Outline: The Long-Term Impact of Exercise on Adolescent Growth and Development.

Adolescence represents a critical developmental window during which lifestyle habits profoundly influence long-term health trajectories. This chapter examines the enduring effects of physical activity (PA) initiated during adolescence on musculoskeletal, cardiometabolic, cognitive, and mental health outcomes. Evidence from longitudinal and epidemiological studies consistently demonstrates that regular PA during this period is associated with reduced risks of obesity, type 2 diabetes (T2DM), cardiovascular disease, osteoporosis, and sarcopenia in adulthood. Mechanistic insights highlight the role of PA in enhancing bone mineral development, muscle hypertrophy, metabolic regulation, and neuroplasticity, partially mediated by factors such as brain-derived neurotrophic factor (BDNF). The chapter further addresses the influence of mediating and moderating variables, including genetic predisposition, biological sex, maturational timing, and sociocultural determinants, in shaping individual responses to exercise. Finally, it underscores the necessity of integrated, multilevel public health strategies and school-based interventions tailored to adolescent needs, aimed at promoting equitable, sustainable engagement in PA. By synthesizing current evidence, this chapter emphasizes the lifelong preventive and therapeutic potential of adolescent PA for reducing the global burden of noncommunicable diseases.