Exercise as it relates to Disease/Sedentary Time's Effect on Risk for Disease Incidents, All-Cause Mortality and Hospitalization in Adults Independent of Physical Activity

This Wikibooks page is a fact sheet and analysis of the journal article “Sedentary Time and Its Association With Risk for Disease Incidence, Mortality, and Hospitalization in Adults” by Biswas et al (2015).

What is the background to this research?
In 2012 an estimated 56 million people died worldwide. Of those deaths 68% were attributed to non-communicable diseases, the four main diseases being cardiovascular disease (CVD), cancers, diabetes and chronic lung diseases. It has been shown consistently in several studies that cases of CVD and diabetes are linked to an increase in sedentary time and a decrease in physical activity. Due to this many governments use the World Health Organisation’s physical activity guidelines that prescribe at least 150 minutes of moderate intensity physical activity or 75 minute of vigorous intensity physical activity per week. However even when these physical activity guidelines are met people can still be at risk if large amounts of time are spent sedentary. It has been observed in population-based studies that more than one half of an average person's day is spent in a sedentary state. This systematic review and meta-analysis aims to quantitatively evaluate the relationship between sedentary time and health outcomes independent of physical activity participation in an adult population.

Where is the research from?
Staff members from the various places listed below all contributed to data gathering and analysis:
 * Institute of Health Policy, Management and Evaluation, and the Faculty of Kinesiology and Physical Education at the University of Toronto
 * University Health Network–Toronto Rehabilitation Institute, Cardiovascular Prevention and Rehabilitation Program
 * Sunnybrook Health Sciences Centre
 * York University
 * Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada

When finding journals for this systematic review and meta-analysis there were no criteria stating that journals had to be from a specific area. Journals that did meet the selection criteria were used meaning that data from all over the world contributed to this article.

The paper was published in the Annals of Internal Medicine in its 162 Volume.

What kind of research was this?
This paper is an example of a systematic review and meta-analysis. A systematic review is a type of review were many articles are collected and analysed on a particular topic to produce a paper that has all relevant and up to date information on said topic. A meta-analysis is when data is taken from many different studies on a given topic and then statistically analysed to show trends in the current and/or past data for said topic. A meta-analysis is often used as part of a systematic review.

'''Table 1. Advantages and Disadvantages of a Systematic Review and Meta-Analysis'''

What did the research involve?
When research commenced as a method of quality control the Preferred Reporting Items and Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used. Papers focusing of the association between sedentary behaviour and various health outcomes were searched for through these databases:
 * MEDLINE
 * Pubmed
 * EMBASE
 * Cochrane Library
 * Web of Knowledge
 * Google Scholar

They were cross check by two reviewers during the data sourcing process. There was also a hand-search for references from relevant publications and review article to bolster the electronic search. The search was limited to English-language primary research from August 2014 and before with no publication date limit. Journals had to be primary research studies that assessed sedentary behaviour in adults as a direct predictor variable independent of physical activity and correlated to at least one health outcome. As a second method of quality control a list of 15 different criteria was used to assess each study considered, this table was taken from a study done by Proper and colleagues. In oder to be included each study had to meet a least 8 of the 15 criteria. In total 21,005 studies were found for potential use however only 41 were chosen. Journals were eliminated from the original 21,005 for several reasons, mainly due to being duplicates of other journals found or because they did not meet the specific selection criteria.

What were the basic results?
The paper used hazard ratios (HR) to quantify the risk of the various health outcomes mentioned when related to sedentary time. The scale was between 0.5 - 2 with over 1 being considered high risk and below 1 being considered low risk.

'''Table 2. Health Outcomes and Hazard Ratios'''

The study findings suggest that extended sedentary time was positively associated with adverse health outcomes such as CVD, diabetes, cancer and most significantly all cause mortality independent of physical activity. In layman's terms this means that even if someone is physically active but they spend most of their time outside of physical activity being sedentary there is still an increased risk of CVD, diabetes, cancer and death. The most alarming result is that incidence of diabetes has a hazard ratio of 1.910 almost reaching 2 meaning that there is a very large increase in risk of developing diabetes the more time spend sedentary. Also due to the 95% Confidence Interval (CI) we can be 95% certain that all of these health outcomes are worsened by being sedentary for extended periods of time.

What conclusions can we take from this research?
This study highlights the importance of not just being physically active but not being sedentary. While meeting physical activity minimum should be of a high priority to all adults it should not be assumed that if met all health benefits will be kept. In order to reduce undesirable health outcomes people should be making an active effort to not be sedentary for long periods during waking hours. In some cases it may be that the health benefits being gained through exercise will be negated by spending the majority of time outside of physical activity in a sedentary state.

Practical Advice
Reduction of sedentary time should be put on equal footing in terms of important as completing physical activity minimums for the best overall reduction in undesirable health outcomes. In cases were meeting the minimum physical activity guidelines is not achievable people should seek to try and reduce sedentary time in order to minimise risk of CVD, diabetes, cancer and death.