Physical Activity and Metabolic Syndrome
Metabolic syndrome, defined as a constellation of risk factors that include dyslipidemia, abnormal glucose tolerance, increased adiposity, and hypertension, has been linked with type 2 diabetes (Liu et al., 2006). The prevalence and incidence of type 2 diabetes mellitus is disproportionately higher and increasingly rapid amongst Aboriginal Canadians than among the non-Aboriginal Canadian population and has reached what some consider as “epidemic proportions” (Ghosh & Gomes, 2011; Sharp, 2009). Diabetes results from an interaction of a host of risk factors. This paper will review a study by Liu et al. (2006) that investigates the etiology of metabolic syndrome which is one of the risk factors for type II diabetes. The study is entitled “Lifestyle variables, non-traditional cardiovascular risk factors, and the metabolic syndrome in an Aboriginal Canadian population.”
Liu et al. (2006) examined the lifestyle risk factors linked to metabolic syndrome in an isolated Canadian Aboriginal community. They used data from 360 non-diabetic adults who had taken part in a population-based study conducted amongst Aboriginal Canadians. For the study, fasting samples were obtained for glucose, lipids, insulin, adiponectin, -C-reactive protein, leptin, interleukin-6 (IL-6), and SAA. Bioelectrical impedance analysis was used to measure percentage body fat. Physical activity as well as fitness level during the preceding one year was also assessed. Metabolic syndrome was diagnosed using three criterions which are the National Cholesterol Education Program, World Health Organization, and International Diabetes Federation. Amongst other findings, the study found that physical activity during the preceding year was independently associated with WHO-defined metabolic syndrome in male subjects. The causal relationship between physical activity and metabolic syndrome is an indirect relationship. Studies have established that physical activity impacts individual components of metabolic syndrome. Physical exercise has been found to reduce weight, accumulation of visceral fats, and blood levels of triglycerides. It also increases HDL-C concentrations and retards development of hypertension and type II diabetes. Therefore, physical activity impacts on factors such as triglyceride and HDL-C levels that in turn influence development of metabolic syndrome.
Regarding the issues of evidence and bias, the authors provide statistics to show that physical activity level were associated with WHO-defined metabolic syndrome amongst male subjects. Male subjects with WHO-defined metabolic syndrome had lower total activity (22.3± 17.5 hours/week and 115.8±97.2 MET-h/wk) as compared to male subjects without the condition who had a mean total activity of 32.1±18.1 h/wk and 166.3±102.9MET-h/wk. physical activity in this study was measured using the modifiable activity questionnaire. Therefore, physical activity was assessed through self-report measures. Self-report measures can be influenced by two types of bias that are social desirability bias and information recall bias. Social desirability bias arises from the tendency of participants to report what is socially acceptable. For instance in this study, participants could have reported engaging in more physical activity than they actually did as this is the socially acceptable behavior. Information recall bias, on the other hand, arises from the tendency of individuals to forget information. In this study, participants were required to recall information about their physical activity over the preceding one year. It is highly likely that the information provided by the participants in the study may not be accurate. Therefore, the findings of the study with respect to physical activity may have been influenced strongly by social desirability and information recall bias.
In summary, this paper has reviewed a study by Liu et al. (2006) that investigated amongst other variables the relationship between physical activity and metabolic syndrome in an Aboriginal Canadian community. Metabolic syndrome is a risk factor for type II diabetes, a condition that has increased to epidemic proportions amongst Aboriginal Canadians. Low physical activity according to the study has an indirect association with the development of metabolic syndrome. Figures are provided to support the association between physical activity and metabolic syndrome. The findings of the study may have been influenced by social desirability and information recall biases as physical activity was assessed via a self-report questionnaire.
References
Ghosh, H. & Gomes, J. (2011). Tyep 2 diabetes among Aboriginal Poeples in Canada: A focus on direct and associated risk factors. A Journal of Aboriginal and Indigenous Community health, 9(2), 245-277.
Liu, J., Young, K., Zinman, B., Harris, S.B., Connelly, P.W., & Hanley, A. J. G. (2006). Lifestyle variables, non-traditional cardiovascular risk factors, and the metabolic syndrome in an Aboriginal Canadian population. Obesity, 14(3), 500-508.
Sharp, D. (2009). Environmental toxins, a potential risk factor for diabetes among Canadian Aboriginals. International Journal of Circumpolar Health, 68(4), 316-327.
