I cannot run because of my knees. I can sprint short distances, however. I heard of the following exercise once; could it be considered HIIT?

Sprint as fast as you can about one hundred feet. Crabwalk back to where you started. Rest for about 30 seconds. Repeat several times. I tried it about a year ago and it was pretty intense.

Thanks.

That would definitely be considered a form of HIIT. I have never heard of crabwalking, is that like Spiderman-walking? My personal trainer used to make me crawl like Spiderman and 100' of that is tough!

What you describe sounds like it would work too, but "crabwalk" is when scuttle like a crab--facing up, back and thighs parallel to the ground, arms bent back. Think back to elementary school!