This section demonstrates that the sustainable enhancement of athletic performance rests on the integrated application of energy systems (ATP-PCr, anaerobic glycolysis, aerobic), evidence-based training planning, and evidence-based nutrition. Accurately understanding the activation dynamics of energy systems according to exercise duration and intensity enables the combination of periodization across the micro–meso–macro–megacycle levels with load–recovery balance, individualization, and specialization principles. In nutrition, the roles of carbohydrates in preserving glycogen economy, proteins in supporting muscle protein synthesis and recovery, and fats in contributing to long-term oxidative energy production are emphasized; vitamins, minerals, and electrolytes are critical for oxygen transport, neural conduction, muscle contraction, and antioxidant defense. Hydration is a key determinant of performance continuity. Pre-, intra-, and post-exercise nutrition timing optimizes energy continuity and recovery; the effectiveness of ergogenic aids such as creatine, beta-alanine, caffeine, and sodium bicarbonate depends on dose, timing, tolerance, and alignment with performance goals. At the level of practical cases, the aerobic system predominates in the marathon, the ATP-PCr system in weightlifting, and a mixed energy profile in team sports; this profile guides the design of training and nutrition. In sum, this monitoring-and-assessment-based, individualized, and integrated approach safeguards not only short-term competitive success but also long-term adaptability, endurance, recovery capacity, and career sustainability.