Exercise as it relates to Disease/The relationship metabolic syndrome has with physical activity and cardiorespiratory fitness

What is the background to this research?
Metabolic syndrome (Mets) does not have an internationally recognised definition, and as such, has caused numerous issues in diagnosing and researching the condition (Huang, 2009; Grundy, 2008; Despres & Lemieux, 2006; Chew et al., 2006; Eckel et al., 2005). In 1998, an attempt was made to solidify various definitions that were being used by clinicians and researchers (Eckel et al., 2005). Although they could not agree on a singular definition, a consensus was reached on the essential components of Mets. These components were glucose intolerance, hypertension, obesity, and dyslipidaemia. The specific range and criteria regarding these components vary among definitions. To be diagnosed with Mets individuals must have a minimum of three abnormal components (Huang, 2009; Grundy, 2008; Despres & Lemieux, 2006; Chew et al., 2006; Eckel et al., 2005).

There is a strong correlation between MetS and the risk of contracting cardiovascular disease (CVD) and diabetes (Huang, 2009; Grundy, 2008; Despres & Lemieux, 2006; Chew et al., 2006; Eckel et al., 2005). Whilst MetS is a cluster of individual risk factors, the combination of these components has exponentially increased the risk. This was demonstrated through the DECODE study (as cited in Eckel et al., 2005) that compared the mortality rate for CVD between those with and without MetS. The hazard ratios were 1.44 and 2.26 in males, while it was 1.38 and 2.78 in females. Grundy (2008) also supported these findings and went on to state that those with MetS were twice as likely to contract atherosclerotic cardiovascular disease than those without the condition. Mets is also linked to non-alcoholic hepatitis, polycystic ovary disease, cancers, and cognitive decline, Singh-Manoux et al (as cited in Rattray, 2020).

The prevalence of MetS has increased in parallel with the rise in obesity across the globe (Eckel et al., 2005). This demonstrates the relationship lifestyle factors, particularly poor nutrition and inadequate physical activity have on the development of MetS. The relationship MetS has with obesity is concerning, as obesity levels are only expected to rise in the future. Therefore, to prevent an expediential growth in MetS actions must be taken now to drastically reduce obesity levels (Huang, 2009; Grundy, 2008; Despres & Lemieux, 2006; Chew et al., 2006; Eckel et al., 2005). Preventing and appropriately managing MetS is essential in reducing the economic burden of these lifestyle diseases. As mentioned above, MetS is a large risk factor in the development of other chronic diseases. The cost of these disease places a large financial and resource burden on the health system. In Australia, CVD alone cost 5.6 billion dollars in 2015-16 (2019). With chronic illness such as diabetes also closely linked to MetS it is essential that interventions are developed to prevent the progression of diseases. Therefore, governments must invest in research to appropriately manage MetS (Huang, 2009; Grundy, 2008; Despres & Lemieux, 2006; Chew et al., 2006; Eckel et al., 2005). This research article has utilised two definitions that highlight slightly different components of MetS (Laaksonen et al., 2002). First, they have used the World Health Organisation’s (WHO) definition, which focuses primarily on diabetes or issues related to glucose and insulin. The second definition is from the National Cholesterol Education Program (NCEP), which focuses equally on the various components associated to MetS. Table 1 identifies the diagnostic criteria for MetS based on the different definitions (Huang, 2009).

Where is the research from?
This journal article was published in Diabetes Care by the American Diabetes Association. The goal of this publication is to increase the knowledge and management of individuals with diabetes (About Diabetes Care | Diabetes Care, 2020). It was established in 1978, has a monthly issue and an 11.06% acceptance rate. The articles published must undergo a heavily scrutinised process, including peer review. Thus, this article is an appropriate and well-developed research paper (About Diabetes Care | Diabetes Care, 2020). This article was designed, performed, and analysed in Eastern Finland. The authors of this article have extensive knowledge in research and public health. As demonstrated through their places of employment: Department of Physiology, University of Kuopio, Kuopio, Finland; Research Institute of Public Health, University of Kuopio, Kuopio, Finland; Department of Public Health and General Practice, University of Kuopio, Kuopio, Finland; Department of Medicine, University of Kuopio, Kuopio, Finland; Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland; Inner Savo Health Center, Kuopio, Finland; and Kuopio Research Institute of Exercise Medicine, Kuopio, Finland (Laaksonen et al., 2002, p. 1612) The overall background, reputation and expertise of the authors and publication has ensured a quality research article.

What kind of research was this?
Researchers collected the Vo2max (ml.kg-1.min-1) and the metabolic components (waist circumference, body mass index (BMI), fasting blood glucose, triglyceride, high density cholesterol (HDL) and blood pressure) of 612 middle-aged Finnish men without MetS. They also conducted a survey using the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) to record the leisure time physical activity (LTPA) levels of participants over the past twelve months.

What did the research involve?
The method accurately measured the cardiovascular fitness (CVF) and metabolic health of participants. It used an appropriate questionnaire to record the LTPA levels of participants. It also accounted for lifestyle differences that could impact the reliability and validity of the results. Participants were tested before the study, at the twelve-month mark and again four years later. This ensured a thorough understanding was obtained about the impact LTPA and CVF has on the development of MetS.

Whilst the method was suitable for the research being conducted, there were issues relating to the article. Firstly, the amount of LTPA conducted was recorded by the participant themselves. This causes issues with the reliability of the data collected. Secondly, the research could not account for the impact other variables, such as occupation, have on the CVF. Despite this, it is clear the research conducted was appropriate, reliable, and valid.

What were the basic results?

 * Men that did not develop MetS had a higher vo2 max and engaged in more LTPA, particularly vigorous LTPA.
 * The moderate to vigorous the exercise improved vo2 max, particularly vigorous exercise
 * At least 60 minutes of vigorous LTPA reduced the likelihood of developing METS by two-thirds
 * CVF mediates all other risk factors
 * Low fit and sedentary men are sevenfold more likely to develop MetS than fit, active men.
 * Men complying with the CDC-ACSM recommendations decrease the risk of developing MetS by one-half compared with men engaging in no more than 6 minutes of mod exercise per week.
 * Low intensity LTPA tended to decrease the likelihood of developing MetS, however, this was statistically insignificant due to inadequate data.

What conclusions can we take from this research?

This article highlights the importance of LTPA and the essential role that cardiovascular fitness has in the prevention of MetS. The evidence generated from this article is well supported by numerous journal articles (Huang, 2009; Grundy, 2008; Despres & Lemieux, 2006; Chew et al., 2006; Eckel et al., 2005). Therefore, this article has demonstrated is it appropriate and relevant in the prevention of MetS.

Practical advice

 * Follow the ACSM and CDC’s physical activity guidelines.
 * Encouraging overweight/obese individuals to participate in low intensity LTPA is both realistic and beneficial for reducing MetS risk factors (something is better than nothing).

Further information/resources
ACSM: https://www.acsm.org/read-research/newsroom/news-releases/news-detail/2018/11/12/updated-physical-activity-guidelines-now-available

CDC: https://www.cdc.gov/physicalactivity/basics/index.htm

Department of Health (Australia): https://www1.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-phys-act-guidelines