My wife and I both do HITT with an elliptical machine and we do 3 min around 50-60 rpm then 1 min of 90 rpm. We do this for 30 min and sometimes we will do the reverse option to change it up. Are we doing it right? Do we need to change any aspects of it? Thanks.

If your going as fast as you humanely can for that 1 minute of high interval training, and by the end of that minute you can't go on and your tired and breathing hard, etc you get the point, then you are doing it right

BUT. If you have enough energy to do that 1 minute of extreme exercise and then do another 3 minutes of a slower speed, your not doing it right.

You're doing it right. There are no hard and fast rules when it comes to HIIT - except perhaps that your work interval should be very intense - and I will assume that's what 90 rpm represents for you. Times for work and rest intervals can vary quite a bit.

The norm for most is to simply make sure your work interval is one in which you are going ' flat out ' - i.e as hard as you can. And, that your rest interval is simply long enough allow you to recover comfortably - which for some is to get all your breath back ( full recovery ) and for others it is to simply be at a pre-determined lower training heart rate for recovery, but not one in which you get all your breath back.

I do know that there is a reputable trainer ( Alywn Cosgrove ) who advocates his own HIIT protocol to optimize fat loss. His protocol calls for 1 minute ' flat out ' as hard as you can stand followed by 2 minutes of active recovery - a 1:2 ratio. Actually, the ratio of 1:2 is the one I have seen used most often - for example, this is the ratio I used when training hockey players during lactate threshold training - but again, there is no hard and fast rule. Right now your work / rest ratio is 1:3. So, one thing you can try is to go from a 1:3 ratio down to a 1:2 ratio and see how that goes for awhile....again, just make sure your 1 minute work interval is ' flat out ' .