Because I get shin splints easily, I do cardio workouts by walking up steep inclines. My routine is this: I raise my heart rate to 180 for 30 minutes straight with only a water break in the middle. Without stopping at the end, I start jogging until I hit my VO2max (around 195 to 200 bpm, it takes about 3 minutes). Then I cool down. I do this 3 times a week and I am 21 years old and in good health. My question is: Am I risking damage to my cardiovascular system due to the intensity of the workout?