Cardiovascular disease remains one of the leading causes of death worldwide. However, a large proportion of research in the field focuses primarily on middle- to old- age, by which time much damage to the heart and vascular system has been incurred. The rationale for this research was to gain a clearer picture of cardiovascular health in late adolescence, prior to the onset of adulthood. In this thesis I characterise the cardiac structure and function of individuals from the ALSPAC cohort (average age 17.7 years) through analysing M-Mode, two dimensional and Doppler echocardiographic measures and haemodynamic, biochemical and anthropometric measures. Adiposity, sex and genetic predisposition are considered as key exposures which impact a range of cardiovascular outcomes. I consider the relationships of fat mass and lean mass with cardiovascular outcomes and the ways in which left ventricular mass indexation is affected by adiposity, lean mass, height and body surface area. I then discuss the roles which particular haemodynamic and biochemical biomarkers have in mediating associations between fat mass and left ventricular structural and functional outcomes. Finally I consider the influence which genes associated with body mass index have on key cardiovascular measures, including cardiac structural and functional measures. Adiposity has a direct and detrimental effect on cardiovascular health. My findings provide insights into the way in which adiposity affects the development of an adverse cardiometabolic phenotype from a comparatively young age and also have interesting implications for future research. Furthermore, they serve as another important reminder of the need for adiposity to be monitored throughout the life course
