High-intensity training positively affects cardiovascular fitness by improving heart and lung function. Such workouts elevate heart rates, maximizing oxygen uptake and efficiency. Over time, this adaptation enhances endurance and aerobic capacity. High-intensity intervals also promote fat burning and can lead to significant improvements in health markers like cholesterol and blood pressure. The intense nature of these workouts stimulates both the cardiovascular and metabolic systems, yielding greater fitness gains in shorter periods compared to moderate-intensity training.