaviors (i.e., activities performed while sitting or reclining) has been consistently shown as an independent risk factor for increased cardiometabolic risk and all-cause mortality, whereas breaking up sedentary time is associated with improved cardiometabolic profile. However, there is still great controversy with the respect to what would be the optimal or minimum type, intensity, and frequency of physical activity necessary to revenue such positive outcomes in different populations.

Objective: In this review, we aimed to discuss the available evidence from prospective experimental studies regarding the beneficial effects of breaking up prolonged sitting time on cardiometabolic risk factors, and the influence of intensity, frequency, and volume of the physical activity replacing sitting.

Methods: A structured computer-based search on the electronic databases PUBMED and SCOPUS was independently conducted by two researchers. Only prospective intervention studies (controlled and uncontrolled) evaluating the effects of explicitly replacing sitting time with physical activity (including standing) on metabolic parameters as outcomes were included.

Results: Seventeen studies were included in the review.

Discussion: The currently available prospective experimental studies do advocate that breaking up sitting time and replacing it with light-intensity ambulatory physical activity and standing may be a stimulus sufficient enough to induce acute favorable changes in the postprandial metabolic parameters in physically inactive and type 2 diabetic subjects, whereas a higher intensity or volume seems to be more effective in rendering such positive outcomes in young habitually physically active subjects.

Conclusion: Prospective experimental studies provide considerable evidence of the positive effects of breaking up prolonged time spent sitting on metabolic outcomes. However, it seems that the type, intensity, and frequency of physical activity necessary to effectively counteract the detrimental effects of prolonged sitting may differ according to the subjects' characteristics, especially with respect to the subjects' habitual physical activity level.

Introduction

Prolonged time spent in sedentary behaviors, defined as activities done while sitting or reclining (i.e., TV watching, computer-related activities, driving a car, etc.)[1] has been consistently considered an important risk factor for abnormal glucose and lipid metabolism, type 2 diabetes (T2D), and all-cause mortality independent of moderate-and-vigorous physical activity (MVPA).[17,19,29] For instance, Koster et al.[17] objectively measured sedentary time in 1906 participants from the US nationally representative National Health and Nutrition Examination Survey (NHANES) 2003–2004 and reported that even after adjusting for time spent in MVPA, participants in the highest quartile of time spent on sedentary behavior had a 3.3 times increased risk for all-cause mortality when compared with the participants in the lowest quartile.

This evidence has challenged the current guidelines for physical activity and highlighted the importance of not only stimulating MVPA but also reducing sedentary time. In line with this, cumulative evidence from observational studies suggests that breaking up the long periods spent in sedentary time is associated with improved cardiometabolic risk factors[11,12,22] and decreased all-cause mortality risk,[15] even after accounting for MVPA.[5] Notably, this has led to the inclusion of statements on reducing sedentary behavior, more specifically sitting time, in the UK and Australian physical activity guidelines.[6,8] In the Australian guidelines, it is further recommended that sitting time should be interrupted regularly.[6] However, owing to the observational nature of these aforementioned studies, a causal relationship between breaks in sedentary behavior, particularly sitting, and health outcomes cannot be provided.

To establish this potentially causal relationship and elaborate on the most effective way of replacing sitting time, an increasing number of experimental prospective studies have been published. These studies provide exciting data with respect to the positive short-term effects of interrupting prolonged time spent sitting with either light-intensity (i.e., standing and strolling) or moderate-intensity physical activity (i.e., walking and cycling) on the metabolic profile.[7,9,10,13,14,16,21,25,26,28] Although the evidence from these studies seems to corroborate most of the observational studies, there is still great controversy with the respect to what would be the optimal or minimum type, intensity, and frequency of physical activity necessary to revenue such positive outcomes.

Thus, the aim of the present review was to summarize and discuss the available evidence from prospective experimental studies regarding the beneficial effects of breaking up prolonged sitting on cardiometabolic risk factors, and the influence of intensity, frequency, and volume of the physical activity replacing sitting time.

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