The risk of cardiovascular disease and its associations between obesity and physical activity in adolescents: international perspectives

The prevalence of cardiovascular disease (CVD) is increasing and has become the leading cause of death around the world. Though once thought of as an adult problem, it is now recognised that the early manifestations of disease may occur during childhood. Numerous risk factors have been linked to CVD with much of the research focusing on understanding the prevalence and relationship of traditional risk factors such as dyslipidemia, smoking, diabetes mellitus, hypertension, obesity, psychosocial stress, poor diet, physical inactivity and alcohol consumption to the early etiology of disease. Needless to say, the majority of our understanding is from adult studies though evidence from youth populations is beginning to accumulate. It is well established that obesity is linked to nearly all CVD risk factors though untangling the precise reasons whereby individuals become overweight are challenging and complex. The need to untangle this complex web is nonetheless vital. Estimates suggest that at least 20 million children under 5 years of age were overweight while by 2015 it is predicted that approximately 2.3 billion adults will be overweight and more than 700 million will be obese [1]. Public health strategies that aim to reduce the prevalence of obesity and overweight encourage youth to increase their physical activity levels as a means of protecting against poor cardiometabolic profiles. This is in part due to several epidemiological studies involving adults which have demonstrated that high physical activity levels are associated with favorable risk profiles. Whether the same relationships are seen in youth populations though are unclear. Studies have shown that interventions that increase physical activity
can lead to a reduction in certain CVD risk factors but the lack of agreement between findings makes it impossible to give precise recommendations. Yet it is important that research continues and examines the associations between lifestyle behaviors, physical activity behavior and CVD risk factors in order to identify individuals who may be at most need of intervention. Thus, this chapter will provide an in-depth overview of what is currently known about the prevalence of CVD risk in youth while examining the evidence concerning its associations between obesity and physical activity.