This chapter explores the application of sports genomics through two contrasting case studies: a retrospective analysis of a Brazilian Olympic sprinter from the 1980s and a prospective follow-up of two monozygotic middle-distance twins transitioning into high-performance athletics. The first part revisits the career of Paulo Roberto Correia, whose genetic profile, analyzed decades after his athletic peak, offers insights into how individualized strategies for recovery, substrate metabolism, and training load management might have enhanced both performance and longevity. The second part presents a longitudinal, interdisciplinary project in which the functional genomic profile of the twins was used from the outset to guide strength and endurance training, nutritional support, and tissue recovery strategies. Despite being genetically identical, the athletes’ physiological responses and progression highlighted the essential role of environmental and contextual modulation. By comparing these two scenarios, the chapter emphasizes the dynamic interplay between genetic predisposition and adaptive plasticity. It advocates for the integration of genomic testing, field assessments, and multidisciplinary support as foundational elements for a new paradigm in personalized sports development.