Longitudinal Investigation of Physical Activity Trajectories and Cardiometabolic Risk Across Adolescence in Lagos State

Adolescence represents a critical developmental period during which physical activity trajectories are established and cardiometabolic risk factors begin to cluster, yet longitudinal evidence on these relationships within the Nigerian adolescent population is absent from the global literature. This dissertation presents a four-year longitudinal cohort study investigating physical activity trajectories and their association with cardiometabolic risk factor evolution across adolescence in Lagos State, South West Nigeria. A cohort of 480 students aged 11 to 13 years at baseline was recruited from 16 secondary schools and followed annually for four years. Physical activity was assessed annually using accelerometry and self-report, with trajectory modelling using group-based trajectory analysis identifying distinct physical activity trajectory classes. Cardiometabolic risk factors measured at each wave include body mass index, waist circumference, blood pressure, fasting glucose, total cholesterol, and high-density lipoprotein cholesterol. Mixed-effects models and trajectory-outcome analyses examined associations between trajectory membership and cardiometabolic risk evolution. Findings identify four distinct physical activity trajectories including persistently active, early declining, late declining, and persistently inactive. Persistently inactive trajectory membership is associated with significantly elevated cardiometabolic risk factor clustering by wave four. Early declining trajectories, predominantly characterised by female students transitioning to senior secondary examination years, show intermediate risk profiles. The dissertation contributes the first Nigerian longitudinal evidence on physical activity and cardiometabolic health across adolescence, with direct implications for national youth physical activity policy. Keywords: physical activity trajectories, cardiometabolic risk, longitudinal study, adolescence, Lagos State