Exercise triggers complex effects on kidney physiology that vary with intensity, duration, and environmental conditions. While moderate physical activity improves cardiovascular and renal outcomes, intense or prolonged exertion, particularly in endurance sports, can lead to acute kidney injury. Adaptations in kidney physiology during exercise include reduced plasma flow, altered glomerular filtration, and hormone-mediated fluid retention. These changes are protective but may become maladaptive with dehydration, heat stress, or excessive fluid intake.