Assess students' understanding of chronic physiological adaptations of the cardiovascular and respiratory systems to regular aerobic training in high‑school athletes. Scope includes central and peripheral cardiovascular changes (stroke volume, resting and submaximal heart rate, cardiac output, blood volume, hemoglobin), respiratory adaptations (ventilation, tidal volume, diffusion capacity), cellular and vascular changes (capillarization, mitochondrial density, oxidative enzymes), expected effects on VO2max and endurance performance, and practical implications for training and monitoring. Students should explain underlying mechanisms, distinguish acute versus chronic responses, and interpret typical assessment findings for youth athletes.