I have a question about HIIT while working on a elliptical what type of duration should I go for and should I up the resistance during the HI part? This morning I was on for 45mins started with a moderate pace for 15 mins then upped the resistance and went as hard as I could for about 3mins (I know I am out of shape), slowed it and dropped it down and stayed there for about 5 mins then picked it up again for another 2mins ( Yesterday was legs and they still are sore), dropped it down for about 10mins, and did my best for 5 min but the intensity was down just because of the shape I am in (I hit 205bpm by the end and had to slow down) after that I just sorta did a cool down.

So, do I have the right idea or do I need to pick up the intensity? Longer intervals???? I have to build a base to work from so can you help with some HIIT goals?