Im not asking if it will burn fat cause I know slow pace morning cardio is alot better for that(and I do that every morning).

But to increase my cardiovascular capability so I can push myself harder in the gym I have begun doing 15 minutes of intense stairmaster after every workout. Real high intensity I guess heart rate around 190 or so for periods.

My question is will this hurt me in anyway? I know for sure that it doesnt interefer with my post workout recovery cause I gain strenght better since I started doing it. But is there any other hidden "danger" with the high intensity cardio?