HIIT question...

I didn't want to jump on the other post about HIIT but I do have a question for anyone familar with HIIT. I split my cardio between boxing classes and working out on a stationary bike. A few weeks ago I heard about HIIT and decided to try it. Okay.. so my question is 2 fold.

1.) I warm up for 5 minutes (12mph) and cool down for 5 minutes (12mph) at the end of the workout. My intervals consist of 1 minute at 20 mph and 1 minute resting at 10 mph. Is this enough speed? I am really pushing myself.. sweating and short of breath while at 20 mph.

2.) I know HIITs main attraction is that you can workout less and still get the benefits of a longer workout, however I do HIIT fo 45 minutes. I am having a heard time working out for only 25 minutes.. Am I doing this for too long??

 

I do HIIT at least 3 times a week. I think if you are able to go a whole minute during your "all out" phase, you are not going hard enough. If you are truley going all out, you should be wanting to die in 30 seconds. I don't know how this is possible, but according to my heart rate monitor (Polar F6) I had my heart rate to 107%. No wonder I was wanting to die!! Try pushing as hard as you can for 30 seconds and see how that works.